DE1668627B - Process for the dimerization of aldehydes or ketones - Google Patents

Description

R '

From US Pat. No. 2,751,407, it is already known that phenylacetone reacts with atmospheric oxygen 3,4 - diphenyl - 2,5 - hexanedione can be dimerized. From "Monthly Books for Chemistry", 95, p. 1702 to 1712 (1964), it is also already known that p-methoxy- or p-acetoxyphenylacetone by oxidation in the presence of persulfate to 3,4-bis- (p-methoxyphenyl) - or 3,4-bis- (p-acetoxyphenyl) -hexanedione- (2,5) can be dimerized. These well-known

ίο procedures have the disadvantage that they are on the one hand are not suitable for the dimerization of aldehydes and that they are, on the other hand, relatively cumbersome and must be carried out in several stages. It has therefore long been the aim to find a more economical process for the dimerization of aldehydes or ketones, which can be found in a single step can be carried out in an economical manner and the dimerization of Aldehydes made possible on an industrial scale.

The process of the invention provides in a simple and economical one-step process the desired dimeric reaction products. The dimeric aldehydes and ketones obtained can can be used in a wide variety of fields.

For example, the 1,4-dialdehydes and 1,4-diketones are suitable as intermediates for the production of 5-ring lactones or cyclopentanones, which have a pleasant smell and as fragrances can be used in the perfumery industry. The 1,4-dialdehydes can also be used as starch thickeners be used. The 1,4-dialdehydes and 1,4-diketones, which according to the invention Process can also be obtained as intermediates for the manufacture of 1 ^ -Di-SS oils, dicarboxylic acids, diimines and diamines are used that are used in the polymerization (e.g. as crosslinking agents). Besides that They can be used as intermediates for the preparation of n-alkylpyrrolidine derivatives with a herbicidal Activity as well as for making compounds with both toxic and anesthetic as well herbicidal properties are used.

The dimerization of the aldehydes by the process of the invention can be carried out as follows Represent the reaction equation:

R '
R.

C-CH = O

MnO, or / NiO _x (or NiO ₂ ) \

R '
R.

C - CH = O

CH = O

R '

CH

R '

Correspondingly, the dimerization of ketones can be represented by the following reaction equation:

R O

• \ Il

CH- C - R '
R '

MnO ₇ or

R O

\ Il

C — C —R "

R '

NiO, (or NiO ₂ ) _R

C —C —R "

/ Il

R 'O

where R, R 'and R "each have the meanings given above.

Typical meanings for the radicals R and R 'are phenyl, ρ - methoxyphenyl, 4 -1 - butylphenyl. 4 - hexylphenyl, 4 - phenylhexyl, ρ - chlorophenyl, p-nitrophenyl, m - methoxyphenyl, methyl, ethyl, Propyl, isopropyl, butyl, pentyl and isobutyl, where R and R 'can be the same or different. R " In addition to hydrogen, phenyl, ρ-methoxyphenyl, ρ-chlorophenyl, p-nitrophenyl, m-methoxyphenyl, methyl, ethyl, propyl, butyl, isobutyl, Mean pentyl or 4-phenylhexyl.

The process according to the invention is carried out by bringing an aldehyde or a ketone into contact with activated manganese dioxide or nickel peroxide until the desired reaction has taken place. The aldehyde or ketone can be brought into contact with the special metal oxides used as a catalyst in the customary manner. For example, an aldehyde or a ketone can be slurried together with the specific metal oxide in a solution of an inert solvent. The reaction can be conducted at temperatures ranging from about ambient temperature to 200 "C, preferably in the range of 70 to 180 ° C, and still be completed as long has elapsed until the reaction was '/ 2 b' ^s may take 200 hours. The reaction is preferably carried out, especially in the case of aldehydes, in an inert atmosphere in order to prevent air oxidation to acids. Methylene chloride or chloroform can be used.

Another way of carrying out the reaction is that one of the aldehyde or passing the ketone through a bed of the metal oxide concerned. Preferably the aldehyde or the ketone is passed through the metal oxide bed in the form of a solution in an inert solvent. The aldehyde or ketone can be repeatedly passed through the metal oxide bed to achieve high conversion. The unreacted aldehyde is preferred or the unreacted ketone is circulated through the catalyst bed until a conversion at least 40 to 90% has been achieved.

