There is no question about if the first letter of the question title should be capitalized.
However, there are situations, when the capitalization of the very first first character is not possible, which however does not mean, that the capitalization should not occur at all. In many (most?) cases, the capitalization should occur at the first Latin letter, that is not part of a special prefix.
Usual cases are titles starting with a chemical name (or related term)
starting with a digit
Example: 2-Bromo-1-chloro-4-nitrobenzene reacts with sodium ethoxide
External example: 1,3-Dipolar cycloaddition
containing Greek or other non-Latin script prefix
Example: α,β-Unsaturated carbonyl compounds and alkyl addition (TODO: FIX the title)
External example: α,β-Unsaturated carbonyl compounds
- containing lowercase and italicised prefix
Examples: p-Nitrophenol and sodium bicarbonate test (TODO: FIX the title),
p-Phenylenediamine Production Process (TODO: FIX the title)
It might not be possible to preserve entire typography in the title here at SE, however we still should preserve the case, I think.
For cis-/trans- starting titles, we should differentiate if the initial prefix is part of the name, or a term, where the italicising does not usually occur (e.g. Trans-hydrogenation of alkenes seems OK).
Note that the proper capitalization style can be verified by the examples in the last IUPAC organic nomenclature, where the capitalization of chemical names was recommended, i.e. the 1979 version (see randomly chosen example(s) here).