PL165608B1 - Method of obtaining n-derivatives of phenyl carbamate - Google Patents

Abstract

1. Process for producing monomeric and polymeric N-derivatives of phenyl carbamate, characterised in that one mol of phenyl carbamate is reacted in the acidic environment with 0.4 to 1.1 moles of formaldehyde, possibly in the presence of other condensing monomers capable of reacting with formaldehyde or the polymeric products of condensing monomers reaction with formaldehyde.<IMAGE>

Description

The present invention relates to a process for the preparation of monomeric and polymeric phenyl carbamate N-derivatives from phenyl carbamate.

Phenyl carbamate C ₆ H 5OCONH 2 is a compound little described in the literature, with limited stability, obtained by the addition of free isocyanic acid to phenol (Beilstein, vol. VI, EII6, p. 157). Phenyl urethane is the simplest phenol-blocked HNCO isocyanate, it can also be treated as a mixed anhydride of two acids: carbolic or phenol and carbamic. Phenyl carbamate N-derivatives are not described in the available literature. The only known reactions of phenyl carbamate lead to its thermal or hydrolytic decomposition. At elevated temperatures, above 100 ° C, phenyl carbamate is decomposed into phenol and free isocyanic acid. Isocyanic acid is unstable and will polymerize or attach to compounds with active hydrogen atoms, if any, to form carbamate groups.

According to the invention the preparation of monomeric and polymeric N-substituted derivatives of the phenyl carbamate by reaction with formaldehyde and optionally other _mon omerami resins or condensation, in an acidic environment, in particular, _SR d _on wisku below pH 4. The so obtained without use of isocyanates wierają products with _a phenol blocked isocyanate groups.

In both _os sp according to the invention 1 mole of the phenyl carbamate is reacted with from 0.4 to 1.1 m l _{of a} F _or maldehydu, optionally with other monomers capable of condensation _and re ctio _with formaldehyde, methylol derivatives and their alkoksymetylowymi or _P lim _e ry _{c n} young reaction products with formaldehyde both resol type or novolak it _{by e.} J _and K _{with a} formaldehyde source used in the aqueous-formaldehyde.

The _striped t _wor with water, in the neutral or alkaline carbamate _and submissive _ro ZKL dowi _a hydrolytically or temicznemu. Under acidic carbamate przyłąc _for fornaldehyd initially form of N-hydroxymethyl (Formula 1) and _a Step _ting these groups are / poly / condensation (Formula 2 and 3), zwłaszczajeśli from the reaction mixture _in slides _t o condensation water to shift the equilibrium reaction to the right. Hydroxymethyl _oure t _n phenyl may be isolated in the first phase of the reaction before it is further

165 608 / poly / condensation. The further course of the poly- condensation of phenyl N-hydroxymethyl carbamate depends on the composition of the reaction mixture and the molar ratios of the reactants. Approximately two times the excess of phenyl carbamate over formaldehyde produces phenyl methylenediurethane (formula 2). With a molar ratio of phenyl carbamate to formaldehyde of 1: 1, polymethylene phenyl urethane is formed (formula 3). In the process according to the invention, other condensation monomers can also be present in the reaction mixture, for example other carbamates, phenol, urea, melamine or their derivatives. These monomers can co-condensate with the phenyl carbamate and formaldehyde onto a poly / condensate containing embedded phenyl carbamate molecules via the formaldehyde methyl bridge. In this way, polycondensates and resins containing phenol-blocked isocyanate groups in the molecule are obtained. According to the invention, the already prepared polycondensates of condensation monomers, for example novolaks and resols, can also be reacted with phenyl carbamate. It is desirable that such a reaction be carried out in an acid medium in the presence in the reaction mixture of an amount at least equivalent to that of phenyl carbamate of formaldehyde, hydroxymethyl groups or their derivatives. This procedure has the advantage of attaching the phenyl carbamate at the end of the macro molecule, where the unsubstituted phenyl urethane is more reactive than the disubstituted phenyl urethane at the center of the macromolecule.

The procedure according to the invention is illustrated in the following non-exhaustive examples.

EXAMPLE 1 27.4 g of phenyl carbamate was dissolved in 139 g of dioxane, 8.33 g of 36% formalin was added, acidified with 1 N HCl to pH 1.6. Then 125 ml of benzene was added and the reaction mixture was dehydrated by azeotropic distillation at 85 ° C, with the depletion of the benzene layer separated from the distillate. When the distillate no longer separated, benzene and part of the dioxane were distilled off. A precipitate formed from the concentrated solution after cooling to -18 ° C, which was recrystallized from benzene, yielding 19.2 g, corresponding to 70% of the theoretical yield of methylene di (phenyl carbamate), mp 182-185 ° C and the composition elementary 60.37% C, 4.81% H, 9.86% N. the infrared absorption spectrum band comprises: at a wavenumber 3320 ^cm-1 NH groups of the aromatic ring at 3070 cm -1, the group -CH 2 2970 cm1 and the carbonyl group of the urethane bond at 1700 cm1

Example II. 27.4 g of phenyl carbamate was dissolved in 220 ml of benzene, 8.3 g of 36% formalin acidified with 1 N HCl to pH 1.5 were added, heated to reflux, cooled and the unreacted phenyl carbamate was filtered off. Benzene was distilled from the filtrate to obtain 5.35 g of crystalline phenyl N-hydroxymethylcarbamate, m.p. 82 ° C. The yield was 16% of theoretical. Its infrared spectrum shows the absorption bands of the -CH 2 - group with CH 2 OH at the wavenumber of 2950 cm ' ¹ , the -OH and -NH groups at 3300 - 3400 cm' *, the CH groups of the aromatic ring at 3050 - 3070 cm '' and the carbonyl group of the urethane bond at 1700 cm'1. The thin layer chromatogram indicates that it is a homogeneous substance.

