JPH02202872A - Production of 1-halo-2,2,6,6-tetraalkyl-4-piperidinol - Google Patents

Abstract

PURPOSE:To easily produce the subject compound in high yield and purity at about normal temperature by reducing 2,2,6,6-tetraalkyl-4-piperidinone with hydrogen in a solvent in the presence of a catalyst and adding a halogen to the product in the presence of a specific compound. CONSTITUTION:The objective compound useful as a component of bleaching detergent, etc., can be produced by (1) reducing 2,2,6,6tetraalkyl-4-piperidinone with hydrogen in an aqueous solvent in the presence of a catalyst (e.g. Raney nickel) under hydrogen pressure of 3-20kg/cm<2>G at 30-100 deg.C for 1-12hr to form 2,2,6,6-tetraalkyl-4-piperidinol, (2) filtering the reaction product in hot state to separate the catalyst, (3) adding a halogen such as Cl2 to the reaction mixture containing 2,2,6,6-tetraalkyl-4-piperidinol in the presence of an alkali metal halide (e.g. NaCl) and an alkali (e.g. NaOH) and (4) reacting at 0-60 deg.C under a pressure of 1-10kg/cm<2> for 1-20hr.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 1-halo-2,2,6,6-tetraalkyl-4-piperidinol.

Conventional ■Limb Blood■-Halo-2,2,6,6-tetraalkyl-4-piperidinol, for example, 1-di-4-2,2,6,6-tetraalkyl-4-piperidinol, was disclosed in JP-A-63 -1
As described in Japanese Patent No. 01498, it is useful as a component of bleaching detergents.

Conventionally, regarding the method of halogenating the hydrogen on the nitrogen of the piperidine ring, for example, Japanese Patent Application Laid-Open No. 47-25718 describes a method in which an aqueous solution or alcohol solution of 2,2,6,6-titramethylpiperidine is cooled with water, A method is known in which an aqueous hypochlorite solution is added to the mixture while stirring to cause a reaction.

However, by halogenating the hydrogen on the nitrogen of 2,2,6,6-tetraalkyl-4-piperidinol, ■-halo-
A method for industrially producing 2,2,6.6-tetraalkyl-4-piperidinol has not been known so far.

As a result of intensive research into the industrial production of 1-halo-2.2,6.6-tetraalkyl-4-piperidinol, the present inventors have already discovered that the first reaction step is , hydrogen reduction of 2,2,6,6-tetraalkyl-4-piperidinone in a solvent in the presence of a catalyst yields 2,2,6.6
-tetraalkyl-4-piperidinol, then
In the latter reaction step, high purity 1-
It has been discovered that halo-2,2.6°6-tetraalkyl-4-piperidinol can be produced in extremely high yield (Japanese Patent Application No. 239480/1982).

As a result of further research into this method, the present inventors discovered that in the latter reaction of the above method, hydrogen on the nitrogen of 2,2,6,6-tetraalkyl-4-piperidinol was removed in a slurry state. The present invention was achieved by discovering that the reaction can be carried out more advantageously by allowing an alkali metal halide to coexist during halogenation.

The method for producing 1-halo-2,2,6,6-tetraalkyl-4-piperidinol according to the present invention for preparing tongues comprises 2.
2.6.6-Tetraalkyl-4-piperidinone was reduced with hydrogen in the presence of a catalyst to give 2,2,6.6-tetraalkyl-4-piperidinol, and the resulting 2,2,6
．． In particular, according to the invention, 2,2,6,6-tetraalkyl-4 is characterized in that a halogen is added to the reaction mixture containing 6-tetraalkyl-4--piperidinol in the presence of an alkali metal halide and an alkali. - Produce high-purity 1-chloro-2゜2.6.6-tetraalkyl-4-piperidinol in high yield by bubbling chlorine into a solvent containing piperidinol in the presence of sodium chloride and an alkali. be able to.

The present invention will be explained in detail below.

First, in the method of the present invention, as the first reaction step, 2,2,6,6-tetraalkyl 4-piperidinone is reduced with hydrogen in a solvent in the presence of a catalyst to produce 2,2,6.
6-tetraalkyl-4-piperidinol.

