Problem 38 - A Complete Resource Book in Chemistry for JEE Main

Question

When a mixture of secondary amines is heated with diethyl oxalate, it forms (a) solid oxamic ester (b) liquid oxamic ester (c) form of oxamic ester (d) gaseous oxamic ester

Step-by-Step Solution

Answer

The answer is (a) solid oxamic ester.

Step 1: Understanding the Reaction

When secondary amines are heated with diethyl oxalate, the reaction typically results in the formation of an oxamic ester. Secondary amines, due to their structure, will lose a hydrogen atom and bond with the carbonyl group in the diethyl oxalate.

Step 2: Recognizing the Product's Physical State

The reaction between secondary amines and diethyl oxalate commonly yields an oxamic ester. The type of oxamic ester formed is typically not gaseous but can be either a solid or a liquid, depending on the specific secondary amine and its substituents used in the reaction.

Step 3: Selecting the Correct Option

Given the choices (a) solid oxamic ester, (b) liquid oxamic ester, (c) form of oxamic ester, and (d) gaseous oxamic ester, the more common result with most secondary amines reacting with diethyl oxalate is the formation of a solid oxamic ester.

Key Concepts

Diethyl Oxalate

Diethyl oxalate is a significant chemical compound used primarily as a reagent in organic synthesis. It is made up of two ethyl groups attached to the oxalate ion.
When it comes to its physical properties, diethyl oxalate presents as a colorless, oily liquid at room temperature. It's known for its ability to dissolve in organic solvents, making it versatile for various chemical reactions.

• It is widely used to prepare esters, amides, and oxamic esters.
• Its reactivity is mainly attributed to the presence of two carbonyl groups.

These carbonyl groups easily undergo reactions with compounds like secondary amines, facilitating the formation of oxamic esters when heated. Overall, it's a crucial component in the landscape of industrial and laboratory chemical processes.

Oxamic Ester

An oxamic ester is a product formed from the reaction between diethyl oxalate and secondary amines. These esters have a general structure consisting of an amide and ester group.
Their formation highlights the interplay between functional groups in organic chemistry. Specifically, the secondary amine reacts with the carbonyl group of the diethyl oxalate, leading to the release of ethanol and the formation of the oxamic ester.

Characteristics of oxamic esters include:

• They are typically either solid or liquid at room temperature.
• Their physical state depends on the R groups attached to the nitrogen atom in the secondary amine.

This reaction showcases the versatility of both diethyl oxalate and amines in forming complex organic compounds.

Chemical Reactions

Chemical reactions are processes where substances, called reactants, transform into new substances, known as products. In this specific scenario with secondary amines and diethyl oxalate, the reaction forming an oxamic ester is an excellent example of esterification.
Here is what happens step by step in this reaction:

• A hydrogen atom from the secondary amine is lost.
• This creates a nucleophilic site that attacks the electrophilic carbonyl carbon on the diethyl oxalate.
• A bond is formed between the amine and the oxalate, releasing ethanol in the process.

The resulting oxamic ester is stable under acidic conditions and showcases the predictable nature of nucleophilic substitution, a common mechanism in organic chemistry.

Physical States of Compounds

Understanding the physical states of compounds is crucial in predicting and controlling chemical reactions. When dealing with reactions like the one involving secondary amines and diethyl oxalate, knowing the resulting oxamic ester's state gives insight into its potential applications.
Physical states of compounds can be:

• Solid
• Liquid
• Gas

The state of oxamic ester is typically solid or liquid, depending on the properties of the secondary amine involved. For example, if the secondary amine has bulkier substituents, the product is more likely to be solid due to more significant intermolecular forces, such as Van der Waals forces.
Recognizing the physical state of products can influence storage conditions and handling procedures in lab and industrial processes.