An alkanethiol is an organic compound with an -SH group attached to an alkane chain. In Organic Chemistry, it is a thiol that often shows up in reactions, oxidation, and metal-surface chemistry.
An alkanethiol is a thiol, meaning it has a sulfur-hydrogen group, written as R-SH, attached to an alkane backbone. The name tells you two things at once: the carbon part is saturated like an alkane, and the functional group is the sulfhydryl group on sulfur.
In Organic Chemistry, the easiest way to recognize an alkanethiol is to look for the -SH group at the end of a carbon chain. Methanethiol, ethanethiol, and propanethiol are simple examples. They are named by taking the alkane name and changing the ending to -thiol.
Alkanethiols behave a little differently from alcohols, even though the structures look similar on paper. Sulfur is larger than oxygen, so the S-H bond is longer and weaker than an O-H bond. That weaker bond makes the proton easier to remove, so alkanethiols are more acidic than alcohols. When they lose H+, they form a thiolate anion, R-S-, which is a useful nucleophile in organic reactions.
That sulfur chemistry matters because sulfur is soft and polarizable. Alkanethiols bind strongly to many metals, especially gold, which is why they are used to build self-assembled monolayers on metal surfaces. In a surface lab or nanochemistry context, the sulfur head group sticks to the surface while the alkyl chain helps organize the layer.
They also oxidize differently than alcohols. Two alkanethiols can be oxidized to a disulfide, RSSR, which links two sulfur-containing groups together. That reaction shows up in biochemistry too, since disulfide bonds help stabilize protein structure. So when you see an alkanethiol, think beyond a simple functional group, because it can act as a source of sulfur, a nucleophile, a surface-binding group, or a precursor to a disulfide.
Alkanethiols come up whenever a course asks you to connect structure to reactivity. The -SH group is a small change from an alcohol, but it changes acidity, bonding, oxidation behavior, and how the molecule interacts with metals.
That makes alkanethiols useful for mechanism questions. If you are tracking a reaction, you may need to decide whether the sulfur is acting as a nucleophile, whether it is being oxidized to a disulfide, or whether the thiol proton can be removed to make a thiolate.
They also show how functional groups affect physical properties. Many thiols have strong odors, which is why simple ones like methyl mercaptan are used as odorants in natural gas. On a test or in discussion, that is a quick clue that sulfur compounds can have strong sensory effects even at low concentrations.
In lab or surface chemistry work, alkanethiols are a common example of molecular self-assembly. Their attachment to metal surfaces helps explain why some organic molecules form ordered films instead of just floating in solution.
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Visual cheatsheet
view galleryThiol
Alkanethiol is a specific kind of thiol. The term thiol refers to any compound with an -SH group, while alkanethiol narrows that to a saturated alkyl chain attached to sulfur. If a problem asks you to identify the functional group, thiol is the broader category you should recognize first.
Disulfide
Two alkanethiols can oxidize to form a disulfide, RSSR. That link is the product of sulfur-sulfur bond formation, and it is a common oxidation pattern for thiols. If you are tracing a reaction sequence, spotting a disulfide tells you the starting material was likely a thiol or thiolate.
Nucleophilicity
The sulfur atom in an alkanethiol or its conjugate base can act as a nucleophile. Because sulfur is large and polarizable, thiolates often react strongly in substitution reactions. That makes alkanethiols useful when you need to predict which atom attacks an electrophile and what product forms.
Sulfhydryl Group
The sulfhydryl group is the -SH functional group that defines a thiol. In alkanethiols, this group is attached to an alkane chain. Recognizing the sulfhydryl group helps you connect naming, acidity, oxidation, and surface-binding behavior in one place.
A quiz or problem set may ask you to name an alkanethiol from its structure, identify the thiol functional group, or predict a product after oxidation. You might also be asked to compare a thiol with an alcohol and explain why the thiol is more acidic or why it forms a stronger bond to gold. In a reaction mechanism, look for the sulfur atom as the reactive site. If the question gives a mercaptan with an -SH group, identify it as an alkanethiol and track whether it becomes a thiolate, a disulfide, or a surface-bound sulfur species.
An alkanethiol is a thiol with an alkane chain attached to an -SH group.
The sulfur-hydrogen bond is weaker than the oxygen-hydrogen bond in alcohols, so alkanethiols are more acidic than alcohols.
Alkanethiols can be oxidized to disulfides, which is a common sulfur reaction pattern in organic and biological chemistry.
The sulfur atom makes alkanethiols good nucleophiles and strong binders to metal surfaces like gold.
Strong odors in simple thiols, like methyl mercaptan, are a practical clue that sulfur compounds behave differently from similar oxygen compounds.
An alkanethiol is an organic compound with an -SH group attached to an alkane chain. It is a type of thiol, so sulfur is the atom doing the chemistry instead of oxygen like in an alcohol. In Organic Chemistry, alkanethiols show up in naming, acidity comparisons, oxidation to disulfides, and metal-surface binding.
Not exactly. A thiol is the broader category for any molecule with an -SH group. An alkanethiol is a specific thiol where that group is attached to an alkane chain, so every alkanethiol is a thiol, but not every thiol has to be an alkanethiol.
The S-H bond is weaker than the O-H bond, and sulfur holds negative charge differently than oxygen. When an alkanethiol loses H+, the thiolate ion is relatively stable because sulfur is larger and more polarizable. That is why thiols give up a proton more easily than alcohols.
A common oxidation product is a disulfide, where two sulfur atoms join to make RSSR. This reaction matters in synthesis and in biochemistry, where disulfide bonds help hold protein shapes in place. If you see thiol oxidation on a problem, disulfide is often the expected product.