JPS5852981B2 - Method for producing 2-(O-nitrophenyl)ethanols - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 2-(o-nitrophenyl)ethanol with good selectivity from 0-nitroalkylbenzenes and toformaldehyde.

2-(o-nitrophenyl)ethanols are compounds useful as intermediate raw materials for polymeric substances, polymeric stabilizers, pharmaceuticals, fragrances, and the like.

Despite this, little research has been conducted on its manufacturing method, for example, Chemica Act
aS candinavica, Vol. 21, p. 1961 (1967) and the same magazine, Vol. 23, p. 3055 (1967).
Only a few cases have been reported, such as in 969).

Moreover, the manufacturing method involves reacting nidoconvex toluene and paraformaldehyde in the presence of sodium ethoxide.

However, this method has the disadvantage that the catalyst, sodium ethoxide, is easily decomposed even by moisture in the air, making its preparation and handling difficult.

Moreover, if sodium ethoxide is further used as a catalyst, undesirable side reactions will proceed at the same time, and the desired 2-
A fatal drawback is that the yield and selectivity of (o-nitrophenyl)ethanol are low.

In addition, the aforementioned Chemica ActaS candi
navica, Vol. 23, p. 3055 (1969) describes a method for reacting 4-nitro-m-xylene and formaldehyde in a dimethyl sulfoxide solvent in the presence of caustic potash.

However, this method has a slow reaction rate, and because it uses a large amount of caustic potassium as a catalyst, it produces many side reaction products.
Even if ditroethylbenzene is applied, the corresponding 2-
(O-nitrophenyl)ethanol cannot be produced in high yield.

The present inventors have demonstrated that by reacting O-nitroalkylbenzenes and formaldehyde in the presence of caustic potash and/or caustic soda under specific conditions, the above-mentioned drawbacks of the conventional production method are improved, and 2-(o -Nitrophenyl) ethanols can be produced with high selectivity and yield, and have arrived at the present invention.

That is, the present invention is characterized in that 0-nitroalkylbenzenes and formaldehyde are reacted in dimethyl sulfoxide at a temperature of 50 to 130°C in the presence of 1 to 5 mol% of caustic potassium and/or caustic soda based on formaldehyde. This is a method for producing 2-(o-nitrophenyl)ethanol.

The 0-nitroalkylbenzenes used in the method of the present invention are 0-nitroalkylbenzenes having a primary alkyl group or a secondary alkyl group in the ortho position,
General formula (wherein R1 and R2 represent the same or different groups selected from the group consisting of hydrogen, an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group).

) is a compound represented by

More specifically, for example, o-nitrotoluene, 0
Examples include -nitroethylbenzene, 0-nitro-n-propylbenzene, 0-nitrocumene, 0-nitroisobutylbenzene, 0-nitrocyclohexylbenzene, and 0-nitrodiphenylmethane.

Among these 0-nitroalkylbenzenes, 〇-
Preference is given to applying the method of the invention to nitrotoluene.

Further, the formaldehyde used in the method of the present invention includes formaldehyde polymers such as formaldehyde and paraformaldehyde that can be easily decomposed under reaction conditions to generate formaldehyde.

The amount of formaldehyde used is 0.05 to 5 times the mole of the 0-nitroalkylbenzenes, preferably 0.05 to 5 times the mole.
It is in the range of 2 to 1.5 times the mole.

The method of the invention is carried out in the presence of caustic potash and/or caustic soda.

The amount of caustic potash and/or caustic soda used is in the range of 1 to 5 mol% relative to formaldehyde.

If the amount of caustic potash and/or caustic soda used is less than 1 mol % with respect to 1 mol of formaldehyde, the reaction rate will be slow, and if it is more than 5 mol %, by-products will increase and the desired 2-(o-di ) 0 phenyl) Since the selectivity of ethanols decreases, it is necessary that it be within the above range.

The amount of dimethyl sulfoxide used is 0.1 to 20, preferably 0.5 to 10, in terms of volume ratio to 0-nitroalkylbenzenes.

The reaction of the present invention needs to be carried out at a temperature of 50 to 130°C.

If the reaction temperature is lower than 50°C, the reaction rate will be slow, making it impractical.

Therefore, in order to proceed with the reaction at a reaction temperature lower than 50°C, it is necessary to use caustic potash and/or caustic soda at a higher concentration than the above.
In this case, the amount of by-products increases and the desired 2-(o-
The selectivity of ethanol (nitrophenyl) decreases.

Furthermore, when the reaction temperature was higher than 130°C, the 2-
(.

The dehydration reaction of ethanol (nitrophenyl) occurs, and (
(o-nitrophenyl) ethylene by-products rapidly increase.

The reaction time is not particularly limited, but is generally 0.25 to 10 hours.

The produced 2-(o-nitrophenyl)ethanol is separated and purified from the reaction mixture by common operations such as distillation and extraction.

The method of the present invention will be specifically explained below using examples.

In the Examples and Comparative Examples, the catalyst amount and yield represent mol % based on the aldehydes used, and the selectivity represents mol % based on the reacted nitroalkylbenzenes.

Examples 1 to 6, Comparative Examples 1 to 8 0-Nitrotoluene 9.2 g (low millimoles), 80%
0.94 g of paraformaldehyde (equivalent to 25 mmol of formaldehyde), dimethyl sulfoxide 7.
The mixture of 8- and catalyst (described in Group 1) was stirred for 1 hour at the temperature shown in Table 1.

After neutralizing the reaction mixture with dilute hydrochloric acid, the product was analyzed by gas chromatography to determine the yield and selectivity of 2-(o-nitrophenyl)ethanol.

The results are shown in Table 1.

Examples 9-19 A mixture of 9.2 g of 0-nitrotoluene, 0.94 g of 80% paraformaldehyde, 7.8** of dimethylformamide and a catalyst (described in Group 2) was heated to 1 at the temperature shown in Table 2.
The mixture was stirred for an hour and the product was analyzed by the method of Example 1.

The results are shown in Table 2. Example 20 The reaction was carried out in the same manner as in Example 5 except that hexamethylphosphoramide was used instead of dimethyl sulfoxide. 2(0-nitrophenyl)ethanol was produced in a yield of 4 and a selectivity of 80%. Obtained with.

9%,

Claims (1)

[Claims] io-nitroalkylbenzenes and formaldehyde are reacted at a temperature of 50 to 130'C in the presence of 1 to 5 mol% of caustic potash and/or caustic soda relative to formaldehyde in a dimethyl sulfoxide solvent. A method for producing 2-(o-nitrophenyl)ethanol, characterized in that: The method according to claim 1, characterized in that 0-nitrotoluene is used as the 2o-nitroalkylbenzene. 3. The method according to claim 1 or 2, characterized in that the reaction is carried out in the presence of caustic potash.