DE1768439C3 - Process for the continuous production of organic isocyanates - Google Patents

Description

(D) the reaction in one stage in the selected (A) the solution or suspension of the amine at a constant temperature above 180 to about below the decomposition temperature of the amine 250 ° C and a pressure in the range of 20 temperature in the range of about 165 up to 150 at. " ⁵ 225 ^c C and

(B) the phosgene in about 2.5 to 5.5 times stoichio-

metric excess to one above its

critical temperature in the range of approx. 185 to 235 ° C preheated,

rv c β α u ♦ β ·, · ν Jt u r ι f ³ ° (Q the preheated components in the reaction zone

The invention relates to a method for merging and _{continuous reactor}

the production of organic isocyanates by Um- _{(D) dje reaction in one} stage at the selected

Settlement of primary amines with phosgene in the liquid phase at a constant temperature above 180 to about

under increased pressures and temperatures. _{250 <> c and a pressure in the} range from 20 to

A continuous process is known for carrying out 35 150 at
Production of organic isocyanates by reaction

of amine solutions with phosgene solutions in organic The reaction temperature is thus close to or

see solvents or in the umlautenden stream higher than the temperature of the beginning of the dissociation

of the reaction masses in a tube reactor in the case of the hydrochloride of the amines and the

a pressure of at most 14 at and a temperature 4 «pressure depending on the properties of the

rature up to 180 ⁰ C with multiple recirculation solvent used equal to or higher than

of the reaction products and uninterrupted ab- to keep all components of the reaction

alternating addition of fresh portions of phosgene mixture in the liquid phase required pressure

and amine solution (see U.S. Patent 2,822,373). held. The unreacted excess phosgene

With the separation of the reaction mixture for the purpose of 45 and the solvent are after the separation

The isocyanates should be separated from the reaction products in the material cycle 3 to 5 hours later

Introduction of the first portions of the solutions from returned.

Amine and phosgene in the circulating pure solution by the separate preheating of amine and

medium, namely as soon as there is an isocyanate content in the reac phosgene, firstly the heat of the transition from

tion mixture of 8 to 10% is reached, started 50 phosgene from the supercritical state into the liquid

will. Phase to achieve a high implementation temperature

However, preference is given to this known method and, secondly, to the degree of preheating

only regulated within the permissible limits for the production of aromatic isocyanates of amines,

used. The Preparation of Aliphatic Isocyanates Any primary amine that

is very cumbersome, since aliphatic amines 55 do not contain any other reactive groups,

under the process conditions with phosgene extremely except for the amines usually used

Reactive carbamyl chloride hydrochloride form- according to the invention, the following amines are also used-

the; these sit immediately with the free amines, for example

to substituted ureas, those under these _{cjs 1 3} diaminocyclohexane

Conditions are not able to react with phosgene 60 trans-l ^ -DiaminocycIohexan,

^ZU «/ T ⁿ 'μ u _t -i ■ ♦ α u ~ u ■ -rr 1 4,4'-Diaminodiphenylathui,

α Y ^e T, T, relatively long 4,4'-diamino-2,2'-dichlorodiphenyl _m ethane,

Stay of isocyanates at elevated temperature, 4,4'-diamino-3,5,3 ', 5'-tetramethyldiphenyl.
which favors the thermal polymerization and polycondensation of the isocyanates. 65 In addition to liquid amines, the amines can be used individually

Carrying out hot phosgenation at or in. Mixture with each other, also in the form of a

low pressures and phosgene concentrations for- solution or suspension in an inert organic

Finally, the formation of hydrochloric acid amines and solvents are used. If that

desired amine has only a low solubility and can also not be suspended in a solvent, the amine can be in the form of its solution in another primary amine are introduced with the addition of a solvent, the choice of second amine by the possibility of a complete separation of the isocyanates obtained at the same time is determined by distillation or rectification.

