VOLCANIC ORGANIC
PROCESSES
AND SYNTHESIS
COMPOUNDS
ON PRIMITIVE
OF SIMPLE EARTH
L. M. M U K H I N
Space Research Institute, Acad. Sci., U.S.S.R.
1. Introduction Development of the models of organic compounds evolution on the primitive Earth based on the continuity principle [1] is of particular interest for the study of the origins of life, and any proposed model should not be contradictory from the viewpoint ofevolutional planetology and chemistry. At present it is usually assumed that in the monomer synthesis the major energy sources were the ultra-violet solar radiation, electric discharges and shock waves. The concentrations of organic compounds in the primitive ocean that have been formed by the ultra-violet solar radiation have been estimated. The concentrations obtained scatter over a wide range. Sagan [2] assumes that 1% solution of amino acids and oxi-acids could be formed in 109 years. Abelson [3] drew attention to the H C N hydrolysis processes which result the formation of N H 4 O H and H C O O H . Assuming that the primitive ocean volume was 1022 ml, the author has obtained the highly diluted solution of H C N (10 4 M). In this case the stationary concentrations of amino acids will prove to be on the order of about 10-6 M. On the other hand Hull [4] showed that taking photochemical destruction processes into account, stationary concentrations of organic compounds in the primitive ocean would be much too low (i0 12 M). The problem on photodestruction of organic molecules in the primitive Earth's atmosphere should be solved more generally based on the vertical transfer in the atmosphere. If it is assumed that nitrogen and argon are the main components of the primitive atmosphere and carbon dioxide and water concentrations do not exceed the up-to-date values then the ozone concentration is about 10-2 from the concentration available. It means that absorption in the region 1700 A - 3000 was insignificant and the ultraviolet radiation flux with 2 ~ 3000 /~ was equalled to ~ 1015 cm- 2 sec- 1. The flux with 2 ~ 1700 A is 5 9 1011 cm- 2 sec- 1, respectively. Energy range of the ultraviolet radiation with these wavelengths is 7.3 ev - 4.13 ev. As known energies of the most important bonds in organic chemistry have the following values [t7]; C - - C : 8.4 ev; C - - O : 7.4 ev; O - - H : 4.8 ev; C - - H : 4.3 ev; N - - M : 4.1 ev; C - - O : 3.7 ev; C - - C : 6.4 ev, etc. It is easily to see that the ultraviolet radiation of the Sun should destruct molecules synthesized due to the long wave UV, of the shock waves and electric discharges. The molecule lifetime in the atmosphere from generation to photodestruction can be estimated by the order of magnitude as follows: r destr. 1 0(pa' where ~ is the photodissociation section, ~o is the photon flux, 0 - quantum efficiency. Then, for some aldehydes z destr. ~ 104 sec. The value of coefficient of Origins of Life 7 (1976) 355 368. All Rights Reserved Copyright @ 1976 by D, Reidet Publishing Company, Dordrechf-Hotland
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L . M . MUKHIN
eddy diffusion for the atmosphere low layers is D ~ 4 . 1 0 4 cm 2 sec-1 with the altitude scale Z ~ 10-15 km [18]. Z2 In this case the transfer characteristic time r diff. ~ - - ~ 15.107 sec. We see that D diff. >> r destr, and molecule is destroyed before it reaches the ocean surface. At heights from 10 to 20 km the value of coefficient of eddy diffusion is D ~ 103 cm 2 sec- 1 and in this layer the molecule photodissociation conditions are more profitable. Nevertheless it should be noted that some thin layer of the atmosphere exists from which molecules will have the possibility to achieve the ocean surface. The layer thickness can be easily estimated from Z 2 < Dr destr. From here Z _< 104 cm. Bur-Nun and Shaviv [19] give the value of the concentration of amino acids which have been formed by Shtrecker mechanism from H C N and H C H O . Hydrocyanic acid and phormaldehyde are formed in the atmosphere (the layer thickness ~ 5 kin) due to the shock wave energy. Taking into account the obtained value of the thickness of layer where the destruction processes are insignificant ( ~ 100 m), the amino acid solution equilibrium concentration should be decreased by two orders, i.e. 6" 10-5 M that is evidently deficient in the further molecular evolution processes. There is, however, a circumstance because of which one cannot be too careful in dealing with the accepted estimates. This circumstance consists in the fact that the presented above are obtained for the equilibrium conditions. Concurrent with this, one can affirm with assurance that the thermodynamic equilibrium was never reached on the primitive Earth. The synthesis processes occurred to best advantage in the local regions of the primitive Earth under the conditions far from equilibrium.
2. Importance of Volcanic Processes What kind of considerations can be advanced on the character of these regions? The analysis of possible conditions for synthesis of organic compounds under the primitive Earth conditions inevitably leads to the consideration of volcanic processes. Attention should be given to some aspects of basic importance. 1. The lifetime of active volcanoes and hydrothermal systems is sufficiently long (103 to 105 years). 2. Volcanic processes constitute a geological factor always present in the history of the Earth. There is every ground to believe that at early stages of the Earth's evolution the number of active volcanoes was considerably larger than now. 3. A volcano is a source of energy and at the same time, a source of initial components for the synthesis of organic compounds (Water, carbon monoxide, carbon dioxide, methane, ammonia, etc.). If the thermal energy of a volcano required for the synthesis of monomers is the the only value estimated it is easy to obtain a value of 0.1 cal sec -1 cm -2 that by many orders exceed those for other energy sources with statistical distribution over the Earth's surface. 4. In the area with an underwater volcano or hydrothermal system there are favorable conditions for the sui'vival of the compounds formed (because of great P and T gradients).
VOLCANIC PROCESSES AND SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
357
5. The presence of a wide range of natural catalysts in volcanic regions is responsible for further evolution of synthesized compounds. 6. Photochemical destruction that accompanies underwater ejections and hydrothermal synthesis is substantially weakened. Significant inequality of the conditions and processes in the regions of volcanic activity should be noted. This circumstance is brought about by the considerable gradients of temperature, pressure, chemical potential, and the processes of organic molecule sorption on mineral matrixes. Prigogin and Glansdorf showed [5] that in case of nonlinear conditions in chemical systems being far from the equality state, as a result of fluctuations, the time and space regulated dissipative structures can be formed stabilized by the external energy flux. For this purpose some limitations must be imposed on the final product concentrations and the rate coefficients (r: and i) for forward and backward reactions
f,
C . . . . --> O, ~ >> 1 k
From the viewpoint of physics it means the final product removal from the reaction zone. It is apparently that the sorption processes can provide the given conditions. The specific quantitative evaluation of the processes that are of interest for us presents a problem. However, inequality enables us to assume the existence of the localized spatial structures (for example, consisting from the amino acids) in the local reaction zones relating to the regions of active volcanoes. The availability of such structures could stimulate the reaction of policondensation. The efficiency of volcanic systems as the sources for organic compounds can be very roughly estimated in the following way. It can be assumed that an ejecting volcano releases about 10 9 m 3 of gas in the atmosphere. With a conventional chemical composition of volcanic exhalation (i.e. 90 ~o of water vapour and 10 ~o of all other components) taken into account, it is easy to estimate that such an ejection should result in the formation of 106 kg of organic compounds. Keeping in mind that along with active ejections long-duration hydrothermal systems (about 104 years) are present producing up to 100 kg of vapor per second or 1 kg of gas per second, we obtain that a hydrothermal system of this kind can generate 107 kg of organic compounds during its lifetime (the factor of organic compounds conversion from CH 4 is assumed to be 1 ~o). Extrapolation of these figures for over the interval time order the 1. 109 years shows that it was volcanic processes on the Earth could produce 1015 to 1016 kg of organic compounds. We are fully aware that these are highly qualitative estimates since no account was taken of conversion processes of volatiles that had entered the atmosphere and suffered a number of chemical transformations due to UV, radiation, electrical discharges and shock waves. Nevertheless, this value can be regarded as a lower limit. The matter is that the analysis of paleovolcanic activity brings about the conclusion that the intensity, the amount of gas, and the degree of reproduction of volcanic exhalation were considerably higher [6, 7] at early stages of the evolution of the Earth. All this confirms the assumption of the dominating role of volcanism in the processes of prebiological evolution.
