Question

When mildly beated with aqueous base or acid, nitriles are hydrolyzed to amides. What may be the product of hydrolysis under stronger conditions? A. aldehyde B. ketone C. ester D. carboxylic acid

Short answer

The product of nitrile hydrolysis under stronger conditions is a carboxylic acid (D).

Step-by-step solution

- Understand the concept of hydrolysis

Hydrolysis is a chemical reaction where water is used to break down a compound. In this case, nitriles (R-CN) can be hydrolyzed to form other compounds.

- Mild hydrolysis

When nitriles are mildly hydrolyzed with an aqueous base or acid, the reaction usually stops at the formation of amides (R-CONH2).

- Hydrolysis under stronger conditions

Under stronger conditions, such as prolonged heating with aqueous acid or base, the amide formed from the initial hydrolysis undergoes further hydrolysis to form carboxylic acids (R-COOH).

- Identify the product

Given the stronger conditions mentioned, the nitrile will ultimately be converted to a carboxylic acid. Therefore, the correct answer is D.

Key concepts

nitrile hydrolysis

Nitrile hydrolysis is an important reaction in organic chemistry. It involves breaking the carbon-nitrogen triple bond in nitriles (R-CN) using water, either in the presence of an acid or a base.
In mild conditions, typically using a weak aqueous acid or base, the nitrile is partially hydrolyzed. This results in the formation of an amide intermediate (R-CONH2).
However, this process can proceed further under stronger conditions. When stronger acids or bases are applied—with additional heat—the reaction continues past the amide stage.
Understanding the progression from nitriles to amides and finally to carboxylic acids is crucial for predicting the outcomes of hydrolysis reactions.

amide formation

Amides are an intermediate product when nitriles are hydrolyzed. They have the general formula (R-CONH2) and form when a nitrile reacts with water under mild conditions.
For students, it's vital to remember that this step involves an initial attack by water on the nitrile's carbon, followed by proton transfers which culminate in the formation of an amide.
The structure of amides includes a carbonyl group (C=O) bonded to a nitrogen atom, which distinguishes them from their precursor nitriles and further hydrolysis product, carboxylic acids.

carboxylic acid synthesis

Carboxylic acid synthesis can be achieved through the complete hydrolysis of nitriles. Under strong conditions, such as applying heat and using a concentrated aqueous acid or base, amides undergo further hydrolysis to become carboxylic acids (R-COOH).
This part of the reaction is essential in organic synthesis because carboxylic acids are versatile and important in both industrial and laboratory settings. They are involved in the production of polymers, pharmaceuticals, and many other chemical compounds.
In summary, understanding the transition from nitriles to amides to carboxylic acids under various conditions helps students predict and explain the outcomes in organic synthesis processes.