DE1543317B2 - Process for the production of amines - Google Patents

Description

The invention relates to a process for the preparation of amines of the general formula

R,

R ₂ -C-NH ₂

R ₃

and

R ₄ -CH CH-R ₅

(CH ₂ ) ,, (CH ₂ ),
C.

R ₆ NH ₂

wherein R ₁ , R ₂ and R ₃ denote hydrogen, alkyl, arylalkyl or cycloalkyl radicals and mixtures of these radicals with at least one radical other than hydrogen, the radicals containing 2 to 48 carbon atoms, R ₄ , R ₅ and R ₆ hydrogen, alkyl -, arylalkyl or cycloalkyl radicals and mixtures of these radicals and the sum of a + b + c is between 2 and 9.

The method is characterized in that at 0 to 13O ⁰ C, a nitrile of the general formula

R ₇ -C = N

(HD

wherein R _{7 represents} hydrogen, an alkyl, aminoalkyl or aryl radical and metal salts of the aminoalkyl radical, the radicals containing 1 to 21 carbon atoms, with an alcohol of the general formula

and

R ₂ -C-OH

R ₃

CH ₂ ) _C

wherein R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , a, b and c have the meaning given above in the presence of anhydrous hydrogen fluoride, the molar ratio of hydrogen fluoride to alcohol being greater than about 3, and that amine formed is hydrolyzed in a manner known per se at a temperature of 50 to 300 ^° C. with a hydrolysis agent.

2. The method according to claim 1, characterized in that the method with a MoI-R ₄ -CH

CH-R,

(CHA (CH ₂ ),

2> b

R ₆ OH

R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , α, b and c have the meaning given above, in the presence of

wherein

anhydrous hydrogen fluoride, the molar ratio of hydrogen fluoride to alcohol being greater than about 3, reacts and the amine formed in a manner known per se at a temperature of 50 to 300 ° C with hydrolyzed with a hydrolysis agent.

The invention thus relates to a process for the amidation of alcohols with a nitrile in solution in the presence of an acidic catalyst. This reaction can be represented by the following scheme will:

RAW

acid
[R ⁺ + H ₂ O]

R'C = N
HO

I Il

\ i / - «r> l

IN L R

Acid or base + H ₂ O
O

IO

20th

RNH ₂ + R ¹ C-OH

3 °

Amidations of alcohols with nitriles of this type are known per se (Bull. Soc. Chim. France 1957, 596-610; C. 1960, 3836 and C. 1965 [12], Ref. 0915). The one in the known amidations achievable yields and the recoverability of the unreacted starting materials and the catalyst are bad. In addition, the prior art methods are compatible with Alcohols that are more difficult to dehydrate, i.e. the secondary and primary alcohols, only very much difficult to perform. It is known that the dehydratability of alcohols usually depends on the tertiary over the secondary to the primary alcohols decreases. Exceptions to this rule are present, for example, when the dehydration leads to a carbonium ion that through a conjugated double bond or resonance stabilized by an adjacent aromatic nucleus is.

In view of this prior art, the invention is based on the object of providing a method for Amidation of alcohols or a process for the production of amines to create that smooth and with high yields with primary, secondary and tertiary alcohols is feasible, and that under simple recovery of the catalyst after the reaction is particularly economical is feasible.

The invention is based on the fact that tertiary, secondary and, surprisingly, even primary Alcohols can then be amidated smoothly with a nitrile, if the amidation in a large Excess of anhydrous liquid hydrogen fluoride is carried out. The hydrogen fluoride is in used in an amount that it not only acts as a catalyst for the reaction, but also as a Reaction medium, i.e. as a solvent for the reaction it catalyzes, acts. In particular, has Surprisingly it has been shown that alcohols can be amidated if a large excess of anhydrous liquid HF, preferably in the range of 8 to 25 moles per mole of alcohol, is used.

The alkyl part of the radical of the formula III can be straight-chain, branched or a cycloalkyl radical.

