DE2950260A1 - METHOD FOR PRODUCING POLYMETHYLENE POLYPHENYL POLYCARBAMATES - Google Patents

Description

The invention relates to an improved process for the preparation of polymethylene polyphenyl polycarbamates. In particular, it relates to an improved method for Production of polymethylene polyphenyl polycarbamates by reacting an N-phenyl carbamic acid ester with formaldehyde or a formaldehyde-forming compound in the presence of an acidic catalyst.

Polymethylene polyphenyl polycarbamates are substances that are used in the manufacture of agricultural chemicals, Drugs, polyamides, polyurethanes, and the like are usable. In addition, polymethylene polyphenyl polycarbamates can be thermally decomposed to give the corresponding To form polymethylene polyphenyl polyisocyanates. Accordingly, it is desirable to find new methods of manufacture of polymethylene polyphenyl polycarbamates with industrial advantages.

A method well known from the prior art for the preparation of polymethylene polyphenyl polycarbamates comprises the reaction of a corresponding polymethylene polyphenyl polyisocyanate with alcohol. However, the manufacture of the polymethylene polyphenyl includes polyisocyanate which is known as Starting material is used, the use of highly toxic aniline and phosgene and also requires a complicated procedure.

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Another process for the preparation of polymethylene polyphenylpolycarbamates, which is well known from the prior art, comprises the reaction of a corresponding polymethylene polyphenyl polyamine with a chloroformic acid ester. However, both have the polymethylene polyphenyl polyamine as well as the chloroformic acid ester used as the starting materials, such serious one Intoxication-inducing and irritating properties that make them difficult to handle and procedures for their Manufacturing are complicated. For these reasons, this process cannot be regarded as industrially useful will.

There is another method well known in the art for preparing polymethylene polyphenyl polycarbamates by reacting an N-phenylcarbamic acid ester with formaldehyde. For example, as in DE-PS 1 042 891 describes, an N-phenylcarbamic acid ester and formaldehyde are heated in an aqueous hydrochloric acid solution to form a condensation product to obtain, which consists predominantly of PolymethylenpolyphenylpoIycarbamaten. The method described in the aforementioned DE-PS, however, shows such a low level Reaction rate that a large amount of unreacted starting materials remain even when the reaction has been carried out for a long period of time.

The aim of the invention is to provide a process for the production of polymethylene polyphenyl polyearbamates, by reacting an N-phenylcarbamic acid ester with formaldehyde, which results in a higher reaction rate can than can be achieved with the aid of the methods known from the prior art.

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According to a further feature of the invention, an N-phenylcarbamic acid ester is reacted with formaldehyde in the presence of an acid having an acid dissociation constant (K _n ) of not less than 1.25 x 10 ^ in acetic acid at 25 ° C, a higher reaction rate can be achieved than in methods known from the prior art.

The invention relates to a process for the preparation of a polymethylene polyphenyl polycarbamate of the general formula

HO

1 M.

HO

1 M.

HCOR ₁

(i)

wherein

R ₁ denotes a lower alkyl radical having 1 to 6 carbon atoms or a cycloalkyl radical,

R ₂ denotes a hydrogen atom, a halogen atom, a lower alkyl radical having 1 to 6 carbon atoms or a lower alkoxy radical having 1 to 6 carbon atoms, η is a positive integer from 1 to 4 and

m is O or a positive integer from 1 to 5,

in which one has an N-phenylcarbamic acid ester of the general formula

H 0 - NCOR ₁ (II)

wherein R ₁ , R ₂ and η have the meanings given above for the general formula (I), with formaldehyde or a formaldehyde-forming compound in the presence of a

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Acid with an acid dissociation constant (K ₀ ) of not less than 1.25 x 10 "'is converted into acetic acid at 25 ° C.

