DE1668166B - Process for the preparation of 1,4-naphthoquinones - Google Patents

Description

3. The method according to claim 1, characterized in that:
draws that the oxidation at 10 to 30 ⁰ C

carried out within 3 to 5 hours. 30 C ₁₀ H ₈ + Na ₂ Cr ₂ O ₇ + 4H ₂ SO ₄ (I)

-> C ₁₀ H ₆ O ₂ + Cr ₂ (SO ₄ ) ₃ + Na ₂ SO ₄ ■ + ■ H ₂ O

C ₁₀ H ₈ -f 3Na ₂ Cr ₂ O ₇ + 12H ₂ SO ₄ (II)

-> C ₈ H ₄ O ₄ + 2CO ₂ + Cr ₂ (SO ₄ ) S + 3Na ₂ SO ₄ -I 13H ₂ O

The invention relates to a process for the preparation obtained due to the high solubility both of 1,4-naphthoquinones by oxidation of sodium dichromate as well as that in the presence of Naphthalene or its chromic acid formed in 2-, 2,3-, 2,6-, 2,7- or 2,8-sulfuric acid in the water position strongly oxidizing Lövates concentrated by methyl groups substituted derigen medium in an inert, water-immiscible solution. The difficulty with this process is solvent by means of an aqueous sulfuric acid, it now stood in the presence of such a strong one »Hexavalent chromium-containing solution under oxidizing agent to such process conditions intensive stirring. create, which the partial oxidation of naphtha

Processes are already known for the production of Un to naphthoquinone according to equation I favoring 1,4-naphthoquinones, but their production and the formation of phthalic acid according to equation II has been found to be suppressed in all previously known processes. Among the procedures of this type has proven to be relatively complicated and costly. In US Pat. No. 2,402,226, it is possible, for example, to produce naphthoquinone as a relatively successful dehydrogenation by means of processes described with regard to the effectiveness of the condensation of benzoquinone with butadiene and regulation of the reaction. Although this 50 pointed, this method is still in use on the use method, it is limited due to fresh sodium dichromate,
a multitude of stages, a complex equipment task of the invention is now, the process for the stung and a required high expenditure of time production of 1,4-naphthoquinones by Oxydasehr cumbersome, which is already evident from the fact that tion of naphthalene or its methyl derivatives so first Benzoquinone must be produced before it is controlled that 1,4-naphthodar can be produced almost exclusively from naphthoquinone. There quinones are formed and the further oxidation to are also already various other, simpler ver Phthalic acid is prevented.

drive has become known to the undesirable subject matter of the invention is a process for the preparation of the above-described condensation of 1,4-naphthoquinones by oxidation by circumventing the process, in this process of nyphthalene or its in 2-, 2, 3-, 2,6-, 2,7- or, in general, naphthalene is oxidized directly in the vapor phase, 2,8-position by methyl groups, or in the liquid phase. With these methods in an inert, water-immiscible drive, however, the difficulty arises that the extraction of the solvent by means of an aqueous sulfuric acid, oxidation in the vapor phase over a stable hexavalent chromium-containing solution under sated vanadium oxide catalyst enables the extraction of the intensive stirring , which is characterized by quinones from the mixture of oxidation products that the oxidation at 5 to 50 ⁰ C in tetrachloro is very difficult, since this is 10 to 40% non-carbon with an electrolytically regenerated naphthalene and phthalic acid performs that contains

a) About 30 to 80% of the chromium in six-hour tiger agitation is ineffective due to excessively high

_% ? " ^S u ^ η · u *", örüicher CrOa concentrations, an overoxidation occurs

*>) ^^ ^s7 _o ° _n S, ^e _/ ^W c ^C ii ^SP ^ f ^ntWass % * ^{on on} - Above 50 ⁰ C are with oxidation with

c) 50 to 200 Λ sulfuric acid in excess over regenerated chromium salt solutions consistent the stochiometnsch required amount, based on 5 low yields of 1,4-naphthobocbinone obtained on the amount of naphthalene, and been.

