DE1923022A1 - Process for the preparation of cyclic imide esters - Google Patents

Description

Badische Anilin- & Soda-Fabrik AG 1923022

Our reference: O.Z. 26 176 WB / Stä

6700 Ludwigshafen, May 5, 1969 Process for the preparation of cyclic imide esters

The invention relates to a process for the production of cyclic Imide esters by cyclization of N-pormylalkanolamines in the presence of solid silica gels or silicates.

It is from US Patent 2,844,589 and British Patent 1 117 121 known that N-formylethanolamine by water removal

p
cleavage to the Λ -oxazoline cyclisiert.be can. Here, the formyl compound is passed under reduced pressure over a dehydration catalyst heated to 150-300 ° C., for example aluminum oxide, iron oxide or super "Piltrol" (diatomaceous earth). However, this process has the disadvantage that the dehydration of the pormyl compound is often accompanied by decarbonylation, and the yields of Δ- oxazoline are therefore unsatisfactory.

It has now been found that cyclic imide esters of the general formula

(RCR) _n

in which the individual radicals R can be identical or different and each have a hydrogen atom, an aliphatic, cycloaliphatic, Araliphatic or aromatic radical and η denotes 2, 3 or 4, in addition two radicals R also members of a common, carbocyclic ring can mean from N-Pormylalkanolaminen with elimination of water at elevated temperature in the presence of silicon compounds advantageously obtained when N-Pormy! alkanolamines of the general formula

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RHO

I ι /

HO- (C) -N-C II,

f ⁿ \

R Ή

in which the radicals R and η have the aforementioned meanings _s in the presence of solid silica gels or silicates, the predominant part of which has pores with a radius of 10 to 200 S, an average pore radius of 20 to 100 Å and a specific surface area of maximum

2
at least 550 m / g have cyclized.

The cyclization can be carried out in the case of using N-formylpropanolamine represented by the following formulas:

2 2 2 ν t 2 -y 2

^H \

Compared to the known processes, the process according to the invention provides cyclic imide esters in a simple way in better yield and purity, in particular at temperatures above 300 ^° C. These results are surprising, since the said British patent (page 1, lines 50-55) teaches that the temperature of dehydration is not an essential characteristic and the interval of 150-300 ° C is preferred. Another advantage is the long service life of the mentioned silica gels and silicates used as catalysts.

Preferred N-formy! Alkanolamines of the general formula II and correspondingly preferred end products I are those in whose formulas the individual radicals R can be identical or different and each represent a hydrogen atom, a straight-chain or branched alkyl or alkenyl radical with 1 or 2 to 6 carbon atoms, a cycloalkyl radical with 5 to 7 carbon atoms, an aralkyl radical with 7 to 12 carbon atoms or a phenyl radical and η denotes 2, 3 or H , in addition two radicals R also

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Members of a common 5- or 6-membered, carbocyclic Ring, which can contain 1, 2 or 3 double bonds and is fused to the imide ester ring, can mean.

The radicals or carbocyclic rings mentioned can also be replaced by groups and / or atoms which are inert under the reaction conditions, e.g. B. Alky! Groups with 1 to 4 carbon atoms, chlorine atoms, fluorine atoms, be substituted.

It can e.g. B. the following N-Pormy! -Alkanolamines as starting materials II are used: The N-Pormy! Compounds of ethanolamine, 2-amine propanol, isopropanolamine, propanolamine-1,3> 3-aminopropenol- (l), o-oxybenzylamine, o-oxy-aniline, 2-amino-cyclohexanol, y £ -phenyl-ß-aminoethanol, at-phenyl-ß-aminoethanol.

Instead of a starting material II you can also use this containing mixtures, for. B. that in the manufacture of the starting material reaction mixture obtained by converting alkanolamine and formic acid, without isolation and purification of the starting material II use.

