JP2000256237A - Production of trimethylolalkane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for easily producing a high-quality trimethylolalkane in high yield without yield drop due to formation of the corresponding formic ester. SOLUTION: This method for producing a trimethylolalkane comprises reacting the corresponding n-alkanal with formaldehyde in the presence of a tertiary amine and water; wherein the reaction mixture after ending the reaction is heated to a temperature enough to thermally dissociate a byproduct formic acid t-amine salt to effect dissociation of the byproduct into the corresponding t-amine and water which, in turn, are distilled off, and thereafter the resulting residues are heated to decompose the trimethylolalkane formic ester produced during the above-mentioned distillation step and included in the residues into the corresponding trimethylolalkane and carbon monoxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing trimethylolalkane by reacting n-alkanal with formaldehyde in the presence of a tertiary amine and water. Trimethylolalkanes are useful as raw materials for alkyd resins, polyurethane resins, (un) saturated polyester resins, synthetic lubricating oils, surfactants, reactive monomers and the like.

[0002]

2. Description of the Related Art As a method for producing trimethylolalkane, it is known to react n-alkanal with formaldehyde in the presence of an alkali metal or alkaline earth metal hydroxide. In this method, alkali metal or alkaline earth metal formate is by-produced. Trimethylolalkane undergoes catalytic pyrolysis by its formate, so when performing distillation, which is a normal isolation and purification method for trimethylolalkane, avoid a decrease in the yield of trimethylolalkane due to its catalytic pyrolysis. Therefore, the separation between trimethylolalkane and alkali metal or alkaline earth metal formate must be sufficient. For this reason, the separation operation becomes complicated.

As an improved method of this production method, a method of producing trimethylolalkane using a tertiary amine and water instead of an alkali metal or alkaline earth metal hydroxide (West German Patent No. 1952738) Official Gazette) has been proposed. In the method using the tertiary amine, the formate as a by-product is a tertiary amine formate having no catalytic thermal decomposition action on trimethylolalkane, and the thermal decomposition of trimethylolalkane can be suppressed. This method uses a boiling point difference between a tertiary amine formate and a trimethylolalkane to separate and remove a tertiary amine formate.

[0004]

However, the above-mentioned improved method has the following disadvantages. That is, during the separation of the tertiary amine formate and the trimethylolalkane using the boiling point difference, the formic acid generated by thermal dissociation of the tertiary amine formate and the trimethylolalkane react to form trimethylol. Alkane formate is formed. As a result, the yield of trimethylolalkane decreases.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have developed a method for producing trimethylolalkane in which n-alkanal and formaldehyde are reacted in the presence of a tertiary amine and water, in which the above-mentioned disadvantages of the conventional method are eliminated. We studied diligently to develop. As a result, the reaction mixture is heated to a temperature at which the by-produced tertiary amine formate contained in the reaction mixture after the reaction is thermally dissociated into formic acid and tertiary amine to distill tertiary amine and water. Then, when the obtained residue is heated, the formate of trimethylolalkane formed in the process of distilling tertiary amine and water is easily and efficiently decomposed into trimethylolalkane and carbon monoxide. As a result, the present inventors have found that the yield of trimethylolalkane does not decrease due to the formation of formate of trimethylolalkane, and the present invention has been accomplished. Further, the present inventors have found that the tertiary amine distilled off from the reaction mixture after the completion of the reaction can be reused in the production of trimethylolalkane, which has led to the present invention.

That is, the present invention relates to (1) a method for producing a trimethylolalkane by reacting n-alkanal with formaldehyde in the presence of a tertiary amine and water; Is heated to a temperature at which the tertiary amine and water are dissociated by heating the reaction mixture to a temperature at which the tertiary amine and water are dissociated. A method for producing trimethylolalkane, which comprises decomposing a formic acid ester of methylolalkane into trimethylolalkane and carbon monoxide by heating, (2) removing a tertiary amine distilled from a reaction mixture after completion of the reaction. It is intended to provide the method for producing trimethylolalkane according to (1), which is reused for producing trimethylolalkane.