d) six-sided chromium in an excess of In a further embodiment, the approximately 50 to 160 ^ above the stoichiometrically required storage container contains a newly prepared aqueous Schwederhche amount of naphthalene, acid solution of the fractionally crystallized Cr ⁺⁶ -

ίο compound made by electrolytic regeneration

where the weight ratio of carbon tetrachloride- of Cr ⁺⁸ in the consumed liquids of an early-

stoff? u naphthalene is 0.3: 1 to 3: 1. earlier oxidation has been obtained, which either

With the help of the method of the invention it is possible with fresh sodium dichromate, sulfuric acid and

borrowed, 1,4-naphthoquinones m much higher levels of water or with an already regenerated solution

prey and in a much purer form than after the 15 of a hexavalent. Chromium compound carried out

to produce previously known processes. had been.

According to a preferred embodiment of the invention, the naphthalene compound is in the reaction

manure, the process is carried out in the manner, vessel introduced, and with vigorous stirring and

that the weight ratio of carbon tetrachloride maintains a temperature of the reaction

to naphthalene is adjusted to 1.4: 1. _ao vessel content of 5 to 50 ⁰ C is calculated

According to a further preferred embodiment, the amount of a solution of - as indicated above-

the Ir! The oxidation will be practiced for 3 to 5 hours - again prepared dichromate oxidation

carried out at ι "to 30 ⁰ C. medium from the storage container gradually into the

The process of the invention is given below in greater detail on the reaction vessel. The implementation is progressing

described in detail: _a5 for a period of 2 to 8 hours, one

Finally, the time required for the addition used in the process according to the invention. The Electrolytically regenerated chromium salt solution is in itself a reaction mixture is then known with a little water and after that in Ulimann, thin and pumped into the peel-off container, where it is used "Encyclopedia of Industrial Chemistry", B. 5 (1954), removal of the solvent under reduced S. 585, and "Chemie-Ingenieur-Technik", B. 35 (1963), 30 pressure is heated with continued stirring. the Pp. 386 to 389, process described, carbon tetrachloride is produced in the charging process. container returned. The residue is then

The process of the invention is subsequently passed through the filter in more detail, with the crude 1,4-naphtha

explained. thoquinone is removed from the circulation after

The reaction can be carried out in a reaction vessel with water, which is then diluted with the filtrate which is agreed with a Hochgerchwindig, has been washed free of chromium salts stirrer, a heating and cooling device as well as was. The 1,4-naphthoquinone is known is equipped with a cooler. Process cleaned.

The concentration of water in the oxidizing liquid that is filtered, consumed

Chromium salt solution is critical. If no water from 40 has been combined with the filtrate, which

the regenerated, sulfuric acid chromium salt solution contains a chromium compound and in the fractionated

before use in the ver according to the invention, crystallization of the hexavalent chromium compound

drive is removed, the yield of 1,4 naph-

thoquinone to half the value it pumped at table regeneration. The regenerated

Keeping all other variables constant will result in the main part of their water being withdrawn,

should be enough. This is likely due to Ver. Then it is cooled in a cooling tank and passed through

Changes in polarity, solubility and another filter sent from which the filtrate

Viscosity, which the production of phthalic acid and with the trivalent chromium sulfate containing a

possibly the polymerization of 1,4-naphtho- part of sulfuric acid, in circulation for regeneration

favor chinone. 50 rungs cell, as given above, is returned,

Too little water is in the reaction mixture while the hexavalent compounds are in the mixture

also not cheap. While the reaction continues with a little sulfuric acid and a little chromium sulphate

progresses, that hydrates itself through the reduction, dilution, storage and reuse in the

of the sodium dichromate formed chromium sulfate and storage container are introduced. That closes

In this way, the water concentration reduces the circulation.

further. The viscosity of the mixture increases, where- The invention is illustrated by the following examples,

by stirring to mix the two phases in which the influence of changing the main one

the reaction vessel becomes less effective. Show bad process parameters, explained in more detail.
Mixing in turn favors the polymerization and

the oxidation to phthalic acid due to a local 60 B is ρ ie 1 1
Overconcentration of chromic acid.

