DE1122058B - Process for the preparation of ª-haloalkyl isocyanates - Google Patents

Description

It is known that -haloalkyl isocyanates by thermal decomposition of -haloalkylcarboxylic acid azides to manufacture. However, this reaction is technically difficult to carry out, especially bumps a transfer to the production of alkyl isocyanates halogenated in the position considerable difficulties.

Acylated Λ-haloalkylamines can be via the corresponding acylated -hydroxyalkylamines with hydrohalic acids or phosphorus halides produce. However, this reaction path cannot be used because of the reactivity of the NCO group on the production of α-haloalkyl isocyanates expand.

A direct chlorination of acylated alkylamines to produce acylated -haloalkylamines has not yet been attempted because it was to be expected that halogenation by attack on the acyl group and cleavage of the N-C bonds not smoothly to acylated -haloalkylamines would lead.

It has now been found that, surprisingly, α-haloalkyl isocyanates can be obtained smoothly can when treating alkyl isocyanates with halogenating agents. This behavior of alkyl isocyanates is in contrast to the known behavior of the alkyl isothiocyanates, in which below comparable conditions initially the isothiocyanate group is halogenated and isocyanide dihalides develop.

For the preparation of -Halogenalkylisocyanaten by the process according to the invention are all Suitable alkyl isocyanates which contain at least one hydrogen atom in the position. Instead of Free isocyanates can also be used with their hydrogen halide adducts (carbamic acid halides) will. It is also possible to use polyisocyanates, the halogenation being carried out at all activated positions of the molecule begins. Suitable isocyanates or carbamic acid chlorides are, for. B. methyl carbamic acid chloride, Methyl isocyanate, ethyl isocyanate, benzyl isocyanate, m - isocyanatobenzyl isocyanate, / S-chloroethyl isocyanate, hexamethylene diisocyanate, Dodecyl isocyanate, phenylethyl isocyanate, carboxyethyl methyl isocyanate.

Suitable halogenating agents are e.g. B. chlorine, bromine, sulfuryl chloride, sulfuryl bromide.

Halogenation with elemental halogen often takes place in an exothermic reaction even at room temperature without the presence of catalysts. In other cases it is expedient at elevated temperature and / or under exposure or under a method of preparation
of α-haloalkyl isocyanates

Applicant:

Paint factories Bayer Aktiengesellschaft,
Leverkusen-Bayerwerk

Dr. Hans Holtschmidt, Cologne-Stammheim,

and Dr. Eberhard Degener, Leverkusen,

have been named as inventors

Use of catalytically active halogen carriers such as iron (III) chloride to work.

Depending on the type of alkyl isocyanate used, one to three Λ hydrogen atoms can be replaced by halogen atoms substitute. Under more energetic reaction conditions it is even possible to use longer alkyl chains further in addition (e.g. also in the / ^ position) halogenate without halogenolytic cleavage of the molecule occurring.

The use of a solvent is not required for halogenation, but it can be used in individual cases bring advantages if the resulting λ-haloalkyl isocyanates condensation or tend to polymerize. Suitable solvents are e.g. B. carbon tetrachloride or trichlorobenzene.

The haloalkyl isocyanates obtained are very reactive substances, which both by her reactive halogen atom as well as through their isocyanate groups to enter into the most varied of reactions capital. They are used as intermediates in the manufacture of pesticides, pharmaceuticals as well as plastics and plastic auxiliaries.

example 1

935 parts of methyl carbamic acid chloride are suspended in 2 l of chlorobenzene. Then under Irradiation with UV light between 40 and 70 ° C initiated chlorine. Care must be taken through cooling be carried so that the temperature does not rise higher, otherwise the carbamic acid chloride splits off HCl and this makes it difficult to control the weight absorption of chlorine. after the calculated amount of chlorine has been added, the reaction mixture is distilled. The chloromethyl carb

109 760/424

amic acid chloride decomposes with the elimination of HCl. The chloromethyl isocyanate-H Cl mixture boils between 82 and 86 ° C. Tn the original is united again with strong heat tint instead of carbamic acid chloride.

Yield: 1002 g.

Analysis of the distillate (calculated on carbamic acid chloride):

Calculated ... C 18.8, H 2.34, N 10.9, Cl 55.4%; Found ... C 19.8, H 2.36, N 10.2, Cl 53.6%.

The carbamic acid chloride is heated to 120 ° C and blown with nitrogen for 3 hours, the free chloromethyl isocyanate is obtained.

