DE2450083A1 - PROCESS FOR THE PRODUCTION OF AROMATIC SULFONYL ISOCYANATES - Google Patents

Description

MAXIMUM
Corporation

File number ί HOE 74 / F 309

Date: October 21, 1974 Dr.GM/W

Process for the preparation of aromatic sulfonyl isocyanates

The preparation of organic sulfonyl isocyanates by reacting sulfonic acid amides with phosgene is known. According to the DT-PS 817 ^ 602 is required when working in the absence of a catalytic converter Temperatures of 160 ° C and higher, with products with a high proportion of the corresponding organic sulfonic acid chloride can be obtained.

According to ÜS-PS 3,371,114, the phosgenation is already successful Temperatures around 100 ° G if you use them in the presence of 1Ό - 80

of a hydrocarbyl isocyanate. But also after Sulfonyl isocyanates obtainable by this process always contain a relatively high proportion of the corresponding sulfochloride. In addition, in certain cases, this process should even use less than 10 to 80 mol of hydrocarbyl isocyanate can achieve the desired reaction, but there is neither a reduction in sulfochloride formation in the reaction mixture other benefits have also been observed.

The sulfochlorides obtained as by-products can be as a result the very similar boiling point position of the sulfonyl isocyanates only with difficulty and possibly only with considerable effort by distillation separate, so that a subsequent cleaning of the latter is not possible in a simple manner. To achieve of sulfonyl isocyanates with only a low content of sulfochlorides, it therefore appears expedient to prevent the formation of these undesirable by-products during the phosphate

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to prevent generation reaction.

Surprisingly, it has now been found that sulfonyl isocyanates obtained in very good yields with only a low content of sulfochlorides,

if the phosgenation of the sulfonamides in the presence of only small, catalytic amounts of aliphatic, cycloaliphatic or araliphatic isocyanates.

The present invention thus provides a process for the catalytic production of aromatic sulfonyl isoeyanates with only a low content of sulfochlorides due to phosgenation the corresponding sulfonamides in an inert solvent in the presence of aliphatic, cycloaliphatic or araliphatic isocyanates, which is characterized in that the isocyanates used as a catalyst in amounts of less than 10 moles, preferably 0.1 to 1 moles, based on the sulfonamide, begins.

Typical isocyanates which can be used as catalysts in the process according to the invention are, for example Ethyl isocyanate, butyl isocyanate, hexyl isocyanate, dodecyl isocyanate, Tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, hexamethylene diisocyanate, Cyclohexyl isocyanate, bis (3-methyl-4-isocyanato-cyclohexyl) methane or benzyl isocyanate. Hexadecyl isocyanate and octadecyl isocyanate are preferred.

As aromatic sulfonamides that are obtained by the process according to the invention can be converted into aromatic sulfonyl isocyanates, for example, the sulfamides of benzene and Naphthalene, which can also be substituted, such as e.g. benzenesulfamide, chlorine- and / or bromine-substituted benzenesulf amides, o-, m-, p-toluenesulfamide, the isomeric xylene sulfamides, Jiaphthalinsulfamides and the optionally substituted disulfamides of benzene and naphthalene.

The reaction is expediently carried out in an inert organic solvent carried out. In general, the aromatic starting sulfonamide and the as

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Catalyst used IsocyanaO along with the inert solvent submitted and at the reaction temperature under continued thorough mixing, such as stirring, treated with phosgene until the reaction has ended. The process can be carried out discontinuously or continuously, e.g. in a cascade stirring apparatus. As an inert organic Solvents are, for example, in particular aliphatic hydrocarbons, which can also be substituted, or aromatic, optionally substituted hydrocarbons, such as toluene, xylene, chlorobenzene or dichlorobenzene, or mixtures of such compounds, are used.

But there can also be other ones commonly used in phosgenation reactions Solvents such as butyl acetate or dioxane are used will. However, the preferred inert solvent is chlorobenzene.

The amounts of inert solvents to be used

are based on practical requirements. In general, they are used up to about 10 times the amount by weight, based on the aromatic sulfonamide used. Larger amounts are also possible, whereby their use by economy is limited.

The reaction temperatures for the process according to the invention are between about 70 and 150 ° C., preferably between 90 and 130 ° C. One conducts at the desired temperature for so long Phosgene in the solution or suspension of the mixture of sulfone. amide and catalyst in the inert solvent until none Phosgene is consumed more. Excess phosgene and hydrogen chloride are then removed in the usual way and that aromatic sulfonyl isocyanate isolated in high purity by simple distillation.

The use of expensive fractionation devices to separate the sulfonyl isocyanates from sulfochlorides is unnecessary due to the already surprisingly high purity of the invention obtained crude sulfonyl isocyanates.

B η 9 R 1 B / 1 η «; /, ■.

In comparison to the relevant prior art, the method according to the invention thus comes along with the clearly
"Better yields and the only small amounts of catalyst in the reaction mixture result in excellent technical progress.

However, the completely unexpected must be "particularly surprising The course of the reaction when using the low amounts of catalyst according to the invention appear, with the desired process products undoubtedly not only in higher yields, but rather in addition, also obtained in significantly better quality be what their re-use as intermediates without

. allows complex cleaning operations.

