35857-70-6Relevant academic research and scientific papers
Etamsylate and calcium dobesilate impurities, and preparation method and application thereof
-
Paragraph 0090; 0120-0124, (2020/05/01)
The invention discloses four types of etamsylate and calcium dobesilate impurities, namely a 2,5-dihydroxy-1,4-benzene disulfonic acid compound, a 2,4-dihydroxy-1,5-benzene disulfonic acid compound, a2,5-dihydroxy benzene sulfonate compound and a 2,3-dihydroxy benzene sulfonic acid compound, and a preparation method thereof. The purity of all the prepared compound is 96% or more, and the compounds can be used for the quality control of etamsylate and calcium dobesilate bulk drugs and preparations.
Sulfonation and sulfation on reaction of 1,2-dihydroxybenzene and its methyl ethers in concentrated aqueous sulfuric acid
Cerfontain, Hans,Coenjaarts, Norbert J.,Koeberg-Telder, Ankie
, p. 325 - 330 (2007/10/02)
The homogeneous sulfonation of 1,2-dihydroxybenzene (1), its monomethyl (2) and dimethyl ether (3) in concentrated aqueous sulfuric acid at 25 deg C has been studied and isomer distributions, as well as rate coefficients for the sulfonation of 1-3 and their monosulfonic acids, have been determined.In 73.5-87.5percent H2SO4, 1 yields the 3- and 4-sulfonic acids in a ratio of 25:75, 2 yields the 4-, 5- and 6-sulfonic acids in a ratio of 46:36:18 in 73.5percent H2SO4 and 50:39:11 in 87.5percent H2SO4, whereas 3 yields only the 4-sulfonic acid.The remarkable absence of the 3-sulfonic acid (87.5percent H2SO4, the 4-sulfonic acid of 1 and the 5-sulfonic acid of 2 are present in part in the form of their hydrogen sulfate.In that acid region, the 3- and 4-sulfonic acids of 1 both yield the 3,5-disulfonic acid, the 4- and 6-sulfonic acids of 2 both yield the 4,6-disulfonic acid and the 4-sulfonic acid of 3 mainly yields the 4,6- together with some 4,5-disulfonic acid.
