Sulfonation Of Naphthalenes In Microreactor

Sulfo-naphthalene products are intermediates used in the production of dyes and dispersants,including reactive dyes,acid dyes,direct dyes,dispersant NNO and dispersant MF.They are important intermediates in dyestuff industry.Concentrated sulfuric acid and oleurn are used in conventional sulfonation.Ten or more times of excess acid is used,which generates a large number of waste acid and secondary pollution.It is well-known that stoichiometric sulfur trioxide is only needed in sulfur trioxide sulfonation,and no waste acid is generated in the SO₃ technology.It is acknowledged as a clean technology.But these kinds of reactions are very rapid and exothermic.The local overheating easily happens,resulting in producing of by-products such as sulfone,and side reactions such as multi-sulfonation,oxidation and coking.So it is difficult to control in industry.This paper describes firstly a microreaction of sulfur trioxide:the sulfonation processes in a microreactor.The advantages are accrurate control of reaction temperature,reaction time,feed ratio ete,acquiring higher yeild,continuous and automatic reaction process and no waste acid.From the solfonations of naphthalene and 2-naphthol with sulfur trioxide in microreactor,α-naphthalene sulfuric acid,G acid and Schaffer's acid are easily obtained in mild conditions. MS and HPLC are used to track the reactions.The effect of reaction temperature,reaction solvent reaction flow rate feed ratio concentration of reagents and volume of time retention...