DE140999C - - Google Patents

Description

IMPERIAL

PATENT OFFICE.

M 140999 CLASS 12 o.

In patent 138790 and in the first amendment

(Patent 139956) has shown that naphtols when heated with alkalis or alkaline solutions and oxidizing metal oxides up to can be oxidized to phthalic acid.

It has now been found that not only naphthols, but also other substitution products of naphthalene, such as nitronaphthalene, Naphthylamine, naphthalene sulfonic acids, also the substituted naphthols, such as nitrosonaphthols, Nitronaphthols, naphthol sulfonic acids, etc., when heated with alkalis or alkaline solutions and oxidizing metal oxides are oxidized up to phthalic acid, whereby here, too, Benzoic acid is probably formed as a cleavage product of phthalic acid.

So you can get phthalic acid in addition to more or less benzoic acid and intermediates for example from the following starting materials and in the following way:

Example I.
From ι-nitroso-2-naphtol.

The nitroso- and nitronaphthols are most expedient for the purpose of oxidation with alkaline solutions and heated the metal oxides.

4.3 kg Nitrosonaphtol be heated with sodium hydroxide 25 1 27 ⁰ B. and 22 kg of copper in the autoclave for about 2 hours at 200 ⁰ then 3 hours at 240 to 260 ⁰ under pressure. The reaction product is suctioned off from the copper oxide, the solution is concentrated and the acids formed are precipitated hot with excess mineral acids. Phthalic acid can be derived from benzoic acid ζ. Β. separated by distillation.

Example II.

From ι-nitro-2-naphtol and i-nitro-4-naphtol.

α-Nitronaphthalene gives when carefully heated with alkalis and metal oxides i-nitro-2-naphtol and 1-nitro-4-naphtol. For this A mixture of nitronaphthols can be used to produce phthalic acid; the isolation of nitronaphthols is not necessary for this purpose, you can rather by heating the nitronaphthalene reach the phthalic acid directly with alkalis or alkaline solutions and metal oxides.

That obtained from nitronaphthalene by heating with caustic alkali and iron or copper oxide Mixture of two nitronaphthols (see Example IV) can be used as such for the preparation of phthalic acid Find use; but one can also use the nitronaphthols known from one another Separate wise and oxidize each nitronaphtol separately, but this offers no advantage.

*) Previous additional patent: 139956.

4.7 kg of the mixture of Nitronaphtole are mixed with 25 I sodium hydroxide solution, a 27 ⁰ B. 18 kg of copper under pressure to 240 to 250 ⁰ 3 hours heated. After the autoclave has cooled down, the ammonia formed is first blown off, then the alkaline solution is sucked off from the copper oxide and the acids are precipitated from the filtrate.

Example III.

Made from a-nitronaphthalene. ■

4.3 kg of a-nitronaphthalene and 26 l of sodium hydroxide solution of 27 ^° B. are heated with 22 kg of copper oxide for 4 hours to 240 to 250 ^° in a closed autoclave. The reaction product is worked up as in Example II.

Example IV.
From ct-Ni tr ο η a ph tali η.

4.3 kg of α-nitronaphthalene, 7 kg of powdered Caustic soda and 9 kg of iron oxide are intimately mixed and, with frequent stirring, on

best in an oil bath, heated to 80 ° for 2 hours, then to 90 ° for 2 hours and 100 to 11 ° for 2 hours. After this time, the nitronaphtols have formed and can be isolated as such. Then allowed to cool slightly and then blends back further 4 kg of caustic soda and 9 kg of iron oxide and heated to 150 ^0; at this temperature begins under simultaneous escape of water vapor and important self-heating a lively Ainmoniakentwicklung which stops, is increased until the temperature of the mixture itself at 210 to 220 °, then is further heated up to 250 ⁰ and allowed to cool. The reaction mixture is boiled with water, the filtered, cooled solution is first carefully mixed with sulfuric acid until a black, resinous by-product has precipitated, then the again filtered solution is concentrated and the phthalic acid and benzoic acid formed are separated off by heating with sulfuric acid.

The naphthalene sulfonic acids corresponding to the naphthols also give directly without them to be converted into naphthols beforehand by fusing with alkali, when heated with alkali lye and metal oxides phthalic acid, but the yields are lower than those obtained using the corresponding amounts Naphthol can be obtained.

Example V.

5.7 kg of a- or ß-naphthalene sulfonic acid sodium, 50 1 sodium hydroxide solution (27 ⁰ B.), 0.9 parts of sodium chlorate and 36 kg of copper oxide are ^{heated to 260 to 270 0} for 8 hours under pressure. The acids are isolated in a known manner from the liquid filtered off from the copper oxide.

The naphthol sulfonic acids, which contain the sulfo and hydroxyl groups in the same nucleus , ■ are also easily oxidized to phthalic acid.

Example VI.

5,!> Kg of Nevile Winther acid, 9 kg of caustic soda, 15 liters of water and 55 kg of manganese peroxide paste with a manganese peroxide content of 65 percent are heated under pressure ^{to 240 to 260 0 for 4 hours.} The work-up is the same as in the other examples.

Phthalic acid can also be obtained from a-naphthylamine in the same way.

Example VII.

3.6 kg a-Naphtylamih, 4 kg of caustic soda, 36 kg barium peroxide and 20 1 of water are heated in an autoclave for 3 hours at 240 to 250 ⁰ under pressure. After cooling, the contents of the autoclave are saturated with carbonic acid, then boiled with the addition of water, sucked off hot with suction and the phthalic acid and benzoic acid isolated from the solution as usual.

Instead of caustic soda, the corresponding amount of caustic potash can also be used in the above examples use. The alkaline solutions can be more concentrated, but also more dilute than in the examples given.

The alkaline solutions can also partly, for. B. half, replaced by alkaline earths will.

Claims (1)

Patent claim: Modification of the process for the preparation of phthalic acid and benzoic acid, which is protected by patent 138790, consists in that instead of naphthols, α-nitronaphthalene, α-naphthylamine, α- or ß-naphthalene sulfonic acid, and also substituted naphthols with the substituents in the same nucleus, such as nitroso -, nitro, sulfonaphthols, as well as the intermediate products occurring in these oxidation cleavages with alkalis and oxidizing metal oxides or superoxides heated to over 200 ⁰ .