Question

R bond OH in presence of red P and X2 gives RX.Explain​

Answer 1

Answer:

As for the second part of the question, this reaction is actually used commercially in the fine chemicals and specialty chemicals industry. An example that comes to mind is the reduction of 4-hydroxymandelic acid to 4-hydroxyphenylacetic acid. This intermediate is used in one route to the popular beta blocker "atenolol". Of course, as mentioned in the comments, other reactions are often favored when possible. In addition to the issues mentioned, phosphorus and iodine are both relatively expensive.