The N-phenylcarbamic acid ester used in the process of the present invention is a compound represented by the general formula (II). In this formula, R _{1 is} an alkyl radical, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec. -Butyl, isobutyl, tert-butyl, one of the pentyl radicals, all led by n-pentane and its isomers, one of the hexyl radicals, derived from η-hexane and its isomers, etc .; or a cycloalkyl group such as cyclopentyl, cyclohexyl, etc .; and R ₂ is a hydrogen atom; a halogen atom such as chlorine, bromine, fluorine, etc .; an alkyl radical such as methyl, ethyl, n-prppyl, isopropyl, η-butyl, sec-butyl, isobutyl, tert- butyl, any of the pentyl radicals derived from n-pentane and its isomers, any of the hexyl radicals derived from η -Hexane and its isomers, etc .; or an alkoxy group consisting of any of the above alkyl groups and an oxygen atom.

In particular, they include phenylcarbamic acid alkyl esters of the general formula (II) in which R _{1 is} an alkyl radical as defined above and R _{2 is} a hydrogen atom ; Halophenylcarbamic acid alkyl esters of the general formula (II), in which R _{1 is} an alkyl radical as defined above and R _{2 is} a halogen atom as defined above; Alkylphenylcarbamic acid alkyl esters of the general formula (II), in which R ₁ and R _{2 are} alkyl radicals as defined above; Alkoxyphenylcarbamic acid alkyl esters of the general formula (II), in which R ₁ denotes an alkyl radical as defined above and R ₂ denotes an alkoxy radical as defined above; Phenylcarbamidsäurecyclopentyl- or cyclohexyl ester of the general formula (II), wherein R _{1 is} a cyclopentyl or cyclohexyl

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and R _{2 is} a hydrogen atom; Halophenylcarbamic acid cyclopentyl or cyclohexyl ester of the general formula (II), in which R. denotes a cyclopentyl or cyclohexyl radical and R ₂ denotes a halogen atom as defined above; Alkylphenylcarbamidsäurecyclopentyl- or · '-cyclohexylester of the general formula (II), in which R ₁ . denotes a cyclopentyl or cyclohexyl _{radical and R 2 is} an alkyl radical as defined above; Alkoxyphenylcarbamidsäurecyclopentyl- or -cyclohexylester of the general formula (II), in which R ₁ denotes a cyclopentyl or cyclohexyl radical and R _{2 is} an alkoxy radical as defined above; and the like ..

The preferred N-phenylcarbamic acid esters are phenylcarbamic acid methyl ester, phenylcarbamic acid ethyl ester, phenylcarbamic acid n-propyl ester, phenylcarbamic acid isopropyl ester, phenylcarbamic acid n-butyl ester, phenylcarbamic acid sec-butyl ester, phenylcarbutyl ester, Phenylcarbamic acid tert-butyl ester, phenylcarbamic acid pentyl ester, phenylcarbamic acid hexyl ester, o-chlorophenylcarbamic acid methyl ester, o-chlorophenylcarbamic acid ethyl ester, o-chlorophenylcarbamic acid isopropyl ester, o-chlorophenylcarbamic acid isopropyl ester, o-chlorophenyl-phenylcarbylcarbisate, o-chlorophenyl-phenylcarbylcarbisate, methyl-phenyl-phenylcarb-bis-ester Cyclohexyl phenylcarbamate, o-chlorophenylcarbamide & urecyclohexyl ester, cyclohexyl o-methylphenylcarbamic acid, cyclopentyl phenylcarbamic acid and methyl m-methoxyphenylcarbamic acid. Among these connections Methyl phenylcarbamic acid, ethyl phenylcarbamic acid, isopropyl phenylcarbamic acid and isobutyl phenylcarbamic acid are particularly preferred.

In the method according to the invention, the. the above N-phenylcarbamic acid ester reacted with formaldehyde or a formaldehyde-forming compound. The formaldehyde

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The compound can be any compound which forms formaldehyde under the reaction conditions of the invention may, and specific examples thereof include paraformaldehyde, methylal, and other formals. Usually one will aqueous solution of formaldehyde used.