358
L.M. MUKHIN
Not only were volcanic processes essential for the syntheses of organic compounds on the primitive Earth; the same should be true: of terrestrial planets, in particular, of Mars, due to the similarity of degasation processes in the mantles. It should be emphasized that the up-to-date means (space vehicles) do not allow the hydrothermal activity (on the ban H 2 0 ) to be observed from the Mars orbit. Powerful eruption can be observed but this event is extremely rare. At any case the existence of the Hawaiian type of volcanoes on Mars is evident and this fact allows one to assume that there are the regions with high concentration of the organic compounds on Mars. These regions, should be associated with the volcanic activity. There is one more class of space objects where volcanic processes are extremely important with respect to the problem of evolution of organic molecules. It is starless planets [8]. On such celestial bodies volcanism should be a dominant source of energy for the synthesis of organic molecules. With the above mentioned arguments we regard volcanics as possible sources of organic molecule synthesis on the primitive Earth.
3. Experimental Experimental tests of the pattern proposed [9] have been made in two directions: investigation of nature samples from volcanic regions and model synthesis. 3.1. VOLCANICSAMPLES In the region of active volcanism, on Kamchatka and the Kuril islands several liquid samples taken in various hydrothermal areas were studied as well as gaseous samples from the scorching slag cone of the Alaid volcano. Liquid samples studied were condensates of vapor and gas jets from the wells drilled in the area of Koshelevski volcano hydrothermal systems, and in the hydrotherm area of the Mutnovka volcano as well as water samples from the hydrothermal sources of the Golovnin volcano caldera.
a. Analytical procedure and microbiological control. Some analyses were made in natural conditions: thin-layer chromatography of amino acids, qualitative tests.* A number of samples were subjected to microbiological tests on the presence of microorganisms. We gave attention to identify some lithotrophic microorganisms on nutrition media of Beijerinck, Rodina, Waksman, Colmer, Borgard, Tauson and analysed also vulgaric microflora on meat-peptone broth. No samples contained organisms capable of growing out in these media except for one (Mutnovka volcano). b. Results and discussions. The results of organic compounds analyses in volcanic samples are summarized in Table I. The data in Table I indicate the presence of a number of organic compounds in the regions of active volcanism. Cyanic and rhodanic compounds as well as * Analyses of liquid volcanicsamples see in the part about studies model underwater samples.
VOLCANICPROCESSESAND SYNTHESISOF SIMPLEORGANICCOMPOUNDSON PRIMITIVEEARTH
359
TABLE I Organic compounds Sample
Temperature Organogenic (~ anions
Volcano Alaid, gaseous samples from rifts of slag come (Atlasov 900-1000 island) Golovnin volcano caldera "Boiling lake" the source 70 "green" "boiling cauldron" (Kunashir island)
Amino acids
Hydrocarbons
CN (0.01-rag/l)
CNS-
Arginine, serine, threonine (1 mg/l)
in presence H2S
the same (0.3 mg/1) Cystine, serine, glycine, oxyproline
72
Bore hole 12 a, depth 140 m (Kunashir island)
167
CNSin presence H2S
Uzon volcano caldera, hydroterms (Kamchatka)
98
(Fe(CN)6)- 3 (Fe(CN)6) -4
Koshelev volcano, bore hole No. 1
98
non
bore hole No. 2 (Kamchatka)
98
CNS-
Mutnovski volcano, solid sublimates (Kamchatka)
Aldehydes
90
--
HCHO, CH3CHO (2.4.10- 6 tool/l) HCHO, CH3CHO (3,2. 10- 6 mol/l)
HCHO, CH3CHO, non-identified carbonyl compounds
Aminobutyric acid, phenylalanine, aliphatic amine
Alkanes C9-C 15, alkenes C 13, C14-normal and isostructure; aromatic hydrocarbons: naphthalene, antracene, phenanthrene, monomethylantracene or phenantrene present (the composition is not studied)
aldehydes found there also deserve attention. As is known, it is these monomers that are major intermediate compounds in the synthesis of more complex molecules [10]. It should be noted that in analysed volcanic samples and subsequent interpretation of the results the possibility of sample contamination by microorganisms or the
360
L.M. MUKHIN
products of their metabolism must be taken into account. As a result it is extremely difficult (if not impossible), to separate out truly juvenile compounds. The more complicated the structure of the discovered compound the more probable that the compound is a contamination product. In individual cases the microbiological analyses yielded a negative result but nevertheless the possibility of microbial contamination cannot be excluded. Therefore a search for hydrocyanic acid, its derivatives and to a less extent, aldehydes is more promising than a search for amino acids. It is obvious that carbon being a constituent of those predecessors of organic molecules we have found has suffered many transformation cycles during the Earth history. It is obvious nevertheless that there was a substantial amount of nitrogen- and carbon-bearing compounds in the products of mantle degasation on the primitive Earth [6]. Hence we have every reason to believe that the present formation of hydrocyanic acid during volcanic eruption is similar to the processes on the Earth is surface at earlier stages of its evolution. As for the genesesis of organic compounds found in volcanic samples some additional remarks are needed. Recently a number of experimental data have been obtained that reveal two extremely essential factors. During Eldfell volcano eruption (Iceland, 1973) it was stated that sulphate and sulphide isotopic composition in thermal events is quite similar to the isotopic composition of meteorite troilite [11]. It implies on the one hand practically complete isolation of a lava channel from the host rocks, and, on the other hand, partial or complete juvenility of sulphuric compounds studied. A convincing evidence at least, to partial juvenility of volcanic exhalations is constituted by anomalously high He3/He 4 - values observed in volcanic gases of Iceland and Kuril-Kamchatka ridges. That ratio is similar to that for the mantle [12]. These data show that a possibility really exists of nonbiological synthesis of organic compounds in the regions of active volcanism. Long-term (two years) generation of hydrocyanic acid from the rifts of the scorching slag cone of the Olympic volcano Alaid break can be one more evidence of this fact (to obtaining nitril by means of pyrolytic destruction of organic compounds a substantial amount of nitrogen compounds is required). Note that the presence of the halogen compounds in the volcanic gases offer additional possibilities for synthesis of a great number of organic molecules. The result obtained open up a possibility of consistent and systematic studies of the processes of abiogenic synthesis in natural conditions.
