The Organic Chemistry question discussed in this video lecture appeared in IIT JEE question paper 1994 and discusses the formation of a carboxylic acid derivative (benzamide). 

How will you bring about the following conversion?
“Benzamide from nitrobenzene” 

Organic reactions cannot be understood without knowing the structures and properties of the organic compounds involved. Students must have a clarity regarding the same to be able to attempt similar questions correctly in IIT JEE papers and AIEEE papers. 
The nitrobenzene molecule needs to be converted to aniline first. Hydrogenation of nitrobenzene is done to carry out this reduction reaction (with the help of stannous chloride (SnCl2) and hydrochloric acid (HCl)). However it is a known fact that diazonium salts are more versatile than aniline; in the sense that it can lead to a greater variety of compounds than aniline. To bring about the conversion, sodium nitrite (NaNO2) along with dilute hydrochloric acid is used (which would lead to the formation of the diazonium salt). This conversion is called diazotization. 
This is further converted to benzonitrile (containing CN functional group) with the help of hydrogen cyanide (HCN) and copper cyanide (CuCN). This reaction is called Sandmeyer reaction. To convert this benxonitrile to benzoic acid its acid hydrolysis is done. Benzoic acid on reaction with Phosphorus pentachloride (PCl5) leads to the formation of benzoyl chloride, which in turn finally leads to the formation of benzamide on reaction with ammonia (NH3).
The video would make the conversion seem simple even if the students have not finished studying this part of Organic Chemistry completely. Such questions are important and can be found in many previous years papers.
In lengthy conversions such as this, students must recognize the correct path to follow. This recognition can be accurate only when they have clarity of all the reactions and intermediate compounds formed. Thus make sure to understand the properties, formation and reactions of all the related organic compounds and then only try to solve such questions from sample test papers. 
One tip for Chemistry preparation to the aspirants for competitive exams as well as board exams is to pay special attention to named reactions. They make frequent appearance in examinations. You would come across many such questions in IIT JEE sample papers and AIEEE sample papers. 


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