In the 2,2,6,6-tetraalkyl-4-piperidinone used in the present invention, the four alkyl groups may be the same or different. Preferred examples of such alkyl groups include, for example, methyl and ethyl group. Therefore, specific examples preferably used in the present invention include 2,2,6,6-titramethyl-4-piperidinone, 2-ethyl-2,6,
Examples include 6-trimethyl-4piperidinone.

The above-mentioned reduction of 2,2,6,6-tetraalkyl-4-piperidinone with hydrogen is usually carried out by adding 2,2,6,6-tetraalkyl-4-piperidinone to Raney nickel in a solvent, preferably water. This can be carried out by reduction in the presence of a compound according to a conventional method. However, as a catalyst, other than Raney nickel, for example, platinum/carbon, palladium/carbon, Raney cobalt, etc. can also be used.

The concentration of 2,2,6,6-tetraalkyl-4piperidinone in the solvent is not particularly limited, but is usually in the range of 5 to 50% by weight, preferably 10 to 40% by weight. is preferred, and the amount of Raney nickel used is usually 2,2,6.6-tetraalkyl-4-
A range of 0.1 to 20% by weight, based on piperidinone, is suitable.

The reaction is usually carried out at a hydrogen pressure of 3 to 20 kg/cIllG and a temperature of 30 to 100°C for 1 to 12 hours, but it is preferably carried out under pressure and heating.

Through this first reaction step, the 2,2,6,6-tetraalkyl-4-piperidinone is converted to the corresponding 2°2.6
．． It is reduced to 6-tetraalkyl-4-piperidinol. Therefore, corresponding to the above-mentioned 2,2,6.6-tetraalkyl-4-piperidinone, for example, 2.2,6.
6-tetramethyl-4-piperidinol and 2-ethyl-
2,6,6-1-dimethyl-4-piperidinol is produced.

Then, according to the method of the present invention, after the first reaction is completed, the catalyst is filtered while hot, and then the filtrate containing the produced 2,2,6,6-tetraalkyl-4-piperidinol is added to the second reaction step. The desired I-halo-2.2,6 is produced by adding an alkali and an alkali metal halide, and if necessary, adding a solvent and adding a halogen to the reaction mixture.
．． 6-tetraalkyl 4-piperidinol can be obtained.

In this latter reaction step, the 2,2,6. 6-tetraalkyl-4-piperidinol is dispersed in a solvent in a slurry state of usually 5 to 50% by weight, preferably 10 to 40% by weight, in a heterogeneous two-phase system. used for reaction.

In the latter reaction step, as in the first step, water is preferably used as the solvent, but if necessary, a mixture of water and an organic solvent that is immiscible therein may be used. When a mixture of water and an organic solvent immiscible with water is used as the solvent, the organic solvent may be added to the reaction mixture in the subsequent reaction.

The organic solvent is not particularly limited as long as it does not have a harmful effect on the reaction, but aliphatic lower halogenated hydrocarbons having 1 to 3 carbon atoms such as methylene chloride and dichloroethane are usually preferably used. .

When a mixture of water and an organic solvent that is immiscible with water is used as a solvent, the 2,2
,6. 6-tetraalkyl-4-piperidinol is
It is subjected to the subsequent reaction in a slurry state (heterogeneous two-phase system) or homogeneous system dispersed in a mixed solvent.

The alkali used in the latter reaction step is preferably an alkali metal hydroxide or an alkaline earth metal hydroxide, with particular preference given to hydroxide, potassium hydroxide, calcium hydroxide, and the like.

The amount of alkali used is usually the same as the 2,2.6. The amount is 1 to 10 times the molar amount of 6-tetraalkyl-4-piperidinone, preferably 1.1 to 3 times the molar amount.

Further, as the alkali metal halide, sodium chloride, potassium chloride, lithium chloride, sodium bromide, potassium bromide, lithium bromide, etc. are used. these are,
Usually 2, 2, 6. 0.3 to 5 times the molar amount relative to 6-tetraalkyl-4-piperidinone, preferably 0
．． It is used in a range of 5 to 2 times the molar amount.

According to the method of the present invention, 2,2,6. A halogen is added to a solvent containing 6-tetraalkyl-4-piperidinol in the presence of an alkali and an alkali metal halide, and the mixture is reacted with stirring. The halogen is usually 1 to 5 times the molar amount of 2.2,6.6-tetraalkyl-4-piperidinone,
It is preferably used in a range of 1,03 to 2 times the molar amount.