The reaction temperature used is between 0 and 130 ⁰ C and preferably between 25 and 100 ⁰ C; the reaction time varies between 5 minutes and 2 hours, whereby the reaction can be carried out in a simple manner in the form of a continuous process.

An excess of nitrile to the stoichiometrically required amount is used in the reaction. Amounts to the nitrile to alcohol molar ratio of about 1.1: 1.0 to about 4.0: 1.0 then becomes particular achieved satisfactory results. Additional nitrile can be used for economic reasons However, this is not appropriate for considerations.

The amount of hydrogen fluoride can vary within wide ranges. The hydrogen fluoride exerts a catalytic effect and also serves as a reaction medium. It becomes a molar ratio Hydrogen fluoride to alcohol greater than about 3 applied. A molar ratio of hydrogen fluoride to Alcohol at 8:25 has been found to be particularly satisfactory. Larger amounts of hydrogen fluoride can also be used can be used, but are of no advantage.

The reaction will proceed over a wide range of pressures. Pressures from atmospheric to to 20 atmospheres give satisfactory results. The preferred pressure used is between atmospheric pressure and 5 atmospheres.

The amides formed can be separated off from the reaction mixture by various processes will. One method is to simply put all of the reaction mixture in large excess cold water is poured. The product can then be extracted with ether, whereupon the Extracts of hydrogen fluoride are washed free and the ether is removed in vacuo. Another Isolation method makes use of the separation by heat, with excess hydrogen fluoride through simply heating the reaction mixture to about 150 to 200 ° C is driven off with stirring. Such a heating separation process is particularly good for larger scale processes suitable because the hydrogen fluoride that is driven off can be recycled into the process.

The hydrolysis of the amide obtained as an intermediate can be carried out with the aid of an acid or base aqueous or alcoholic solution can be carried out. As a hydrolysis agent used preferably be aqueous sulfuric acid, aqueous sodium hydroxide, sodium hydroxide in alcohol and aqueous Alcohol, aqueous potassium hydroxide and potassium hydroxide in alcohol are mentioned, with the concentration is expediently about 50%. Good results have been obtained with concentrations of around 30 up to 70% achieved. Concentrations outside this range result in only partial hydrolysis. Preferred molar ratios of amide to hydrolyzing agent are between about 1: 3 to 1: 6.

The amide can be hydrolyzed over a wide range of temperatures. Good results have been achieved at temperatures of approximately 50 to 300 ^° C., depending on the hydrolysis agent used.

If an aqueous sulfuric acid solution is used, the temperature preferably used is at about 100 to 120 "C. If sodium hydroxide is used in an aqueous or alcoholic solution, then the temperature preferably used is between 150 and 250 ° C.

The hydrolysis can also take place over a wide range of pressures. Pressures of atmospheric pressure up to 20 atmospheres are satisfactory, any pressure sufficient for the reaction mixture Maintaining in the liquid phase can be used. However, excessively high pressures are uneconomical.

The amines can be extracted from the hydrolysis mixture by cooling the mixture to about room temperature, Addition of a large excess of water, separation of the aqueous phase and distillation of the Amines are separated.

The following examples illustrate the invention:

20 Example 1

Amidation of 2-butanol

A 300 ml Monel autoclave is charged with 120 grams (6.0 moles) of liquid hydrogen fluoride, 40.2 grams of acetonitrile (1.2 moles) and 29.65 grams of 2-butanol (0.4 moles) at about O'C . The autoclave is closed and the temperature is increased to 60 to 65 ° C. over the course of one hour. The reactor is then cooled to 5 to 10 ° C and opened, and the reaction mixture is transferred to a 500 ml stainless steel round bottom flask fitted with a thermocouple and magnetic stirrer. The hydrogen fluoride is driven off by heating the reaction mixture to 190 ⁰ C. The residue can then be dissolved in approximately 400 ml of ether and washed with small amounts of potassium carbonate until the washing liquids are clear. The ether solution obtained is dried over anhydrous sodium sulfate and concentrated in vacuo; about 32 g (69.5% yield) of N-butylacetamide are obtained, the analysis of which gives the following values:

