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PROCESS FOR WORKING UP A COMPOSITION COMPRISING SOLID 4,4'-DICHLORODIPHENYL SULFOXIDE AND A SOLVENT

20220213031 · 2022-07-07

    Inventors

    Cpc classification

    International classification

    Abstract

    The invention relates to a process for working up a composition comprising solid 4,4′-dichlorodiphenyl sulfoxide and a solvent, wherein the amount of solvent in the composition is in the range between 5 and 25 wt % based on the total mass of the composition by washing the composition using a carboxylic acid until the amount of solvent in the composition is below 1.5 wt % based on the total amount of the composition after washing.

    Claims

    1.-13. (canceled)

    14. A process for working up a composition comprising solid 4,4′-dichlorodiphenyl sulfoxide and a solvent, wherein the amount of solvent in the composition is in the range between 5 and 25 wt % based on the total mass of the composition, the process comprising washing the composition using a carboxylic acid until the amount of solvent in the composition is below 1.5 wt % based on the total amount of the composition after washing.

    15. The process according to claim 14, wherein the washing is carried out in a filtration apparatus.

    16. The process according to claim 15, wherein the amount of carboxylic acid used for washing the composition is at least 0.15 times the total mass of the composition comprising solid 4,4′-dichlorodiphenyl sulfoxide and solvent.

    17. The process according to claim 15, wherein the amount of carboxylic acid in the composition after washing is in the range between 6 and 30 wt % based on the total mass of the composition.

    18. The process according to claim 15, wherein the composition after washing is mixed with carboxylic acid to obtain a mixture comprising 4,4′-dichlorodiphenyl sulfoxide and carboxylic acid in a weight ratio of 4,4′-dichlorodiphenyl sulfoxide to carboxylic acid of at least 1:2.

    19. The process according to claim 14, wherein after washing the composition comprises 4,4′-dichlorodiphenyl sulfoxide and carboxylic acid in a weight ratio of 4,4′-dichlorodiphenyl sulfoxide to carboxylic acid of at least 1:2.

    20. The process according to claim 14, wherein a liquid mixture comprising solvent and carboxylic acid is withdrawn from the washing and the mixture is separated into a first stream comprising substantially solvent and a second stream comprising substantially carboxylic acid.

    21. The process according to claim 20, wherein the separation into the first stream and second stream is carried out by distillation.

    22. The process according to claim 20, wherein the second stream is recycled into the washing.

    23. The process according to claim 20, wherein the first stream is recycled into a production process of 4,4′-dichlorodiphenyl sulfoxide.

    24. The process according to claim 14, wherein the composition comprising solid 4,4′-dichlorodiphenyl sulfoxide and solvent is a filter cake obtained by filtering a suspension containing 4,4′-dichlorodiphenyl sulfoxide in the solvent.

    25. The process according to claim 14, wherein the solvent is chlorobenzene.

    26. The process according to claim 14, wherein the carboxylic acid is at least one aliphatic C.sub.6 to C.sub.10 carboxylic acid.

    Description

    EXAMPLES

    [0105] Effect of Amount of Carboxylic Acid

    [0106] A suspension comprising 84.7 wt % DCDPSO and 15 wt % monochlorobenzene (MCB) and the balance impurities like isomers of 4,4′-dichlorodiphenyl sulfoxide and further by-products of a production process of DCDPSO were subjected to a washing with heptanoic acid. Table 1 compiles the results regarding the composition of the filter cake depending on the conditions for replacing the MCB by heptanoic acid (HeptA). The amounts in wt % all are based on the total amount of the respective wet filter cake.

    TABLE-US-00001 TABLE 1 Washing of MCB wet filter cake with HeptA Filter Cake Composition Ratio [g/g] 4,4′- 4,4′-DCDPSO Filter Filter MCB HeptA DCDPSO Cake cake:HeptA [wt %] [wt %] [wt %] MCB wet 15.0 — 84.7 Washed with HeptA 1x 1:1 (25° C.) 0.3 16.5 82.9 Washed with HeptA 2x 1:1 (25° C.) — 17.2 82.4 MCB wet 15.0 — 84.7 Washed with HeptA 1x 2:1 (25° C.) 0.8 13.0 85.8 Washed with HeptA 2x 2:1 (25° C.) 0.1 15.0 84.4 MCB wet 15.0 — 84.7 Washed with HeptA 1x 2:1 (10° C.) — 13.7 81.9 Washed with HeptA 2x 2:1 (10° C.) — 13.3 82.9 MCB wet 15.0 — 84.7 Washed with HeptA 1x 4:1 (25° C.) 0.3 14.9 79.6 Washed with HeptA 2x 4:1 (25° C.) — 14.1 81.7

    [0107] As can be seen from the examples, it is possible to replace the MCB by the heptanoic acid in such an amount that no more MCB could be detected in the filter cake.