By combining high temperature with high phosgene concentration in the reaction mixture the isocyanate production time is greatly reduced and the formation of by-products (such as hydrochloric acid amines and substituted ureas) is suppressed and reduces the yields of secondary by-products. This makes the production very diverse Mono-, di- and polyisocyanates from amines and phosgene in high yield in one single temperature level and in a single pass through the reactor.

According to the invention, the remaining starting materials in the reaction zone generally do not exceed this 5 to 60 seconds; the duration depends on the nature of the amine.

The residence time of the reaction components in the »5 Reaction zone, d. H. the implementation time is calculated, for example, on the basis of the following Example 1 specified conditions as follows: In the reactor of 25 ml content are im Over the course of one hour (36C0 seconds) 2CC0 ml of diamine solution and about 1200 ml of liquid phosgene (1680: 1.4) introduced; the extent of the reaction mixture flowing through (without taking into account the thermal Expansion coefficient) is 3200 ml / h, the residence time (τ) of the starting materials in the Reactor accordingly

25 ml · 3600 see
3200 ml

= 28 see.

When the amines are phosgenated in solution or suspension, the preferred solvent is chlorobenzene or other organic solvents such as benzene, toluene, xylene, o-dichlorobenzene or trichlorobenzene, used. Here is to dissolve the phosgene in lower boiling than chlorobenzene Solvents a higher pressure to use, whereas when using high-boiling solvents a lower pressure than with chlorobenzene is sufficient.

The starting materials are introduced into the lower part of the reactor in such a way that a complete Contact of the phosgene with the amine is guaranteed. However, the best results are achieved by introducing the components in countercurrent, preferably at an angle of 180 °.

According to the invention, for example, in addition to the usual, the following diisocyanates are prepared:

cis-cyclohexane- _{1,3-diisocyanate, b.p. 23} 140 ° C, nf 1.4809; trans-cyclohexane-M-diisocyanate, boiling point ₃₂ 145 to 146 ° C, freezing point 58.5 ° C;
DiphenylätheM ^ '- diisocyanate, Kp ₂ 184 ° C, F. ^C 88.5 C;.

2,2'-dichlorodiphenylmethane-4,4'-diisocyanate, bp, 181-182 ° C, F. 105 ⁰ C.

B.p., 168 to 169 ^G C, m.p. 78 ° C.

The inventive method is preferably carried out according to the scheme shown in the drawing carried out as follows:

Liquid phosgene is continuously transferred from the measuring vessel 1 via the pipelines by means of the metering pump 3 2 and 4 are pumped into the heater 5, which is thermostated by means of a heating jacket, in which the Phosgene is heated up to the supercritical temperature and then via the pipe 6 into the lower part of the thermostated reactor 7 is introduced by means of a heating jacket. The metering pump 10 pumps the amine or its solution or suspension continuously from the measuring vessel 8 via the pipes 9 and 11 in the heater 12, thermostated by means of a heating jacket, in which the amine is heated to a temperature heated below its decomposition temperature and then via the pipe 13 - just like that Phosgene - is introduced into the lower part of the reactor 7.

The pressure in reactor 7 is kept at the required level by continuously discharging the reaction products from the reactor via the pipeline 14 with the aid of the throttle valve 15 in the Scheider 16, in which a large part of the hydrogen chloride formed and the unconverted phosgene is separated from the crude isccyanate under atmospheric or higher pressure.

The remaining crude isocyanate is removed from the separator 16 via the pipe 17 to a (not shown) secondary plant in which it is derived from the residues of the phosgene dissolved in the crude product and Liberated hydrogen chloride by bubbling through with inert gas at elevated temperature and in known Way is cleaned.

The solvent is separated from the isocyanate by distillation or rectification and used for Preparation of the starting solution or suspension of the primary amine reused.

