DE1016702B - Process for the preparation of 2,6,6-trimethylcyclohexen- (2) -dione- (1,4) and 2,6,6-trimethylcyclohexanedione- (1,4) or their monoketals - Google Patents

Description

The invention relates to a process for the preparation of 2, 6, 6-trimethylcyclohexen- (2) -dione- (l, 4) and 2,6,6-trimethylcyclohexanedione- (1,4) or their monoketals. The procedure is characterized by that an organic peracid is allowed to act on 2,6,6-trimethylcyclohexen- (l) -one- (4) in a known manner, the reaction product is hydrolyzed, the 2, 6, 6-trimethylcyclohexen- (2) -ol- (l) -one- (4) formed in itself known manner to 2, 6, 6-trimethylcyclohexen- (2) -dione- (1,4) oxidized and, if desired, its double bond hydrogenated in a manner known per se and / or its 4-position oxo group in the customary manner ketalized.

The 2,6,6-trimethylcyclohexen- (1) -one- (4) used as the starting material can be prepared from isophorone, for example. In the first stage of the process according to the invention, the 2, 6, 6-trimethylcyclohexen- (l) -one- (4) is treated with an organic peracid, e.g. B. peracetic acid, benzoic acid, phthalic monoperic acid or performic acid is oxidized in a known manner. The unstable primary oxidation product (probably an oxido compound) is hydrolyzed and dehydrated to 2,6,6-trimethylcyclohexen- (2) -ol- (1) -one- (4) without isolation. In an expedient embodiment of the first process stage, the 2, 6, 6-Trimethylcyclohexen- (l) -one is oxidized (4) in glacial acetic acid with peracetic acid at 0 to 35 °, the oxidising mixture slightly alkaline by the addition of 30 ° / ₀ sodium hydroxide solution made and then shaken at room temperature for 1 to 2 hours. The 2,6,6-trimethylcyclohexen- (2) -ol- (1) -one- (4) can be isolated by extraction with ether and forms an almost colorless oil, boiling point _{0) 1} = 110 to 112 °, « U ⁷ = 1.501, UV absorption maximum at 226 πιμ (E \ °? _M = 1110 in petroleum ether solution). The phenyl semicarbazone melts at 189 to 190 ° and has absorption maxima in the UV spectrum at 240.5 and 285 μm (EJ = 807 and 778 in pure alcohol).

In the second stage, the 2,6,6-trimethylcyclohexen- (2) -ol- (l) -one- (4) is oxidized to the 2,6,6-trimethylcyclohexen- (2) -dione- (1,4) . This oxidation takes place in a manner known per se, for. B. with compounds of hexavalent chromium (such as chromic acid or tertiary butyl chromate), with manganese dioxide or with metal alcoholates or phenolates (such as aluminum isopropylate or phenolate) in the presence of carbonyl compounds. An advantageous embodiment of this stage is that the 2, 6, 6-trimethylcyclohexen- (2) -ol- (l) -one- (4) in an inert solvent such as petroleum ether, benzene or methylene chloride, with excess manganese dioxide treated at a temperature lying between 0 ° and the boiling point of the solvent. It is particularly advantageous to oxidize the 2,6,6-trimethylcyclohexen- (2) -ol- (1) -one- (4) in acetic acid solution with chromic acid at 0 to 40 °. The formed 2, 6, 6 procedure
for the production of 2, 6, 6 -trimethyl-

cyclohexen- (2) -dione- (l, 4)

and 2,6, ö-trimethylcyclohexanedione-fl, 4)

or their monoketals

Applicant:

F. Hoffmann-La Roche & Co.
Aktiengesellschaft, Basel (Switzerland)

Representative: Dr. G. Schmitt, lawyer,
Loerrach (Bad.), Friedrichstr. 3

Claimed priority:
Switzerland from July 6, 1955

Dr. Otto Isler, Dr. Marc Montavon,

Dr. Rudolf Rüegg, Basel,

Dr. Gabriel Saucy, New World, Münchenstein,

and Dr. Paul Zeller, Neuallschwil (Switzerland),

have been named as inventors

Trimethylcyclohexen- (2) -dione- (1,4) can be obtained by extraction with petroleum ether. It forms a pale yellow oil that solidifies in the refrigerator; Kp. _U = 92 to 94 °, rc = 1.490, UV absorption maximum at 238 πιμ (E} = 942 in petroleum ether solution). The phenylsemicarbazone melts at 190 °, then solidifies again at about 200 °, and then melts again at 230 °; it has maxima in the UV absorption spectrum at 242.5 and 325.5 ηαμ (E] *. = 875 and 580 in pure alcohol).