As the halogen, chlorine, bromine or iodine is used depending on the desired halide, but the method of the present invention is particularly suitable for using chlorine, 1-chloro-2,2,6,6
-Tetraalkyl-4-piperidinols are advantageously obtained.

When using chlorine as a halogen, 2.2.6.6-
Bubbling chlorine into the solvent containing the tetraalkyl-4-piperidinol. Furthermore, when chlorine is used as the halogen in this manner, an alkali metal chloride, particularly sodium chloride, is preferably used as the alkali metal halide.

The reaction temperature is usually in the range of 0 to 60°C, preferably 10 to 40°C, particularly preferably 20 to 35°C.
is within the range of In addition, the reaction is not particularly limited, but is usually 1 to 10 kg/cI (preferably 1 to 10 kg/cI).
It is carried out under a pressure of 2 kg/c+fl for 1 to 20 hours, preferably for 2 to 5 hours.

The method of the present invention is particularly advantageous when the first stage reduction reaction is carried out under relatively harsh conditions, or when the first stage reduction reaction is carried out using a catalyst whose activity has decreased due to repeated use. It can be applied to

That is, when the first stage reduction reaction is carried out under relatively high reaction conditions of about 90°C or higher, or when a catalyst whose activity has decreased due to repeated reduction reactions,
In the first reaction step, a relatively large amount of low-boiling byproducts are produced, and when the reaction mixture containing such byproducts is directly subjected to the second halogenation reaction, under the reaction conditions 2.
2,6.6-tetraalkyl-4-piperidinol and its halide 1-halo-2.2,6.6-tetraalkyl-4-piperidinol are melted in a solvent,
The resulting 1-halo-2.2,6.6-tetraalkyl-
The purity and yield of 4=-piperidinol are significantly reduced.

However, according to the present invention, in the subsequent reaction,
Although the reason for this is not necessarily clear, the presence of an alkali metal halide in the reduction reaction mixture reduces the amount of 2.2.6.6-tetraalkyl-4-piperidinol and its halide, 1-halide, as described above. -2.
Under the reaction conditions of 2,6.6-tetraalkyl-4-piperidinol, it is prevented from melting in the solvent, thus producing ■-halo-2,2.6.6-tetraalkyl-4-piperidinol with high purity. It can be obtained in high yield.

After the latter reaction is completed, if water is used as the reaction solvent, the reaction mixture is cooled to room temperature, the formed crystals are separated, washed with water, and dried to obtain the desired 1-halo- 2.2,6.6-tetraalkyl-as a reaction solvent,
When a mixture of water and an organic solvent that is immiscible with water is used, the organic layer is separated, washed with water, the organic solvent is distilled off from the organic layer, and the residue is dried. -Hello-2. 2, 6.

6-tetraalkyl-4-piperidinol can be obtained.

Furthermore, according to the present invention, 2.2, 6. 6-Tetraalkyl-4-piperidinone is reduced with hydrogen in the presence of a catalyst to produce 2,2,6. 6-
After converting into tetraalkyl-4-piperidinol, the catalyst was filtered off while hot, and then, as a subsequent reaction step, the produced 2,2,6. A halogen is added to a reaction mixture containing 6-tetraalkyl-4-piperidinol in the presence of an alkali to form 1-halo-2.2,6. 6-tetraalkyl-
4-piperidinol is produced, which is filtered to give 1-piperidinol.
Halo-2. , 2,6.6-tetraalkyl-4-piperidinol, the above 1-halo-2.2,6. 6-tetraalkyl-4-
By adding the filtered mother liquor of piperidinol,
In the latter reaction step, similar results can be obtained when an alkali metal halide is added to the reaction mixture.

That is, in the first reaction step, 2 in a solvent.