The emerging from the separator 16 mixture of phosgene and hydrogen chloride vapors is through the Pipeline 18 passed into the low-temperature condenser 19, in which a large part of the Phosgene condenses, while the hydrogen chloride is mixed with phosgene via the pipeline 20 leads to a (not shown) neutralization system. The liquid phosgene flows out of the Condenser 19 in the collecting tanks, from which it flows via pipe 22 into measuring vessel 1 is returned.

example 1
Hexamethylene diisocyanate

2CC0 ml of a chlorobenzene solution of 205 g of hexamethylenediamine are in a preheater Preheated to 216 to 219 ° C and then continuously and evenly through a 25 ml tubular flow heater for 1 hour directed. At the same time, 1680 g of phosgene are in a preheater with one temperature preheated from 220 to 224 ° C and then also continuously and evenly through the reactor guided. The temperature of the heating medium in the reactor heating jacket is kept at 218 to 220 ° C. in the reaction zone on the other hand to 233 to 235 ° C and the pressure in the reactor to 60 to 62 atü by adding the reaction products continuously discharges into the separator. The resulting solution of the crude product is blown to Liberation of phosgene and hydrogen chloride with

5 6

dry nitrogen at a temperature of 110 56 at. Yield 1600 g (95.2%); Kp _3o 103 to 104 "C, to 125 ° C and then distilled in vacuo. Nf 1.5578..
Yield 265 g (89% of theory, based on hexamethylenediamine); _{Bp 3} 105 to 106 ° C, nf 1.4530. Example 7

5
Example 2 phenyl isocyanate

Decamethylene diisocyanate wihind Γ " ^^ * ^" ^ ^ " ^ ™

According to Example 1, 1500 ml of a preheated solution of 150 g of decamethylenediamine in chlorophosgene, preheated at 220 to 225 ° C., are passed through the reactor in the preheated solution of 200 g of aniline in chlorobenzene over the course of one hour. The temperature of the heating agent benzene and 840 g of a preheated phosgene passed. in the reactor heating jacket is 218 to 222 ° C, the yield 170 g (87%); _{B.p. 8} 140 to 142 ° C, nf 1.4564. those of the reaction zone 215 to 225 ° C, the pressure

in the reactor 60 to 62 at. Yield 243 g (95%); B.p., ₆ 15 55 to 57 ° C.
Example 3

(B) Comparative example

Tolylene diisocyanate

The procedure is as in (A), but without a solvent

According to Example 1, 1560 ml of one in one ao are passed through the reactor for one hour while passing 365 g of aniline and 700 g of phosgene through the reactor. The tempe temperature of 174 to 178 ° C own preheater temperature of the reaction zone is 231 to 234 ° C, the preheated solution of 150 g of toluenediamine, pressure in the reactor 50 to 51 atm. Yield 303 g (65%); consisting of 65% of the 2,4- and 35% of the 2,6-isomer, bp "55 to 57 ° C.
in chlorobenzene and 1246 g of phosgene in one

Preheater was preheated to 216-220 ° C. The aj example 8

Temperature of the heating medium in the reactor heating jacket

is 220 to 225 ° C, that of the reaction zone diphenylmethane-4,4'-diisocyanate

220 to 223 ° C, the pressure in the reactor 50 to 54 at. According to Example 1 are through the reactor

Yield 220 g (94.3%): 65% of the 2.4 and 35% of the 2380 ml of a 2,6 isomer ^{at 200 to 205 ° C. over one hour;} Bp. ₅ 101 to 102 ° C, w? 1.5676. 30 preheated solution of 191 g of 4,4'-diaminodiphenyl

methane in chlorobenzene and 750 g of phosgene heated to 220 to Example 4 224 ° C (temperature in the heater

Chlorobenzene-l 4-diisocyanate ²² ° ^{to 224} ° ^C > passed. The temperature of the heating

Chlorobenzene 1,4-dnsocyanate ^^ _{in the reactor} heating jacket , ^ tngt 215 to 220 ⁰ C,

According to Example 3, that of the reaction zone 215 to 220 ° C., the pressure for one hour 1825 ml of a preheated in the reactor 50 to 60 at. Yield 225 g (93%); Bp. _Z solution of 158 g of 2,4-diaminochlorobenzene in chlorine -187 to 188 ° C, mp 37 to 38 ° C.
benzo! and 1120 g of a preheated phosgene geleitel.

