If a compound is reduced, what is the result?
Fewer C-H bonds
Increased number of C-H bonds
Fewer C-Z bonds
Both increased number of C-H bonds and fewer C-Z bonds
The Correct Answer and Explanation is:
Correct Answer:
Both increased number of C-H bonds and fewer C-Z bonds
Explanation
In chemistry, reduction refers to a gain of electrons by an atom, molecule, or ion. In organic chemistry, this process often correlates with changes in the types and numbers of bonds around a carbon atom. Specifically, reduction typically results in an increase in the number of carbon-hydrogen (C-H) bonds and a decrease in the number of carbon-heteroatom bonds (C-Z bonds), where Z is usually an electronegative atom like oxygen, nitrogen, or a halogen.
For example, consider the reduction of a carbonyl group (C=O) to an alcohol (C-OH). The carbon in the carbonyl is double bonded to oxygen (a strong C=O bond), but after reduction, it forms a single bond with oxygen and gains a hydrogen, thus increasing the C-H bond count and reducing the strength or number of C-Z bonds.
Another common example is the reduction of an alkene (C=C) to an alkane (C-C), where the pi bond is broken, and each carbon gains a hydrogen, increasing the total number of C-H bonds.
In terms of oxidation states, carbon atoms that are more oxidized have more bonds to electronegative atoms (like oxygen or halogens). When reduced, those bonds to electronegative atoms (C-Z) are often broken and replaced with bonds to hydrogen (C-H), which is less electronegative. This means that in the process of reduction:
- C-H bonds increase (more electrons localized around carbon).
- C-Z bonds decrease (fewer bonds to electronegative atoms, meaning electrons are less withdrawn from carbon).
This dual change makes “both increased number of C-H bonds and fewer C-Z bonds” the best and most complete answer, as it accurately reflects the molecular changes associated with a reduction process in organic chemistry.