In the method of the present invention, the tertiary amine formate as a by-product is thermally dissociated, and the formate of trimethylolalkane contained in the residue is also decomposed to produce trimethylolalkane. This is a method for producing trimethylolalkane which does not produce byformate or formate. In the present invention, the tertiary amine distilled from the reaction mixture after the completion of the reaction can be reused for producing trimethylolalkane.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a method for producing a trimethylolalkane by reacting an n-alkanal with formaldehyde in the presence of a tertiary amine and water comprises the following steps: Formation of aldol by an aldol condensation reaction between n-alkanal and formaldehyde under the following conditions: (2) Trimethylolalkane and tertiary amine formate by cross-cannizzaro reaction with aldol, formaldehyde, tertiary amine and water Consisting of generation.

After the above-mentioned aldol condensation reaction and cross-cannizzaro reaction, the resulting reaction mixture is heated to a temperature at which by-product tertiary amine formate can be thermally dissociated to form formic acid and tertiary amine. The secondary amine is distilled off. The generated formic acid reacts with trimethylolalkane to form a formate of trimethylolalkane.

Taking, for example, the case of using triethylamine as the tertiary amine and n-butanal as the n-alkanal, the aldol condensation reaction, the cross-cannizzaro reaction, the thermal dissociation of the tertiary amine formate and the trimethylol of the present invention. The reaction for forming the formate of the alkane is shown by the following reaction formulas.

(1) Aldol condensation reaction CH ₃ CH ₂ CH ₂ CHO + 2HCHO → CH ₃ CH
₂ C (CH ₂ OH) ₂ CHO

(2) Cross-cannibalism reaction CH ₃ CH ₂ C (CH ₂ OH) ₂ CHO + HCHO + N (C ₂ H ₅ ) ₃ + H ₂ O → CH ₃ CH ₂ C (CH
^{_{2 OH) 3 + HCOO - ·}} N + H (C 2 H 5) 3

[0013] (3) formic acid tertiary reaction of generating formic acid esters of thermal dissociation and trimethylol alkane amine salts ^{HCOO - · N + H (C} 2 H 5) 3 → HCOOH +
_{N (C 2 H 5) 3} CH 3 CH 2 C (CH 2 OH) 3 + nH
COOH → CH ₃ CH ₂ C (CH ₂ OCHO) _n (CH ₂
OH) _3-n (where n is 1, 2 or 3)

The tertiary amine produced by the reaction (3) is distilled off by heating. The formate of trimethylolalkane by-produced by the reaction (3) remains in the residue. In the present invention, trimethylolalkane formate ester contained in this residue is heated to produce trimethylolalkane. Heating the formate of trimethylolalkane produces trimethylolalkane and carbon monoxide.

CH ₃ CH ₂ C (CH ₂ OCHO) _n (CH ₂
OH) _3-n → CH ₃ CH ₂ C (CH ₂ OH) ₃ + nCO (where n is 1, 2 or 3)

Next, the aldol condensation reaction and the cross-Cannizzaro reaction in the present invention will be described. Examples of the n-alkanal in the present invention include propanal, n-butanal, n-pentanal, 3-methylbutanal, and n-alkanal.
-Hexanal, 3-methylpentanal, n-heptanal, 4-methylhexanal, n-octanal and the like.

Formaldehyde is usually 5 to 50% by weight.
An aqueous solution containing formaldehyde (i.e., formalin) is used, preferably 5 to 50% by weight formalin having a methanol content of 1% by weight or less.

The tertiary amine having a boiling point lower than that of trimethylolalkane and that of formate of trimethylolalkane is used. If such a tertiary amine is used, the tertiary amine can be easily distilled and recovered by heating the reaction mixture after the reaction. Preferred tertiary amines include trimethylamine, triethylamine, tri (n-propyl) amine, triisopropylamine, tri (n-butyl) amine, triisobutylamine, diethylmethylamine,
Aliphatic tertiary monoamines such as dimethylethylamine, dimethyl-n-propylamine, dimethylisopropylamine, dimethyl-n-butylamine and dimethylisobutylamine, triethylenediamine, N, N, N ',
N'-tetramethylethylenediamine, N, N, N ',
Aliphatic tertiary diamines such as N'-tetramethyl-1,3-propanediamine; nitrogen-containing heterocyclic tertiary such as N-methylmorpholine, N-ethylmorpholine, N-methylpiperidine, N-ethylpiperidine Amines and the like. These can be used alone or in combination of two or more.
A particularly preferred tertiary amine is triethylamine.