The temperature of the heating medium in the reactor heating jacket Example 9

is 235 to 240 ° C, that of the reaction zone 40

210 to 215 ° C. Yield 195 g (90.5%); Kp. ^ 145 bis diphenylethane-4,4'-diisocyanate

146 ° C., m.p. 65 to 67 "C. According to Example 8, the mixture is passed through the reactor

in the course of one hour 2300 ml of a preheated Example 5 solution of 180g4,4'-diaminodiphenylethane in chlorine

Nanhthalin-1 5-diisocvan't ⁴⁵ ^ ⁰ ' ^{and 85} ° ^{e of a pre-} heated phosgene. The end-

Naphthalene 1.5 dnsocyana ^^ _{m g (g5%);} ^ _m ^ ^ "^ _p | _goc

Example 1 is followed through the reactor
for one hour 2600 ml one in one 221 bis

223 ³ C hot heater preheated suspension from Example 10

200 g 1,5-diaminonaphthalene in chlorobenzene and 50, «-,. _ς , · ** _ »"", _Λ,. · ·,. ",".
12519g of phosgene, which in a heater to a ³ A3,5-tetramethyldiphenylmethane ^ '- diisocyanate

Temperature of 226 to 230 ⁰ C was preheated. The same as in Example 8 are passed through the reactor

Temperature of the heating medium in the reactor heating jacket for one hour 2000 ml of a preheated is 230 to 235 ° C that of the reaction zone solution of 130 g 4,4 ^ diammo-3,5,3% 5'-tetramethyl-220 to 225 ⁰ C, the pressure in the reactor 50 to 55 at. 55 diphenyunethane in chlorobenzene and 500 g of a pre-Aasbeute 233g (87.6%); Bp., “220 to 221 ° C, F. 130 heated phosgene passed. Yield 142 e (91VV to 131 ⁰ C. Kp ^ 177 to 178 ⁰ C, m. 130 to 131 ⁰ C.

Examples Example 11

m-Chlorophenyl isocyanate 2, Z'-DichlordiphenyimeÜian - ^ '- diisocyanate

According to Example 1, through the reactor According to Example 1 are selected through the reactor

ml within one hour of 3000 to 165 to 170 ⁰ C rend one hour 3000 ml of a 190 to 195 ° C.

Pre-heated solution of 1395 g of m-cfaloranflin in pre-heated solution of 290 g of 4,4 * -diammo-2 ^ '- di-chlorobenzene and 2800 g of a pre-6 ₅ chlorodiphenylmethane ia chlorobenzene and 11 € 0 g at 185 to 190 ° C one

heated phosgene passed. The temperature of the heating phosgene preheated to 222 to 227 ° C passed the

means in the reactor heating jacket and the reaction zone temperature of the heating element in the reactor heating jacket

is 195 to 200 ⁰ C, the pressure in reactor 52 bis is 230 to 235 ⁰ C, that in the reaction zone

ir C oil
η

Is

■ eil ·.; ·
■ Jis.S

218 to 220 ^U C, the pressure in the reactor 50 to 52 at. Yield 287 g (82.8%); Kp _n 181 to 182 ° C, F. 105 ⁰ C.

Example 12
Dicyclohexyl methane 'M' diisocyanate

According to Example 1 is passed through the reactor for one hour to 1,000 ml of a 223-225 ⁰ C preheated solution of 100 g of 4,4'-diaminodicyclohexylmethane in chlorobenzene and 450 g of 228-230 ⁰ C preheated phosgene. The temperature of the heating medium in the reactor heating jacket is from 240 to 245 ° C., that in the reaction zone is from 245 to 250 ° C., the pressure in the reaction zone from 60 to 62 atm. Yield 100 g (80%); b.p. _1> 5,167 to 168 ° C, nf 1.4977.

