Sentence:  We are reporting these investigations here briefly because of their relevancy to problems of the study of apparently simple exchange reactions of <WSD>chlorine</WSD> and because the results furnish some information on the activation energy for abstraction of chlorine atoms from carbon tetrachloride . 
Meaning of the word marked with <WSD> tags:  a common nonmetallic element belonging to the halogens; best known as a heavy yellow irritating toxic gas; used to purify water and as a bleaching agent and disinfectant; occurs naturally only as a salt (as in sea water)