The acid used in the method of the present invention can be any acid that has an acid dissociation constant (K.) of not less than 1.25 x 10 "'in acetic acid at 25 ° C. The term" acid dissociation constant (K-) "as used herein means

the dissociation constant, which is generally defined for the dissociation of an acid in its solution. Suppose that the equilibrium reaction in which an acid HX dissociates in a solvent S is caused by the the following equation is shown:

HX (acid) + S (solvent) X "(conjugate base of the acid) + SH⁺ (conjugate acid of the solvent),

then the acid dissociation constant (K_) is defined by

[X "T [SH *] ^K a ⁼ LHXJ

Specific examples of the acid include hydriodic acid, hydrobromic acid, perchloric acid, chlorosulfonic acid, fluorosulfonic acid, trifluoromethanesulfonic acid and polysulfuric acids represented by the formulas H ₂ S ₂ O. ,, H ₂ S ^ O ₁₀ , H? ^ 4 ^ 13 'etc. These acids can alone or can be used in the form of a mixture of two or more. Moreover, they can be used in the form of a mixture with one or more common acids such as hydrochloric acid, sulfuric acid, acetic acid, etc. All common acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, boric acid, etc., which are described in the above-mentioned DE-PS

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-ΙΟΙ 042 819 are described »have an acid dissociation ·

ty

on constant (K_) of less than 1.25 x 10 in vinegar

satire. Accordingly, they can be used alone does not give a satisfactorily high reaction rate.

Although the process of the present invention can be carried out in the absence of a solvent, a suitable one can be used Solvents are used, for example, to handle the starting materials and / or reaction products with high melting points to facilitate. In this case the solvent must be inert to formaldehyde be. Specific examples of suitable solvents include aliphatic hydrocarbons, such as hexane, heptane, Etc.; alicyclic hydrocarbons, such as cyclopentane, Cyclohexane, etc .; halogenated hydrocarbons, such as Chloroform, methylene chloride, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, etc .; Fatty acid alkyl esters, such as ethyl acetate, etc .; aromatic compounds such as benzene, toluene, nitrobenzene, monochlorobenzene, Dichlorobenzene, etc .; and the like. Water is also one of the suitable solvents.

When carrying out the method according to the invention, there is with respect to the amounts of N-phenylcarbamic acid ester, formaldehyde or formaldehyde-forming compound and used Acid no special restriction. However, formaldehyde or formaldehyde-forming is usually used Compound is used in an amount of 0.1 to 10 mol, and preferably 0.2 to 2.0 mol / mol of N-phenylcarbamic acid ester. The acid is usually used in an amount of from 0.001 to 20 equiv. and preferably from 0.1 to 10 equiv / mol N-phenylcarbamic acid ester used. Similarly, there is no particular limitation on the amount used Solvent. However, the solvent is usually

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borrowed in an amount of 0.1 to 20 parts by weight / part by weight N-phenylcarbamic acid is used.

The reaction temperature may be up to 10O ⁰ C in the range of 20 to 150 ⁰ C and preferably from 30th

In general terms, the method according to the invention can be carried out by the N-phenylcarbamic acid • ster as it is or in the form of its solution or suspension in a suitably chosen solvent provides, adds the formaldehyde or a formaldehyde-forming compound and the acid to this and then the reaction mixture is stirred at a predetermined temperature. Alternatively, the method according to the invention can also be carried out by adding a formaldehyde solution dropwise to a solution or suspension of the N-phenylcarbamic acid ester and add to the acid.

The inventive method may continue in a continuous Arbeltssystem performed v / ground, in which • Ine solution or suspension containing the starting materials, and fed to the acid in an appropriate ratio continuously to a reactor and continuously withdrawn therefrom after a predetermined residence time.

The reaction time depends on the types or amounts of the starting materials and the acid used, the type of process, the reaction conditions, and the like. In the case of a batch procedure, it can generally range from 0.5 to 40 hours.

After the completion of the reaction, the reaction product usually becomes in the form of an oily layer or a solid obtained spontaneously from the layer of aqueous,

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acidic solution separates. Thus, the reaction product or the layer containing it can be used in any suitable manner Techniques such as turning a separatory funnel, filtration, etc., washed with water, through Stripping the solvent and then drying to obtain an end product.

According to the process of the invention, a variety of polymethylene polyphenyl polycarbamates of the general Formula (I) depending on the N-phenylcarbamic acid ester used as the starting material. Under normal reaction conditions, the reaction product is a mixture which comprises a larger amount of dinuclear compounds of the general formula (I), where m is O, and a smaller amount of trinuclear, tetranuclear, pentuclear and higher polynuclear compounds of the general formula (I), wherein m is 1, 2, 3 or is more.