Neutralization equivalent .... 126.5

(calculated 115)

Amide 91% 45-

At game 2
Amidation of 2-heptadecanol

A 300 ml Monel autoclave is charged with 90 g of liquid hydrogen fluoride (4.5 mol), 36.8 g of acetonitrile (0.9 mol) and 77.0 g of 2-heptadecanol (0.3 mol) at approximately ⁰ ° C . The reactor is then closed and the temperature is increased to 60 to 65 ^° C. over the course of one hour. The reactor is then cooled to approximately 5 to 10 ^° C. and opened, whereupon the reaction mixture is washed in 1000 ml of cold water. 1 liter of ether is added and the aqueous layer is separated off. The organic phase is then washed free of hydrogen fluoride with a few portions of salt water. The ether solution is then dried over anhydrous sodium sulfate and concentrated in vacuo; 84.0 g (yield 94.5%) of N- (sixeptadecyl) acetamide are obtained, the analysis of which gives the following values:

Neutralization equivalent .... 319.5

(calculated 297.5)

Amide 93%

Example 3
Amidation of 2-ethylhexanol

A 300 ml Monel autoclave is charged with 120 grams of liquid hydrogen fluoride (6.0 moles), 49.2 grams of acetonitrile (1.2 moles) and 13.02 grams of 2-ethylhexanol (0.1 moles) at about OC. The reactor is then closed and the temperature is increased to 60 to 65 ^° C. over a period of 30 minutes. The reactor is then cooled to about 5 to 10 ° C. and opened, whereupon the reaction mixture is poured into 1000 ml of cold water. 1 liter of ether is added and the aqueous layer is separated off. The organic phase is then washed free of hydrogen fluoride with a few portions of salt water. The ethereal solution is then dried over anhydrous sodium sulfate and concentrated in vacuo; approximately 9.5 g (yield 55.5%) of an N-octylacetamide are obtained, the analysis of which gives the following values:

Neutralization equivalent .. .. 243

(calculated 171.2) amide 70.5%

Example 4
Amidation of n-decanol

A 300 ml Monel autoclave is filled with 90 g of liquid hydrogen fluoride (4.5 mol), 18.4 g of acetonitrile (0.45 mol) and 47.5 g of n-decanol (0.3 mol) at approximately 0-2 ^° C The autoclave is closed and the temperature is increased over a period of 20 minutes to 80 to 85 ^° C. Then an additional 18.4 g of acetonitrile (0.45 mol) are pumped into the reaction mixture over the course of 5 minutes, which is continued for a further 15 minutes is maintained at 80 to 85 ° C. After the reaction, the reactor is cooled to about 5 to 1O ⁰ C opened, after which the reaction mixture is poured into 1000 ml cold water. 1 1 of ether is then added and the aqueous layer separated. the The organic phase is washed free of hydrogen fluoride with a few portions of salt water. The ether solution is then dried over anhydrous sodium sulfate and concentrated in vacuo, 27.0 g (yield 45.2%) of N-decylacetamide are obtained, the analysis of which gives the following values:

Neutralization equivalent ... 1000

(calculated 199.3) amide 19.9%

B is ρ i el 5
Amidation of cyclohexanol

A 300 ml Monel autoclave equipped with a stirrer is charged with 120 g of liquid hydrogen fluoride (6.0 moles) and 39.2 g of acetonitrile (1.20 moles) at approximately 0 ° C. The reactor is closed, whereupon the temperature is brought to 54 ° C; then 40.0 g of cyclohexanol (0.40 mol) are pumped in over a period of 27 minutes at 45 to 56.degree. Stirring is continued for an additional 30 minutes at 56-62 ° C. The contents are then ^{cooled to 5 °} C. and the autoclave is opened. The reaction mixture is poured into 1000 ml of cold water, whereupon 1000 ml of ether are added. The organic phase is separated off and washed free of hydrogen fluoride. The ether solution is then dried over anhydrous sodium sulfate. When concentrating in vacuo, 33.5 g of a white fall