Essentially the same can be used for the conversion of both aldehydes and ketones Apply reaction conditions, however, the ketones react more slowly, and therefore it can in some In some cases it may be desirable to use longer reaction times and higher temperatures for the ketones.

After the reaction time has elapsed, the metal oxides can be filtered (in the case of a slurry procedure) separated and the solvent and the unreacted starting materials by distillation, crystallization, or chromatography removed by other means. The products obtained can be purified by distillation, chromatography separated in the liquid phase or gas chromatography or a combination of these procedures will.

In the process according to the invention, the nickel peroxide or the activated manganese dioxide is used used in amounts ranging from about 1.5 to 10 moles per mole of starting aldehyde or ketone.

The latter is prepared according to the method of Attenburrow in "Journal of the Chemical Society", 1952, pp. 1094-1111. The nickel peroxide used according to the invention is prepared according to "Journal of Organic Chemistry", 27, pp. 1592 to 1601 (1962), although other nickel peroxides can also be used.
The following examples illustrate the invention:

example 1

A mixture of 14 g of isobutyraldehyde, 30 g of activated manganese dioxide and 100 ml of dioxane for 24 hours in a round bottom flask, equipped with stirrer and reflux condenser, heated to reflux (about 100 ⁰ C). An inert atmosphere of nitrogen at a very slight positive pressure was maintained over the reflux mixture by means of a balloon connected to a gas inlet / outlet valve attached to the outlet port of the condenser.

was brought. After the end of the reaction time, the vessel was cooled and the manganese oxide removed by filtration. Gas chromatography analysis over a column of 20% Carbowax Chromosorb W showed two major product peaks in a ratio of approximately 1: 1. The solvent and unreacted starting material were removed by distillation, leaving a highly viscous Mass was obtained which, upon further distillation, contained about 4.1 g of a material boiling at 130 to 198 ° C which was taken in four fractions. About 4.5 g of the residue remained in the distillation flask back, which after sublimation gave 0.8 g of a white crystalline material. the Gas chromatography analysis of the combined distilled and sublimed material showed four products, of which the first two were the same as those used in gas chromatography in the context of "the Analysis of the starting product before distillation

were observed. The four products (A, B, C, and D) were made in the order of their bleeding Chromatography column, as described above, identified as follows. The cleaning of the individual products was carried out by gas chromatography.

The product B was determined on the basis of its highly characteristic spectra (the infrared spectrum gave bands at 3.66 μ (weak) and 5.75 μ (strong) corresponding to a saturated aliphatic aldehyde (- CH = O), and a band at 5.93 μ of moderate intensity corresponding to the olefinic absorption the vinyl ether bond

while the ether absorption (= C - O - C =) at 8.75 µ appeared (very strong); the nuclear magnetic resonance spectrum showed a common dimethyl absorption

20th

at 8.75 τ, allylmethyl groups with a center at 8.45 τ, an olefinic proton

30th

at 4.34 τ and the aldehyde proton at 0.55 r; the nuclear magnetic resonance proton integration corresponded the above structural arrangement; the mass spectrum revealed a molecular ion at m / e 142, identified as 2-methyl-2- (2'-methyl-1-propenoxy) -propionaldehyde.

Product C was determined on the basis of its spectral properties (the infrared spectrum showed absorptions at 3.59 and 5.76 μ corresponding to the saturated aldehydes (—CH = O); the nuclear magnetic resonance spectrum showed a dimethyl absorption at 8.84 r and an aldehyde proton absorption at 0.53 τ in a ratio of 6: 1; the mass spectrum indicated a molecular ion at m / e 142 as Tetramethylsuccinaldehyde identified.

The product A was identified by its spectral properties as 2-isopropyl-4,4-dimethyi-1,3-dioxoIane

H ₁ C

H ₃ C

H ₃ C identified. The peak of product D was determined to be the _r lactone of 2,2,3,3-tetramethyl-4-hyaroxybutyric acid. Both products A and D formed during the distillation.

Example 2

A solution of 35 g of isobutyraldehyde and 160 g of tetrahydrofuran was added (C approximately 100 ⁰⁾ was passed at the reflux temperature through a bed of 25 g of activated manganese dioxide in a manner such that the unreacted aldehyde was continuously recirculated in the circuit, while the reaction products were concentrated in Rückflußkolben . The reaction was carried out so that the condensed solvent and aldehyde vapors could drip back into the reflux flask through a fiber beaker (containing the manganese dioxide).

