DE1670720A1 - Process for the preparation of aliphatically substituted uretdiones - Google Patents

Description

COLOR FACTORY BAYER AQ670720

LBVIRSU SIN-Β ·? «* Patsat Abeeiluag

2 0. Wed im

G / O

Process for the production of aliphatically substituted uretdione

Aromatically substituted uretdiones (1,3 - dlazacyclobutanedione 2,4) and their preparation by dimerizing isocyanates with suitable catalysts are already known. Aliphatic substituted uretdiones, d. H. Dimers of aliphatic isocyanates » have not yet been produced Connections completely unstable. Attempts to dimerize aliphatic isocyanates always gave the trimerization product. Reference is made to "Chemical Reviews 57 (1957) p. 55 and Saunders and Frisch (Polyurethanes I), Interscience Publishers (1962, p. 91)

This invention relates to aliphatically substituted retdiones (1,3 - Diazacyclobutanediones 2,4) and a process for their preparation. It has been found that aliphatically substituted

1.3 - Diazacyclobutanedione - 2,4 is obtained if aliphatic ^ isocyanates are optionally dimerized in an inert organlachen solvent and preferably in the presence of catalysts at temperatures of 0-180 ⁰ O, the reaction being terminated at a conversion of 5-5Ο5έ and that formed 1,3 - diazacyclobutanedione

2.4 isolated from the reaction mixture. Particularly suitable catalysts are tertiary phosphines with at least one aliphatic ^

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see substituents and boron trifluoride. The unreacted part the aliphatic isocyanates can be recovered from the reaction mixture and used again in the reaction.

As a starting material for the present process all mono- and polyisocyanates of the aliphatic series, are suitable. If di- or polyisocyanates are used, uretdiones containing isocyanate groups can be obtained accordingly. Suitable isocyanates are, for. B. methyl isocyanate, ethyl isocyanate, propyl isocyanate, n-butyl isocyanate, i3ohexyl isocyanate, dodecyl isocyanate, oleyl isocyanate, stearyl isocyanate, cyclohexyl isocyanate, 2-chloroethyl isocyanate, 2-cyanoethyl isocyanate, 6-chlorohexyl isocyanate, 1, 4-chlorohexyl isocyanate, 1, 4-ethyl isocyanate, isocyanate, isocyanate, isocyanate, isocyanate, isocyanate, isocyanate, propyl isocyanate, isocyanate, propyl isocyanate, propylene propyl isocyanate, propylproisocyanate, benzyl propyl isocyanate, propylproisocyanate, propylproisocyanate -Tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, CO / Ü-diisocyanatodipropyl ether, 1,4- and 1,3-xylylene diisocyanate- CD ₁ CO *, cJ ^ diisocyanato) -t, 4-diethyl.t> enzene, 1 ^ -diisocyanatocyQlollexane , 1-Isocyana-10-3- (isocyanatomethyl) -3,5,5-trimethylcyclohexane, 2,2,4-trimethylhexamethylene diisocyanate-1,6, 2,4,4-trimethylhexamethylene diisocyanate -1,6, 1, 6,1I-triisocyanatoundecane. Further aliphatic isocyanates are described in Annalen 562, p.122 f.

The reaction is also applicable to aliphatically bound isocyanate groups in Voradduktenf which can be obtained from aliphatic polyisocyanates by partial ümsetziing with water, alcohols, amines ^v or carboxylic acids. The separation and Reindarstel ·.

However, treatment of such uretdiones is difficult or impossible.

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The mono- and polyisocyanates can be used individually or in a mixture with one another. In order to limit the formation of byproducts, the starting substances should be distilled in vacuo with the exclusion of atmospheric moisture before use, since all isocyanates contain dissolved carbon dioxide in varying amounts when they come into contact with traces of moisture. Such cleaning is particularly recommended when using tertiary phosphines as the catalyst and when working at temperatures below 100 ⁰ C. When using di- or polyisocyanates, uretdiones can also be formed which contain two or more uretdione rings in the molecule. These compounds are very difficult to isolate in pure form Jedooh.

The uretdiones of the invention are compounds of the general formula

In this formula, R denotes an aliphatic radical. The radicals can be identical or different. In particular, R means a linear or branched alkyl radical, preferably alkyl having 1 to 6 carbon atoms and an alkenyl radical preferably having 3 to 6 carbon atoms. The radicals R can also be substituted be. Examples of suitable substituents are the NGO group, Halogen, such as chlorine, the nitrile group, also alkoxy, carbalkoxy-dialkyl aino radicals, as well as aromatic radicals such as phenyl and naphthyl.