3.2. SIMULATIONEXPERIMENTS In this connection the simulation of volcanic processes and thorough investigation of the formed organic matter are of particular interest. The use of the experimental models of ground and underwater volcanoes allow the thermal synthesis products directly obtained in the gas phase and the compounds generated as a result of the subsequent transformation in the condensated phase to be separately studied.
361
VOLCANIC PROCESSES A N D SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
a. Ground Volcahic Action
The model, which simulates the volcanic action in the zone of vapor-gas mixture throwing out from the melted lava with the fast "quenching" of the forming products, consists of a quartz reactor filled with the volcanic basaltic lava (controlled temperture up to 1200 ~ and a system of independently controlled fluxes" of inert gascarrier and the reaction mixture component (CH,~(CO) - 5~o, NH 3 - 5~o, HzO - 90~o) (Figure 1). A reactor is provided with the direct connection to the chromatograph or chromatomass-spectrometer system where the analysis of hightemperature synthesis products is made. ~e
Fig.
1.
He
t
CH§
2
5
6
1. He-flow-rate regulator. 2. CH4-flow-rate regulator. 3. Saturator. 4. Six-position valve.
5. Oven for quartz reactor. 6. Chromatographor chromatomass-spectrometer. Chromatograph Varian 1800 and chromatomass-spectrometer LKB 9000 were used in the work, with the columns containing: a) Porapak T (2 m • 4 ram) for the analysis of light hydrocarbons and HCN; b) 2~o methylsilicon DC-410 on chromosorb W (2 m x 4 mm) for the analysis of heavy hydrocarbon under the temperature programming conditions. Results and Discussions
An effect of the reaction zone temperature on the yield of the products obtained was studied; the maximum yield takes place under the temperature of 1050 ~ i.e. during the transition of the basaltic volcanic lava (being a catalyzer in the given process) into viscous flowing state. The time chosen for a contact of the synthesis components with the incondencent lava (< 1 sec.) corresponded with some natural cases. Among the products of reactions hydrocyanic acid and aliphatic amine were discovered and identified in addition to the unsaturated compounds and condensated aromatic hydrocarbons (phenanthrene, naphthalene, anthracene). The analysis of the data obtained should give due regard to the following a) Aromatic fraction of hydrocarbons prevails over aliphatic. This can be attributed to the lower stability ofaliphatic compounds under higher temperatures that naturally reduces the value of theis equilibrium concentration b) Low yield of hydrocyanic acid (~0.1~) and other nitrogen-bearing monomers, Obviously it can be explained the following way. Since fractional concentrations of methane and ammonia are low thermal reactions mainly yield methane cracking products rather than nitrogen-bearing monomers. It is well-known that the methane-
362
L. M, MUKHIN
ammonia system (without water) produce about 90~o of hydrocyanic acid in chosen temperature range (i.e. H C N appears to be a major product of reaction). In our experiments the H C N yield was only about 0.1 ~o. The yield of other monomers was naturally by an order of magnitude lower. Alongside with this the low yield of hydrogen cyanide can be due to processes of hydrolysis and water poisoning of active catalist centers. Netherless, the local concentrations of organic compounds in volcanic areas could be high enough. Figures 2 to 5 and Table II give the results of the quantitative and qualitative analyses. (Gas chromatogramms from LKB-9000.) b. Under Water Volcanic Action
A reactor that simulates the underwater volcano activity is the thick-wall quartz tube with volcanic lava. Under the pressure up to 100 atm. the reacting matters are delivered to the reactor (90~o H20, 5 ~ NH 3, 5~o CH 4 and/or CO). The reaction temperature is 1100-1200 ~. The contact time of the synthesis components with the lava is ,-~0.1 sec. The values of temperature and of contact duration were chosen for the following reasons. According to the values of lava temperature of Hawaii volcanoes [6], temperature can reach its maximum of 1400 ~ but, as a rule it does not exceed 1000 to 1100~ There is no reason to assume that initial temperatures of volatiles and lavas during underwater erruptions will substantially differ from the values given above.
8
~.
/ Fig. 2. Chromatogram of light products of high-temperature synthesis (Porapak T). 1. Methane. 2, Acetylene and alyphatic amine. 3. Propylene. 4. Cyctopropene. 5. Methylacetylene. 6. Butadiene or butyne. 7. Vinytacetylene. 8. Water.
363
VOLCANIC PROCESSES AND SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
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As regards the duration of contact, the values chosen were determined only really natural velocities of gas stream. It does not of course mean that the model chosen covers all possible types of volcanoes effluence. Vapor and gas mixture is delivered from a reactor via a throttle and the condenser to the sterile collector9 Condensate (colourless liquid containing ammonia) was analyzed as follows: A sum of low aldehydes was determined by ferment reduction with the use of alcohol dehydrogenase [13]. In addition thin layer chromatography of dinitrophenylhydrazones on siluphol was used. 100 ml of alkaline condensate were evaporated in vacuum at 40 ~ to ~0.5 ml. 20 mkl of this solution were taken to identify amino acids as I-dimethylaminonaphthalene-5-sulphonil (DNS) derivatives by means of two-dimensional microthin layer chromatography [14, 15]. An amount of amino acids estimated by this method is 10-4 g/l. The rest of concentrate (0.5 ml - 20 mkl) was evaporated to dryness, esterified n-C4H9OH/HC1 and acylated by threefluoroacetic anhydride [16]. The obtained mixture of derivatives was analyzed by the chromatomass-spectrometer
364
L. ~. MUKHIN
5
6
1
,d f (M~.) a'o
io
~b
Fig. 4. Chromatogram of heavy products of high-temperature Synthesis (DC-410). 1. Benzene and toluene. 2. Inden. 3. Naphthalene. 4. Monomethylnaphthalene. 5. Biphenyl. 6. Naphthylacetylene or acenaphthylene. 7.8. Alkane and alkene C~0.9. Anthracene. 10. Phenanthrene or/and diphenylacetylene. method. A chromatomass-spectrometer LKB 9000 was used. The glass chromatographic columns (180 x 0.4 cm) packed with 0.65~o P E G A (fixed phase) on chromosorb W with temperature programming mode were also used. Mass-spectra were obtained with 70 ev. Organic matters were not discovered in the control analyses made, in acordance to the mentioned standard scheme for twice-distilled water (BW) as well for BW, BW + N H 3 and BW + CH 4 passed through a reactor under experimental conditions. Results and Discussions
The results are presented in Table III. After about 6 months in sterile conditions sample No. 2 has a set of amino acids different from that of No. 1. This example is given to show a possibility of the next cycle of the reaction of predecessors (e.g. hydrolysis of nitriles) in a liquid plaase. In particular, an assumption can be made about the reaction of glutamic acid formation in the process of complete hydrolysis from nitrile. As for the presence of glycine and e-alanine, probably they may also form through the hydrolysis of corresponding nitriles. Of interest is to compare HCN-yield recorded in our experiments with the total yield of aminoacids amounting to 10 - 4 g/h Not too arbitrarily (usually experimental temperature did not exceed 1100 ~ it can be assumed that H C N yield in the experiments that simulate underwater
V O L C A N I C PROCESSES A N D SYNTHESIS OF SIMPLE O R G A N I C C O M P O U N D S ON PRIMITIVE E A R T H
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18o
'~/e
365
366
L. M. MUKHIN TABLE II
Gas-chromatography
Chromatomass-spectrometr y
Products
Weight ~
Light products
Initial methane
58.94
Acetylene
18
Ethylene HCN
Weight ~
Heavy products
87.27
CvH 8 (toluene)
Amine (ethylamine or dimethylamine)
2.0
CgH 8 (inden)
23
Propylene
1.0
CIoH8 (naphthalene)
0.06
Cyclopropene
0.5
C11H10 (monomethylnaphthalene)
Methylacetylene
6.2
Initial methane, acetylene, ethylene
C12Hlo
(biphenyl) C4H6 (butadiene or butyne)
0.5
Vinylacetylene
0.03
Alkanes and alkenes Clo
Benzene
2.5
C~4Hlo (anthracene)
1- cyano-butene-2 or threemer of HCN ? (M.V. 81 )
C 12Hs (naphthylacetylene or acenaphthylene)
C14H10 (phenanthrene or biphenylacetylene)
volcanism is similar to that in the experiments on earth volcanism, i.e., a b o u t 0.1~o It means that the a m o u n t of H C N in 1 1 of a condensate a m o u n t s to slightly less than 10-2 g/1. So, if an assumption is made that a m i n o acids are synthesized t h r o u g h a Strecker mechanism with the participation of H C N , the yield of a m i n o acids in this reaction can be regarded as equal to several per cent, it is a reasonable value.