The cyclization is carried out in the presence of solid silica gels or silicates as catalysts. Xerogels, silica gels, silica gel powder, silica gel beads, silica airgel can be used as silica gels. Preferred silicates are alkali and / or alkaline earth silicates. The solid silica gels * or silicates have predominantly, preferably more than 75 %, pores with a radius of 10 to 200 S, preferably with a radius of 12 to 100 S, an average pore radius of 20 to 100 S, preferably 20 to 60 % _Λ and a specific upper

2

area of at most 55 square meters / g, preferably of at most 500 m / g.

In continuous operation, generally 0.1-10, preferably 1-5 parts by weight of starting material II per hour and Part by weight of catalyst implemented.

Suitable catalysts are advantageously obtained by precipitating silica sols or silicate solutions by heating or by adding acids, treating the gels with electrolytes and then drying them. The preparation of suitable silica gels is for example in the German patents

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914, 523 585, 527 370, 530 730 and 536 5 ^ 6.

The mentioned relatively wide-pored and poor in surface area Catalysts are obtained in particular if the gels are proportioned before drying or during drying highly alkaline treated. In this case the catalysts have an exchange acidity above a pH value of 3 · below The exchange acidity of a silica gel is known to mean the pH value that is set when one a certain amount of the gel treated with a certain amount of a potassium chloride solution of a defined concentration. The best results are achieved with catalysts that show exchange acidities between pH values 3 and 7. Catalysts with exchange acidities below a pH value of 3 are already quite narrow-pored and less suitable.

The determination of the distribution of the pore diameter can be done according to the information in the Journal of the American Chemical Society, Volume 73, 1951, page 373, can be made. The determination is based on the measurement of the rate of adsorption and desorption of Nitrogen. One method for determining the specific surface area of porous materials is in the Journal of the American Chemical Society, Vol. 60, 1938, p. 309. Finally, the mean pore radius can be determined according to the German interpretation 1 054 071 from the inner surface and the total pore volume be calculated.

Catalysts with a particularly long service life are those which additionally contain a metal oxide, in particular an oxide of a metal the III. to VI. Group of the Periodic Table, e.g. B. aluminum oxide, titanium oxide contain. The proportion of this metal oxide is generally between 0.1 and 10 percent by weight, based on the total catalyst.

The catalysts activated by metal oxides are prepared, for. B. by common precipitation or by subsequent Applying the metal oxides to the catalyst, for example by mixing silica gel or silicates with solutions of in the

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Heat decomposable metal salts soaks, dries and all in one Gas stream heated.

The effectiveness of the catalysts remains unchanged for a long time. In general, 3000 to 4000 parts by weight of an N-pormylamino compound can be converted per part by weight of catalyst before the effectiveness declines noticeably. The catalyst can be regenerated by passing oxygen or gases containing oxygen over it ^{at 450 to 70O 0 C.} It is advantageous to regenerate the catalyst four to five times, additionally at room temperature or at a moderately elevated temperature, e.g. B. 50 ° C, to treat with a dilute solution, especially with an aqueous solution, a volatile acid. _Λ Diluted hydrochloric acid has proven to be the best. ™

The cyclization is generally carried out at a temperature between 300 to 600 ° C, preferably between 350 to 45O ⁰ C, under atmospheric or reduced pressure, preferably at 0.1 to 100, preferably 1 to 50 Torr,

carried out continuously or discontinuously. For example, the starting material II can be cyclized in the following way: The starting material is in the presence of a solid silica gel or silicate of the properties mentioned for 0.5 to 2 hours held at the reaction temperature and pressure. It is more expedient to make this reaction continuous by passing the starting material over a catalyst layer at ( the mentioned conditions. The reaction mixture is then washed with a suitable solvent, e.g. B. a chlorinated hydrocarbon such as methylene chloride, extracted. The end product is obtained from the extract in the usual way, e.g. B. by filtering the mixture, optionally with the addition of animal charcoal and sodium sulfate, and fractional distillation of the filtrate, isolated.