The water content of the aqueous oxidizing solution An oxidizing solution was prepared by

is preferably 50 ± 5 percent by weight. electronic regeneration of a used one

The oxidation temperature must be between 5 and chromium salt solution. The regeneration got so far

Maintained 50 ⁰ C to achieve satisfactory _{results 6 5} that 50% of the chromium ions present

yields of 1,4-naphthoquinone. Below were converted into the hexavalent state,

from 5 ° C there are problems with solubility. Water was distilled off, so that only 55% of the

and ^v iscosity to an extent that even comparable present during regeneration total

1 s

Water remained. The ready-to-use oxidizing agent had the following composition:

Weight parts

Cr ⁸ + (calculated as Na ₂ Cr ₂ O ₇ ) 186.1

(= 76.7 parts Cr ⁸⁺ )

H ₂ SO ₄ 389.8

Na ₂ SO ₄ 104.2

Cr ₂ (SOJ ₈ 288.4

(= 76.7 parts Cr ⁸⁺ )

H ₂ 0 984.5

A total of 1953.0

This solution was gradually added to the reaction vessel over a period of 4 hours, into which previously introduced a solution of 60 parts of naphthalene and 168 parts of carbon tetrachloride had been. The reaction mixture was kept in the for 1 hour after the addition was complete Leave the reaction vessel. The entire time was stirred vigorously and a temperature of 16 "C. maintain. The reaction mixture was drained into a container where carbon tetrachloride removed by distillation under reduced pressure and reused. The aqueous residue was filtered and the filter cake was washed with a very small amount of water of green chromium salts and sulfuric acid washed free. The filter cake was dried in a compressed air oven at 80 ° C. After separation by a known method, 18.64 parts (31.06% of the charge) failed recovered converted naphthalene, some phthalic acid (6.24 parts) and 29.82 parts 1,4-naphthoquinone. The naphthalene conversion was thus 166

68.9% at a ratio of 1,4-naphthoquinone to 'phthalic acid of 4.78: 1; the 1,4-naphthoquinone yield was 40.3% based on naphthalene. Most of the hexavalent chromium is consumed 185.1 parts or 99.46% at a weight ratio to naphthocbinone of 6.2: 1.

The filter cake washing water was combined with the KiI-step, and in addition, such an amount of water was added that the regeneration of the trivalent chromium ions to hexavalent chromium ions was facilitated. In the present case a total of 805 parts by weight of water (or 45% of the total required water) was added, including the filter cake wash water. In the routine regeneration of previously regenerated materials there is no need to add sulfuric acid, but it should be noted that if one uses a spent oxidation solution, which was originally prepared with fresh 100% sodium dichromate according to the stoichiometric ratios according to equation (i), wants to regenerate for the first time after its use in the Hyman and Peters process, sulfuric acid must be added in an amount of about 13 parts per 100 parts of solution used, minus the water.

Further oxidations of naphthalene were carried out in a manner practically corresponding to the procedure of Example 1 Wise carried out, with the modification that changes in the concentration of hexavalent Chromium and sulfuric acid were made. These changes are indicated in the table, the addition quantities and results of the preparation according to for comparison purposes Example 1 contains.

Effect of the variations in the concentrations of hexavalent chromium and sulfuric acid ¹ )

example

Parts by weight

Na ₂ Cr ₂ O ₇

Molar

Excess ² )

H ₂ SO ₄

Parts by weight

Molar excess ² )

effectiveness
NQ / PA I Cr ° + / NQ

186
220
210

51%
79%
71%

390
450
440

112% 152% 140% 31.0%
30.6%
22.5%

8.0%
8.8%
6.4%

40.3%
38.2%
35.8%

4.8
4.1
5.4

6.2

7.4
7.8

ι) All other variables as in example I.
ϊ) Calculated according to equation (I).
s) Unoxidized portion of the naphthalene charge.

i) Yields based on the naphthalene feed according to equations (I) and (II). PA Naphthoquinone.

