NTA Abhyas JEE Main2020ChemistryCarboxylic Acid DerivativesPractice
What represents the best method for converting a carboxylic acid to an aldehyde?
Options
- AConvert the acid to an acid chloride, and react the acid chloride with water.
- BReduce the acid with L i A l H 4 .
- CConvert the acid to an acid chloride, and reduce the acid chloride with lithium aluminium tri(t-butoxy) hydrid
- DConvert the acid to an acid chloride, react the acid chloride with a Grignard reagent, and reduce the product
Correct answer
C. Convert the acid to an acid chloride, and reduce the acid chloride with lithium aluminium tri(t-butoxy) hydrid
Step-by-step solution
(i) This method will not work R C O O H → S O C l 2 / P C l 3 / P C l 5 R C O C l → H 2 O R C O O H Aldehyde will not form (ii) Carboxylic acid are not reduced by L i A l H 4 . (iii) This method is best R C O O H → S O C l 2 / P C l 3 / P C l 5 R C O C l → l i t h i u m a l u m i n i u m t r i t - b u t o x y h y d r i d e . R C H O a l d e h y d e (iv) This method will produce alcohol rather than aldehyde: R C O O H → S O C l 2 / P C l 3 / P C l 5 R C O C l → I R ′ M g B r R C O R ′ → L i A l H 4 3 ο a