The molar ratio of n-alkanal, formaldehyde and tertiary amine is 3 to 4 mol, preferably 3. mol, per mol of n-alkanal.
2 to 3.6 moles and the tertiary amine is 1 to 2 moles, preferably 1.1 to 1.5 moles. If formaldehyde is used in an amount larger than the above range, it becomes difficult to recover the tertiary amine, which is not preferable. Further, even if the tertiary amine is used in an amount larger than the above range, the yield of trimethylolalkane will not be further improved, and the cost of the acid required for neutralization and the time required for the recovery of the tertiary amine will be rather long. Absent.

The amount of water used is 200 to 6 based on the total of n-alkanal, formaldehyde and tertiary amine.
00% by weight, preferably 250-500% by weight.

The aldol condensation reaction and cross-cannizzaro reaction of the present invention proceed sequentially. The reaction temperature for performing these reactions is usually -5 to 90C, preferably 10 to 80C. If the reaction temperature is lower than −5 ° C., the reaction rate is extremely slow, and if it is higher than 90 ° C., it is not preferable because by-products are easily generated.

After completion of the aldol condensation reaction and the cross-Cannizzaro reaction, the resulting reaction mixture is heated to a temperature at which by-product tertiary amine formate can be thermally dissociated to distill tertiary amine and water. When the reaction mixture is finally heated to 140 to 250 ° C., the tertiary amine formate is thermally dissociated into formic acid and tertiary amine, and the tertiary amine and water can be distilled from the reaction mixture. Heating of the reaction mixture may be performed under reduced pressure, normal pressure, or under pressure. The tertiary amine distilled off can be reused in the production of the trimethylolalkane of the present invention.

The tertiary amine and water are distilled off by heating the reaction mixture so that the water content in the residue is less than 20 parts by weight, preferably 1 part by weight, per 100 parts by weight of the residue. Do so to make it less. In this way, the tertiary amine can be recovered in good yield, and when almost all of the water is distilled off, the tertiary amine can be recovered in high yield.

The residue obtained by distilling off the tertiary amine and water contains the formate of trimethylolalkane in which formic acid produced by thermal dissociation has reacted with trimethylolalkane.

In the present invention, the residue obtained as described above is heated as it is or in the presence of a noble metal catalyst to remove the formate of trimethylolalkane contained in the residue with trimethylolalkane. Decomposes into carbon oxide.

The noble metal catalyst includes a ruthenium catalyst, a rhodium catalyst, a palladium catalyst, an osmium catalyst, an yttrium catalyst, a platinum catalyst and the like. Among them, a palladium catalyst is particularly preferable. Further, a noble metal catalyst obtained by modifying these noble metal catalysts with a Group 14 element of the periodic table may be used. In particular, a noble metal catalyst modified with a lead element is preferable. One or more of these noble metal catalysts can be used.

The noble metal catalyst is generally used as a carrier of the catalyst, such as carbon, alumina, silica, etc., and a polymer compound having a basic nitrogen atom group is used as a carrier. What is carried at 5% by weight to 10% by weight is used. The usage form is powder, granule, or pellet.

The amount of the noble metal catalyst used is 0.1 to 15 parts by weight of the noble metal as a noble metal based on 100 parts by weight of formic acid (HCOOH) that can be generated when the formate of trimethylolalkane contained in the residue is hydrolyzed. Range. A suspension method or a fixed bed method is used as a method for decomposing the formate of trimethylolalkane in the presence of a noble metal catalyst.

