Q46E - Organic Chemistry (Mcmurry)

Question

What products would you obtain from reaction of 1-pentanol with the following reagents?

(a) ${\mathbf{PBr}}_{\mathbf{3}}$

(b) ${\mathbf{SOCl}}_{\mathbf{2}}$

(c) ${\mathbf{CrO}}_{\mathbf{3}}\mathbf{ }\mathbf{,}\mathbf{ }{\mathbf{H}}_{\mathbf{2}}\mathbf{O}\mathbf{ }\mathbf{,}\mathbf{ }{\mathbf{H}}_{\mathbf{2}}{\mathbf{SO}}_{\mathbf{4}}$

(d) Dess- Martin periodinane

Step-by-Step Solution

Answer

(a) 

(b) 

(c) 

(d) 

Step 1: Reaction of alcohols with PBr 3   ,   SOCl 2 ,   CrO 3 and Dess-Martim periodinate

The reaction of alcohols with ${\mathbf{PBr}}_{\mathbf{3}}$ produces the corresponding bromides. Alcohols produce the corresponding chlorides when reacted with ${\mathbf{SOCl}}_{\mathbf{2}}$ .Primary alcohols are oxidized into carboxylic acids and secondary alcohols are oxidized into ketones in the presence of ${\mathbf{CrO}}_{\mathbf{3}}$ .   

Step 2: Product obtained by the reaction of pentanol with several reagents

(a)The reaction of alcohol with ${\mathrm{PBr}}_3$ generates the corresponding bromide. The compound 1-pentanol reacts with ${\mathrm{PBr}}_3$  to form 1-bromopentane. The reaction can be given as:

                      Reaction (a)

(b)The reaction of alcohol with ${\mathrm{SOCl}}_2$  produces the corresponding chloride. The compound, 1-pentanol reacts with ${\mathrm{SOCl}}_2$  to form 1-chloropentane. The reaction can be given as:

                   Reaction (b)

(c)The reaction of alcohol with ${\mathrm{CrO}}_3$  and  gives carboxylic acids or ketones. The compound, 1-pentanol reacts with ${\mathrm{CrO}}_3$ and ${\mathrm{H}}_3{\mathrm{O}}^{+}$  to form pentanoic acid. The reaction can be given as:

(d)The reaction of alcohol with Dess-Martin periodinate produces aldehydes or ketones depending on the alcohol. The compound, 1-pentanol reacts with periodinane and ${\mathrm{CH}}_2{\mathrm{Cl}}_2$  to form pentanal. The reaction can be given as:

                     Reaction (d)