Research On The Synthesis Of1,6-Naphthalenedisulfonic Acid Sodium

1,6-Naphthalenedisulfonic acid and1,6-naphthalenedisulfonic acid sodium are very important intermediates for the manufacture of dyes, organic pigments, medicines and agricultural chemicals.This paper relates to the synthesis and separation of1,6-naphthalenedisulfonic acid sodium. The synthesis of1,6-naphthalene disulfonic acid is divided into two stages: synthesis of2-naphthalene disulfonic acid at first, then continue to sulfonation. The influence of several conditions, such as acidy, ratio of naphthalene to sulfuric acid, reaction temperature, absorbent and reaction time were studied, and the optimum reaction conditions were determined.(1) Under conditions of98%H2SO4,2-naphthalene disulfonic acid is obtained by sulfonation of naphthalene.Under conditions of the amount of naphthalene,64g, the amount of98%H2SO4,64g, maintaining the reaction temperature150℃for2h, the content of2-naphthalenedisulfonic acid is92.45%.(2) When the reaction of2-naphthalene disulfonic acid is over, it is necessary to decrease the reaction temperature and sulfuric acid is added to continue the sulfonation. When using the98%H2SO4to sulfonation, the conversion rate of raw materials is low, and the content of1,6-naphthalenedisulfonic acid is only46.38%. So the optimium sulfuric acid is oleum. After the reaction of2-naphthalenedisulfonic acid, the amount of oleum,224g, the reaction temperature70℃for1.5h, the content of1,6-naphthalenedisulfonic acid is64.43%. (3) The separation of1,6-naphthalenedisulfonic acid sodium also includes two parts. One is directly converted into1,6-naphthalenedisulfonate sodium. After the reaction, the yield of1,6-naphthalene disulphonate sodium is42.63%and the content of it is96.93%.The other is the separation of1,6-naphthalenedisulfonic acid, then converted naphthalenedisulfonic acid into naphthalene disulphonate sodium. Through the study of the influence of several conditions, the yield of1,6-naphthalene disulphonate sodium is57.06%and the content of it is96.95%.(4) Solubility of1,6-naphthalenedisulfonic acid disodium in binary sodium chloride+water was measured with temperature range from (273.15to323.15K) by a steady-state method.