Summary Diaryl lead dichlorides react in some cases with mercury diaryls to form the aryl mercuric chloride and a triaryl lead chloride. Triaryl or alkyl lead halides disproportionate on heating to form a tetrasubstituted lead derivative and a disubstituted lead dihalide. Diaryl or alkyl lead dihalides react with their corresponding tetraaryl or alkyl derivatives to form trisubstituted lead halides in good yields.