Kp. _7eo 81 to 82 ° C.
Analysis:

Calculated ... C 26.2, H 2.19, N 15.3, Cl 38.8%; Found ... C 26.25, H 2.25, N 15.04, Cl 39.6%.

Example 2

105.5 parts / 3-chloroethyl isocyanate are irradiated with UV light at 80 to 150 ° C for as long chlorinated until there is no more weight gain. This is the case when 110 parts of chlorine are added have been.

After blowing with nitrogen at 12O ⁰ C the 1,1,2,2-Tetrachloräthylisocyanat distilled over constant.

Yield: 95%; Bp ₁₂ 70 to 72 ° C. Analysis:

Calculated ... C 17.2, H 0.48, N 6.7, Cl 68.1%; Found ... C 16.6, H 0.47, N 6.65, Cl 69.5%.

Example 3

133 parts of benzyl isocyanate are dissolved in 250 cm ^{3 of} carbon tetrachloride. The mixture is then chlorinated between 40 and 60 ° C under irradiation with UV light until 71 parts of chlorine have been absorbed.

After distilling off the carbon tetrachloride, the Carbaroidsäurechlorid is destroyed by blowing with nitrogen at 12O ⁰ C. The -chlorobenzyl isocyanate is obtained in a yield of 68% of theory.

Kp.13 120 to 130 ⁰ C. It remains a resinous residue.
Analysis:

Calculated ... C 57.4, H 3.6, N 8.3, Cl 21.2%; Found ... C 56.6, H 3.66, N 8.8, Cl 22.5%.

Example 4

In 193 g of methyl carbamic acid chloride in 825 ml of trichlorobenzene, chlorine is passed in at 80 ° C. with UV exposure until the weight increases by 216 g. The reaction product boiling up to 160 ^{° C. is then distilled off.}

When fractionating at atmospheric pressure, the following fractions are obtained.

I: 92 to 10 3 ° C 57 g

II: 111 to 119 ⁰ C 40 g

III: 119 to 123 ⁰ C 53 g

Analyzes C ₂ Cl ₃ ON = molecular weight 160.4.

Calculated

C 14.98, H -, N 8.74, Cl 66.32%;
found

Group II

C 15.77, H under 0.5, N 7.95, Cl 65.50%,
Group III

C 15.59, H under 0.5, N 8.87, Cl 66.05%.

Example 5

Chlorine is passed into 100 g of methyl isocyanate at 0 to 10 ^° C. with exposure to UV light. After a few days, the reaction solution has taken up 74 g of chlorine.
The following fractions are used in the distillation

ao received:

I. 60 g mixture of methyl carbamic acid chloride, chloromethyl isocyanate and dichloromethyl isocyanate,

Kp. _Loomm 50 to 54 ° C, η - 1.4690 (partly crystalline).

Analysis: found C 21.25%, H 2.8% »Cl 50.4%. II. 27 g mixture of chloromethyl isocyanate and dichloromethyl isocyanate,
Kp. _5omm 46 to 50 ⁰ C, η = 1.4740,

Analysis: found Cl 50.4%.

III. 10 g mixture of dichloro- and trichloromethyl isocyanate and traces of higher molecular weight condensation products,
_Bp . 2omm 59 to 80 ° C, η = 1.4932,
Analysis: found Cl 60.0%.

Example 6

Chlorine is passed in 35 g of iS-chloroethyl isocyanate for 90 minutes at 140 ° C. without exposure. 4 g of chlorine are taken up with the simultaneous evolution of hydrogen chloride.
With vacuum distillation one obtains:
I. 25 g mixture of 3-chloroethyl isocyanate with a little «, yS-dichloroethyl isocyanate,
Kp. 12 mm 40 to 46 ⁰ C, η = 1.4608.
II. 10 g mixture of «, / S-dichloroethyl isocyanate, / 3, / 9-dichloroethyl isocyanate and the isomeric trichloroethyl isocyanates,
_Bp . 12mm 50 to 60 ° C, η = 1.4782.
III. 3 g mixture of isomeric trichloroethyl isocyanates and tetrachloroethyl isocyanate and pentachloroethyl isocyanate,
Kp. _12mm 70 to 86 ⁰ C, η = 1.5009.

Claims (1)

PATENT CLAIM: Process for the preparation of a-haloalkyl isocyanates, characterized in that alkyl isocyanates or alkyl carbamic acid halides, which have at least one hydrogen atom in the «position are reacted with halogenating agents. 760/424 1.62