Example III. 34.8 g of phenyl carbamate was dissolved in 140 g of dioxane, 16 g of 36% formalin was added, acidified with 1 N HCl to pH 1.5, 60 ml of benzene was added and dehydrated by azeotropic distillation with the recycle of the benzene layer of the distillate at 85-87 ° C . When the distillate no longer separated the water layer, the solvent was distilled off and 23 g of the resin product (phenyl methylene urethane) was obtained with a molecular weight of 557, which corresponds to the degree of polycondensation n = 4.

P r x l a d IV. 41.2 g (0.3 mol) of phenyl carbamate, 84.6 g (0.9 mol) of phenol and 88.9 g of 36% formalin (1.08 mol CH2O) were mixed, heated to a homogeneous solution and acidified with 1 N HCl to pH 2. The molar ratio of formaldehyde to the remaining monomers was 0.9: 1. The mixture was kept under stirring for 15 minutes at 90 ° C, then cooled to room temperature and the aqueous to gummy layer was separated. The resin layer was dehydrated by azeotropic distillation with toluene at atmospheric pressure, and the toluene was then distilled off. 112 g of novolak resin were obtained, corresponding to 80% of theory. In the infrared spectrum of resin there is sharp

165 608 absorption band for the carbonyl group of the urethane bond at a wavenumber of 1700 cm- ¹ . The resin contains 18.6% of phenylurethane groups, a third of which can be determined by analysis with dibutylamine.

EXAMPLE 5 17.4 g (0.1 mol) of phenyl carbamate was mixed with 39 g (0.1 mol) of hexamethoxymethylmelamine, acidified with 1N acetic acid solution to pH 3.6, and then heated while stirring in a distillation flask under vacuum. at 90 ° C until 0.1 mol (3.2 g) of methanol had distilled off. The reaction mixture was then cooled. 52.8 g of five (methoxymethyl) mono (phenylurethane, N-methyl) melamine containing 35.6% by weight of phenylurethane, N-methyl groups, which could be determined by the analysis with dibutylamine, were obtained.

Example VI. 8.7 g of phenyl carbamate was dissolved in 100 g of a 60% solution of a butylated urea-formaldehyde varnish resin with a pH of 3.5 in the water extract. The solution was applied in a thin layer to a glass plate and its solvent was evaporated at room temperature to give a layer of 68.7 g of solid resin. This resin layer was then heated to a temperature of 80-100 ° C until 3.7 g of n-butanol was lost in weight. 65.0 g of urea resin containing 13.5% of phenylurethane, N-methyl groups, which could be determined by the analysis with dibutylamine, were obtained.

Example VII. 93.6 g of phenyl carbamate was dissolved in 58.0 g of formalin 36.1%, acidified with 1N hydrochloric acid to pH 1.5, and heated for 30 minutes under reflux. Then the reaction mixture was cooled, the aqueous layer was separated, 34.8 g of phenyl carbamate were dissolved in the remaining resin, 16.6 g of 36.1% formalin was added at pH 1.0, heated with stirring until dissolved, kept at 80 ° C for 30 minutes then cooled, the aqueous phase was separated and the residual water was distilled off under vacuum at a temperature of about 60 ° C. A viscous, clear, liquid poly (methylene urethane butyl resin) terminated with phenylurethane, N-methylene groups that could be determined by the dibutylamine analysis method was obtained.

If the polycondensation reaction is carried out in the same way simultaneously with butyl and phenyl carbamate, an analogous resin is obtained, in which, however, the phenyl carbamate is statistically distributed in the resin molecule and only 30% of the introduced resin is determined.

165 608

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165 608 θ-0ΰ0ΝΗ € Η ₂ 0Η - »> Η Pn-CH _z -T-0H + (n-4) H ₂ OL | Jn

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Price: PLN 10,000

Claims (5)

Patent claims Method for the preparation of monomeric and polymeric phenyl carbamate N-derivatives, characterized in that 1 mole of phenyl carbamate is reacted in an acid medium with up to 0.4 to 1.1 mole of formaldehyde, optionally in the presence of other condensation monomers capable of reacting with formaldehyde or with polymeric reaction products of condensation monomers with formaldehyde. 2. The method according to p. The process of claim 1, wherein the condensation monomers are phenol, urea, carbamates and melamine or their derivatives. 3. The method according to p. The process of claim 1, wherein the formaldehyde source is its aqueous solution - formalin. 4. The method according to p. The process of claim 1, wherein the formaldehyde-reactable condensation monomers are their hydroxymethyl and alkoxymethyl derivatives and condensation resins of the novolak resole type. 5. The method according to p. The process of claim 1, wherein the reaction is carried out at the pH of the reaction mixture if the reaction is carried out in the presence of water lower than 4.