DE1101409B - Process for the production of tetrahydrobenzyl alcohol - Google Patents

Description

GERMAN

It has been proposed to produce Δ ³ -Tetrahydrobenzylalkohol by reduction of Δ ³ -Tetrahydrobenzaldehyd using such reducing agents which reduce aldehyde to the alcohol group without hydrogenating simultaneously present olofmische double bonds. Such a process is described by H. Fiesselm an η in reports of the German chemical society, vol. 75, 1942, p. 881, aluminum isopropylate in isopropanol being used as reducing agent (Meerwein-Ponndorf reaction). However, these known selective reduction methods are far too expensive to be used for the large-scale production of tetrahydrobenzyl alcohol from tetrahydrobenzaldehyde. There is a strong need for such an inexpensive process because tetrahydrobenzaldehyde or its homologue, 6-methyltetrahydrobenzaldehyde itself, is easily accessible on an industrial scale by diene synthesis from butadiene and acrolein or crotonaldehyde.

It is also known that aldehydes in the presence of copper chromite catalysts catalytically to the Alcohols can be hydrogenated. This method has the advantage of cheapness; it was, however, true for them selective hydrogenation of the aldehyde group to the alcohol group in olefinically unsaturated aldehydes as unsuitable. Thus, Ch. Grundmann presents in his work "Hydrogenation with Copper-Chromium Oxide Catalysts" in Angewandte Chemie, Vol. 54, 1941, p. 472, concerning the hydrogenation of carboxyl groups in aldehydes and Ketones in the presence of copper chromite solid:

“If olefinic double bonds are present at the same time, they are also hydrogenated; a selective one Hydrogenation does not succeed under these conditions. "

It would therefore have been expected that in the catalytic hydrogenation of tetrahydrobenzaldehyde in Presence of copper chromite would mainly form hexahydrobenzyl alcohol or that tetrahydrobenzyl alcohol at most, the yield would be so poor that its technical production would occur under no circumstances would it have been worthwhile after this procedure.

It has now been found extremely surprising that currently ^three -TetrabenzylaIkohoI can be hydrogenated ³ -Tetrahydrobenzaldehyd in Gegenwatr of copper in virtually quantitative yield of 4 and that this, contrary to expectations, the hydrogenated in the olefinic double bond Hexahydrobenzylalkohol only in very small quantities (at most about 1 , 5 ° / ₀ , calculated on the aldehyde used as starting material) is formed.

The present invention thus relates to a process for the production of Δ ^ tetrahydrobenzyl alcohol and its production process in the cyclohexene ring by means of alkyl groups
of tetrahydrobenzyl alcohol

Applicant:
CIBA Aktiengesellschaft, Basel (Switzerland)

Representative: Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse and Dipl.-Chem. Dr. rer. nat. E. Frhr. v. Bad luck man,

Patent Attorneys, Munich 9, Schweigerstr. 2

Claimed priority:
Switzerland from January 22, 1959

Dr. Erwin Nikles, Basel (Switzerland),
has been named as the inventor

homologues substituted with 1 to 4 carbon atoms and / or a 2,5-methylene bridge by reduction of Δ ³ -tetrahydrobenzaldehyde or its homologues substituted in the cyclohexene ring by alkyl groups with 1 to 4 carbon atoms and / or a 2,5-methylene bridge, which is characterized is that the aldehyde is catalytically hydrogenated in the presence of a copper-chromium oxide catalyst.

As homologues of the type of tetrahydrobenzaldehyde or tetrahydrobenzyl alcohol mentioned, in particular 6-methyltetrahydrobenzaldehyde or 6-methyltetrahydrobenzyl alcohol as well as 2,5-endomethylenetetrahydrobenzaldehyde and methyl-2,5-endomethylenetetrahydrobenzyl alcohol called.

The production of the copper chromite catalyst and the implementation of the hydrogenation take place in and of themselves in a known manner (cf. above-mentioned work by Ch. Grundmann in Angewandte Chemie, Vol. 54, 1941). If desired, the hydrogenation of the unsaturated Aldehyde in a solvent such as cyclohexane.

In the following examples, parts are parts by weight and percentages are percentages by weight. The relationship from parts by weight to parts by volume is the same as kilograms to liters. The temperatures are in Degrees Celsius.

example 1

110 parts of 93.6% iger Δ ³ -tetrahydrobenzaldehyde are diluted with cyclohexane to a total of 300 parts by volume and after addition of 5 parts of copper chromite catalyst in an autoclave in a hydrogen atmosphere

109 529/720

10

70 to 200 atm. Pressure and shaken 125 °. After taking up 21,300 parts by volume (normal conditions) Hydrogen, the hydrogenation is terminated. The catalyst is filtered off and the solvent is evaporated. When the residue is distilled, 99 parts with a boiling point of 82 to 88 ° / 12 mm Hg are obtained. The product is analyzed by gas chromatography. It contains:

97.73% ^ ³ -tetrahydrobenzyl alcohol,

1.51% hexahydrobenzyl alcohol,

0.42% ^ ³ tetrahydrobenzaldehyde.