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Preferred catalysts for the process according to the invention are tertiary phosphines which contain at least one aliphatic sub-

have stituents, e.g. B. Trialkyphosphine, tributylphosphine, phenyldimethyphosphine, also boron trifluoride, its adducts or etherates. With less success, strongly polarizing ones also become Compounds such as dry hydrogen halide gas or diazabicyclooctane (22.2) used.

To carry out the process according to the invention, it is essential to stop the reaction very early, long before all of the isocyanate has taken part in the reaction, since otherwise an undesirably high proportion of isocyanurate structures is formed. The reaction is therefore expediently interrupted after a conversion of 5-50 % and unconverted isocyanate is separated off, which can be fed back into the reaction in a further batch. The advantage of such a procedure is illustrated by the experimental data given in Example 2. The amount of diethyluretdione that can be isolated during the polymerization of ethyl isocyanate with phosphines. is z. B. at 57 % conversion still 35 1 ° and goes back to 17 ° at 77 $> conversion.

The reaction temperature varies depending on the catalyst used. Boron trifluoride is advantageously used at room temperature or up to temperatures of 50 °, since the solubility of this catalyst in the reaction mixture decreases faster with increasing temperature than the reaction rate is increased. For tertiary aliphatic or mixed allphatisch-aromatic phosphines, the range of 50 - 8Q ⁰ C, the optimum temperature at which also the uretdione content in the polymer is at a maximum. But you can also choose higher or lower temperatures, since urethral

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dlone between 0 and 120 ° can arise in larger quantities. At higher temperatures and, above all, with prolonged thermal stress and low catalyst concentration, other by-products, such as alkylimino-dialkyloxadiazinediones, carbodiimides and uretoneimines, are formed in increasing amounts in addition to isocyanurates. k For thermal dimerization without a catalyst, temperatures between 120 and 150 ° are most favorable. At lower temperatures it takes too long to set the equilibrium; at higher temperatures, the uretdione is converted to a large extent into isocyanurate.

The amount of catalyst required varies depending on the type and purity of the isocyanate used and the temperature used. Amounts of 0.1 - 5 wt. $> Based on starting isocyanate are tertiary aliphatic phosphines when applied generally sufficient. Preferably $ 0.3 - $ 2 apply. - Boron trifluoride is required in an amount of 1-10 fo, preferably 2-5 $. The same applies to the amount of polarizing agents that may be used in the thermal dimerization, such as, for. B. hydrochloric acid. Diazabicyclooctane (2,2,2) is very effective with 1 - 2 $ at 120 - 150 °.

The reaction can take place in polar solvents such as esters, chlorinated hydrocarbons: Hydrogen, ethers and ketones or without solvents will. It is preferable to work solvent-free, since the resulting uretdiones are generally fluids and excess Isocyanate itself is effective as a polar solvent.

In the case of phosphines, the known ones are used to stop the reaction Abatopper, namely alkylating agents such as dimethyl sulfate U 1 10 UB 00 <J8_83 / 2190

and methyl toluenesulfate or acylating agents such as benzoyl chloride and Carbarn acid chlorides, which through use ' of the catalytically active lone pair of electrons on phosphorus die interrupt further reaction. The use of increased temperatures of up to 80 ° accelerates the stopping process. Boron trifluoride as a catalyst The easiest way to remove is by applying a vacuum and increasing the temperature.

The reaction mixture is preferably worked up by vacuum distillation. Since the boiling points of the monomers, dimers and polymers are usually far apart, fractionation via columns is generally not necessary and only needs to be used where the uretdiones are to be obtained in particular purity. In order to keep the ITretdione losses as low as possible during work-up, the temperature load must remain as low as possible. In a normal distillation, the amounts used should therefore be small and the bottom temperature does not exceed 100 ⁰ C.

In the case of higher-boiling mono- and polyisocyanates, therefore, different ones have to be used Choose separation methods. So you can z. B. in a thin film distillation in the vacuum the monomer as a distillate from the polymer- ^ · Partly separate, whereby the uretdiones are only heated for a short time. The uretdiones then separate by extraction with suitable gasoline or benzene hydrocarbons or by molecular distillation. In special cases are other types of combination of distillation and Extraction preferable.

The aliphatic. Uretdiones are predominant at room temperature Le a 10 HB 0 0 9 ξ Ö_3 / 2 I y CJ

ÖÄD ORIGINAL

colorless, partly easily mobile, partly oily liquids, which lack the pungent odor of the monomeric isocyanates. They can be identified by analysis, molecular weight and above all by their IR spectrum, where they have characteristic absorptions at 5.65-5.70 / ^u , 7.12 - 7.18 / ^u and 12.65 - 12.s75 / ^u have. Their constitution has been proven by a series of characteristic reactions.

