CS273983B1 - Method of 2-and- 4-toluene sulphonamide's mixture insulation - Google Patents

Abstract

The invention simplifies the technology of isolation of 2- and 4-toluene sulphonamide from residue after refining toluene sulphonamide. The essence of the invention is that an aqueous suspension is prepared after refining which is maintained at 1 to 60 minutes at 105 to 200 degrees C under uniform pressure in the system. After cooling the water layer is separated and from that, after further cooling, a mixture of 2- and 4-toluene sulphonamide is crystallised. The aqueous suspension can contain sulphuric and/or hydrochloric acid.

Description

The invention 3a relates to a process for the isolation of a mixture of 2- and 4-toluenesulfonamide from the crude 2-toluenesulfonamide refining residue in the production of saccharin by the Fahlbarg-Remsan process.

Mixture of 2- and 4-toluenesulfonamide It is a useful raw material used, for example, as a property modifier; especially phenol-formaldehyde; urea-formaldehyde and non-aminoformaldehyde resins, as a raw material for the manufacture of chloramine-based disinfectants and as brighteners for the electroplating baths. These mixtures (for example KetjenQ flex - Netherlands, Naramid - Czechoslovakia) are obtained by treatment of the crude 2-toluenesulfonamide refining residue, which also contains the remaining isomers (3- and 4-toluenesulfonaraid), ditolylsulfones and various resinous substances.

The treatment of the crude 2-toluenesulfonamide refining residue has so far been carried out in two ways. According to Ča. No. 25S 641, the refining residue is dissolved in an aqueous solution of alkaline hydroxide and, after separation of insoluble impurities and physical ionic sorption of coloring impurities, the mixture of 2- and 4-toluenesulfonamide is released from the solution of the respective salts by treatment with mineral acid. In this way, more than 90% of the toluenesulfonamides contained therein can be obtained from the refining residue. The disadvantage of this method, however, is the imperfect removal of coloring impurities, which is a defect in many applications. The crude 2-toluenesulfonamide residue can be treated to the desired mixture of 2- and 4-toluenesulfonamide by leaching at 80-90 ° C with water at atmospheric pressure. The aqueous phase is saturated with toluenesulfonamides; which crystallize upon cooling. The mother liquor contains a portion of toluenesulfonamide and concentrated ditolylsulfones and resinous substances. The quality of the product obtained makes it suitable for use in any industry. The disadvantage of this process is the low process yield of about 30% relative to the original toluenesulfonamides content. waste water.

More preferably, the process of laolacating 3-mixtures of 2- and 4-toluenesulfonamide with the residue after refining the crude 2-toluenesulfonamide; further comprising, in particular, 3-toluenesulfonamide and ditolylsulfones, according to the present invention, characterized in that the residue is prepared from an aqueous suspension having a concentration of 1 to 30% by weight, which is maintained at 105 to 105 ° C for 1 to 60 minutes. 200 ° C at system pressure; thereafter the aqueous layer is separated from the reaction mixture after cooling, from which 2- and 4-toluenesulfanamide are mixed by cooling the crystals. The aqueous suspension solution may contain sulfuric and / or hydrochloric acid in a concentration of 0.05-10% by weight. The cooling crystallization can be carried out at a rate of 1 to 25 k / h in the presence of a nucleation batch of crystals of the same phase in an amount of 1 to 20% by weight. secreted phase.

The invention is based on the finding that toluenesulfonamides are miscible with water at a temperature above 100 ° C and a pressure corresponding to the water vapor pressure at a given temperature, so that they completely pass into the water phase, while other undesirable substances, ie ditolylsulfones, remain resinous and coloring agents.

An advantage of the process for the isolation of toluenesulfonamide according to the invention is that a mixture of 2- and 4-toluenesulfonamide of high purity can be prepared with a high yield of up to about 65%. The process according to the invention is characterized by low laboriousness in industrial implementation; low water consumption with a minimum amount of waste. The purity of the product can be increased by repeating the entire purification process.

Addition of ε-lrcvó or hydrochloric acid to the defective suspension increases the separability of the water layer; the addition of a nucleation batch increases the size of the crystals produced.

Examples

Example 1

100 g of waste amide having the following composition: 31.7 wt. 4-toluenesulfonamide; 9; % 3-toluenesulfonamide, 46.3% wt. 2-toluenesulfonamide; 0; 8 wt.

2, 2'-ditolylsulf one, ⁵ 0, 2% by weight. 2 ', 3'-ditolylsulfone;8; 2/4 * -ditclylsulfon,

CS 273 983 80

0; 8 wt. % 3; 4'-di-tolyl-3-sulfone; 4,4 ' -ditolylsulfone and added to a total weight of 1000 g water. The autoclave was heated to 150 ° C (0/4 MPa overpressure) and held for 20 minutes under the above conditions. The autoclave was then freely cooled to 90 ° C. and the upper aqueous sulfur layer was separated from the lower oil layer. The aqueous layer was cooled with stirring to 25 ° C at a rate of 10 K / h. The ³ crystalline solids were separated, washed with 9-water and dried. 48 g of a white crystalline substance having a composition were obtained. % By weight 38; 4-toluenesulfonamide; 5/0 wt. % 3-toluenesulfonamide, 54; % Of 2-toluene sulfonamide and 0.4 wt. % 2; 4'-ditolylsulfone / 0.1% wt. 4; 4'-ditolylsulfone.

Example 2

The embodiment is the same as in Example 1; The composition is characterized in that 0.06 ml of conc. H2SO4 are added to the waste amide / water mixture. The yield increased compared to Example 1 to 58 g due to better separability of the aqueous and oily layers in the autoclave.

Example 3

Same as Example 1; The yield was reduced from 65% at 50 g batch to 30% at 250 g batch.

Example 4

Carrying out the same procedure as in Example 1, 5% of the precipitated solid phase from the previous operation was introduced into the separated aqueous phase at 85 ° C. The mean particle size of the product was increased from 0.2 mm to 0/45 mm by this measure.

object of the invention

Claims (3)

A process for the isolation of a mixture of 2- and 4-toluenesulfonamide from a residue containing in particular 3-toluenesulfonamide and ditolylsulfones as additional ingredients; which is omitted when refining the crude 2-toluenesulfonamide; characterized! with it; the remainder of this aqueous suspension with a concentration of 1-30% on a weight that ee for 1 to 60 minutes is maintained at 105 to 200 ° C under the equilibrium pressure in the system, then ^one from the reaction mixture, optionally after cooling, separating said aqueous layer from which a mixture of 2- and 4-toluenesulfonamide crystallizes by cooling. 2. The process according to claim 1, wherein the aqueous suspension solution comprises sulfuric acid and / or hydrochloric acid in a concentration of 0.05 to 10% by weight. 3. The process according to claim 1, wherein the cooling crystallization is carried out at a controlled rate of 1 to 25 K / h in the presence of a nucleation batch of crystals of the same phase in an amount of 1 to 20% by weight. secreted phase.