After 105 hours at reflux and recycling, the solvent and unreacted isobutyraldehyde were removed by distillation to leave 23.5 g of a moderately viscous oil which contained a small amount (0.1 g) of white crystalline material which was separated by filtration would. Gas chromatographic analysis both before and after the distillation showed two main dimeric products which were identified by direct comparison with known samples as 2-methyl-2 - (T - methyl - Γ - propenoxy) - propionaldehyde and tetramethylsuccinaldehyde. The distillation of part of this product mixture gave a material with a boiling point of 50 to 55 ° C./7 mm, which was practically pure 2-methyl-2- (2'-methyl-l'-propionaldehyde, and a material with a boiling point of 75 to 83 ° C / 7 mm, which soon solidified and was identified as consisting essentially of tetramethylsuccinaldehyde.The ratio of the two products to one another was 5: 4.

Example 3

An experiment similar to Example 2 using 18 g of isobutyraldehyde, 50 g of activated Manganese dioxide and 150 g of tetrahydrofuran gave 16.7 g of a mixture after 48 hours, which to 50% from 2-methyl-2- (2'-methyl-propenoxy) -propionaldehyde, consisted of 38% tetramethylsuccinaldehyde and 12% of by-products The reaction is illustrated by the following equation:

CH ₃

CH - CH = O

-2H

H ₃ CH ₃ CC - CH = O + CH ₃ - C - CH = O

CH
C.

C - CH =

H ₃ C

Example 4

A reflux mixture similar to Example 1 was prepared, but with the modification that 45 g of 2-methylbutyraldehyde, 35 g of activated manganese dioxide and 230 ml of dioxane were used. After a reaction time of 48 hours, the manganese oxides were removed by filtration and the resulting solution

H ₃ C CH ₃

showed only 2 peaks, A and B, in a ratio of 3: 2 on gas chromatography. The samples were freed of solvent and unreacted starting material by distillation under reduced pressure and the two products were separated by preparative gas chromatography.
The product A was made as a mixture of cis-

and trans - 2 - methyl - 2 - (2 '- methyl -Y- butenoxy) -butyraldehyde identified on the basis of the following specific data: The IR spectrum showed aldehyde - (- CH = O) absorptions at 3.70 and 5.74 μ, an olefin

yC = CH - O absorption

at 5.95 μ and a strong band at 8.74 μ leading to the ether

= c — o — c—

suggested. The nuclear magnetic resonance spectrum, by which the postulated structure is confirmed, showed absorptions with a center at 9.02 to 9.12 τ, corresponding to the - CH ₂ CH ₃ groupings, a singlet methyl absorption at 8.77 τ, corresponding to

R - C - CH ₃ bond
R.

Allylmethyl absorptions at 8.37 and 8.45 τ, an olefinic proton absorption, corresponding to the

^ C = CH - O protons

30th

at 4.15 τ and an aldehydic proton absorption at 0.35 τ. By doubling many of the absorptions occurring here it was evident that the sample was a 3: 2 mixture of trans and cis isomers; the proton integration was consistent with this. The mass spectrum of A revealed a molecular ison peak at m / el70 and an M- (CHO) peak at m / e 141.

Product B was identified as a 1: 1 mixture of meso- and dl-2,3-diethyl-2,3-dimethyisuccinaldehyde, based on the following data: The IR spectrum showed absorptions at 3.70 and 4, 80 μ corresponding to the saturated aldehyde groups; the nuclear magnetic resonance spectrum showed absorptions for the - CHjCH ^ groups with a center at 9.24 t, the R ₃ C-CH ₃ groups occurred at 8.97 τ, and the aldehydic protons absorbed at 0.42 and 0.49 τ . The doubling of both the aldehydic proton absorption and other relevant peaks indicated the presence of equal amounts of two (dl and meso) diasteroisomers. Nuclear magnetic resonance proton integration was applicable to this structure. The mass spectrum showed a small molecular ion peak at m / e 170 as well as an extended M — CH = O (M-29) peak at m / e 141.