c. Comparison of Under Water and Ground Eruption It is rather exciting to c o m p a r e underwater and g r o u n d volcanoes as chemical reactors synthesizing organic molecules. Let's now consider a schematic case of incandescent gaseous jet e m a n a t i o n from a volcanic vent into a more dense (underwater eruption) and into a less dense (ground eruption) medium. A purely qualitative picture will be considered, t h o u g h exact estimates can be made. It is obvious that the range of a jet will be m u c h longer in case of a g r o u n d eruption, under other equal conditions, than in that of an underwater eruption. The ratio of the values for these two cases is estimated as being a b o u t 100. With the same initial amounts, this means m u c h higher concentrations of reagents in a
VOLCANIC PROCESSES AND SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
367
TABLE III Amino acids and other non-volatile hydrophilic c o m p o u n d s Microthinlayer chromatography a
Sample a
Lower aldehydes
Colouring with ninhydrin
free amino acids
after hydrolysis of terminal after full amino acids hydrolysis
Chromatomass spectrometry e
No. 1
HCHO CH3CHO b
Stable
non-albuminous amino-acid or amine
glycine, fl-alanine, aliphatic amine C6HsCOO/C,,H 9
No. 2
the same (1.4.10- ~ tool/l) ~
Stable
glycine, e-alanine, serine (trace), nonalbuminous aminoacid or amine
glycine, c~-alanine, aliphatic amine, C6HsCOOC4H 9
the same glutaminic acid
a Sample No. 1 is treated and analyzed immediately after synthesizing; sample No. 2 six m o n t h s after. b TO be discovered by method of T L C of dinitrophenylhydrozones. c To be determined by ferment reduction by means of alcohol dehydrogenase [10]. d After obtaining DNS-derivatives. ~ After C4HgOH/HCI and ( C F 3 C O ) 2 0 treatment.
reaction zone near the vent of an underwater volcano (the jet in this case is less "spread" in space). This situation is obviously more favorable for the synthesis of organic molecules than that of ground eruption. 3.4. CONCLUSION Of course our information about the monomer synthesis on the primitive Earth cannot be regarded as exhaustive. A "volcanic" model looks promising since it renders a unique possibility of studying natural processes. Our experimental results substantially confirm the adequacy of this model. One more aspect should be mentioned. In the processes simulating the volcanic activity not only are the biologically valid monomers formed but also the "stock" of wide spectrum of hydrocarbons, the quantitative yield of hydrocarbons being higher than that of biological monomers. This fact can be associated with the problem of genesis of the crude oil. It should be noted that some simple compounds identified in our experiments can later react thus forming biologically active molecules. These are unsaturated compounds: acetylene, propylene, vinyl acetylene, methyl acetylene, divinyl. The analyses of the volcanic samples as well as the results of the model experiments confirm the significant role of the volcanic processes in the evolution of organic compounds on the primitive Earth.
Acknowledgements I thank acad. A. I. Oparin for attention to this work. I express special gratitude to S. V. Vitt, V. B. Bondarev, E. N. Safonova for constructive discussions and experimental help.
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L.M. MUKHIN
I thank also V. I. Kalinitchenko, R. I. Fedorova, U. S. Petrenko for assistance in experiment. I particularly thank the referee for his detailed criticism of an earlier draft of the manuscript. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19]
Oparin, A. I.: 1957, The Origin of Life on the Earth, Acad. Press., Inc., New York. Sagan, C.: 1966, The Origin of Prebiological Systems, Mir, Moscow. Abelson, P. H.: 1966, Proc. Nat. Acad. Sci. 55, 1365. Hull, D. E.: 1960, Nature 186, 693. Glansdorff, P. and Prigogine, I.: Thermodynamic Theory of Structure, Stability and Fluctuations, Universite libre de Bruxelles, Brussels, Belgium and University of Texas, Austin, Texas. Luchitski, I. V.: 1971, Advances ofPaleovolcanology, Nauka, Moscow. Fox. S. W. and Dose, K.: 1975, Molecular Evolution and the Origin of Life, p. 70, Mir, Moscow. Mukhin, L. M.: 1973, Astron. Acta 18, 451-454. Mukhin, L. M.: 1973, in CETI, Washington, ed. C. Sagan. Kenyon, D. H. and Steinman, G.: 1972, Biochemical Predestination, Mir, Moscow. Pollack B. et al.: 1975, Report on Intern. Symp. The Problems of Riftogenesis, Irkutsk, U.S.S.R. Kononov, V. I. and Mamyrin, B. A.: 1974, Dokl. Akad. Nauk U.S.S.R. 217 (1), 172. The Enzymes, Academic Press, New York and London, Vol. 7, p. 26, 1961. E. Racker in Methods in Enzymology, Vol. 3, p. 295, 1969. Vinogradova, E. I. and Feygina, M. Yu. et al.: 1973, Biochimiya 38 (1), 3. Belenki, B. G., Gankina, E. S., and Nesterov, V. V.: 1967, Dokl. Akad. Nauk U.S.S.R. 172 (1), 91. Vitt, S. V. and Saporovskaya M. B. et al.: 1974, Izv. Akad. Nauk U.S.S.R. 6, 1310. Carl Sagan: 1970, Encyclopedia Britannica, pp. 1083-1087. Davidson et al.: 1966, Tellus 18, 3a. Bar-Nun, A. and Shaviv, A.: 1975, Icarus 24, 197-210.
