Question

N)C(C)(C)C(=O)O (1) geometrical isomerism. (2) optical isomerism. (3) geometrical and optical isomerism. (4) tautomerism. # The structure shows CC(C)=C(C#N)C(C)(C)C(=O)O (1) geometrical isomerism. (2) optical isomerism. (3) geometrical and optical isomerism. (4) tautomerism.

Short answer

The structure exhibits geometrical isomerism.

Step-by-step solution

Identify the Functional Groups

Examine the structure to identify the functional groups. The structure contains a carboxylic acid group (C(=O)O) and a nitrile group (C#N).

Identify Potential Chiral Centers

Check for any carbon atoms that are attached to four different groups. In this structure, no carbon atoms meet this criterion, so there are no chiral centers.

Check for Geometrical Isomerism

Identify any double bonds that could exhibit cis/trans (geometrical) isomerism. The structure has a carbon-carbon double bond (C=C) which can show geometrical isomerism.

Check for Tautomerism

Tautomerism typically involves the interconversion between keto and enol forms or similar structures. There are no such species identified in this molecule.

Conclusion

Based on the analysis, the structure has a carbon-carbon double bond that allows for geometrical isomerism but does not have chiral centers for optical isomerism, nor does it exhibit tautomerism.

Key concepts

Functional Groups

Functional groups are specific groups of atoms within molecules that dictate the chemical reactions of those molecules. They are the key to understanding organic chemistry. In the given structure CC(C)=C(C#N)C(C)(C)C(=O)O, we can identify several functional groups:

• A carboxylic acid group (C(=O)O)
• A nitrile group (C#N)

Understanding these functional groups is essential because they influence the molecule's chemical properties and reactions. Carboxylic acids, for instance, are acidic and participate in reactions such as esterification. Nitriles can undergo hydrolysis, reduction, or reactions with nucleophiles. Knowing these details helps in predicting behavior and possible chemical transformations of the molecule.

Geometrical Isomerism

Geometrical isomerism, also known as cis/trans isomerism, arises from the restricted rotation around a double bond or a similar rigid structure. It occurs when two substituents on a molecule can have different spatial arrangements around a central point, typically around a carbon-carbon double bond. In the given structure, the C=C double bond allows for geometrical isomers:

• Cis isomer: Both substituents are on the same side of the double bond.
• Trans isomer: The substituents are on opposite sides of the double bond.

This type of isomerism significantly affects the physical and chemical properties of the substances. For example, cis and trans isomers can have different boiling points, melting points, and solubilities.

Optical Isomerism

Optical isomerism occurs when a molecule can exist in two non-superimposable mirror image forms. These isomers are called enantiomers. For a molecule to exhibit optical isomerism, it must have at least one chiral center — a carbon atom attached to four different groups. In the given structure, there are no carbon atoms that fulfill this criterion. Therefore, the molecule does not show optical isomerism.

Optical isomerism is crucial in chemistry, especially in fields like pharmacology, because different enantiomers can have drastically different effects in biological systems. One enantiomer of a drug may be therapeutic, while the other could be inactive or even harmful.

Tautomerism

Tautomerism is a type of isomerism where isomers, called tautomers, interconvert mutually and exist in dynamic equilibrium. Most commonly, this involves keto-enol tautomerism, where the tautomers are a keto form and an enol form (has an alcohol adjacent to a double bond). In this exercise, no such keto-enol tautomerism is identified in the provided structure CC(C)=C(C#N)C(C)(C)C(=O)O due to the absence of the necessary functional groups involved, such as -OH adjacent to a double bond.

Tautomerism plays a significant role in organic chemistry and biochemistry, impacting the stability, reactivity, and mechanisms of various reactions. For example, tautomerism is essential in processes like amino acid synthesis and nucleotide base pairing in DNA.