Example 5

In an experiment similar to Example 4 using 22 g of 2-methylbutyraldehyde, 50 g of activated manganese dioxide, 65 ml of tetrahydrofuran and 90 ml of dioxane, a yield of 19.4 g of a crude dimer mixture was obtained, the gas chromatographic analysis of which was a mixture of 54.6 % 2 - methyl -2- (T- methyl - Γ - butenoxy) butyraldehyde

2,3 - diethyl - 2,3 - dimethylmeso) and 2.1% others

(ice and trans), 43.3%
succinaldehyde (dl and
Products revealed.

Example 6

A mixture similar to that of Example 1 was prepared, but with the modification that 20 g of 2-methylbutyraldehyde, 15 g of nickel peroxide and 150 ml of dioxane were used. The reaction mixture was stirred for 30 minutes at room temperature before it was heated under reflux (about 100 ⁰ C). When the reaction temperature reached 95 ° C, the black color of the nickel peroxide slurry turned light green. The reaction was cooled and the mixture filtered to remove the nickel oxides. The solvent and unreacted starting aldehyde were removed by distillation under reduced pressure to give 2.93 g of a dimeric material, which is obtained from a mixture of 2-methyl -2- (T- methyl -1 '-butenoxy) butyraldehyde (ice and trans) and 2,3-diethyl-2,3-dimethylsuccinaldehyde (dl and meso) in a ratio of about 2: 1. The identification was carried out by separating the components with the aid of preparative gas chromatography and comparative spectral examinations with the aid of known samples.

Example 7

A reflux mixture similar to that of Example 2 was prepared, but with the modification that 105 g of 2-ethylbutyraldehyde, 25 g of activated manganese dioxide and 80 ml of dioxane were used. After a reaction time of 48 hours, the solvent and excess 2-ethylbutyraldehyde were removed, giving 27.5 g of a crude product, the gas chromatographic analysis of which was 50% 2-ethyl-2- (T- ethyl -1'-butenoxy) -butyraldehyde and 13% tetraethylsuccinaldehyde together with 37% of numerous components occurring in smaller amounts. The two main components were isolated by preparative gas chromatography and identified on the basis of their characteristic spectral properties.

The spectral properties of 2-ethyl-2- (2'-ethylbutenoxy) butyraldehyde ■ ren following: The IR spectrum showed absorption egg. at 3.68 and 5.74 u that are characteristic of the aldehyde group (- CH = O); an absorption at 5.96 μ became the olefinic absorption

assigned and the etheric function

U = C-O-C-

absorbed at 8.6 to 8.8 μ. The nuclear magnetic resonance spectrum showed a singlet aldehyde proton absorption (- CH = O) at 0.40 τ ; an olefinic "proton absorption

209547 / 5Y

at 4.18 τ, two allylmethyl groups

CH ₃ -CHj -C = CC

as a quartet with a center at 7.90 t; two saturated methyl groups (CH ₃ -CH ₂ -C-) with a center at 8.30 τ and four saturated methyl groups with a center at 9.1 τ. The proton integral was correct. The mass spectrum indicated a molecular ion at m / e 198.

The tetraethylsiccinaldehyde showed IR absorptions at 3.69 and 5.80 μ, which indicate a saturated aldehyde, while the nuclear magnetic resonance spectrum showed a SinguieU-aldehyde proton absorption at 0.25 r, quartet methylene absorptions (-CH ₂ -CH ₃ ) at 8.28 τ and triplet methyl absorptions (- CH ₂ - CH ₃ ) with a center at 9.20 τ.

A fraction isolated by preparative gas chromatography comprising 3.8% of the total product mixture was identified as 2-ethylbutanol by IR comparison with a known sample ; furthermore, 0.65 g of a substance identified as the manganese salt of a carboxylic acid could be isolated from the crude product mixture.

The 2-ethyl-2- (2'-ethyl-1 '-butenoxy) butyraldehyde was conveniently obtained by distillation from the product mixture detachable, b.p. 69 to 73 ° C / 5mm. A total of 13.0 grams of relatively pure material was obtained in this way from 27.5 g of the crude product mixture. The tetraethyl succinaldehyde remained in the flask as a residue.

Example 8

In an experiment similar to Example 7, but using 24 g of 2-ethylbutyraldehyde, 70 g of pyridine, 70 ml of dioxane and 50 g of activated manganese dioxide with a reaction time of 48 hours obtained a total of 21.5 g of a crude product mixture, its gas chromatographic Analysis 85.6% of 2-ethyl-2- (2'-ethyl-l'-butenoxy) butyraldehyde. 10.6% tetraethyl succinaldehyde and 3.8% showed other products.