The method of the present invention can achieve a reaction rate 2 or more times that which is achievable in well known prior art processes using common acids. This improvement in the reaction rate has a great industrial advantage in that the yield of the final product per unit time can be increased and the size of the reaction device can be reduced.

The process according to the invention is further illustrated by the following examples. In each of these examples, the constant (k) for the initial reaction rate is determined by taking small amounts of sample at intervals of 30 minutes or 1 hour, measured the N-phenylcarbamic acid ester concentrate ion of the samples, and then the value

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for k calculated according to the following equation:

Reaction rate "dt, ~

kfN-phenylcarbamic acid ester] [formaldehyde]

where the square brackets denote the moles of the compound indicated therein which are contained in each liter of the organic layer. The molar concentration of formaldehyde was calculated on the assumption that 1 mole of N-phenylcarbamic acid ester reacted with 1/2 mole of formaldehyde. In all cases, the reaction of the present invention in its initial stage was in close agreement with the above equation.

example 1

A 100 ml flask was charged with a thermometer, a stirrer and a dropping funnel was equipped with 20 g phenylcarbamic acid ethyl ester, 18 g trifluoromethane

sulfonic acid [with an acid dissociation constant (K ₀ ) c _ a

χ of 1.26 10 ^"y in acetic acid at 25 C] and 50 g of water. After the flask to 100 ⁰ C in an oil bath was heated, with stirring of its contents, were added 5.2 g of 35 # aqueous formaldehyde solution through the The resulting reaction mixture was ^{stirred for 5 h at 100 °} C., cooled to room temperature and then shaken with 100 ml of chloroform The chloroform layer was separated from the aqueous layer, washed three times with 100 ml of water each time and then to obtain 20 g of product concentrated. After dissolving the product in tetrahydrofuran and analyzing by liquid chromatography using naphthalene as an internal standard was found to be 27%%% wt. binuclear compounds, 14 wt. trinuclear and higher polynuclear compounds and 18 wt. nichtumgesetz- th Phenylcarbamidsäureäthylester These results mean that the degree of conversion of the starting material

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terlal carbamic acid ester used was 8296, the yield of dinuclear compound based on the amount of carbamic acid ester consumed was 36% , and the yield of trinuclear and higher polynuclear compounds based on the amount of carbamic acid ester consumed was 1996. The initial reaction rate constant (k) was 25 10 " ⁶ l / min. Mol.

Examples 2 to 4

In these examples the procedure of Example 1 was repeated with the exception that three of trifluoromethanesulfonic acid were used different acids were used. The results obtained are shown along with the acid distillation constants (K) of these acids in acetic acid given in Table 1.

Comparative examples 1 and 2

In these comparative examples, the procedure of Example 1 was repeated except that hydrochloric acid was used or used sulfuric acid in place of trifluoromethanesulfonic acid. The results thus obtained are given in Table 1. With a fixed response time, all of the examples in Table 1 showed a higher one Degree of conversion than the comparative examples given there, an indication that the process according to the invention can result in a faster reaction rate.

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Supplied · Materials: Phenylcarbamide acid ethyl ether (0.12 hol) »acid (0.12 mol), formaldehyde

(0.06 mol) and water (30 g) reaction temperature: 98 to 100 ^{° C.}

E.g.
respectively.
VgIB.

Super acid Results

Type

Constant (k; d.Initial reaction speed

(x10 ⁶ l / min mol)

Reaction conversion Yield based on d. duration of the carbamide acid ester

consumption (%)

(Hours) amic acid ester

two-core, three-core and higher multiple bonds "robust connections

Example 2 perchloric acid 1.26 10 "* ^>

E.g. 3 hydrobromic acid 2.5 x 10

E.g. 4 hydrogen iodic acid 1.59 x 10

22 7

77 66

60

48 42

40

12 9

10

o> VgIB.1 Hydrogen chloride-2.5 χ 10 acid

VgIB.2 sulfuric acid 6.3 x 10

3 3.5

48

50

42

50

6 4

Examples 5 and 6

In these examples, the procedure of Example 1 was repeated except that each of the two of Phenylcarbamidsäureäthylester different N-Phenylcarbamidsäureester was used. The results thus obtained are given in Table 2. For comparison purposes the initial reaction rate constants determined using hydrochloric acid instead of Trifluoromethanesulfonic acid, as also shown in Table 2.

