JPH0273027A - Production of aromatic carbinol - Google Patents

Abstract

PURPOSE:To produce the subject substance useful as a raw material for pharmaceutical and agricultural raw materials in high selectivity and short time with a simple apparatus compared with conventional process by hydrogenating an aromatic ketone in the presence of a Pd catalyst supported on a basic carrier such as calcium carbonate or magnesium oxide. CONSTITUTION:The subject substance can be produced by hydrogenating a compound of formula (R' is H, 1-5C alkyl, 1-22C alkoxy or halogen; R'' is alkyl or arylalkyl) at 50-150 deg.C and 2-20kg/cm<2> pressure in the presence of a Pd catalyst supported on a basic carrier (selected from calcium carbonate, magnesium oxide and strontium carbonate). The concentration of the catalyst in the reaction system is 0.25-0.5wt.% in terms of pure Pd based on the aromatic ketone. The solvent may be absent. The objective compound can be produced with 100% selectivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for hydrogenating aromatic ketones to produce aromatic carbinol.

The aromatic carbinol produced by the method of the present invention is
It is a compound mainly used as a raw material for medicines and agrochemicals.

[Prior art and problems to be solved by the invention] In the production of carbinol by the hydrogenation reaction of aromatic ketones, unlike the case of hydrogenation of aliphatic ketones, not only the carbonyl group but also the aromatic ring participates in the reaction. Moreover, since carbinol, the hydrogenation product, has a benzyl alcohol type hydroxyl group, it is easily subject to subsequent hydrogenolysis of the hydroxyl group, which complicates the reaction. Therefore, the desired product is usually obtained by using a palladium catalyst supported on activated carbon or an alumina carrier, or by selecting a Raney nickel catalyst and by selecting reaction conditions. Among these, it is well known that alkaline additives have the effect of suppressing the hydrogenolysis of benzyl alcohol-type hydroxyl groups and also improve the reaction rate [Kusano et al., Pharmaceutical Research, Vol. 30,
26N 1950]].

The alkaline additives used as cocatalysts include:
In addition to alkali metal salts of organic acids such as sodium acetate, alkali metal hydroxides (e.g., sodium hydroxide, potassium hydroxide) are said to be effective for boat fishing [New Experimental Chemistry Course Vol. 15 Oxidation and reduction (n) P408'l.

In addition, in reactions using Raney nickel catalysts, usually 1
00kg/cm2.It requires operation at high temperature and high pressure conditions of 100℃ or higher, which is not preferable in terms of equipment costs in industrial scale production, whereas similar effects can be obtained at relatively low temperature and low pressure. A palladium catalyst supported on activated carbon has been reported [Journal of
Organic Chemistry (JOC), Volume 24,
P1855 (1959)).

The inventor carried out the operations shown in the comparative example to be described later and obtained alkali I.
It was confirmed that using a palladium catalyst in which J is supported on activated carbon in the presence of an additive, the same effect as Raney nickel can be obtained even at low pressure. However, since alkali metal hydroxides or alkali metal salts of organic acids have very low solubility in aromatic ketones, a solvent such as methanol or ethanol is required.

Furthermore, when the solvent is separated and recovered in the post-isolation and purification process of the product, alkali metal hydroxides such as sodium hydroxide or alkali metal salts of organic acids are precipitated from the aromatic carbinol remaining in the bottom liquid. I'll come. This is because alkali metal hydroxides such as sodium hydroxide or alkali metal salts of organic acids have only a small solubility in aromatic carbinol. This causes problems such as clogging of perforated plates during the carbinol rectification process and fouling of the reboiler itself. Therefore, in order to remove this precipitate, operations such as filtration and decantation are performed, but in production on an industrial scale, the process becomes complicated and it is not preferable from the viewpoint of equipment costs.

An object of the present invention is to solve the problem of precipitation of alkali hydroxides and alkali metal salts as promoters when producing aromatic carbinol from aromatic ketones without using them.

[Means to solve the problem]

The present inventors solved this problem by using a palladium catalyst supported on a basic carrier as a catalyst.

That is, the present invention is a method for producing aromatic carbinol, which is characterized by hydrogenating an aromatic ketone in the presence of a palladium catalyst supported on a basic carrier.

The present invention will be described in detail below, including implementation conditions.

The catalyst used in the present invention has palladium supported on a basic carrier. The amount of palladium supported on the basic carrier is preferably 0.1 to 20% by weight. The basic carrier used must be insoluble in the aromatic ketone as a raw material and the aromatic carbinol as a product, and any commercially available carrier may be used. Specific examples include calcium carbonate, magnesium oxide,
Strontium carbonate is preferably used. All of these basic carriers are insoluble in aromatic ketones and aromatic carbinol, and do not cause any problem of elution of the catalyst carrier. The concentration of catalyst used is, for aromatic ketones,
0.1 to 1% by weight of pure palladium, preferably 0.2
If the amount is 5 to 0.5% by weight, and less than 0.1% by weight, the reaction rate will be low, and if the amount of the catalyst is more than 1% by weight, the hydrogenolysis reaction of the produced aromatic carhyryl will tend to occur as a by-product.

The aromatic ketone used in the present invention has the following general formula (1)
This is shown in .