7 8

Solid material with a temperature of 105 to 106 ° C (washed out. The chloroform solution is then over

loot 61.7%). Melting point stated: 104 ° C. dried anhydrous sodium sulfate. At the con-

% Amide: 97.5. centering in a vacuum, 42.2 g of a dark

Gas chromatography only shows a peak of brown, mobile oil (yield 61.8%).

obtain. _,. . . , 5% amide: 6.87.
Example 6

Amidation of 2-Nonanol Example 8

A 300 ml nonel autoclave is amidated with 90 g (4.5 mol) of tert-amyl alcohol

liquid hydrogen fluoride and 36.9 g (0.9 mol) aceto- A 300 ml Monel autoclave is filled with 120 g (6.0 mol)

nitrile charged at about O ^{0 C.} The autoclave is ίο »liquid hydrogen fluoride and 49.2 g (1.2 mol) aceto

closed, whereupon the temperature charged to a value nitrile at 0 to 5 ° C. The autoclave is

is brought up to 49 ⁰ C; then 43.3 g are closed, whereupon the temperature to a value up to

(0.3 mol) 2-nonanol is ^{brought to 60 °} C. over a period of time; then 35.4 g

36 minutes at a temperature of 49 to 58 "C (0.4 mol) of tertiary amyl alcohol for a period of time

pumped in. Stirring is continued for another 30 minutes at 15 of 20 minutes at a temperature of 60 to 65 ° C

58 to 63 ⁰ C continued. The content is then pumped at 5 ⁰ C. Stirring is continued for another 30 minutes

cooled, whereupon the autoclave is opened. Which continued at 60 to 65 ° C. The content will then

The reaction mixture is cooled in 1000 ml of cold water to approximately 5 ° C, whereupon the reactor

poured, whereupon 1000 ml of ether are added. Which is opened. The reaction mixture is in a

The organic phase is separated and transferred from the fluorine 20 500 ml round bottom flask made of stainless steel,

washed hydrogen free. The ethereal solution is then followed by the hydrogen fluoride by heating the

dried over anhydrous sodium sulfate. The reaction mixture is driven off ^{to 200 ° C.} Of the

Concentration in vacuo falls 51.7 g of a light residue is then dissolved in ether and removed from traces

yellow viscous oil (yield 93.0%). Washed free hydrogen fluoride. The ethereal solution becomes

% Amide: 93.5. ■ 25 then dried over anhydrous sodium sulfate

Infrared analysis shows that the sample came out of and concentrated in vacuo; 15 g of tertiary

monosubstituted amide exists without amylacetamide (yield 29%).

there is still alcohol present. % Amide: 83.5.

The isomer distribution is determined by gas chromatography

graph determined as follows: 30. .,. . ...,, ,,,

Amidation of 3-ethyl-3-pentanol

2-aminononane, 23.9%. . / _{£ η} - \ Λη

3-aminononane 33 6% ^A 300 ml Monel autoclave is added with 120 g (6.0 mol)

4 ⁺ -Aminononan 425% liquid hydrogen fluoride and 49.2 g (1.2 mol) acetonitrile charged at 0 to 5 ⁰ C. The reactor is

B eis ρ ie I 7 ³⁵ concluded, whereupon the temperature rose to a value up to

. . is increased to 60 ° C; then 46.5 g (0.4 mol)

Amidation of n-dodecanol '3-ethyl-3-pentanol over a period of

A 300-ml Monelautoklav is reacted with 90 g (4.5 mol) of 20 minutes at a temperature of 60 to 65 ⁰ C.

liquid hydrogen fluoride and 55.9 g (0.3 mol) are pumped in. Stirring is continued for another 30 minutes

n-Dodecanol charged ^{at about 0 0 C.} The Auto-40 continued at 60 to 65 ° C. The content is then on

klav is closed, whereupon the temperature is cooled to about 5 ° C., whereupon the reactor is opened

a value up to 90 ⁰ C is brought; then will. The reaction mixture is cold in 1000 ml

36.9 g (0.9 mol) of acetonitrile are poured during a water, whereupon 1000 ml of ether are added

Period of time of 35 minutes at a temperature of. The organic phase is separated and

90 to 98 ° C pumped in. The stirring is washed free of hydrogen fluoride for another 45 minutes. The ethereal solution

Continued at 92 to 95 ° C for 30 minutes. The contents are then dried over anhydrous sodium sulfate.

is then cooled to 0 to 5 ° C, whereupon the net. When concentrating in a vacuum, 39.5.g

Reactor is opened. The reaction mixture turns into des-product (yield 62.5%).

