question_answer 5)

                Draw the structures of major monohalo products in each of the following reactions:   (i) (ii)   (iii) (iv) (v)   (vi)  

Answer:

(i)   Note The reaction takes place in the presence of pyridine. The method is known as Darzen?s method. (ii) Note Bromination does not take place in benzene ring. (iii)   Note Phenolic ? OH group is not replaced by  group. (iv)   Note According to Markownikoff?s rule, iodine will odd to the caron atom having less number of hydrogen atoms. (v) Note Iodide ion is a strong nucleophile so it displaces bromide ion. (vi) Note Under above specified conditions, allylic halogenations takes place.Addition reaction can take place only if reaction is at room temperature.