Beginning color - 5 drops Final color- 5 drops plus Acetone Observations in each

Question

Beginning color - 5 drops Final color- 5 drops plus Acetone Observations in each tube after adding in each tube est tube - 5 drops 1-2 drops of Chromic acid hromic acid ube became warm, muggy blue color formed, precipitate formed at bottom of tube, chemical reaction occurred 1: 1-Butanol lear muggy blue color ube got hot, turned a muggy blue color, formed 2-Butanol lear muggy blue color precipitate at the bottom, chemical reaction ccurred ube became hot, muggy blue color, precipitate ormed at the bottom of the tube, chemical reaction occurred 2-Methyl 1-Propanol lear muggy blue color color change appeared, no chemical reaction occurred : 2-Methyl 2-Propanol lear range

Explanation / Answer

2. Chemical equation occuring above is,

1. CH3-CH2-CH2-CH2-OH + H2CrO4 ---> CH3-CH2-CH2-COOH (ppt) + H2CrO3

2. CH3-CH2-CH(OH)-CH3 + H2CrO4 ---> CH3-CH2-CO-CH3 (ppt) + H2CrO3

3. CH3-CH(CH3)-CH2-OH + H2CrO4 ---> CH3-CH(CH3)-COOH (ppt) + H2CrO3

4. CH3-C(CH3)(OH)-CH3 + H2CrO4 ---> No reaction

This is an oxidation reaction wherein the alcohol gets oxidized to a carboxylic acid or a ketone. Decolorisation of initial chromic acid reagent proves the reaction has occured.

3. In 1. and 3. the alcohol is primary in nature. In 2. the alcohol is secondary in nature. In 4 the alcohol is tertiary in nature.

4. The primary and secondary alcohols react with chromic acid reagent to give carboxylic acid and ketone, respectively. On the other hand the tertiary alcohol fails to react with the added reagent as it does not have a hydrogen to loose on the carbon to which -OH group is attached.

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