JPS6136733B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a new method for producing acetal. Acetals have a variety of industrial uses, such as as organic solvents, raw materials for the synthesis of fragrances and agricultural chemicals, and as derivatization through dealcoholization into vinyl ethers, which are raw materials for water-soluble polymers. Conventionally, acetals have been produced industrially by reacting alcohols with aldehydes or by oxidizing alcohols with manganese dioxide and sulfuric acid. Further, Proc.Chem.SOC., 1961, 370 discloses a method for producing acetaldehyde diisopropyl acetal by reacting ethylene, isopropanol, and oxygen in the presence of palladium chloride and sodium hydrogen phosphate. However, this method has drawbacks such as extremely slow reaction rate and poor yield of the target product. As an improved method, US Pat. No. 3,285,970 discloses a method for producing an acetal in which α-olefin, alcohol and oxygen are reacted in the presence of a palladium catalyst, a mineral acid and a halogen ion.
However, this method requires special corrosion-resistant equipment because it uses mineral acids and halogen ions as cocatalysts, and the catalyst system is complex, so operations such as separation, recovery, and regeneration are complicated. It has the following disadvantages. As described above, all of the previously proposed methods for producing acetal by reacting α-olefin with alcohol and oxygen have problems from an industrial standpoint, and have not yet been put to practical use. . The present inventors aimed to establish a method that can apply this reaction industrially, and searched for the catalytic action of various substances. As a result, it was discovered that nitrite ester is extremely useful as a co-catalyst, and the present invention was achieved. That is, the present invention provides an aliphatic α-olefin or styrene having 1 to 12 carbon atoms, and styrene having 1 to 12 carbon atoms.
The present invention provides a method for producing an acetal in which an aliphatic alcohol having a molecular weight of 12 to 12 is catalytically reacted with oxygen in the presence of palladium metal or a salt thereof and a nitrite ester. In the present invention, for example, when ethylene is used as the olefin, acetal is produced according to the following formula. (However, in the formula, R represents an alkyl group.) α-olefin, which is a raw material of the present invention, includes ethylene, propylene, 1-butene, 1-pentene, 1
-hexene, 1-heptene, 1-octene, 1-
Aliphatic α-olefins having 1 to 12 carbon atoms, such as nonene, 1-decene, 1-undecene, and 1-dodecene, or styrene are used, and these may have substituents that do not inhibit the reaction. The other raw material alcohol is methanol, ethanol, n-(or i-)propanol, n-(or i-)butanol, sec-butanol, n-(or i-)pentanol, n-(or i-) -) hexanol, n-(or i-)heptanol, n-(or i-)octanol n
- (or i-) decanol, n- (or i-)
Aliphatic alcohols having 1 to 12 carbon atoms are used, such as dodecanol. Further, the oxygen may be diluted with an inert gas such as nitrogen, or may be air.
This partial pressure is determined taking into account the explosion limit. The catalyst in the present invention is palladium metal, or a nitrate, sulfate, or phosphate of palladium metal.
Salts such as acetate are used. Its usage is
It is preferable to use within the range of 0.001 to 5 g in terms of palladium metal per 100 ml of raw material alcohol. In addition, when implementing the present invention industrially,
In order to facilitate the recovery of catalysts or products and to prevent loss of catalysts, these catalysts can be treated with activated carbon, silica gel, alumina, silica alumina, etc.
It may be used by being supported on a carrier such as diatomaceous earth, magnesia, pumice, or monocular sieve. As the nitrite ester used as a promoter,
Methyl nitrite, ethyl nitrite, propyl nitrite,
Butyl nitrite, amyl nitrite, hexyl nitrite,
Heptyl nitrite, nonyl nitrite, decyl nitrite,
Tridecyl nitrite, hexadecyl nitrite, benzyl nitrite, and the like are useful. The concentration of these nitrite esters can be varied over a wide range, but in order to obtain a satisfactory reaction rate, they should be used in the reaction system at least 0.05 times by volume, preferably 0.1 to 5 times by volume, relative to the raw material alcohol. It is better. This reaction may be carried out without a solvent or in a solvent inert to this reaction. Suitable solvents include, for example, lower aliphatic esters such as ethyl acetate, propyl acetate, butyl acetate, amyl acetate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate;
Aliphatic dicarboxylic acid diesters such as dimethyl oxalate, diethyl oxalate, dipropyl oxalate, dibutyl oxalate, dimethyl succinate, diethyl succinate, dimethyl adipate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, dibutyl carbonate. Aromatic carboxylic acid esters such as diester carbonate, methyl benzoate, ethyl benzoate, and dimethyl phthalate; ethers such as dioxane and dibutyl ether; and hydrocarbons such as benzene, toluene, xylene, cyclohexane, and n-hexane. In addition, monochlorobenzene, dichlorobenzene, nitrobenzene, acetophenone, alkyl sulfone, alkyl sulfoxide, etc. can be used. In the method of the present invention, the reaction is usually preferably carried out at a temperature of 20 to 150°C, and the reaction is carried out under normal pressure to increased pressure. Compared to conventionally known methods, the reaction rate of the present invention is extremely high, side reactions are suppressed, there is no corrosion of equipment caused by the catalyst, and the catalyst system is simplified. It has many industrial advantages, such as being extremely easy to recycle or recycle. Next, examples of the present invention and comparative examples will be given. Examples 1 to 6 A predetermined amount of n-butanol, n-butyl nitrite, a solvent, and 10 wt% were placed in a three-necked flask with an internal volume of 100 ml equipped with a thermometer, gas blowing tube, and condenser.
Charge Pd-C and add 42ml/42ml of ethylene while stirring.
min, while supplying air at a rate of 104ml/min.
The reaction was carried out at 70°C for a predetermined period of time. After the reaction, the product was analyzed by gas chromatography. The results are shown in Table 1. Note that in each Example, when n-butyl nitrite was not used, no acetal was produced at all.

[Table] Examples 7 to 10 A predetermined amount of n-butanol, 10 ml of nitrite ester, and a palladium catalyst were charged into an autoclave with an internal volume of 300 ml equipped with a thermometer, a gas blowing pipe, and a cooling pipe, and a predetermined amount of olefin was charged. It was press-fitted. Next, the temperature was raised to 90℃, and air was added at a rate of 5 kg/ ^cm2 .
After pressurizing the mixture twice, the reaction was carried out at 90°C for a certain period of time. After the reaction, the product was analyzed by gas chromatography. The results are shown in Table 2.

【table】

Claims (1)

[Scope of Claims] 1. An aliphatic α-olefin or styrene having 1 to 12 carbon atoms, an aliphatic alcohol having 1 to 12 carbon atoms, and oxygen, (A) palladium metal or its salts (B) A method for producing acetal, which is characterized by carrying out a contact reaction in the presence of a nitrite ester.