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Table 2 Materials supplied: N-phenylcarbamic acid ester (0.12 Hol), trifluoromethanesulfonic acid

(0.12 mol), formaldehyde (0.06 mol) and water (50 g)
Reaction temperature: 98 to 100 ^{° C}
Response time: 4 hours

Example no.

N-phenylcarbamic acid ester

Results

constant

for conversion yield, rel.

W agA,

d.Initial reaction- d.Carbamide- on carbamidhidikit ät ät

G
speed

(x10 ⁶ 1 / billion mbl)

acid ester acid ester consumption ^)

two-core.
Verb.

tri-core,
and higher
multicore.
Connection

Initial reaction rate constant, determined with HCl f- (x 10 ⁶ )

z
ω ■ Ό
m
ο

5 methyl phenylcarbamic acid

6 Isobutyl phenylcarbamic acid

50 5

87 52

45
20th

22nd
30th

7th
0.8

Claims (1)

Dr. F. Zumstein Sr. - Dr. E. Assnann - Dr. R. Koenigsberger Dipl.-Phys. R. Holzbauer - Dipl.-Ing. F. Klingseisen - Dr. F. Zumstein jun. PATENT LAWYERS ■ 000 Munich 2 - BrauhausstraOe 4 - Tel. Semmel No. 23 5341 ■ Telegrams Zumpal - Telex 529978 Case FMT-242 Claims Process for the preparation of a polymethylene polyphenyl polycarbamate of the general formula (Ro) 2'n Il N-O-O-R-, wherein R ₁ denotes a lower alkyl radical having 1 to 6 carbon atoms or a cycloalkyl radical, R ₂ denotes a hydrogen atom, a halogen atom, a lower alkyl radical having 1 to 6 carbon atoms or a lower alkoxy radical having 1 to 6 carbon atoms, η is a positive integer from 1 to 4 and m 0 or a positive, whole number from 1 to 5 1st, 030026/0776 ORf & NAL INSPECTED characterized in that an N-phenylcarbamic acid ester of the general formula H Ό ι η -NCOR ₄ wherein R ₁ , R ₂ and η have the meanings given above, with formaldehyde or a formaldehyde-forming compound in the presence of an acid with an acid dissociation constant (K.) of not less than 1.25 χ 10 "'in acetic acid at 25 ° C. 2. The method according to claim 1, characterized in that the acid is selected from hydriodic acid, hydrobromic acid, perchloric acid, chlorosulfonic acid and polysulfuric acids of the formulas H ₂ S ₂ CU, ^H 2 ^S 3 ° 10 ' ^{H <} * ^S 4 ° 13 ^{USWa <} 3. The method according to claim 1, characterized in, that the N-phenylcarbamic acid ester is selected from phenylcarbamic acid methyl ester, phenylcarbamic acid ethyl ester, phenylcarbamic acid n-propyl ester, phenylcarbamic acid isopropyl ester and phenylcarbamic acid isobutyl ester. 4. The method according to claim 1, characterized in, that the formaldehyde or the formaldehyde-forming compound is used in an amount of 0.1 to 10 mol / mol of N-phenylcarbamic acid ester. 5. The method according to claim 1, characterized in that the acid in an amount of 0.001 to 20 equiv. / Mol N-phenylcarbamic acid ester is used. 030026/0776 6. The method according to claim 1, characterized in that the reaction is carried out in an organic solvent which is inert to formaldehyde. 7. The method according to claim 6, characterized in that the organic solvent in an amount of 0.1 to 20 parts by weight / weight. Part of N-phenylcarbamic acid ester is used. 8. The method according to claim 1, characterized in that the reaction is carried out at a temperature of 20 to 150 ⁰ C. 030026/0776