Evaluating alternatives to water as solvents for life: the example of sulfuric acid

Bains, William, Petkowski, Janusz Jurand, Zhan, Zhuchang and Seager, Sara 2021. Evaluating alternatives to water as solvents for life: the example of sulfuric acid. Life 11 (5) , 400. 10.3390/life11050400

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Abstract

The chemistry of life requires a solvent, which for life on Earth is water. Several alternative solvents have been suggested, but there is little quantitative analysis of their suitability as solvents for life. To support a novel (non-terrestrial) biochemistry, a solvent must be able to form a stable solution of a diverse set of small molecules and polymers, but must not dissolve all molecules. Here, we analyze the potential of concentrated sulfuric acid (CSA) as a solvent for biochemistry. As CSA is a highly effective solvent but a reactive substance, we focused our analysis on the stability of chemicals in sulfuric acid, using a model built from a database of kinetics of reaction of molecules with CSA. We consider the sulfuric acid clouds of Venus as a test case for this approach. The large majority of terrestrial biochemicals have half-lives of less than a second at any altitude in Venus’s clouds, but three sets of human-synthesized chemicals are more stable, with average half-lives of days to weeks at the conditions around 60 km altitude on Venus. We show that sufficient chemical structural and functional diversity may be available among those stable chemicals for life that uses concentrated sulfuric acid as a solvent to be plausible. However, analysis of meteoritic chemicals and possible abiotic synthetic paths suggests that postulated paths to the origin of life on Earth are unlikely to operate in CSA. We conclude that, contrary to expectation, sulfuric acid is an interesting candidate solvent for life, but further work is needed to identify a plausible route for life to originate in it.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Additional Information:	This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/
Publisher:	MDPI
ISSN:	2075-1729
Date of First Compliant Deposit:	27 July 2021
Date of Acceptance:	24 April 2021
Last Modified:	23 May 2023 18:57
URI:	https://orca.cardiff.ac.uk/id/eprint/142938

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