Reducing 2,6,'6-titraalkyl-4-piperidinone with hydrogen in the presence of a catalyst, 2.2.6. After converting to 6-tetraalkyl-4-piperidinol, the catalyst is filtered off while hot, and then, as a subsequent reaction step, the above-mentioned 2.2, 6
．． A halogen is added to a reaction mixture containing 6-tetraalkyl-4-piperidinol in the presence of an alkali to produce ■-halo-2.2,6.6-tetraalkyl-4-piperidinol, which is obtained by filtration. The mother liquor produced contains alkali metal halides produced by the reaction between the alkali and halogen, so in the new subsequent reaction, the mother liquor is used and added to the reaction mixture from the previous reaction step. An alkali metal halide can be supplied to the reaction mixture by adding to the reaction mixture.

For example, when sodium hydroxide is used as the alkali and chlorine is used as the halogen in the later reaction step, the mother liquor contains sodium chloride.

Furthermore, according to the method of the present invention, in the latter reaction step, 2
, 2,6.6-tetraalkyl-4-piperidinol and the halogen are added directly into the alkali-containing solvent for reaction, so there is no need for an excess alkali, and,
The desired 1-halo2,2,6,6-tetraalkyl-4-piperidinol can be obtained in high yield by carrying out the reaction at a temperature around room temperature. Furthermore, since the reaction is carried out in a slurry state, productivity is high, there is little elution loss to the mother liquor, and the yield is high.

As described above, according to the method of the present invention, the first reaction step is carried out under relatively harsh conditions, or the first reaction step is carried out using a catalyst whose activity has decreased due to repeated use. Even if low-boiling point by-products are produced,
In the latter reaction step, 2,2,6.6-
Tetraalkyl-4-piperidinol and its halide 1-halo-2.2,6.6-tetraalkyl-
Prevents the melting of 4-piperidinol in the solvent and thus
Piperidinol can be obtained with high purity and high yield.

Furthermore, the method of the present invention does not require an excessive amount of alkali in the subsequent reaction step, and is more industrially efficient than when an aqueous hypohalite solution is prepared in advance and the reaction is carried out. By reaction at an advantageous temperature of about room temperature,
1-halo-2.2,6.6=tetraalkyl-4-piperidinol can be obtained with high purity and high yield. Furthermore, since the reaction is carried out in a slurry state, productivity and yield are high.

The present invention will be described below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 115.9 g (0,725 mol) of 2,2,6,6-tetramethyl-4-piperidinone with a purity of 97.1%, 260 g of water
g and 4.1 g of Raney nickel was heated and stirred at 90° C. for 6 hours at a hydrogen pressure of 15 kg/c+flG.

After the reaction was completed, the catalyst was filtered while hot, and 35 g (0.6 mol) of sodium chloride and 70.3 g (0,844 mol) of a 48% aqueous sodium hydroxide solution were added to the obtained filtrate to form a slurry. While maintaining the temperature of this slurry at 35°C, 53.0 g (0,747 mol) of chlorine was blown into it over a period of 2 hours.

After completion of the reaction, the reaction mixture was allowed to cool to room temperature, and the formed crystals were centrifuged, reslurried and washed with 60 ml of water, and then dried under reduced pressure to a constant weight to give a purity of 98.6.
% (based on iodometry; the same applies hereinafter). 126.4 g of 1-chloro-2,2,6,6-tetramethyl-4-piperidinol was obtained. The yield based on 2.2.6.6-tetramethyl-4-piperidinone was 89.7%.

Example 2 In Example 1, the amount of sodium chloride used was 25g.
The reaction was carried out in the same manner as in Example 1 except that the amount was changed to (0.43 mol). As a result, 1-chloro-2,2,6,6-tetramethyl-4-piperidinol with a purity of 98.8% was obtained with a yield of 88.4% based on 2.2,6.6-tetramethyl-4-piperidinone. Obtained.

Example 3 In Example 1, the amount of sodium chloride used was 45g.
The reaction was carried out in the same manner as in Example 1 except that the amount was changed to (0.77 mol). As a result, 1-chloro-2,2,6,6-tetramethyl-4-piperidinol with a purity of 98.2% was obtained with a yield of 90.2% based on 2.2.6.6-tetramethyl-4-piperidinone. Obtained at.

