SULFONATION OF 1-NAPHTHOL AND 2-NAPHTHOL AND THEIR METHANESULFONATE ESTERS WITH SULFUR-TRIOXIDE - THE INFLUENCE OF INITIAL SULFATION ON THESULFO-PRODUCT COMPOSITION

The sulfonation of 1- and 2-naphthol with sulfur trioxide in C2H3NO2 h as been studied by using H-1 NMR. 1-Naphthol (1) yields, upon reaction with 1.0 mol-equiv of SO3, a mixture of 2-and 4-sulfonic acids (2- an d 4-S); upon increasing the reaction temperature, the relative amount of 2-S increases. Upon reaction with 4.0 mol-equiV of SO3, the initial ly observed products are the hydrogen sulfate 1-0,2,4-S3 and some corr esponding sulfonic anhydrides. After prolonged reaction times, some 1- 0-4,7-S3 is formed. 2-Naphthol (3), upon reaction with 1.0 mol-equiV o f SO3, yields a 85:15 mixture of 1-S and 8-S, whereas upon reaction wi th 2.0 mol-equiv of SO3, a 8:14:78 mixture of the 5-S, 6-S and 8-S are formed. Sulfonation of 3, either by (i) reaction with 1.2 and, subseq uently, an additional 2.0 mol-equiv of SO3, or (ii) by direct addition of 4.0 mol-equiv of SO3, yields a mixture of the carbyl sulfates 5-5- S and 5-6-S and the hydrogen sulfate 3-0,6,8-S3, the relative yield de pending on the method used. The results are discussed in terms of init ial formation of the corresponding naphthyl hydrogen sulfates and on t he basis of a comparison with the reactions of 1- and 2-naphthyl metha nesulfonates, the chosen model compounds for the hydrogen sulfates, wi th SO3.