The formate of trimethylolalkane
To carry out the decomposition, the residue obtained by distilling the tertiary amine and water
At normal pressure or 2.9 as such or in the presence of a noble metal catalyst.
4MPa (30kgf / cm^Two) Preferred under the following pressure
Or 0.49 to 2.45 MPa (5 to 25 kgf / cm
^Two), Usually at 150 to 300 ° C, preferably 2
What is necessary is just to heat to 10-280 degreeC. Pressurizes heating of residue
If done below, the trimethylolalkane contained in the residue
Can easily and efficiently decompose formate
it can. When a noble metal catalyst is used, the pressure and pressure
More moderate conditions in the temperature range, i.e., normal pressure
1.96MPa (20kgf / cm ^Two) Less pressure
Lower, preferably 0.49 to 1.47 MPa (5 to 15 k
gf / cm^Two) Under pressure, 50-300 ° C, preferably
Just heat at 80-250 ° C, trimethylol alcohol
Oxidation of formate of can with trimethylolalkane
Can be decomposed into carbon.

For the decomposition of the formate of trimethylolalkane, an organic solvent may be used. Examples of the organic solvent include ethers such as diethyl ether, dichloroethyl ether, diisopropyl ether, and di-n-butyl ether, dimethyl ketone, methyl ethyl ketone, and methyl-
ketones such as n-propyl ketone, methyl-n-butyl ketone, methyl isobutyl ketone and diethyl ketone; nitro compounds such as nitromethane, nitroethane, 1-nitropropane, 2-nitropropane and nitrobenzene; formamide; N, N-dimethylformamide; Examples include amides such as acetamide, and nitriles such as acetonitrile and benzonitrile. One or more of these organic solvents can be used.

The method of the present invention may be carried out in any of a batch system and a continuous system. A method for carrying out a preferred embodiment of the present invention batch-wise will be described.

Formaldehyde (3.2 to 3.6 mol per mol of n-alkanal) and water (250 to 500% by weight relative to the total amount of n-alkanal, formaldehyde and tertiary amine) While maintaining the reaction temperature at 10 to 80 ° C., n-alkanal and a tertiary amine (1.1 mol per mol of n-alkanal) are charged into the reactor.
To 1.5 mol) for 1 to 3 hours to carry out the reaction, and the temperature is maintained at the same temperature for 1 to 5 hours to complete the reaction.

After completion of the reaction, a copper oxide catalyst and optionally a tertiary amine are added to the resulting reaction mixture,
The excess formaldehyde is converted to methanol and formic acid tertiary amine salt. The copper oxide catalyst is used in an amount of 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, based on the reaction mixture.

After the treatment with the copper oxide catalyst, the excess tertiary amine is neutralized with formic acid, methanol and water are distilled off from the reaction mixture under reduced pressure, then most of the water is distilled off, The amine is distilled off and recovered as an azeotrope with water. The distillation of methanol, water and tertiary amine is carried out by finally heating to 140-250 ° C. The tertiary amine and water mixture recovered as an azeotrope with water can be reused as it is or by circulating the tertiary amine separated from water to the reaction system.

The residue obtained by distilling off the tertiary amine and water is used as it is or formic acid (HCOOH) which can be generated when the formate of trimethylolalkane contained in the residue is hydrolyzed. ) 0.1 to 15 parts by weight of a noble metal catalyst as a noble metal is added to 100 parts by weight, and 0.49 to 2.45 MPa (5 to 25 kgf /
Heating to 210 to 280 ° C. under a pressure of ² cm ² ) decomposes the formate of trimethylolalkane contained in the residue into trimethylolalkane and carbon monoxide. The decomposition conditions when using a noble metal catalyst are 0.49 to
Heating at 80 to 250 ° C. under a pressure of 1.47 MPa (5 to 15 kgf / cm ² ) is sufficient. Thus, the formate of trimethylolalkane is decomposed into trimethylolalkane and carbon monoxide, and carbon monoxide is removed out of the system.

A high-quality trimethylolalkane can be easily isolated by distilling the residue obtained by decomposing the formate of trimethylolalkane to remove carbon monoxide out of the system.

[0037]

EXAMPLES The present invention will be described below with reference to examples, but these are illustrative, and the present invention is not limited to these.

