Question

What functional group resembles a hydroxyl group?

Answer 1

You may be asking about sulfhydryl groups (`-"SH"`), which resemble a hydroxyl group (`-"OH"`), so compounds that only contain `-"SH"` as a unique functional group are named based off of the original alcohol.

NOTE: Entire compounds are not functional groups; ethanol cannot be a functional group, because it is a complete, defined compound.

However, `-"OH"` is a molecular fragment and is called a functional group.

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Normally alcohols have IUPAC names ending in "-ol", and have prefixes based off of the original alkane (e.g. `\mathbf("Ethan")"ol"`).

`"CH"_3"CH"_2"SH"`, or ethanethiol, is the sulfur analog of `"CH"_3"CH"_2"OH"` (ethanol). Ethanethiol is a thiol, while ethanol is a regular alcohol.

A simple way to name the sulfur analog of an alcohol, if the alcohol exists, is to simply add "thi" before "-ol" and utilize the entire name of the would-be alkane instead of omitting the vowel before the suffix.

`"Ethan"\mathbf("ol")` `->` `"Ethan"\mathbf("ethiol")`