Electrophilic Attack by Phosphorus

Electrophilic Attack by Phosphorus. A detailed discussion has appeared of the displacement reactions of l-chloro-2,2,3,4,4-pentamethylphosphetan (8) and its oxide and sulphide. The chloride (8) always undergoes inversion as a result of substitution at phosphorus, and this is rationalized on the basis of a transition state (9) in which the entering nucleophile (Nu) and the chloride leaving-group occupy apical sites. Although a pathway via (9) 

Simple displacement reactions leading to the cyanides (13), and to the phosphinothioites (14) and (15) have been described. 

Rizpolozhenskii, V. D. Akamsin, and R. M. Eliseenkova, Izvest. Akad. Nauk 

Potapov, E. A. Krasil nikova, and A. I. Razumov, Zhur. obshchei Khim., 1970, 

Reactions.—Electrophilic Attack by Phosphorus. This year has seen a resurgence in Friedel-Crafts and related chemistry of the halogenophosphines, with the general objective of establishing mechanisms. For example, the conversion of phosphorus trichloride into complexes of either dichlorophenylphosphine (28) or chlorodiphenylphosphine (29) has been studied in order to establish the 

PhH + PClj + AlCL PhPClj.AlCIj PhjPCl.AlClj 

A similar treatment of the ethylene-phosphorus tribromide reaction has been published. When aluminium tribromide is used as catalyst, the AlBrg PBra ratio is important, and determines whether the product is the dibromo-phosphine (30) (ratio 1 320), or whether the complex (31) predominates 

The related reaction of ethylene with phosphorus trichloride in the presence of aluminium halides has had a chequered history. The original paper on this route to P—C bonds made no mention of the use of ethylene as olefinic component. Subsequently, Russian workers reported the isolation of the phosphines (32) and (33) from ethylene-phosphorus trichloride reactions. 

The addition of phosphorus trichloride to olefins in the presence of per-chloryl fluoride (36) has been further studied. The olefinic component of 

---