Poured 1000 ml of cold water, whereupon 1000 ml of% amide: 85.5.

Chloroform can be added. The organic phase 50 The results of the preceding examples are in

is separated off and summarized in the table below, free of hydrofluoric acid:

alcohol Molar ratio 3.0: 15.0 Addition time reaction time yield Amide Starting alcohol 3.0: 15.0 Min./Temp. Min./Temp. CH ₃ CNiHF 3.0: 15.0 12.0: 60.0 ( ⁰ C) ( ⁰ C) (%) (%) 2-butanol 1: 3.0: 15.0 3.0: 15 60 / 60-65 69.5 91.0 2-nonanol ■ 1 3.0: 15 36 / 49-58 30 / 58-63 93.0 93.4 2-heptadecanol 1 3.0: 15 - 60 / 60-65 94.5 93.0 Cyclohexanol 1 3.0: 15 27 / 54-56 30 / 56-62 61.7 97.5 2-ethylhexanol 1 - 30 / 60-65 55.5 70.5 n-decanol 1 - 40 / 80-85 45.2 19.9 n-dodecanol 1 35 / 90-98 30 / 92-95 61.8 6.87 tertiary amyl alcohol 1 20 / 60-65 30 / 60-65 29.0 83.5 3-ethyl-3-pentanol 1 20 / 60-65 30 / 60-65 62.5 85.5 509 545/417

Example 10

A purified sample of 30.7 g (0.125 mol) of N-dodecylacetamide was taken for 72 hours Hydrolyzed reflux with 40% aqueous sulfuric acid. After the sulfuric acid with sodium hydroxide had been neutralized, the free amine was extracted with ether. The ethereal solution was washed with water, dried over anhydrous sodium sulfate and removed under reduced pressure.

distilled. 27.2 g of a crude dodecylamine were obtained. Distillation at 130 to 132 ° C./15 mm gave 20.8 g of the purified product (89.7% yield).
5

analysis

Neutralization equivalent 205.0

(calculated 185.4) ίο primary amine 90.3%

Claims (1)

Patent claims: 1. Process for the preparation of amines of the general formula R ₂ -C-NH ₂ (CH ₂ ) _a (CH ₂ ), R ₆ NH ₂ wherein R ₁ , R ₂ , R _{3 are} hydrogen, alkyl, arylalkyl or cycloalkyl radicals and mixtures of these radicals with at least one radical other than hydrogen, the radicals containing 2 to 48 carbon atoms, R ₄ , R ₅ , R ₆ hydrogen, alkyl -, arylalkyl or cycloalkyl radicals as well as mixtures of these radicals and the sum of a + b + c is between 2 and 9, characterized in that at 0 to 130 ⁰ C a nitrile of the general formula is obtained R ₇ -C = N wherein R _{7 represents} hydrogen, an alkyl, aminoalkyl or aryl radical and metal salts of the aminoalkyl radical, the radicals containing 1 to 21 carbon atoms, with an alcohol of the general formula ^R i R ₂ -C-OH R ₃ (CH ₂ ), R ₄ -CH CH-R ₅
(CH ₂ ). (CH ₂ ), / \
R "OH nitrile to alcohol ratio of about 1.1: 1.0 to about 4.0: 1.0. 3. The method according to claim 1, characterized in that the method with a molar ratio Performs hydrogen fluoride to alcohol about 8:25. 4. The method according to claim 1, characterized in that the method is carried out at a temperature between approximately 25 and 100 C.