PROCESSES
AND SYNTHESIS
COMPOUNDS
ON PRIMITIVE
OF SIMPLE EARTH
L. M. M U K H I N
Space Research Institute, Acad. Sci., U.S.S.R.
1. Introduction Development of the models of organic compounds evolution on the primitive Earth based on the continuity principle [1] is of particular interest for the study of the origins of life, and any proposed model should not be contradictory from the viewpoint ofevolutional planetology and chemistry. At present it is usually assumed that in the monomer synthesis the major energy sources were the ultra-violet solar radiation, electric discharges and shock waves. The concentrations of organic compounds in the primitive ocean that have been formed by the ultra-violet solar radiation have been estimated. The concentrations obtained scatter over a wide range. Sagan [2] assumes that 1% solution of amino acids and oxi-acids could be formed in 109 years. Abelson [3] drew attention to the H C N hydrolysis processes which result the formation of N H 4 O H and H C O O H . Assuming that the primitive ocean volume was 1022 ml, the author has obtained the highly diluted solution of H C N (10 4 M). In this case the stationary concentrations of amino acids will prove to be on the order of about 10-6 M. On the other hand Hull [4] showed that taking photochemical destruction processes into account, stationary concentrations of organic compounds in the primitive ocean would be much too low (i0 12 M). The problem on photodestruction of organic molecules in the primitive Earth's atmosphere should be solved more generally based on the vertical transfer in the atmosphere. If it is assumed that nitrogen and argon are the main components of the primitive atmosphere and carbon dioxide and water concentrations do not exceed the up-to-date values then the ozone concentration is about 10-2 from the concentration available. It means that absorption in the region 1700 A - 3000 was insignificant and the ultraviolet radiation flux with 2 ~ 3000 /~ was equalled to ~ 1015 cm- 2 sec- 1. The flux with 2 ~ 1700 A is 5 9 1011 cm- 2 sec- 1, respectively. Energy range of the ultraviolet radiation with these wavelengths is 7.3 ev - 4.13 ev. As known energies of the most important bonds in organic chemistry have the following values [t7]; C - - C : 8.4 ev; C - - O : 7.4 ev; O - - H : 4.8 ev; C - - H : 4.3 ev; N - - M : 4.1 ev; C - - O : 3.7 ev; C - - C : 6.4 ev, etc. It is easily to see that the ultraviolet radiation of the Sun should destruct molecules synthesized due to the long wave UV, of the shock waves and electric discharges. The molecule lifetime in the atmosphere from generation to photodestruction can be estimated by the order of magnitude as follows: r destr. 1 0(pa' where ~ is the photodissociation section, ~o is the photon flux, 0 - quantum efficiency. Then, for some aldehydes z destr. ~ 104 sec. The value of coefficient of Origins of Life 7 (1976) 355 368. All Rights Reserved Copyright @ 1976 by D, Reidet Publishing Company, Dordrechf-Hotland
356
L . M . MUKHIN
eddy diffusion for the atmosphere low layers is D ~ 4 . 1 0 4 cm 2 sec-1 with the altitude scale Z ~ 10-15 km [18]. Z2 In this case the transfer characteristic time r diff. ~ - - ~ 15.107 sec. We see that D diff. >> r destr, and molecule is destroyed before it reaches the ocean surface. At heights from 10 to 20 km the value of coefficient of eddy diffusion is D ~ 103 cm 2 sec- 1 and in this layer the molecule photodissociation conditions are more profitable. Nevertheless it should be noted that some thin layer of the atmosphere exists from which molecules will have the possibility to achieve the ocean surface. The layer thickness can be easily estimated from Z 2 < Dr destr. From here Z _< 104 cm. Bur-Nun and Shaviv [19] give the value of the concentration of amino acids which have been formed by Shtrecker mechanism from H C N and H C H O . Hydrocyanic acid and phormaldehyde are formed in the atmosphere (the layer thickness ~ 5 kin) due to the shock wave energy. Taking into account the obtained value of the thickness of layer where the destruction processes are insignificant ( ~ 100 m), the amino acid solution equilibrium concentration should be decreased by two orders, i.e. 6" 10-5 M that is evidently deficient in the further molecular evolution processes. There is, however, a circumstance because of which one cannot be too careful in dealing with the accepted estimates. This circumstance consists in the fact that the presented above are obtained for the equilibrium conditions. Concurrent with this, one can affirm with assurance that the thermodynamic equilibrium was never reached on the primitive Earth. The synthesis processes occurred to best advantage in the local regions of the primitive Earth under the conditions far from equilibrium.
2. Importance of Volcanic Processes What kind of considerations can be advanced on the character of these regions? The analysis of possible conditions for synthesis of organic compounds under the primitive Earth conditions inevitably leads to the consideration of volcanic processes. Attention should be given to some aspects of basic importance. 1. The lifetime of active volcanoes and hydrothermal systems is sufficiently long (103 to 105 years). 2. Volcanic processes constitute a geological factor always present in the history of the Earth. There is every ground to believe that at early stages of the Earth's evolution the number of active volcanoes was considerably larger than now. 3. A volcano is a source of energy and at the same time, a source of initial components for the synthesis of organic compounds (Water, carbon monoxide, carbon dioxide, methane, ammonia, etc.). If the thermal energy of a volcano required for the synthesis of monomers is the the only value estimated it is easy to obtain a value of 0.1 cal sec -1 cm -2 that by many orders exceed those for other energy sources with statistical distribution over the Earth's surface. 4. In the area with an underwater volcano or hydrothermal system there are favorable conditions for the sui'vival of the compounds formed (because of great P and T gradients).
VOLCANIC PROCESSES AND SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
357
5. The presence of a wide range of natural catalysts in volcanic regions is responsible for further evolution of synthesized compounds. 6. Photochemical destruction that accompanies underwater ejections and hydrothermal synthesis is substantially weakened. Significant inequality of the conditions and processes in the regions of volcanic activity should be noted. This circumstance is brought about by the considerable gradients of temperature, pressure, chemical potential, and the processes of organic molecule sorption on mineral matrixes. Prigogin and Glansdorf showed [5] that in case of nonlinear conditions in chemical systems being far from the equality state, as a result of fluctuations, the time and space regulated dissipative structures can be formed stabilized by the external energy flux. For this purpose some limitations must be imposed on the final product concentrations and the rate coefficients (r: and i) for forward and backward reactions
f,
C . . . . --> O, ~ >> 1 k
From the viewpoint of physics it means the final product removal from the reaction zone. It is apparently that the sorption processes can provide the given conditions. The specific quantitative evaluation of the processes that are of interest for us presents a problem. However, inequality enables us to assume the existence of the localized spatial structures (for example, consisting from the amino acids) in the local reaction zones relating to the regions of active volcanoes. The availability of such structures could stimulate the reaction of policondensation. The efficiency of volcanic systems as the sources for organic compounds can be very roughly estimated in the following way. It can be assumed that an ejecting volcano releases about 10 9 m 3 of gas in the atmosphere. With a conventional chemical composition of volcanic exhalation (i.e. 90 ~o of water vapour and 10 ~o of all other components) taken into account, it is easy to estimate that such an ejection should result in the formation of 106 kg of organic compounds. Keeping in mind that along with active ejections long-duration hydrothermal systems (about 104 years) are present producing up to 100 kg of vapor per second or 1 kg of gas per second, we obtain that a hydrothermal system of this kind can generate 107 kg of organic compounds during its lifetime (the factor of organic compounds conversion from CH 4 is assumed to be 1 ~o). Extrapolation of these figures for over the interval time order the 1. 109 years shows that it was volcanic processes on the Earth could produce 1015 to 1016 kg of organic compounds. We are fully aware that these are highly qualitative estimates since no account was taken of conversion processes of volatiles that had entered the atmosphere and suffered a number of chemical transformations due to UV, radiation, electrical discharges and shock waves. Nevertheless, this value can be regarded as a lower limit. The matter is that the analysis of paleovolcanic activity brings about the conclusion that the intensity, the amount of gas, and the degree of reproduction of volcanic exhalation were considerably higher [6, 7] at early stages of the evolution of the Earth. All this confirms the assumption of the dominating role of volcanism in the processes of prebiological evolution.
