Xanthenyl chloride adds readily to asymmetric diarylethylenes to give after dehydrochlorination, 1,1-bis-(p-substituted phenyl)-2-(xanthen-9-yl)ethylenes. The nature of the para-substituent in the olefinic products has an influence on their reaction with bromine. In the presence of p-alkoxy-groups 1,1-bis-(p-alkoxyphenyl)-2-bromo-2-(xanthen-9-yl)ethylenes are obtained as main products; small quantities of xanthenyl tribromide, 1,1-diaryl-2-bromoethylenes, and xanthen are also isolated. The latter three compounds are the main products when the para-substituents are bromine, chlorine, or hydrogen.

The structures of the 1,1-bis-(p-alkoxyphenyl)-2-bromo-2-(xanthen-9-yl)ethylenes were confirmed by (a) ozonolysis and (b) transformation with alcoholic potassium hydroxide into the corresponding allenes [1,1-bis-(p-alkoxyphenyl)-2-(xanthen-9-ylidene)ethylenes].