DE95830C - - Google Patents

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CLASS 12: Chemical processes and apparatus.

It has been found that primary aromatic amines convert smoothly into sulfinic acids leave if you diazotirl them in sulfuric acid solution and the diazo solution if present of sulphurous acid with copper powder (see Ber. d. d. former Ges. 23, 1218 and 25, 1086) offset. The reaction probably proceeds in such a way that it emerges from the diazosulphate Diazosulphite forms which, through the sulphurous acid or the copper, one atom of oxygen is withdrawn, while at the same time the diazo nitrogen is eliminated by the copper.

C ₆ H ₅ -N ₂

SO ₄ ^ H + H ₂ SO ₃ = C ₆ H _h -N ₂ S O ₃ H + H ₂ S O ₄ ,

C ₆ H _t ■ N ₂

SO ₃ H +] , ^S " ² = C ₆ Hs-SO ₂ H + N ₂ +] 1 η η ³ (or Cu. ^{6 5} 2121 ( _or the Cm 0.

The present method is essentially different from that in Ber. d. d. former Ges. 23, 1454. While according to Landsberg (1. c.) By treating diazobenzene sulfate with cupro hydroxide and aqueous sulphurous acid, benzene sulphonic acid, which was obtained in poor yield, arrives one in the present way for the first time in a smooth manner to aromatic sulfinic acids.

For the implementation of the procedure, which is generally applicable, let the following be Examples are given from which it is also clear in what way the procedure can be varied.

Example 1.

Part of aniline is cone in a mixture of 3 parts. Dissolved sulfuric acid and 15 parts of water and diazotized in a known manner. This diazo solution is added as quickly as possible, with good cooling, to a saturated aqueous solution of sulphurous acid, which must be present in excess, and in which about 6 parts of copper powder are suspended, care must be taken to ensure good stirring. There is a violent evolution of nitrogen. The reaction is ended as soon as this development has ceased and no more diazo compound can be detected. The benzenesulfinic acid formed can easily be isolated by etherification. It shows the known properties; Mp. 83-84 ⁰ etc. (d Beilstein, Handbuch. Organ. Chemie, III Ed., Volume II, page 108).

Example 2.

Part o-anisidine is cone in 3 parts. Sulfuric acid, diluted with 15 parts of water, is dissolved and diazotized in the usual way. Excess gaseous form is passed into the diazo solution thus obtained, with good cooling sulphurous acid and then, just like

if under cooling and with thorough stirring, as quickly as possible with 6 parts of copper powder. When the reaction has ended, the sulfinic acid is isolated by etherification.

The new acid is easily soluble in hot water and sparingly soluble in cold water. It crystallizes from it in colorless needles united in tufts of F. P. 87 to 88 °. From diluted It can easily be salted out with an aqueous solution. The alkali salts of the acid are in water Extremely easily soluble, as is the barium salt. The acid is easily soluble in ether, alcohol, Chloroform and acetone, almost insoluble in carbon disulfide and ligroins.

Example 3.

1 part of o-toluidine is cone in a mixture of 4 parts. Dissolved sulfuric acid and 10 parts of water and converted into the diazo compound. Six parts of copper powder are added, with good cooling and thorough stirring. It then gives as quickly as possible to 5 parts sodium bisulfite 40 ⁰ B.. It is then limed, the solution of the lime salt evaporated to dryness and the sulfinic acid calcium extracted from the residue with alcohol. The free acid has a melting point of 80 ° and otherwise shows all the properties described in the literature (Beilstein, III. Edition, Volume II, page 110).

Example 4.

Part of Kj-naphthylamine-a ₂ -sulfonic acid is cone with 3 parts. Sulfuric acid and 5 parts water are added and diazotized. The procedure is then exactly as indicated in Example 2 for the o-anisidine. When the reaction has ended, it is made alkaline with soda, filtered off, and the sulfinic sulphonic acid is separated from the filtrate as the sodium salt by salting out. The sodium salt is very easily soluble in water; it crystallizes from hot cone, aqueous solutions on cooling in white, six-sided, iridescent leaflets. It can be easily salted out of the aqueous solution with table salt. Likewise, the potash salt of acid is easily soluble in hot water; When the hot aqueous solutions cool, it crystallizes in needles combined into woolly aggregates. The barium salt is extremely sparingly soluble in cold and hot water; from the solutions of the alkali salts it precipitates with chlorbarium in the cold in white flakes, which turn into an indistinctly crystalline, sandy powder when cooked.

The acid can be converted smoothly into the known Ci ₁ O ₂ -naphthalene disulfonic acid by oxidation with potassium permanganate.

Example 5.

Part of the condensation product of o-toluidine and tetramethyldiamidobenzhydrol of the constitution

NfCHJ.

CH ₃

NfCH ₃ Y,

is cone in a mixture of 2 parts. Sulfuric acid and 10 parts water are diazotized with the calculated amount of nitrite. It will saturated with sulphurous acid and then with cooling and with good stirring for so long 4 to 5 parts of copper powder are added until no more nitrogen escapes. It is dated Filter off copper powder and add excess soda solution to the filtrate while it is warm. When it cools down, the sodium salt of sulfinic acid separates into pale greenish colored, shiny rhombic leaves. The deposition is achieved by adding table salt of the salt completed.

The barium salt of the acid is very sparingly soluble, even in hot water; from the Solutions of the alkali salts are precipitated as a white amorphous precipitate by chlorobarium. The potassium salt, obtained from the barium salt by reaction with potash, is easily soluble in hot water and crystallized from it when cooling in white microscopic needles. Color while lying in the air all salts turn green by oxidation.

The aromatic sulfinic acids described above are said to be used in the manufacture of medicinal products and dyes are used.

Claims (1)

Patent claim: Process for the preparation of aromatic sulfinic acids, consisting in that aromatic Diazo compounds decomposed by copper powder in the presence of sulphurous acid.