92-41-1Relevant academic research and scientific papers
Method of synthesizing, purifying and refining 2,6-naphthalene disulfonic acid
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Paragraph 0028; 0029; 0030; 0031, (2018/11/22)
The invention discloses a method of synthesizing, purifying and refining 2,6-naphthalene disulfonic acid. The method comprises the following steps of 1) sulfonation and solventing-out: heating refinednaphthalene and concentrated sulfuric acid for sulphonation to produce 2,6-naphthalene disulfonic acid and 2,7-naphthalene disulfonic acid, and performing solventing-out with water and filtering to obtain a 2,6-naphthalene disulfonic acid filter cake and a 2,7-naphthalene disulfonic acid mother liquor; 2) washing: by taking ammonia water with the mass percentage being 0.08-0.20 percent or a 0.15-0.28 percent ammonium sulfate aqueous solution as a washing reagent, washing the 2,6-naphthalene disulfonic acid filter cake to obtain a 1-grade 2,6-naphthalene disulfonic acid filter cake and a 1-grade refined filtrate, performing circulation washing on the 2,6-naphthalene disulfonic acid filter cake for 2-4 times at this way to obtain a 2,6-naphthalene disulfonic acid product with the purity larger than 99 percent; and 3) washing solution indiscriminate application: enabling the 1-grade refined filtrate to return for indiscriminate application to a solventing-out procedure in the step 1) and/or a washing procedure in the step 2), and enabling the residual refined filtrate to return for indiscriminate application to the washing procedure in the step 2). The method provided by the invention realizes the purposes of acquiring high-quality 2,6-naphthalene disulfonic acid with separation, refining and purification, increasing the yield of 2,7-naphthalene disulfonic acid and lowering wastewater discharge.
Environmental-friendly H-acid synthesis method
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Paragraph 0036-0038, (2017/10/13)
The invention relates to a synthesis method and in particular relates to an environmental-friendly H-acid synthesis method which comprises the following steps: performing disulfonic treatment, performing bromination treatment, performing nitration treatment, and separating a middle body, namely 1-bromine-8-nitro-3,6-naphthalene disulfonic acid. The environmental-friendly H-acid synthesis method is capable of reducing environment pollution and preventing such potential safety hazard, and thus an operation environment is relatively safe and environmentally friendly.
On the positional reactivity order in the sulfuric acid sulfonation of the two naphthalenesulfonic acids
Wit, Peter De,Cerfontain, Hans
, p. 1453 - 1455 (2007/10/02)
The sulfonation in 98.5percent H2SO4 at 25.0 deg C of naphthalene-1-sulfonic acid yields 58percent 1,5-, 32percent 1,6-, and 10percent 1,7-disulfonic acids and that of the 2-sulfonic acid 4percent 1,3-, 74percent 1,6-, 18percent 1,7-, and 4percent 2,6- + 2,7-disulfonic acids.Further sulfonation of the latter disulfonic acid mixture in 105.2percent H2SO4 at 25.0 deg C yields 78percent 1,3,6- and 12percent 1,3,5- + 1,3,7-trisulfonic acids.Reaction of naphthalene-1,5-disulfonic acid with 105.2percent H2SO4 at 25 deg C yields 5-sulfonaphthalene-1-sulfonic anhydride.Partial rate factors for the sulfonation of naphthalene-1- and -2-sulfonate in highly concentrated aqueous sulfuric acid (where the sulfonating entity is H2S2O7) are reported.They are discussed in terms of the difference in the reactivity of the α- and β-positions of the naphthalene skeleton and the electronic and steric effects of the sulfonate substituent already present.
Process for separation of naphthalenedisulfonic acids
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, (2008/06/13)
A process for separating 1,6-naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid or 2,7-naphthalenedisulfonic acid selectively from reaction mixtures obtained by disulfonation of naphthalene under different reaction conditions is disclosed. For example, a particular disulfonation reaction of naphthalene is carried out which favors the formation of a particular isomer. This reaction mixture is diluted with water to adjust the sulfuric acid concentration to 35 to 90% by weight and the temperature is maintained at 0° to 80° C.; 1,6-naphthalene-disulfonic acid is selectively separated at high purity.
