Halogenation reagents for

In addition to carbonyl substrates, imines have been used extensively with phosphorus-halogen reagents for the preparation of a variety of phosphonates and phosphinates. Combined in a reaction medium, secondary amines react with formaldehyde and phosphorus trichloride134 135 or alkyldichlorophosphines136 to produce N,N-disubstituted aminomethylphosphonates or -phosphinates. These reactions occur under mild conditions with good yield. Similarly, aliphatic carboxylic amides react with aldehydes to generate imines, which can be used in situ with diphenylchlorophosphine to produce... 

Ketone formation can also be avoided if one of the functional acyl halogens ia phosgene is blocked. Carbamyl chlorides, readily obtained by the reaction of phosgene with ammonia or amines, are suitable reagents for the preparation of amides ia direct Friedel-Crafts acylation of aromatics. The resulting amides can be hydroly2ed to the corresponding acids (134) ... 

Butylhypochlorite is one of the most effective reagents for the direct chlorination of ketones, and it may also be employed for combined oxida-tion-halogenation ... 

Halogenation (Section 11.12) Free-radical halo-genation of alkylbenzenes is highly selective for substitution at the benzylic position. In the example shown, elemental bromine was used. Alternatively, A/-bromosuccinimide is a convenient reagent for benzylic bromination. 

Anhydrous HX are versatile and vigorous reagents for the halogenation of metals, non-metals, hydrides, oxides and many other classes of compound, though reactions that are thermodynamically permissible do not always occur in the absence of catalysts, thermal initiation or photolytic encouragement, because... 

Halogens a to carbonyl groups can be successfully coupled using organocopper reagents. For example, 3,9-dibromocamphor is selectively arylated a to the carbonyl. 

Trivalent phosphorus-halogen reagents have been noted to be of use in obtaining simple Abramov-type products with chloral199 200 and with aldimines.201 Similarly, phosphorus-carboxylate anhydrides have been useful in overcoming the stereochemical difficulties associated with alkyl transfer for obtaining Abramov-type products in a direct manner.202 205... 

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