In the same way, instead of the starting material, a reaction mixture can be used which, by reacting an alkanolamine with Formic acid was obtained. The water of reaction formed and excess formic acid are expediently distilled from the mixture from and then used it without separating off the starting material II formed in the process according to the invention. '

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The new and known compounds which can be prepared by the process of the invention are solvents and valuable Starting materials for the production of vulcanization accelerators, stabilizers, antistatic agents »textile finishing agents, and Pesticides. With regard to the use, reference is made to the patents mentioned as well as to the French U.S. Patents 1,478,076, U.S. Patents 3,209,035, 3 129 178 and Dutch patent application 64.04397.

The parts given in the following examples are parts by weight.

example 1

To 590 parts of ethanolamine, 500 parts of formic acid are added portionwise and the mixture is then heated for one hour at 110 ⁰ C to reflux. Then the mixture is gradually heated to 150 ^° C. and the water formed and excess formic acid are distilled off,

267 parts of the mixture are then at 400 ⁰ C and 4 Torr within one hour over 150 parts of a catalyst consisting of a silica gel containing 90 % pores with a radius of 10 to 200 8, a mean pore radius of 48.9 S and a specific Has a surface of 314 m / g and also contains an addition of 1 % titanium oxide. The reaction mixture is extracted twice with 250 parts of methylene chloride, then 10 parts of animal charcoal and 100 parts of sodium sulfate are added to the combined extracts and the mixture is filtered. The piltrate is distilled. Is obtained (62% of theory) in the form of a Δ -oxazoline at 96 134 parts of - 98 C boiling, colorless liquid.

Example 2

The formyl compound of 3-aminopropanol is prepared analogously to Example 1. 206 parts of this N-formylpropanolamine are fed evenly into the reactor in 1 hour, a pressure of 3 torr being maintained at 450.degree. After working up as described in Example 1, 111 parts are obtained (65 % of theory)

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5,6-Dihydro-4-Hl, 3-oxazine in the form of a colorless liquid with a boiling point of 64 ° C. at 100 torr. C ₁₁ H ₇ NO; n ^ ⁰ = 1.4508

Analysis: Calcd. C 56.44, H 8.31, N 16.46, 0 18.80 % found . C 56.3 H 8.3, N 16.0, 0 19.5 %

Example 3

206 parts of N-formylisopropanolamine are cyclized analogously to Example 1 at 400.degree. C. and at a pressure of 4 Torr. 98 parts (57.6 % of theory) of 5-methyloxazoline with a boiling point of 107 ° C., C. ₁₁ H ₇ NO; are obtained; ng ^u = 1.4250

Analysis: Calcd. C 56.44, H 8.3I ₉ N 16.46, 0.18.8O % |

found C 56.9, H 8.7, N 16.0, 0 18.4 %

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Claims (2)

- 8 - 'O.Z. 26 176 1923U22 patent claims 1. Process for the preparation of cyclic imide esters of the general formula (RCR) _n CH I, in which the individual radicals R can be identical or different and each represent a hydrogen atom, an aliphatic, cycloaliphatic, araliphatic or aromatic radical and η denotes 2, 3 or k , in addition two radicals R can also denote members of a common, carbocyclic ring, from N-formylalkanolamines with elimination of water at elevated temperature in the presence of silicon compounds, characterized in that N-formylalkanolamines of the general formula RH .0 Il / HO- (C) -N-C II, I ⁿ \ R ^N H in which the radicals R and η have the aforementioned meanings, in the presence of solid silica gels or silicates which for the most part pores with a radius of 10 to 200 8, a mean pore radius of 20 to 100 S and a specific pore radius ρ
Have a surface area of at most 550 m / g, cyclized. 2. Cyclic imide esters of the general formula (RCR) _n in which the individual radicals R can be identical or different and in each case a hydrogen atom, an alkyl radical with 1 to 6 009847/1855 " ⁹ " - 9 - O.Z. 26 176 Carbon atoms or an alkenyl radical having 1 to 6 carbon atoms and η denotes 2 or 4, where η does not denote 2 if all radicals R denote hydrogen atoms. Badische Anilin- & Soda-Fabrik AG 009847/1866