358
L.M. MUKHIN
Not only were volcanic processes essential for the syntheses of organic compounds on the primitive Earth; the same should be true: of terrestrial planets, in particular, of Mars, due to the similarity of degasation processes in the mantles. It should be emphasized that the up-to-date means (space vehicles) do not allow the hydrothermal activity (on the ban H 2 0 ) to be observed from the Mars orbit. Powerful eruption can be observed but this event is extremely rare. At any case the existence of the Hawaiian type of volcanoes on Mars is evident and this fact allows one to assume that there are the regions with high concentration of the organic compounds on Mars. These regions, should be associated with the volcanic activity. There is one more class of space objects where volcanic processes are extremely important with respect to the problem of evolution of organic molecules. It is starless planets [8]. On such celestial bodies volcanism should be a dominant source of energy for the synthesis of organic molecules. With the above mentioned arguments we regard volcanics as possible sources of organic molecule synthesis on the primitive Earth.
3. Experimental Experimental tests of the pattern proposed [9] have been made in two directions: investigation of nature samples from volcanic regions and model synthesis. 3.1. VOLCANICSAMPLES In the region of active volcanism, on Kamchatka and the Kuril islands several liquid samples taken in various hydrothermal areas were studied as well as gaseous samples from the scorching slag cone of the Alaid volcano. Liquid samples studied were condensates of vapor and gas jets from the wells drilled in the area of Koshelevski volcano hydrothermal systems, and in the hydrotherm area of the Mutnovka volcano as well as water samples from the hydrothermal sources of the Golovnin volcano caldera.
a. Analytical procedure and microbiological control. Some analyses were made in natural conditions: thin-layer chromatography of amino acids, qualitative tests.* A number of samples were subjected to microbiological tests on the presence of microorganisms. We gave attention to identify some lithotrophic microorganisms on nutrition media of Beijerinck, Rodina, Waksman, Colmer, Borgard, Tauson and analysed also vulgaric microflora on meat-peptone broth. No samples contained organisms capable of growing out in these media except for one (Mutnovka volcano). b. Results and discussions. The results of organic compounds analyses in volcanic samples are summarized in Table I. The data in Table I indicate the presence of a number of organic compounds in the regions of active volcanism. Cyanic and rhodanic compounds as well as * Analyses of liquid volcanicsamples see in the part about studies model underwater samples.
VOLCANICPROCESSESAND SYNTHESISOF SIMPLEORGANICCOMPOUNDSON PRIMITIVEEARTH
359
TABLE I Organic compounds Sample
Temperature Organogenic (~ anions
Volcano Alaid, gaseous samples from rifts of slag come (Atlasov 900-1000 island) Golovnin volcano caldera "Boiling lake" the source 70 "green" "boiling cauldron" (Kunashir island)
Amino acids
Hydrocarbons
CN (0.01-rag/l)
CNS-
Arginine, serine, threonine (1 mg/l)
in presence H2S
the same (0.3 mg/1) Cystine, serine, glycine, oxyproline
72
Bore hole 12 a, depth 140 m (Kunashir island)
167
CNSin presence H2S
Uzon volcano caldera, hydroterms (Kamchatka)
98
(Fe(CN)6)- 3 (Fe(CN)6) -4
Koshelev volcano, bore hole No. 1
98
non
bore hole No. 2 (Kamchatka)
98
CNS-
Mutnovski volcano, solid sublimates (Kamchatka)
Aldehydes
90
--
HCHO, CH3CHO (2.4.10- 6 tool/l) HCHO, CH3CHO (3,2. 10- 6 mol/l)
HCHO, CH3CHO, non-identified carbonyl compounds
Aminobutyric acid, phenylalanine, aliphatic amine
Alkanes C9-C 15, alkenes C 13, C14-normal and isostructure; aromatic hydrocarbons: naphthalene, antracene, phenanthrene, monomethylantracene or phenantrene present (the composition is not studied)
aldehydes found there also deserve attention. As is known, it is these monomers that are major intermediate compounds in the synthesis of more complex molecules [10]. It should be noted that in analysed volcanic samples and subsequent interpretation of the results the possibility of sample contamination by microorganisms or the
360
L.M. MUKHIN
products of their metabolism must be taken into account. As a result it is extremely difficult (if not impossible), to separate out truly juvenile compounds. The more complicated the structure of the discovered compound the more probable that the compound is a contamination product. In individual cases the microbiological analyses yielded a negative result but nevertheless the possibility of microbial contamination cannot be excluded. Therefore a search for hydrocyanic acid, its derivatives and to a less extent, aldehydes is more promising than a search for amino acids. It is obvious that carbon being a constituent of those predecessors of organic molecules we have found has suffered many transformation cycles during the Earth history. It is obvious nevertheless that there was a substantial amount of nitrogen- and carbon-bearing compounds in the products of mantle degasation on the primitive Earth [6]. Hence we have every reason to believe that the present formation of hydrocyanic acid during volcanic eruption is similar to the processes on the Earth is surface at earlier stages of its evolution. As for the genesesis of organic compounds found in volcanic samples some additional remarks are needed. Recently a number of experimental data have been obtained that reveal two extremely essential factors. During Eldfell volcano eruption (Iceland, 1973) it was stated that sulphate and sulphide isotopic composition in thermal events is quite similar to the isotopic composition of meteorite troilite [11]. It implies on the one hand practically complete isolation of a lava channel from the host rocks, and, on the other hand, partial or complete juvenility of sulphuric compounds studied. A convincing evidence at least, to partial juvenility of volcanic exhalations is constituted by anomalously high He3/He 4 - values observed in volcanic gases of Iceland and Kuril-Kamchatka ridges. That ratio is similar to that for the mantle [12]. These data show that a possibility really exists of nonbiological synthesis of organic compounds in the regions of active volcanism. Long-term (two years) generation of hydrocyanic acid from the rifts of the scorching slag cone of the Olympic volcano Alaid break can be one more evidence of this fact (to obtaining nitril by means of pyrolytic destruction of organic compounds a substantial amount of nitrogen compounds is required). Note that the presence of the halogen compounds in the volcanic gases offer additional possibilities for synthesis of a great number of organic molecules. The result obtained open up a possibility of consistent and systematic studies of the processes of abiogenic synthesis in natural conditions.