(In the formula, R" represents H or a C1 to C5 straight chain or branched alkyl group, a C1 to C2 lower alkoxy group, or a halogen, and R' represents an alkyl group or an arylalkyl group.) Examples include acetophenone, propiophenone, n-propylphenyl ketone, i-furobylphenyl ketone, n-7'tylphenyl ketone, l-butylphenyl ketone, SeC-butylphenyl ketone, t-
These include butylphenyl ketone, benzylphenyl ketone, halogen-substituted phenylmethyl ketone, and the like.

In the reaction of the present invention, a solvent may or may not be used, but when used, compounds that react with hydrogen in the presence of the palladium catalyst used in the present invention, such as olefins, acetylenes, etc. It is inappropriate to use , nitro compounds, etc. as a solvent because the hydrogenation efficiency of aromatic ketones becomes poor. For example, methanol, ethanol, n-
It is preferable to use alcohols such as 7' lovanol, l-7' lovanol, n-butanol, l-butanol, 5eC-butanol, and t-butanol in an amount of 0.6 parts by weight or less per 1 part by weight of the aromatic ketone. It is not preferable to use more solvent than this because it increases both recovery energy and recovery time, and above all, reduces production capacity.

The hydrogenation reaction can be carried out at a temperature in the range of 10°C to 200°C, but preferably 50°C to 150°C. Generally, if the temperature is below 50°C, the time required for the reaction will be longer, whereas if the temperature exceeds 150°C, side reactions of aromatic ketones, such as hydrogenation of aromatic rings and hydrogenolysis of aromatic carbinol, will more easily occur.

The hydrogenation pressure may be in the range of normal pressure to 150 kg/cm', more preferably about 2 to 20 kg/cm2.

At low pressures, the reaction rate is slow, at high pressures there is a risk of side reactions, and above all, production equipment that can withstand high pressures is required.

The resulting reaction crude liquid is subjected to a rectification process after the palladium-supported catalyst is separated and removed by filtration.

If a solvent is used, a solvent recovery step is required prior to rectification of the product aromatic carbinol. Both this step and the rectification step can be carried out without any problem by using a general distillation apparatus.

Therefore, the present invention does not require any special equipment and can be easily carried out using conventional general reaction and purification equipment.

〔Example〕

EXAMPLES The present invention will be described below with reference to Examples and Comparative Examples for detailed explanation of the present invention.

Into a 1β autoclave with a magnetic stirrer, 130 g of p-inbutylacetophenone and 65.0 g of methanol.
, 13.0 g of a catalyst made of 5% by weight of palladium supported on calcium carbonate was added, and H2 of G was poured into 8.
Stirring was continued for 18 hours at 0°C until gas absorption stopped.

Thereafter, the residual H2 in the autoclave was depressurized, and the palladium catalyst in the reaction crude liquid was removed by suction filtration. The liquid was quantitatively determined by gas chromatography.
It was found that isobutylphenyl)methyl carbinol was produced at a conversion rate of 85% and a selectivity of 100%. Further, from this reaction filtrate, methanol was distilled off at normal pressure using a rotary evaporator to obtain 126.4 g of a concentrated solution, with no precipitate present in the reactor residue.

When this concentrated liquid was analyzed by gas chromatography, it was found to be almost 100% (p-inbutylphenyl)methyl carbinol.

Comparative Example-1 In the same manner as in Example-1, 130 g of p-inbutylacetophenone was placed in an autoclave equipped with a magnetic stirrer.
65.0 g of methanol and 13.0 g of a catalyst in which 5% by weight of palladium was supported on activated carbon were added, 8 KG of H2 was charged, and the mixture was stirred at 60° C. for 3.5 hours until gas absorption stopped. After the reaction was completed, the palladium catalyst in the crude reaction solution was removed by suction filtration, and the solution was quantified by gas chromatography, and it was found that (p-isobutylphenyl)
Methyl carbinol is 0.29 mo1%, p-isobutylethylbenzene is 95. The selectivity of (p-inbutylphenyl)methylcarbinol was 0.3%.

Comparative Example-2 As in Comparative Example-1, 130 g of p-inbutylacetophenone, 65.0 g of methanol, 1.6 g of sodium hydroxide,
Catalyst 13.0% by weight of palladium supported on activated carbon
8 kg of H2 was added thereto, and stirring was continued for 3.5 hours at 60°C until gas absorption stopped.

After the reaction was completed, the palladium catalyst in the crude reaction solution was removed by absorption filtration, and the solution was quantified by gas chromatography, and it was found that (p-inbutylphenyl)methyl carbinol was present at a conversion rate of 97% and a selectivity of 99%. It was found that 7. However, when methanol was distilled off from this reaction filtrate at normal pressure using a rotary evaporator, sodium hydroxide precipitated.

〔Effect of the invention〕

As is clear from the above examples, aromatic carbinol is produced from aromatic ketone represented by formula (1) with a selectivity of 100% by the method of the present invention using a palladium catalyst supported on a basic carrier. , can be manufactured quickly and with simpler equipment than conventional methods.

Claims (1)

[Scope of Claims] 1. A method for producing aromatic carbinol, which comprises hydrogenating an aromatic ketone in the presence of a palladium catalyst supported on a basic carrier. 2. The method according to claim 1, wherein the aromatic ketone is an aromatic ketone represented by the following formula (1). ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (1) (In the formula, R' represents H or a linear or branched alkyl group of C_1 to C_5, a lower alkoxy group of C_1 to C_2, or a halogen, and R" is an alkyl group. 3. The method according to claim 1 or 2, wherein the basic carrier is selected from the group consisting of calcium carbonate, magnesium oxide and strontium carbonate.