The aliphatic uretdiones are to be used as intermediates for manuf ellation tone pesticides and, especially if they are still have free isocyanate groups as intermediates for manufacture of plastics, paints and foams are used. They are especially valuable because they are their base Because of the vapor pressure, they are physiologically harmless and because they allow the isoeyanate groups defined in the uretdione ring to be released again by applying higher temperatures. In this sense, the isocyanate group-free uretdiones are also called disguised To understand isocyanates.

example 1

657 parts of butyl isocyanate freshly purified by distillation are stirred with 9.85 parts of tri-n-butylphosphine (1.5 pounds) at 60 °, and the reaction occurs after about A hours at an NGO value of 35.6 . # is terminated by adding 6.3 g of dimethyl sulfate and brief heating to 80 ° «The conversion achieved is approx. 16.5 ^. The batch is then fractionated over a small column at 1 _f 2 Torr. In the cold trap, 546 parts (83.5 #) of butyl isocyanate are recovered. The following fractions are obtained:

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Advance 3.6 parts. Kp 45-92 ° Uretdione 49.0 Tl. 92-93 ° Yield 44 # in between 1.9 parts 94 -154 ° added 40.7 parts 155 -158 ° to EoIy isocyanurate Swamp 13.0 tsp.

The molecular weight of the dibutyluretdione was determined to be 200/201 (theory 198). The IR spectrum shows the characteristic bands at 5.68 - 7.16 and 12.75 / ^u . Elemental analysis C: 50.6 / 50.8 ί (calc. 50.7) Hi 7.2 / 7.4 (calc. 7.1) N 19.4 / 19.4 (calc. 19.7) 0: 23.0 / 22.8 (calc. 22.5).

Example 2

100 Tl. Of freshly distilled ethyl isocyanate are mixed with 3 "Tl. Tri-n-buthylphosphine added and at room temperature up to Reaching the desired NCO content stirred. Then the further reaction is carried out by adding 2.4 parts each, dimethyl sulfate and . One hour heating to 60 ° interrupted and the approaches are Fractionated by vacuum distillation over a Widmer column.

Seed «a) is stopped after. 8 hours at a HOO value of 40.35 * Approach b) is stopped after 70 hours at an NGO value of

22.7 i>
Approach c) is stopped after 168 hours at an NCO value of

Distillation at 14 torr gives the following composition Approaches:

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approach

Partial advance up to 73 °

Tl. Uretdione 73-74 °

Tl. Intermediate run

Tl. Isocyanurate 140-142

Tl. Residue

a b 1670720
C. 2.3 1.2 4.8 12.8 19.4 13 * 1 1.6 6.4 3.4 12.5 28.0 47.6 7.3 7.2 8.0

Parts of polymer in total 36.5 62.2 76.9

Tl. Recovered Iso- 63.4 37.4 22.9

cyanate -.

Part of the stake * 99.9 99.6 99.8

Uretdione yield of 35 $ 31.2 $ 17.1 fi> based on polymer

Turnover 375έ 62 f> 77 f>

Ratio of iso _n Q ₈ * * - ■ * c * * cyanurate to uretdione> 2 * "■:> *.

As the comparison of the 3 approaches shows, the yields are high Uretdione can only be obtained with low sales, otherwise the Iaocyanurate content increases too much,

The diethyluretdione iat a colorless liquid of bp _{2 5} = 47-48 ° bp ₁ . = 74 °. The molecular weight is determined to be 143/143 (over 142). The IR spectrum shows the characteristic bands at 5.68 -7.18 and 12.75 / ^U.

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Claims (4)

Claims 1. A process for the preparation of aliphatic-substituted 1,3-2,4 Diazacyclobutandioner characterized in that allphatische isocyanates, optionally in an inert organic solvent and preferably in the presence of a catalyst at temperatures of O - dimerized 180 ⁰ C, wherein the reaction is at a conversion of 5-50 £> and the 1 _t 3 ^ diazacyclobutanedione 2,4 isolated from the reaction mixture. 2. The method according to claim 1, characterized in that the Dimerization in the presence of tertiary phosphines with at least one aliphatic substituent or boron trifluoride or its Performs adducts. 3. The method according to claim 1, characterized in that the recovered from the reaction mixture, unreacted aliphatic isocyanates are used again in the reaction. 4. Aliphatically substituted t _t 3-diazacycloi> utaadione (2,4) of the formula R, where R is an aliphatic radical. 009883/2190
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