3.2. SIMULATIONEXPERIMENTS In this connection the simulation of volcanic processes and thorough investigation of the formed organic matter are of particular interest. The use of the experimental models of ground and underwater volcanoes allow the thermal synthesis products directly obtained in the gas phase and the compounds generated as a result of the subsequent transformation in the condensated phase to be separately studied.
361
VOLCANIC PROCESSES A N D SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
a. Ground Volcahic Action
The model, which simulates the volcanic action in the zone of vapor-gas mixture throwing out from the melted lava with the fast "quenching" of the forming products, consists of a quartz reactor filled with the volcanic basaltic lava (controlled temperture up to 1200 ~ and a system of independently controlled fluxes" of inert gascarrier and the reaction mixture component (CH,~(CO) - 5~o, NH 3 - 5~o, HzO - 90~o) (Figure 1). A reactor is provided with the direct connection to the chromatograph or chromatomass-spectrometer system where the analysis of hightemperature synthesis products is made. ~e
Fig.
1.
He
t
CH§
2
5
6
1. He-flow-rate regulator. 2. CH4-flow-rate regulator. 3. Saturator. 4. Six-position valve.
5. Oven for quartz reactor. 6. Chromatographor chromatomass-spectrometer. Chromatograph Varian 1800 and chromatomass-spectrometer LKB 9000 were used in the work, with the columns containing: a) Porapak T (2 m • 4 ram) for the analysis of light hydrocarbons and HCN; b) 2~o methylsilicon DC-410 on chromosorb W (2 m x 4 mm) for the analysis of heavy hydrocarbon under the temperature programming conditions. Results and Discussions
An effect of the reaction zone temperature on the yield of the products obtained was studied; the maximum yield takes place under the temperature of 1050 ~ i.e. during the transition of the basaltic volcanic lava (being a catalyzer in the given process) into viscous flowing state. The time chosen for a contact of the synthesis components with the incondencent lava (< 1 sec.) corresponded with some natural cases. Among the products of reactions hydrocyanic acid and aliphatic amine were discovered and identified in addition to the unsaturated compounds and condensated aromatic hydrocarbons (phenanthrene, naphthalene, anthracene). The analysis of the data obtained should give due regard to the following a) Aromatic fraction of hydrocarbons prevails over aliphatic. This can be attributed to the lower stability ofaliphatic compounds under higher temperatures that naturally reduces the value of theis equilibrium concentration b) Low yield of hydrocyanic acid (~0.1~) and other nitrogen-bearing monomers, Obviously it can be explained the following way. Since fractional concentrations of methane and ammonia are low thermal reactions mainly yield methane cracking products rather than nitrogen-bearing monomers. It is well-known that the methane-
362
L. M, MUKHIN
ammonia system (without water) produce about 90~o of hydrocyanic acid in chosen temperature range (i.e. H C N appears to be a major product of reaction). In our experiments the H C N yield was only about 0.1 ~o. The yield of other monomers was naturally by an order of magnitude lower. Alongside with this the low yield of hydrogen cyanide can be due to processes of hydrolysis and water poisoning of active catalist centers. Netherless, the local concentrations of organic compounds in volcanic areas could be high enough. Figures 2 to 5 and Table II give the results of the quantitative and qualitative analyses. (Gas chromatogramms from LKB-9000.) b. Under Water Volcanic Action
A reactor that simulates the underwater volcano activity is the thick-wall quartz tube with volcanic lava. Under the pressure up to 100 atm. the reacting matters are delivered to the reactor (90~o H20, 5 ~ NH 3, 5~o CH 4 and/or CO). The reaction temperature is 1100-1200 ~. The contact time of the synthesis components with the lava is ,-~0.1 sec. The values of temperature and of contact duration were chosen for the following reasons. According to the values of lava temperature of Hawaii volcanoes [6], temperature can reach its maximum of 1400 ~ but, as a rule it does not exceed 1000 to 1100~ There is no reason to assume that initial temperatures of volatiles and lavas during underwater erruptions will substantially differ from the values given above.
8
~.
/ Fig. 2. Chromatogram of light products of high-temperature synthesis (Porapak T). 1. Methane. 2, Acetylene and alyphatic amine. 3. Propylene. 4. Cyctopropene. 5. Methylacetylene. 6. Butadiene or butyne. 7. Vinytacetylene. 8. Water.
363
VOLCANIC PROCESSES AND SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
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As regards the duration of contact, the values chosen were determined only really natural velocities of gas stream. It does not of course mean that the model chosen covers all possible types of volcanoes effluence. Vapor and gas mixture is delivered from a reactor via a throttle and the condenser to the sterile collector9 Condensate (colourless liquid containing ammonia) was analyzed as follows: A sum of low aldehydes was determined by ferment reduction with the use of alcohol dehydrogenase [13]. In addition thin layer chromatography of dinitrophenylhydrazones on siluphol was used. 100 ml of alkaline condensate were evaporated in vacuum at 40 ~ to ~0.5 ml. 20 mkl of this solution were taken to identify amino acids as I-dimethylaminonaphthalene-5-sulphonil (DNS) derivatives by means of two-dimensional microthin layer chromatography [14, 15]. An amount of amino acids estimated by this method is 10-4 g/l. The rest of concentrate (0.5 ml - 20 mkl) was evaporated to dryness, esterified n-C4H9OH/HC1 and acylated by threefluoroacetic anhydride [16]. The obtained mixture of derivatives was analyzed by the chromatomass-spectrometer
364
L. ~. MUKHIN
5
6
1
,d f (M~.) a'o
io
~b
Fig. 4. Chromatogram of heavy products of high-temperature Synthesis (DC-410). 1. Benzene and toluene. 2. Inden. 3. Naphthalene. 4. Monomethylnaphthalene. 5. Biphenyl. 6. Naphthylacetylene or acenaphthylene. 7.8. Alkane and alkene C~0.9. Anthracene. 10. Phenanthrene or/and diphenylacetylene. method. A chromatomass-spectrometer LKB 9000 was used. The glass chromatographic columns (180 x 0.4 cm) packed with 0.65~o P E G A (fixed phase) on chromosorb W with temperature programming mode were also used. Mass-spectra were obtained with 70 ev. Organic matters were not discovered in the control analyses made, in acordance to the mentioned standard scheme for twice-distilled water (BW) as well for BW, BW + N H 3 and BW + CH 4 passed through a reactor under experimental conditions. Results and Discussions
The results are presented in Table III. After about 6 months in sterile conditions sample No. 2 has a set of amino acids different from that of No. 1. This example is given to show a possibility of the next cycle of the reaction of predecessors (e.g. hydrolysis of nitriles) in a liquid plaase. In particular, an assumption can be made about the reaction of glutamic acid formation in the process of complete hydrolysis from nitrile. As for the presence of glycine and e-alanine, probably they may also form through the hydrolysis of corresponding nitriles. Of interest is to compare HCN-yield recorded in our experiments with the total yield of aminoacids amounting to 10 - 4 g/h Not too arbitrarily (usually experimental temperature did not exceed 1100 ~ it can be assumed that H C N yield in the experiments that simulate underwater
V O L C A N I C PROCESSES A N D SYNTHESIS OF SIMPLE O R G A N I C C O M P O U N D S ON PRIMITIVE E A R T H
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18o
'~/e
365
366
L. M. MUKHIN TABLE II
Gas-chromatography
Chromatomass-spectrometr y
Products
Weight ~
Light products
Initial methane
58.94
Acetylene
18
Ethylene HCN
Weight ~
Heavy products
87.27
CvH 8 (toluene)
Amine (ethylamine or dimethylamine)
2.0
CgH 8 (inden)
23
Propylene
1.0
CIoH8 (naphthalene)
0.06
Cyclopropene
0.5
C11H10 (monomethylnaphthalene)
Methylacetylene
6.2
Initial methane, acetylene, ethylene
C12Hlo
(biphenyl) C4H6 (butadiene or butyne)
0.5
Vinylacetylene
0.03
Alkanes and alkenes Clo
Benzene
2.5
C~4Hlo (anthracene)
1- cyano-butene-2 or threemer of HCN ? (M.V. 81 )
C 12Hs (naphthylacetylene or acenaphthylene)
C14H10 (phenanthrene or biphenylacetylene)
volcanism is similar to that in the experiments on earth volcanism, i.e., a b o u t 0.1~o It means that the a m o u n t of H C N in 1 1 of a condensate a m o u n t s to slightly less than 10-2 g/1. So, if an assumption is made that a m i n o acids are synthesized t h r o u g h a Strecker mechanism with the participation of H C N , the yield of a m i n o acids in this reaction can be regarded as equal to several per cent, it is a reasonable value.
