Thiols have structures similar to alcohols except that they contain.
A) sulphur in place of oxygen in the functional group.
B) lithium in place of oxygen in the functional group.
C) more than one carbon.
D) three alcohol groups.
E) nitrogen in place of oxygen in the functional group.
The Correct Answer and Explanation is :
Correct Answer:
A) Sulphur in place of oxygen in the functional group.
Explanation:
Thiols are organic compounds similar in structure to alcohols, but they have a significant difference in their functional group. While alcohols contain a hydroxyl group (-OH), thiols have a sulfhydryl group (-SH). This means sulfur replaces the oxygen atom in the functional group of alcohols.
Key Points:
- Structural Similarity:
Both alcohols and thiols follow a similar basic formula. Alcohols have the general formula R-OH, where R is an alkyl or aryl group. Thiols, on the other hand, have the formula R-SH. - Sulfur Substitution:
Sulfur and oxygen are both in Group 16 of the periodic table, which means they have similar chemical properties, such as forming two bonds. However, sulfur is less electronegative and has a larger atomic size compared to oxygen. This substitution leads to distinct physical and chemical properties for thiols. - Properties of Thiols:
- Odor: Thiols are often associated with strong, unpleasant odors, such as the smell of skunk spray or rotten eggs.
- Polarity: The S-H bond is less polar than the O-H bond in alcohols because of sulfur’s lower electronegativity. This results in weaker hydrogen bonding in thiols.
- Reactivity: Thiols are more reactive than alcohols due to the weaker bond between sulfur and hydrogen compared to oxygen and hydrogen.
- Applications:
Thiols are important in biochemistry and industrial chemistry. For example, cysteine, an amino acid, contains a thiol group, which is critical in protein structure formation through disulfide bonds.
By understanding that thiols have sulfur replacing oxygen in their functional group, you can distinguish them from alcohols and appreciate their unique characteristics.