Example 1 A 3822.4 g (8.91 mol of formaldehyde) of a 7% aqueous solution of formaldehyde was charged into a 5-liter reactor equipped with a thermometer, a reflux condenser, a stirrer, and a dropping funnel. N-butanal 1
94.7 g (2.70 mol) and triethylamine 30
3.6 g (3.00 mol) were added dropwise from separate dropping funnels over 1.5 hours each. Subsequently, the reaction was carried out for 3.5 hours while maintaining the internal temperature at 60 ° C. After the completion of the reaction, 100 g of a copper oxide catalyst was added, and 53.5 g of triethylamine was further added.
(0.53 mol) and stirred at 70 ° C. for 2 hours to treat excess formaldehyde. The reaction solution was filtered to remove the copper oxide catalyst, and 14.0 g of formic acid was added to the filtrate to adjust the pH.
Was adjusted to 5. This pH-adjusted liquid was added at 18.66 kPa.
The mixture was heated to 60 ° C. under reduced pressure (140 mmHg) to distill 17.9 g of methanol and 360 g of water.
Under reduced pressure of 32 kPa (250 mmHg), the mixture was heated to 80 ° C. to distill out 720 g of water, and further heated to 180 ° C. under normal pressure to distill and collect 355 g (3.51 mol) of triethylamine as a mixed liquid with 2470 g of water. did. Then, 465.3 g of the residue [trimethylolpropane 5
7.7 g (0.43 mol, 16% yield based on n-butanal), trimethylolpropane formate 33
5.2 g (monoester 160.6 g: 0.99 mol,
148.4 g of diester: 0.78 mol, 26.2 g of triester: 0.12 mol), 3.1 g (0.02 mol) of triethylamine formate, water 4.6 g, and other high boiling components derived from trimethylolpropane 1.96M
The mixture was heated to 260 ° C. for 3 hours under a pressure of Pa (20 kgf / cm ² ) to decompose the formate of trimethylolpropane into trimethylolpropane and carbon monoxide in the residue, and to remove carbon monoxide out of the system. Removed. 380 g of a residue were obtained, which did not contain formic acid and the formate of trimethylolpropane. The obtained residue was heated to distill off water. Then 0.4 kPa (3 m
mHg) under reduced pressure to give trimethylolpropane 3
11 g (2.32 mol; yield based on n-butanal 8)
6%).

Comparative Example 1 The procedure from the reaction to the pH adjustment was carried out in the same manner as in Example 1 to obtain 4388.2 g of the same pH adjusting solution as in Example 1. The pH-adjusted liquid was added at 18.66 kPa (140 mm
Under reduced pressure of Hg), heat to 60 ° C.
1 g and 374.9 g of water were distilled off, and then 33.32 kP
a, heated to 80 ° C. under reduced pressure of 250 mmHg to distill 827.5 g of water,
Under reduced pressure of Hg), 2301.5 g of water, 70.8 g (0.70 mol) of triethylamine and 364 g (2.47 mol) of triethylamine formate were distilled off at 50 ° C. 431.4 g of the obtained residue [trimethylolpropane 26
6 g (1.98 mol, yield based on n-butanal 73)
%), 58 g of formate of trimethylolpropane
(52 g of monoester: 0.32 mol, diester 6)
g: 0.03 mol, triester: trace), 52 g (0.35 mol) of triethylamine formate, 20.9 g of water,
In addition, contains high boiling components derived from trimethylolpropane]
Was distilled under reduced pressure of 0.4 kPa (3 mmHg) to obtain 76 g of formate of trimethylolpropane (68 g of monoester: 0.42 mol, 8 g of diester: 0.04 mol, triester: trace amount) and 250 g of trimethylolpropane. 9 g (1.87 mol; yield 69% based on n-butanal) were obtained.

Example 2 A mixture of triethylamine and water recovered in Example 1 was separated at 40 ° C. to separate triethylamine. Triethylamine 15 separated above as triethylamine
1.8 g (1.50 mol) of trimethylolpropane was produced in the same manner as in Example 1 except that the scale of the reaction was reduced to half. As a result, 152 g (1.13 mol; yield based on n-butanal of 84%) of trimethylolpropane was obtained. The residue after decomposition of the formate of trimethylolpropane did not contain formic acid or formate of trimethylolpropane.