The aromatic sulfonyl isocyanates obtainable by the process according to the invention are valuable intermediates for
Pharmaceuticals and plastics.

The invention is illustrated by the following examples.

6 0 9 8 18/1 05 /,

example 1

A mixture of 78.5 g (0.5 mole) benzenesulfamide, 470 g chlorobenzene and 1.5 g of octadecyl isocyanate (with 0.005 mol of NCO groups, corresponding to 1 mole based on benzenesulfamide) is given under continuous Stirring heated to 120.degree. C. and treated with phosgene at this temperature until one was kept at -20.degree Reflux condenser strong phosgene reflux occurs. In this way, about 130 g of phosgene are metered in. Now one leaves without further supply of phosgene for about 1 hour at the same temperature stir, then replace the freezer with a water-operated cooler, leaving most of the excess Gas off phosgene and the hydrogen chloride. The reaction mixture is then distilled under reduced pressure, the Benzolsulfon.ylisocyanat passes over after the solvent.

This gives 82.3 g of benzenesulfonyl isocyanate (90.0 = # of theory, based on Benzolsulfamid) containing 0.3 i ° Benzolsulf ochlorid ·

Comparative Example 1 a

Is used instead of the 'used in Example 1 amount of 1 Mo1% octadecyl isocyanate 2o mol%, then you get about 85 % yield of a berizolsulfonyl isocyanate, which is 1.2% Bsnzenesulfochlorid is contaminated.

Example 2

If, as in Example 1, 85.5 g (0.5 mol) of o-toluenesulfamide are reacted with phosgene instead of benzenesulfamide, 89.0 g of o-toluenesulfonyl isocyanate (= 90.2 $> d. Theory) with a content of 0.3 ^ o-toluene sulfochloride.

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Comparative Example 2 a

If, instead of the amount of 1 mol% octadecyl isocyanate used in Example 2, 20 mol% is used, the result is 88.6% strength Yield of an o-toluenesulfonyl isocyanate containing 2.2% o-toluenesulfochloride.

Example 3

A mixture of 85.5 g (0.5 mol) of p-toluenesulfamide, 500 g of chlorobenzene and 0.95 g of hexadecyl isocyanate (with 0.0035 mol of isocyanate groups, corresponding to 0.7 mol $ "based on p-toluenesulfamide) is used treated with phosgene, as described in Example T, with about 140 g of phosgene being taken up at 120 ° C. After working up the reaction mixture by distillation, 93.2 g of p-toluenesulfonyl isocyanate (= 94.7 ° of theory) are obtained, the is practically free of p-toluenesulfonyl chloride.

Comparative Example 3 a

If the phosgenation of Example 3 is carried out with the addition of 18.7 g of hexadecyl isocyanate in 300 g of chlorobenzene, then this is obtained a p-toluenesulfonyl isocyanate is obtained in 85.2% yield with a content of $ 1.8 p-toluenesulfonyl chloride.

Examples 4 to 6

In the following Examples 4, 5 and 6, 85.5 g (0.5 mol) of p-toluenesulfamide are in each case in 500 g of chlorobenzene at about 125.degree reacted analogously to Example 1 with phosgene. In Table I below, the type, amount and proportion of NCO groups in mol $ (based on on p-toluenesulfamide used) of each used Catalyst, and also the pure yields of p-toluenesulfonyl isocyanate and its p-toluenesulfonyl chloride (TSC) content.

In an analogous manner, Table I also gives the results of the corresponding comparative tests 4a, 5a and 6a, which according to the known prior art, were carried out comparatively with in each case 20 times the amount of catalyst.

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Table I.

E.g. cr> Comp. Ex K a t a Iy Art ■ s a t ο r Molfo p-toluenesulfonyl isocyanate TSC share No. ο 6 Ur. Amount g NCO ₊ S Yield * co
OO Butyl cyanate 1" $> d. Th. 0.2 4th OO Butyl isocyanate 0.5 20th 85.9 1.1 4 a Hexame.thylene diisocyanate 9.9 1 83.4 0.3 5 Hexamethylene diisocyanate 0.4 20th 86.4 3.6 5 a, techn. Octadecyl isocyanate ++) 8.4 1 81.7 <0.1 techn. Octadecyl isocyanate ++) 1.4 20th 94.0 1.9 |. 6 a 28.0 84.2 -j
I.

+) based on p-toluenesulfamide.
++) Consists of approximately equal parts by weight of octadecyl and hexadecyl isocyanate.

CD O OO

Claims (4)

1. A process for the catalytic production of aromatic sulfonyl isocyanates by phosgenation of the corresponding sulfonamides in an inert solvent at temperatures of about 70 to 150 ° C in the presence of aliphatic, eycloaliphatic or araliphatic isocyanates, characterized in that the isocyanates are used in amounts of less than 10 Mo1 $, based on the sulfonamide, begins. 2. The method according to claim 1, characterized in that the isocyanates are based in amounts between 0.1 and 1 mol $ on the sulfonamide. 3. Process according to Claims 1 and 2, characterized in that hexadecyl isocyanate and / or octadecyl isocyanate are used. 4. Process according to Claims 1 to 3 »characterized in that that p-toluenesulfamide is used. 609818/1054