Question

Why phosphorus pentachloride is used for chlorination of organic compounds

Answer 1

I dont know really sorry.....

Answer 2

Phosphorus pentachloride is the chemical
compound with the formula PCl 5 . It is one of
the most important phosphorus chlorides,
others being PCl 3 and POCl 3. PCl 5 finds use
as a chlorinating reagent. It is a colourless,
water-sensitive and moisture-sensitive solid ,
although commercial samples can be
yellowish and contaminated with hydrogen
chloride.

synthetic chemistry, two classes of
chlorination are usually of interest: oxidative
chlorinations and substitutive chlorinations.
Oxidative chlorinations entail the transfer of
Cl 2 from the reagent to the substrate.
Substitutive chlorinations entail replacement
of O or OH groups with chloride. PCl 5 can be
used for both processes.
Upon treatment with PCl 5, carboxylic acids
convert to the corresponding acyl
chloride.
The following mechanism has
been proposed:
It also converts alcohols to alkyl chlorides .
Thionyl chloride is more commonly used in the
laboratory because the resultant sulfur dioxide
is more easily separated from the organic
products than is POCl 3.
PCl 5 reacts with a tertiary amides, such as
dimethylformamide (DMF), to give
dimethylchloromethyleneammonium chloride,
which is called the Vilsmeier reagent ,
[(CH 3) 2N=CClH]Cl. More typically, a related
salt is generated from the reaction of DMF
and POCl 3. Such reagents are useful in the
preparation of derivatives of benzaldehyde by
formylation and for the conversion of C−OH
groups into C−Cl groups. [12]
It is especially renowned for the conversion of
C=O groups to CCl 2 groups. [13] For example,
benzophenone and phosphorus pentachloride
react to give the

diphenyldichloromethane :
(C 6H 5) 2CO + PCl 5 → (C 6H 5) 2CCl 2 +
POCl 3

The electrophilic character of PCl 5 is
highlighted by its reaction with styrene to
give, after hydrolysis , phosphonic acid
derivatives.