Which term refers to the conversion of one isomer into another organic compound that differs from the first in the position of a hydrogen atom and a double bond?

Which term refers to the conversion of one isomer into another organic compound that differs from the first in the position of a hydrogen atom and a double bond?

• A. Disproportionation
• B. Polymerization
• C. Tautomerization
• D. Isomerization

Answer: (C)

The term describes a specific kind of rearrangement where an isomer forms another isomer by moving a hydrogen and shifting the location of a double bond. This is tautomerization, best exemplified by keto–enol tautomerism. In this process, a carbonyl compound (the keto form) can interconvert with its enol form as a proton relocates from the alpha carbon to the carbonyl oxygen and the C=O bond becomes a C=C bond with an adjacent O–H. This exact shift of hydrogen position and double-bond placement is what defines tautomerization. Other terms refer to different processes: disproportionation involves redox changes producing species with different oxidation states, polymerization builds long chains from monomers, and isomerization is a broader rearrangement to another isomer without specifying the proton transfer and pi-bond shift characteristic of tautomerization.

The term describes a specific kind of rearrangement where an isomer forms another isomer by moving a hydrogen and shifting the location of a double bond. This is tautomerization, best exemplified by keto–enol tautomerism. In this process, a carbonyl compound (the keto form) can interconvert with its enol form as a proton relocates from the alpha carbon to the carbonyl oxygen and the C=O bond becomes a C=C bond with an adjacent O–H. This exact shift of hydrogen position and double-bond placement is what defines tautomerization. Other terms refer to different processes: disproportionation involves redox changes producing species with different oxidation states, polymerization builds long chains from monomers, and isomerization is a broader rearrangement to another isomer without specifying the proton transfer and pi-bond shift characteristic of tautomerization.