To obtain the 2,6,6-trimethylcyclohexanedione (1, 4) the double bond of the 2, 6, 6-trimethylcyclohexen- (2) -dione- (l, 4) hydrogenated. Zinc and glacial acetic acid at 20 to 80 ° are particularly suitable for this. The crystalline After filtering the reaction mixture, product can be obtained by diluting the filtrate with water and extracting can be obtained with ether or petroleum ether. It forms colorless crystals, melting point 63 to 65 °, which are in the UV absorption spectrum between 220 and 280 πιμ have no maximum. The phenyl semicarbazone melts at 218 to 220 ° and has a maximum in the UV absorption spectrum at 250 πιμ (E] *, = 1030 in pure alcohol).

The ketals of 2, 6, 6-trimethylcyclohexen- (2) -dione-

(1, 4) or of the 2, 6, 6-trimethylcyclohexanedione (l, 4)

709 693/425

Claims (4)

3 4 can be washed in the usual way by heating with saturated ammonium chloride solution to which a little ammonia has been added to alcohols in inert solvents in the presence of, and then washed with pure saturated amino acid catalysts while continuously distilling off the sodium chloride solution. After drying over the water formed or by means of orthocarboxylic acid sodium sulfate and evaporation of the solvent, ester and acid catalysts are produced. It is only 5, the 2,6,6-trimethylcyclohexen- (2) -dione- (1,4) in the water, the keto group is ketalized in the 4-position. Suitable jet vacuum distilled, b.p. _n = 92 to 94 °, yellowish ketals are the ethylene ketals, which are particularly resistant to oil, solidify crystalline in the refrigerator, n% - 1.490, UV absorption and are therefore good for an organometallic condensation sorption maximum at 238 ΐημ (EJ * _ra = 942 in petroleum ion on the free keto group are suitable. Ether). The phenylsemicarbazone first melts at The process products have fragrance properties of io 190 °, then solidifies again and melts again at 230 °; and can therefore be used in fragrance mixtures and perfumes UV absorption maximum at 242.5 and 325.5 πιμ. They are also valuable intermediate (EJ * "= 875 and 580 in pure alcohol), products in the synthesis of natural dyes, Example 2 such as zeaxanthin, rhodoxanthin, kryptoxanthin or". , _. ,,,,,. ,. “Astaxanthin (see, for example, BP Karrer and E. Jucker, x ₅ ² ' ⁶ ' 6-methylcyclohexanedione- (1,4) carotenoids, 1948, pp. 176, 182, 223 and 232). So for 65 parts by weight of 2, 6, 6-Trimethylcyclohexensie z. B. after ketalization of the 4-position keto group (2) -dione- (l, 4) (prepared according to Example 1) in 250 rooms by condensation with lithium ethoxyacetylide, partial glacial acetic acid, 130 hydrogenation and hydrolysis are slowly added with stirring to the corresponding, in parts by weight of zinc dust, the temperature of the 2-position possibly hydrogenated 2,6-trimethyl-4-oxo-20 mixture not being allowed to rise above 50 °. The cyclohexen- (2) -ylidene acetaldehyde, and this in turn reaction mixture, is then stirred for a further 1 hour and then nitrated by repeated acetalization and condensation. The filtrate is diluted with 1000 parts by volume of a propenyl or vinyl ether and hydrolysis first water and saturated with ammonium chloride in the corresponding C ₁₄ aldehyde, then in the C ₁₆ Al- The mixture is twice with 800 parts by volume of petrol and finally in the C ₁₉ aldehyde converted 25 ether (boiling range 30 to 60 °) extracted. The petrol. The C ₁₉ aldehyde can then be washed through metal ether solutions with 300 parts by volume of saturated organic condensation with acetylene, dehydration ammonium chloride solution, to which a little ammonia has been added under allyl rearrangement, partial hydrogenation and isomerization, and then converted into the desired carotenoid solution with pure saturated ammonium chloride solution . If part of the pro. 30 products crystallized out of the petroleum ether solution, Example 1 is filtered, the crystals are dissolved in ether, the ethereal solution, _ -, _. ,,,,, ",,,., ,,, as above, washed and after drying over Na-2,6,6-Tnmethylcyclohexen- (2) -ol- (1) -one- (4) trium sulfate with the petroleum ether solution combined. Man The solvent evaporates off to 138 parts by weight of 2,6,6-trimethylcyclohexene until the 2,6,6-trimethyl- (l) -one- (4) in 50 parts by volume of glacial acetic acid is added within 35 