Phthalic acid; NQ = 1.4-

Examination of these results shows that the concentrations of the oxidizing agents are up to can deviate to a certain extent from the optimal values, although they are still acceptable Showing yields of 1,4-naphthoquinone with reasonable potency.

The hexavalent chromium content of the regenerated oxidizer, which is different from the point of view of the Conversion concentrations and volumes as well as costs proven to be the most practical has is about 50%. However, any hexavalent chromium content is between about 30 and about 80% suitable if, on the one hand, one is willing to use larger equipment or, on the other hand, higher amounts of electricity with less effectiveness is.

Example 4

Another experiment was carried out essentially as in Example 1 with the modification that the The reaction mixture was more concentrated and that the reaction was carried out at a higher temperature and one shorter total time. Specifically, a weight ratio of carbon tetrachloride became to napl · thalin of 1.9: 1 used, and the Addition of the oxidizing solution was carried out in 3 hours and 25 minutes. One that goes beyond that Implementation time was not given. The reaction temperature was 26.5 ° C.

Under these modified conditions, a yield of 1,4-naphthoquinone was found to be 35.7% and a Phthalic acid yield of 8.27%, based on naph-

thalin, received. The ratio of phthalic acid to 1,4-naphthoquinone was 4.1, and the consumption by weight of Na ₂ Cr ₂ O ₇ per part by weight of 1,4-naphthoquinone was 6.94. The recovered naphthalene was 32.4% of the charge. These results permit an advantageous comparison with those of the previous examples, although more phthalic acid was produced than in Example 1 and, as could be expected from equation (II), less effective use of the Cr ^{6+ was} achieved.

Example 5

The procedure of Example 1 was followed with minor changes to obtain 50 grams of 2-methylnaphthalene to oxidize. The chosen weight ratio of carbon tetrachloride to methyhiaphthalene was 2.8: 1 and a 50% excess of regenerated chromic acid was used. The implementation proceeded over 6 hours at an average temperature of 16 ° C. The yield of 2-methyl-1,4-naphthoquinone was 62%.

209539/562

Claims (2)

are cleansed. For these reasons, the patent claims: Oxidation of naphthalene ia liquid P base with hexavalent chromium was carried out (cf. the British 1. Process for the preparation of 1,4-naphtho patent specification 645 061), although in this process Quinones by oxidation of naphthalene or mainly phthalic acid, a more highly oxidized one which is formed in the 2-, 2,3-, 2,6-, 2,7- or 2,8-position by the product of naphthalene. By adding Derivatives substituted by methyl groups in an acetic acid naphthalene solution to an aqueous one inert, water-immiscible acetic acid solution of chromium trioxide could, however medium by means of an aqueous sulfuric acid, the yields of naphthoquinone to 20 to 33%, hexavalent chromium-containing solution below io based on the naphthalene used, increased intensive stirring, thereby to be identified. draws that the oxidation is at 5 to A further improvement of this previously used 50 ⁰ C in carbon tetrachloride with an electrolyzed oxidation with chromic acid carried out the process described in the table regenerated chromium salt solution, USA patent specification 2402 226, which a) about 30 to 80% of the chromium in the hexavalent i _S in the naphthalene by chromic acid Present state, b) 40 to 70 percent by weight water, a diluent, e.g. B. in the presence of c) 50 to 200% sulfuric acid in excess over benzene or carbon tetrachloride, the stoichiometrically required amount, based on this made it possible to produce the chromium on the amount of naphthalene, and d) hexavalent acid in situ by gradual addition of sulfur-chromium in an excess of about 50 to 160% 20 acid during the reaction contains naphthoquinone from the stoichiometrically required naphthalene beutes of about 40% in the case of oxidation, the weight ratio of naphthalene and of up to almost 100% in The case of carbon tetrachloride to naphthalene is 0.3: 1 to oxidation of certain substituted naphtha 3: 1. to achieve linen. Although in the oxidation of 2. The method according to claim 1, characterized in 25 naphthalene with hexavalent chromium to naphtho- that the weight ratio of tetraquinone. Phthalic acid and carbon dioxide according to the 1.4: 1 chlorocarbon to naphthalene. using the following equations, large amounts of oxygen