Example 3 The procedure from the reaction to the distillation and recovery of triethylamine was carried out in the same manner as in Example 1.
5.3 g were obtained. To the obtained residue, 23.2 g of 5% palladium / carbon powder was added, and 0.98 MPa (10 kg
The mixture was heated at 200 ° C. for 2 hours under a pressure of f / cm ² ) to decompose the formate of trimethylolpropane in the residue into trimethylolpropane and carbon monoxide, and the carbon monoxide was removed from the system. 403.2 g of the residue obtained are then obtained
Was filtered to remove 5% palladium / carbon powder, and the filtrate (the filtrate contained no formic acid or formate of trimethylolpropane) was heated to distill off the remaining water. Thereafter, distillation was performed under a reduced pressure of 0.4 kPa (3 mmHg), and 311 g of trimethylolpropane (2.
32 mol; yield based on n-butanal: 86%).

Example 4 A mixture of triethylamine and water recovered in Example 3 was separated at 40 ° C. to separate triethylamine. Triethylamine 15 separated above as triethylamine
Trimethylolpropane was produced in the same manner as in Example 3 except that 1.8 g (1.50 mol) was used and the scale of the reaction was reduced to half. As a result, 152 g (1.13 mol; yield based on n-butanal of 84%) of trimethylolpropane was obtained. The filtrate obtained by filtering 5% palladium / carbon powder from the residue after the decomposition of the formate of trimethylolpropane contained no formic acid or formate of trimethylolpropane.

Example 5 5% palladium / carbon powder in Example 3 23.2
5% palladium-1% lead / carbon powder instead of g
The same procedure as in Example 3 was carried out except that 2 g was used, to finally obtain 311 g of trimethylolpropane (2.32 mol; yield based on n-butanal: 86%). The decomposition of the formate of trimethylolpropane was completed in 1 hour, and the filtrate obtained by filtering 5% palladium-1% lead / carbon powder from the residue after decomposition contained formic acid and formate of trimethylolpropane. Had not been.

[0044]

According to the method for producing trimethylolalkane of the present invention, the yield of trimethylolalkane does not decrease due to the formation of formate of trimethylolalkane, and high-yield and high-quality trimethylolalkane can be easily and efficiently obtained. Methylol alkanes can be produced. Also, since tertiary amines can be recovered and the tertiary amines recovered can be reused in the production of trimethylolalkane, a great advantage can be expected as compared with conventionally known production methods. The process for producing alkanes is a very advantageous industrial process.

Claims (11)

[Claims] In producing trimethylolalkane by reacting n-alkanal with formaldehyde in the presence of a tertiary amine and water, a temperature at which by-product tertiary amine salt of formic acid can be thermally dissociated is used. The tertiary amine and water dissociated by heating the reaction mixture after completion of the reaction are distilled off, and the formate of trimethylolalkane generated in the process of distilling the tertiary amine and water and contained in the residue is obtained. A method for producing trimethylolalkane, comprising decomposing into trimethylolalkane and carbon monoxide by heating. 2. The method according to claim 1, wherein the formate of trimethylolalkane is heated at normal pressure or under a pressure of 2.94 MPa or less. 3. The method according to claim 2, wherein the formate of trimethylolalkane is heated at 150 to 300 ° C. 4. The process according to claim 1, wherein the formate of trimethylolalkane is heated in the presence of a noble metal catalyst. 5. The method according to claim 4, wherein the noble metal catalyst is a palladium catalyst. 6. The method according to claim 4, wherein the noble metal catalyst is a noble metal catalyst modified with a lead element. 7. The method according to claim 4, wherein the noble metal catalyst is a palladium catalyst modified with elemental lead. 8. The method according to any one of claims 4 to 7, wherein the formate of trimethylolalkane is heated at normal pressure or under a pressure of 1.96 MPa or less. 9. The method according to claim 8, wherein the formic acid ester of trimethylolalkane is heated at 50 to 300 ° C. 10. The process according to claim 1, wherein the tertiary amine distilled off from the reaction mixture after the completion of the reaction is reused in the production of trimethylolalkane. 11. The method according to claim 1, wherein the tertiary amine is triethylamine.