cyclohexanedione- (1,4) to crystallize out in colorless needles for 2 hours at 0 to 10 ° with stirring 160 parts by volume begins. Melting point 63 to 65 °. The product of a solution of peracetic acid in acetic acid (containing in the ultraviolet spectrum between 220 and 280 ΐημ 530 mg peracetic acid per cm) and the mixture does not have an absorption maximum. The phenylsemicarbazone stand overnight at 20 °. Thereupon the reaction melts at 218 to 220 ° and has at 250 πιμ a mixture with the addition of ice with 30 ° / ₀ iger soda 40 UV absorption maximum (EJ * _m = 1030 in pure caustic slightly alkaline (p _H = about 8) made and an- alcohol). then shaken for 1 hour at 20 °. Now example 3 Reaction mixture twice with 800 parts by volume of ether each time. . ". . ,. ..., ... ,, _. ... extracted, whereupon the ether solutions once with 200 space ² ' ⁶ - 6-Tnmethyl-4-ethylenedioxycyclohexen- (2) -one- (l) parts of saturated ammonium chloride solution washed 45 34.6 parts by weight of 2,6,6-trimethylcyclohexene (2) -dione. After drying the combined ether (1, 4) (prepared according to Example 1), 100 parts by volume of solutions over sodium sulfate by evaporating off the ether benzene, 19 parts by weight of ethylene glycol and 0.2 parts by weight residue is distilled in a high vacuum. Parts of p-toluenesulphonic acid are boiled for 7 hours with separation of the water formed after a flow between 70 and 80 °. After the 2,6,6-trimethylcyclohexen- (2) -ol- (1) -one- (4) is heated to 50% cold, the reaction mixture becomes almost colorless oil in 300 parts by volume with a boiling point of _{0) 1} = 110 to 112 ° obtain; Poured 5% sodium bicarbonate solution and the M ² J = 1.501; UV absorption maximum at 226 πιμ 2,6,6-trimethyl-4-ethylenedioxycyclohexen- (2) -one- (l) (Ej * _ra = 1110 in petroleum ether solution) after standing for some time. obtained by extraction with ether. Destilla phenylsemicarbazone: mp. 189 to 190 °, UV absorption gives the product as a colorless oil _{, b.p. 0> 03} = 65 °, maximum ion at 240.5 and 285 ηιμ (Ε} *, = 807 and 55 «f? = 1.490, UV absorption maximum at 225.5 πιμ 778 in pure alcohol). (EJl = 560 in petroleum ether). 2,6,6-Trimethylcyclohexen- (2) -dione- (1,4) Example 4 To 154 parts by weight of 2, 6, 6-trimethylcyclohexene- ² > ⁶ <6-trimethyl-4-ethylenedioxycyclohexanone- (l) (2) -ol- (l) -one- (4) in 200 parts by volume of glacial acetic acid and 500 60 34, 6 parts by weight of 2,6,6-trimethylcyclohexanedione parts by volume of water are treated, 70 parts by weight of chromic acid (1, 4) (prepared according to Example 2) are added dropwise rapidly in 200 parts by volume of water, as described in game 3. This is obtained, with stirring and cooling in order not to let the temperature rise above 30 °, the 2,6,6-trimethyl-4-ethylenedioxycyclohexane. The reaction is then (1) as a colorless oil, boiling point _{0> 02} = 70 °, n% - 1.469. tion mixture is stirred further overnight at 20 ° and 65
finally saturated with ammonium chloride and with 1000 Parts of space petroleum ether (boiling range 30 to 60 °) extra- Pate ν ta ns ρ β Oc he ·. here. The aqueous layer is shaken again with 500 parts by volume of petroleum ether in a second separating funnel. 1. Process for the preparation of 2,6,6-trimethyl. The petroleum ether solutions are mixed with 70 cyclohexen- (2) -dione- (1,4) and 2, 6, 6-trimethylcyclo- hexanedione- (l, 4) or their monoketals, characterized in that one is based on 2, 6, 6-trimethylcyclohexen- (l) -one- (4) allows an organic peracid to act in a known manner, hydrolyzes the reaction product, the resulting 2, 6, 6-trimethylcyclohexen- (2) -ol- (l) -one- (4) oxidized in a manner known per se to 2, 6, 6-trimethylcyclohexen- (2) -dione- (l, 4) and, if desired, hydrogenated its double bond and / or its 4-position oxo group in the usual way Way ketalized. 2. The method according to claim 1, characterized in that 2,6,6-trimethylcyclohexene (l) -one- (4) oxidized in glacial acetic acid with peracetic acid. 3. The method according to claim 1, characterized in that 2,6,6-trimethylcyclohexene (2) -ol- (l) -one- (4) oxidized with chromic acid. 4. The method according to claim 1, characterized in that 2,6,6-trimethylcyclohexene (2) -dione- (l, 4) Hydrogenated at the double bond using zinc in glacial acetic acid.