Example 2

440 parts of 93.6% iger Δ ³ -tetrahydrobenzaldehyde are diluted with cyclohexane to 1500 parts by volume and in an autoclave in a hydrogen atmosphere at 104 to 181 atm. Pressure and shaken 126 ° with 20 parts of copper chromite. The hydrogenation is interrupted after 93,900 parts by volume of hydrogen have been taken up. The catalyst is filtered off, the solvent is evaporated and the residue is distilled through a 60 mm high Raschig column at a pressure of 15 mm Hg. At 40 to 86 °, 57.8 parts and at 86 to 88 ° go 359 parts of distillate above.

The gas chromatographic decomposition of the two Fractions results in the following composition:

Leader:

1.38% hexahydrobenzyl alcohol,
40.7% I ³ tetrahydrobenzaldehyde,

33.2% ^ ³ tetrahydrobenzyl alcohol.

Main run:

98.14% Δ ³ -tetrahydrobenzyl alcohol,
1.03% Δ ³ -tetrahydrobenzaldehyde,
0.83% hexahydrobenzyl alcohol.

At 54 to 85 °, 146.8 parts of first runnings and at 85.0 to 86.0 ° 934.2 parts (85% of theory) of 6-methyl-4 ³ -tetrahydrobenzyl alcohol pass over.

Analysis: C ₈ H ₁₄ O:

Calculated ...
found

Hydroxyl content

35

Example 3

1540 parts of 93.6% iger / d ^s -tetrahydrobenzaldehyde are in the presence of 50 parts of copper chromite in a stirred autoclave at 150 atm. Initial pressure and 125 ° hydrogenated. The reaction is terminated after 306,100 parts by volume of hydrogen have been absorbed (normal conditions). Distillation through a 60 cm high Raschig column gives 1250 parts of Δ ³ -tetrahydrobenzyl alcohol with a boiling point of 80 to 82 ° / 10 mm Hg. The product shows the following analytical data:

Hydroxyl content 8.89 equivalents /

kg (theory: 8.92) hydrogenation number (= g H ₂ / 10,000 g substance) 175.4

(Theory: 179.7)

Example 4

1170 parts of 92.5% 6-MethyLd ³ -tetrahydrobenzaldehyde are in a stirred autoclave (content 3000 parts by volume) with 30 parts of copper chromite at 145 atm. (Initial pressure at room temperature) and hydrogenated 125 to 131 °. The reaction is interrupted after the uptake of 205,500 parts by volume of hydrogen (normal conditions). The catalyst is filtered off and the filtrate is distilled at 10 mm Hg through a 60 cm high Raschig column. C = 76.14%, H = 11.18%;
C = 76.17%, H = 11.14%.

7.84 equivalents / kg
(Theory 7.93)

Example 5

244 parts of 2,5-endomethylene-Zl ³ -tetrahydrobenzaldehyde and 15 parts of copper chromite are diluted with dioxane to a total of 500 parts by volume and placed in an autoclave in a hydrogen atmosphere at 150 atm. Initial pressure and shaken 126 to 141 °. The hydrogenation is interrupted after 45,700 parts by volume of hydrogen have been taken up (normal conditions). The catalyst is filtered off and the filtrate is distilled through a Raschig column. The 2,5-endomethylene-zJ ³ -tetrahydrobenzyl alcohol boils at 103.0 to 103.5 ° / 20 mm Hg.

C = 77.37%, H = 9.74%;
C = 77.28%, H = 10.03%.

Analysis: C ₈ H ₁₂ O:
Calculated
found .

Hydroxyl content 7.90 equivalents / kg

(Theory: 8.06)

Hydrogenation number 150.5 (g H ₂ / 10,000 g

Substance) (theory: 162.3)

Example 6

363 parts of methyl-2,5-endomethylene-4 ³ -tetrahydrobenzaldehyde (produced from technical methylcyclopentadiene and acrolein) and 15 parts of copper chromite are made up to 500 parts by volume with dioxane. The mixture is autoclave in a hydrogen atmosphere at 130 atm. Initial pressure and shaken 127 °. After the uptake of 43,500 parts by volume of hydrogen, the hydrogenation is interrupted. The catalyst is filtered off and. the filtrate is distilled. The methyl-2,5-endomethylene-Zl ³ -tetrahydrobenzyl alcohol goes over at 99 to 103720 mm Hg.

Hydroxyl content 7.11 equivalents / kg

(Theory: 7.24)

Hydrogenation number 142.8 (g H ₂ / 10,000 g

Substance) (theory: 145.9)

Claims (1)

PATENT APPLICATION: Process for the preparation of I ³ tetrahydrobenzyl alcohol and its im. Cyclohexene ring substituted by alkyl groups with 1 to 4 carbon atoms and / or homologues substituted by a 2,5-methylene bridge by reduction of Δ ³ -tetrahydrobenzaldehyde or its homologues substituted in the cyclohexene ring by alkyl groups with 1 to 4 carbon atoms and / or a 2,5-methylene bridge, characterized in that the aldehyde is catalytically hydrogenated in the presence of a copper-chromium oxide catalyst known as a hydrogenation catalyst. © 109 529/720 2.61