Example 13
Cyclohexane 1,3 (cis) diisocyanate

According to Example 12, 1000 ml of a preheated solution of 100 gl, 3- (cis) -diaminocyclohexane in chlorobenzene and 880 g of a preheated phosgene HOg (75.5%) diisocyanate are obtained. Bp. ₂₃ 140 to 140.5 ⁰ C, nf 1.4809.

Example 14
Cyclohexar-1 ^ -itransJ-diisocyanate

According to Example 12, 1000 ml of a preheated solution of 100 g of 1,4 (trans) -diaminocyclohexane are used in chlorobenzene and 850 g of a preheated phosgene 115 g (78.8%) diisocyanate

won. Bp. ₃₂ 145 to 146 ° C, crystallization temperature 58.5 ⁰ C.

Example 15
Triphenylmethane-4,4 ', 4 "-triisocyanate

According to Example 1 is passed through the reactor in the course of one hour 1520 ml of a ⁰ to 220 C preheated to 215 solution of 105 g of 4,4 ', 4 "-triaminotriphenylmethane and 580 g of an at 225-228 ⁰ C preheated phosgene. The temperature of the heating medium in the reactor heating jacket is 230 to 235 ° C., that of the contact zone is 212 to 217 ° C., the pressure in the reactor is 50 to 55 atmospheres. Yield 123 g (91%) with a base material content of 99%.

Example 16

3,4-dichlorophenyl isocyanate (1) and 3,3'-dimethoxydiphenyl-4,4'-diisocyanate (II)

According to Example 1, 1070 ml at 193 to 197 ° C. are passed through the reactor for one hour preheated chlorobenzene solution of 200 g of 3,4-dichloroaniline and 81.5 g of o-dianisidine and 880 g of one at 204

as to 206 ⁰ C preheated phosgene passed. The temperature of the heating medium in the reactor heating jacket is from 208 to 212 ° C., that of the reaction zone from 230 to 235 ° C., and the pressure in the reactor from 51 to 53 atmospheres. The crude product obtained is subjected to vacuum distillation. Yield 216.7 g (93.3%) I, _{b.p. 3O} 117 to 118 ° C, mp 43 to 44 ° C, and 72 g (73.3%) Ii, b.p. ₃ 210 to 211 ° C, F. 117 to 118 ⁰ C.

1 sheet of drawings

Claims (1)

1 2 substituted ureas, whereby as a side reaction Payment claims the deamination of the hydrochloric acid amines as well Process for continuous production organizing the formation of allophanoic acid and biuret derivatives shear isocyanates by reaction in an inert one. Solvents of dissolved or suspended primary 5 Those on which the present invention is based Amines with phosgene in the liquid phase with increased task consists in the elimination of the mentioned Pressures and temperatures with subsequent disadvantages due to the development of such a Conveying the liquid reaction mixture in driving for the production of mono-, di- and poly- a low pressure zone, characterized by phosgenation of isocyanates in an inert draws that io dissolved or suspended primary solvent ia \ λ ι - jo j λ r aliphatic, aromatic, fatty aromatic, ali- (A) the solution or suspension of the amine to "g? ^ _{Un 'd} heterocyclic mono, di- and PoIyeme below the decomposition temperature of the ^^" which the reaction, although in a ^ esT ^ rTd ^{In by} Pannier manner in liquid phase at increased , ". *? ** I? ^{5 bls 225 C and,.} .., _,. ₁₅ pressures and temperatures below (B) the phosgene in about 2 x 5.5 times the liquid reaction mixture in a stoch.ometnschen excess to an upper ^ m ™ g ^ _ß . ^ Half its critical temperature hegende ™ £ η "ι_ and by-products either completely te-SsTTrerhL ^{of about} setts or at least substantially reduced. (C) the vLrhimen ingredients in the reaction - ₍ "This object is inventively gezone the reactor brings together and ^{lost 'Dau one}