Example 4 In Example 1, in place of sodium chloride, Example 1
300 g of mother liquor after centrifugation of 1-chloro-2,2,6,6-tetramethyl-4-piperidinol obtained by chlorination without adding sodium chloride (38 g of sodium chloride)
(0.65 mol). ) was used, but the reaction was carried out in the same manner as in Example 1. As a result, the purity is 97
．． 2% 1-chloro-2,2,6,6-tetramethyl-
4-piperidinol to 2,2,6,6-tetramethyl-
The yield was 87.6% based on 4-piperidinone.

Example 5 In Example 4, 250 g of mother liquor (sodium chloride 3
Contains 2 g (0.55 mol). ) was used.
The reaction was carried out in the same manner as in Example 4, and the purity was 97.
8% 1-chloro-2,2,6,6-tetramethyl-4
-piperidinol to 2,2,6,6-tetramethyl-4
- Obtained with a yield of 87.0% based on piperidinone.

Comparative Example 1 In Example 1, 2,2,6.6-tetramethyl 4-
After reducing the piperidinone in water, the catalyst is filtered hot;
48 without adding sodium chloride to the obtained filtrate.
% aqueous sodium hydroxide solution (70.3 g (0,844 mol)) was added to form a slurry. While maintaining the temperature of this slurry at 35"C, 53.0 g of chlorine (
0,747 mol) was injected over a period of 2 hours.
At the point when about 20% of it is blown in, the reactant melts,
Further blowing of chlorine solidified the melt.

The reaction mixture was allowed to cool to room temperature, the product was centrifuged, washed with 60 ml of water, and dried under reduced pressure to a constant weight to give 1-chloro 2.2,6. 96.3 g of 6-tetramethyl-4-piperidinol was obtained. 2
The yield based on ,2,6.6-tetramethyl-4-piperidinone was 65.1%.

Patent applicant Mitsui Petrochemical Industries Co., Ltd. Agent Patent attorney Itsube Makino

Claims (4)

[Claims] (1) 2,2,6,6-tetraalkyl-4 in a solvent
-Piperidinone is reduced with hydrogen in the presence of a catalyst, 2,2,
6,6-tetraalkyl-4-piperidinol, and then adding a halogen to the reaction mixture containing the obtained 2,2,6,6-tetraalkyl-4-piperidinol in the presence of an alkali metal halide and an alkali. 1-halo-2,2,6,6-tetraalkyl-4- characterized by
Method for producing piperidinol. (2) 2,2,6,6-tetraalkyl-4 in a solvent
-Piperidinone is reduced with hydrogen in the presence of a catalyst, 2,2,
After converting into 6,6-tetraalkyl-4-piperidinol, chlorine is bubbled into the reaction mixture containing the obtained 2,2,6,6-tetraalkyl-4-piperidinol in the presence of sodium chloride and an alkali. A method for producing 1-chloro-2,2,6,6-tetraalkyl-4-piperidinol. (3) 2,2,6,6-tetraalkyl-4 in a solvent
-Piperidinone is reduced with hydrogen in the presence of a catalyst, 2,2,
After converting to 6,6-tetraalkyl-4-piperidinol, halogen was added to the reaction mixture containing the obtained 2,2,6,6-tetraalkyl-4-piperidinol in the presence of an alkali to form 1-halo- In a method for producing 1-halo-2,2,6,6-tetraalkyl-4-piperidinol by producing 2,2,6,6-tetraalkyl-4-piperidinol and filtering it, the above reaction The above 1-halo-2,2,6,6-tetraalkyl-4 is added to the mixture.
- 1-halo-2,2,6,6-tetraalkyl-4-, characterized in that the mother liquor after filtration of piperidinol is added.
Method for producing piperidinol. (4) 2,2,6,6-tetraalkyl-4 in a solvent
-Piperidinone is reduced with hydrogen in the presence of a catalyst, 2,2,
After converting into 6,6-tetraalkyl-4-piperidinol, chlorine was bubbled into the reaction mixture containing the obtained 2,2,6,6-tetraalkyl-4-piperidinol in the presence of an alkali to form 1-chloro- 2,2,6,6-tetraalkyl-4-piperidinol is produced which is filtered to give 1-chloro-2,2,6,6-tetraalkyl-4
- A method for producing piperidinol, characterized in that a filtered mother liquor of the 1-chloro-2,2,6,6-tetraalkyl-4-piperidinol is added to the reaction mixture. , 6,6-tetraalkyl-4-piperidinol production method.