c. Comparison of Under Water and Ground Eruption It is rather exciting to c o m p a r e underwater and g r o u n d volcanoes as chemical reactors synthesizing organic molecules. Let's now consider a schematic case of incandescent gaseous jet e m a n a t i o n from a volcanic vent into a more dense (underwater eruption) and into a less dense (ground eruption) medium. A purely qualitative picture will be considered, t h o u g h exact estimates can be made. It is obvious that the range of a jet will be m u c h longer in case of a g r o u n d eruption, under other equal conditions, than in that of an underwater eruption. The ratio of the values for these two cases is estimated as being a b o u t 100. With the same initial amounts, this means m u c h higher concentrations of reagents in a
VOLCANIC PROCESSES AND SYNTHESIS OF SIMPLE ORGANIC COMPOUNDS ON PRIMITIVE EARTH
367
TABLE III Amino acids and other non-volatile hydrophilic c o m p o u n d s Microthinlayer chromatography a
Sample a
Lower aldehydes
Colouring with ninhydrin
free amino acids
after hydrolysis of terminal after full amino acids hydrolysis
Chromatomass spectrometry e
No. 1
HCHO CH3CHO b
Stable
non-albuminous amino-acid or amine
glycine, fl-alanine, aliphatic amine C6HsCOO/C,,H 9
No. 2
the same (1.4.10- ~ tool/l) ~
Stable
glycine, e-alanine, serine (trace), nonalbuminous aminoacid or amine
glycine, c~-alanine, aliphatic amine, C6HsCOOC4H 9
the same glutaminic acid
a Sample No. 1 is treated and analyzed immediately after synthesizing; sample No. 2 six m o n t h s after. b TO be discovered by method of T L C of dinitrophenylhydrozones. c To be determined by ferment reduction by means of alcohol dehydrogenase [10]. d After obtaining DNS-derivatives. ~ After C4HgOH/HCI and ( C F 3 C O ) 2 0 treatment.
reaction zone near the vent of an underwater volcano (the jet in this case is less "spread" in space). This situation is obviously more favorable for the synthesis of organic molecules than that of ground eruption. 3.4. CONCLUSION Of course our information about the monomer synthesis on the primitive Earth cannot be regarded as exhaustive. A "volcanic" model looks promising since it renders a unique possibility of studying natural processes. Our experimental results substantially confirm the adequacy of this model. One more aspect should be mentioned. In the processes simulating the volcanic activity not only are the biologically valid monomers formed but also the "stock" of wide spectrum of hydrocarbons, the quantitative yield of hydrocarbons being higher than that of biological monomers. This fact can be associated with the problem of genesis of the crude oil. It should be noted that some simple compounds identified in our experiments can later react thus forming biologically active molecules. These are unsaturated compounds: acetylene, propylene, vinyl acetylene, methyl acetylene, divinyl. The analyses of the volcanic samples as well as the results of the model experiments confirm the significant role of the volcanic processes in the evolution of organic compounds on the primitive Earth.
Acknowledgements I thank acad. A. I. Oparin for attention to this work. I express special gratitude to S. V. Vitt, V. B. Bondarev, E. N. Safonova for constructive discussions and experimental help.
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L.M. MUKHIN
I thank also V. I. Kalinitchenko, R. I. Fedorova, U. S. Petrenko for assistance in experiment. I particularly thank the referee for his detailed criticism of an earlier draft of the manuscript. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19]
Oparin, A. I.: 1957, The Origin of Life on the Earth, Acad. Press., Inc., New York. Sagan, C.: 1966, The Origin of Prebiological Systems, Mir, Moscow. Abelson, P. H.: 1966, Proc. Nat. Acad. Sci. 55, 1365. Hull, D. E.: 1960, Nature 186, 693. Glansdorff, P. and Prigogine, I.: Thermodynamic Theory of Structure, Stability and Fluctuations, Universite libre de Bruxelles, Brussels, Belgium and University of Texas, Austin, Texas. Luchitski, I. V.: 1971, Advances ofPaleovolcanology, Nauka, Moscow. Fox. S. W. and Dose, K.: 1975, Molecular Evolution and the Origin of Life, p. 70, Mir, Moscow. Mukhin, L. M.: 1973, Astron. Acta 18, 451-454. Mukhin, L. M.: 1973, in CETI, Washington, ed. C. Sagan. Kenyon, D. H. and Steinman, G.: 1972, Biochemical Predestination, Mir, Moscow. Pollack B. et al.: 1975, Report on Intern. Symp. The Problems of Riftogenesis, Irkutsk, U.S.S.R. Kononov, V. I. and Mamyrin, B. A.: 1974, Dokl. Akad. Nauk U.S.S.R. 217 (1), 172. The Enzymes, Academic Press, New York and London, Vol. 7, p. 26, 1961. E. Racker in Methods in Enzymology, Vol. 3, p. 295, 1969. Vinogradova, E. I. and Feygina, M. Yu. et al.: 1973, Biochimiya 38 (1), 3. Belenki, B. G., Gankina, E. S., and Nesterov, V. V.: 1967, Dokl. Akad. Nauk U.S.S.R. 172 (1), 91. Vitt, S. V. and Saporovskaya M. B. et al.: 1974, Izv. Akad. Nauk U.S.S.R. 6, 1310. Carl Sagan: 1970, Encyclopedia Britannica, pp. 1083-1087. Davidson et al.: 1966, Tellus 18, 3a. Bar-Nun, A. and Shaviv, A.: 1975, Icarus 24, 197-210.