Example 9

A reflux mixture similar to that in Example 1 was prepared, but with the modification that 20 g of 3-methyl-2-butanone, 25 g of activated manganese dioxide and 75 ml of dioxane were used. After a reaction time of 48 hours, the solvent and unreacted starting ketone were removed by distillation under reduced pressure, giving 3.2 g of a crude product mixture. The distillation of this sample over a short path distillation head gave 1.48 g of a material boiling at 96 to 108 ° C./12 mm, which consisted practically of 85 to 90% of one component, as the gas chromatographic analysis showed. This main component can be further purified by preparative gas chromatography. The IR spectrum of a pure sample of this main product component showed a saturated ketone carbonyl absorption at 5.84 μ. The nuclear magnetic resonance spectrum showed only two singlet absorptions at 8.82 and 7.88 τ ir a ratio of 2: 1. The mass spectrum showed a molecular ion peak at m / e 170, an MH ₂ O peak at m / e 152 and an M-ketene peak at m / e 128. 4-tetramethyl-2,5-hexanedione identified.

Example 10

A mixture of phenyl-2-propanone (13.4 g), dioxane (110 ml), and activated manganese dioxide (35 g, was prepared and stirred under reflux (about 100 "C) in an inert nitrogen atmosphere for a period of 24 hours The solution was filtered to separate the insoluble manganese oxides and the solvent removed under reduced pressure to give a yellow crystalline solid which yielded 8.4 g of a light yellow crystalline material from ethanol with a melting point of 205 ° C Product was identified as 3,4 - diphenylhexane - 2,5 - dione by means of its extremely characteristic spectra, and the IR spectrum showed bands at 3.45, 5.85, 6.24, 6.31, 6.67, 6 , 87, 7.04, 7.26, 7.35, 7.84, 8.67, 9.31, 9.68, 10.36, 13.41 and 14.20 μ. The nuclear magnetic resonance spectrum showed the acetylmethyl group ( -COCH ₃ ) at 8.12 r, the

HO

C - C protons

at 5.40 τ and the aromatic protons at 2.58 τ The spectrum was found to be correct for 3,4-diphenylhexane-2,5-dione integrate. The mass spectrum showed a molecular ion at m / e 266.

Example 11

A mixture of 2-phenylcyclohexanone (25 g), Dioxane (115 ml) and activated manganese dioxide (35 g)

was made and refluxed (about 100 ° C) for 48 hours under an inert nitrogen atmosphere touched. The solution was filtered to separate the insoluble manganese oxides and the solvent was removed under reduced pressure

pulled to give a dark oil (20.1 g), from which a total of 8.51 g of a crystalline material were obtained from an ethanol solution. The crystallization led to dl and meso isomers with melting points 186 to 188 ° C and 132 to 134 ° C, respectively in roughly equal amounts. The IR spectra of these samples showed a highly saturated ketone carbonyl absorption at 5.87 µ. The nuclear magnetic resonance spectra showed an integration of five aromatic and eight aliphatic protons. The mass spectrum gave peaks at m / e 174 (1/2 M + 1), me / e 172 (1/2 M-I) and also at 144 and 130. A molecular ion peak was present in the range m / e 346 ± 5.

Claims (1)

Claim: Process for the dimerization of aldehydes or ketones, characterized in that that you have an aldehyde or a ketone of the general formula CH-C —R " R ' in which R and R 'are each alkyl, aryl, alkaryl or aralkyl and R "is hydrogen or a the radicals R 'means, with the proviso that 1. R is hydrogen when R' is aryl and R "is not hydrogen, or 2. R is phenyl when R 'and R" are taken together 1,4-Butylene radical means with activated manganese dioxide or with nickel peroxide in the liquid phase implements. The invention relates to a process for dimerization of aldehydes or ketones, which is characterized in that one is an aldehyde or a Ketone of the general formula CH-C —R " R ' in which R and R 'are each alkyl, aryl, alkaryl or aralkyl and R "is hydrogen or one of the R 'denotes, with the proviso that 1. R is hydrogen when R' is aryl and R "is not Is hydrogen, or 2. R is phenyl if R 'and R "together are 1,4-butylene, with activated manganese dioxide or with nickel peroxide in the liquid phase.