This video lecture from Carboxylic Acids (F.Sc. second year Chemistry) covers the reactions of carboxylic acids in which the hydroxyl group is involved. Thionyl chloride (sulfur equivalent of carbonyl chloride) reacts with carboxylic acids giving acid halides (halo group replaces hydroxyl-), HCL and sulfur dioxide. The detailed reaction mechanism is discussed in the lecture. Find more e-learning material and educational video lectures in Urdu at maktab.pk. These videos are free to use for promotional and commercial purpose by keeping the credits to Maktab.