Download full text in PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Tetrabromo- - and -dichlorobenzenes are only dilithiated, even with excess -butyllithium, although more than two bromines are replaced by methyl groups when such solutions are treated with methyl sulfate. ... For : mp 215–217°C; 1 H NMR (CCl 4 ) δ 2.43 (s, 6 H), 2.55 (s, 3 H); ...