1. 3.20 Thiols Contain the functional group -SH
Chp 3.20
3.20 Thiols
Contain the functional group -SH
Named by adding thiol to the name of the longest carbon chain
Number the -SH group in longer chains
CH3-SH methanethiol
CH3-CH2SH ethanethiol SH
CH3-CH-CH3 2-propanethiol

2. Thiols (cont.) and 3-methyl-1-butanethiol
Many thiols have disagreeable odors
Used to detect gas leak
Found in onions, oysters, garlic and oysters
Onions CH3CH2CH2-SH 1-propanethiol
Garlic CH2= CHCH2-SH 2-propene-1-thiol
Skunk spray
CH trans-2-butene-1-thiol
CH = CH
CH2SH
and 3-methyl-1-butanethiol

3. The oxidized product is called a disulfide.
Oxidation of Thiols
Thiols also undergo oxidation by a loss of hydrogen atoms from the –SH groups.
The oxidized product is called a disulfide.
[O]
R1—S—H + H—S—R2 R1—S—S—R2 + H2O

4. Much of the protein in the hair is cross-linked by disulfide, which occur between the thiol groups of the amino acid cysteine.
When a person is given a “perm”, a reducing substance is used to break the disulfide bonds.
While the hair is still wrapped around the curlers, an oxidizing substance is applied that cause new disulfide bonds to form between different parts of the person hair strands, which gives the hair a new shape.
COOH
COOH
COOH
COOH
[O]
NH2—CH—CH2SH + HSCH2—CH—NH NH2—CH—CH2—S—S—CH2—CH—NH2
Cysteine