Note: Descriptions are shown in the official language in which they were submitted.
1~366~1
The invention relates to a new process for the preparation of iso-
cyanic acid esters of the general formula (I),
R - (NCO)n (I)
wherein
n is one and R stands for a straight-chained or branched Cl 10 alkyl, benzyl,
cyclohexyl, phenyl, halophenyl, methylphenyl or methoxyphenyl group, or
n is two and R stands for a hexamethylene, phenylene, methylenebis(phenylene),
ethylenebis(phenylene) or methylenebis(halophenylene) group.
Isocyanic acid esters are very important products of modern chem-
ical industry. Great amounts of aromatic isocyanates, particularly toluylene-
diisocyanate and diphenylmethane diisocyanate, are utilized for the prepara-
tion of polyurethane foams, whereas aromatic monoisocyanates, particularly
the halophenylisocyanates, are widely applied as starting substances in the
pr~paration of plant protecting agents. Aliphatic monoisocyanates have a
similarly wide industrial use.
A large number of publications deal with the preparation of iso-
cyanic acid esters. The known methods can be classified essentially into two
main groups, i.e. methods utilizing phosgene as reactant and those utilizing
other reactants.
Several papers and patent specifications are concerned with methods
based on the reaction of phosgene with amines, amine salts or diarylureas. A
comprehensive review of these methods is given in the paper of Babad, H. and
Zeiler, A.G. (Chemical Reviews, 73, 75-91 /1973/).
The main difficulty in the processes for the prepara-
~r
,~ .
1~3ti~4~
tion of isocyanates by reacting an amine or an amine salt with phosgene is
that phosgene, applied as reactant, must not contain chlorine impurity,
since otherwise undesired side reactions would occur. Chlorine-free phosgene
can be prepared, however, only by liquifying gaseous phosgene and then
evaporating the liquid, which requires much energy for cooling.
Several other problems also emerge when performing these reactions
on industrial scale. Upon reacting an amine with phosgene, carbamoyl
chlorides always form in the reaction mixture, which can be converted into
the respective isocyanates at elevated temperatures only. Furthermore,
amine hydrochlorides and urea derivatives may form as well, which do not
react with phosgene at all, or even at elevated temperatures an incomplete
reaction can be initiated. At these high temperatures, however, phosgene
is imperfectly soluble in the solvents appliedl making impossible to set
the required molar ratio of the reactants.
The introduction of the necessary amount of phosgene at high
temperatures involves serious technological problems, too, since a large
volume of phosgene gas is to be fed into the reactor. It is also known
that at higher temperatures the degree of the thermal dissociation of
phosgene increases.
The methods known so far attempted to overcome these difficulties
by various means, such as by performing the reaction in many steps at
different temperatures, conducting the reaction in vapour phase, applying
various catalysts, etc. Thus e.g. according to the method disclosed in
the German Democratic Republic patent specification No. 88,315 (March 5,
1972, Magyar Tudomanyos Akademia) isocyanates are prepared in a continuous
process by reacting a primary amine or the hydrochloride thereof with
phosgene at 0-25C, in the presence of an acid amide catalyst. This
method has the disadvantage that the catalyst should be separated from the
reaction mixture at the end of the conversion, and the recovery of the
catalyst is a complicated and expensive operation.
According to the method disclosed in the Federal Republic of
1~3~
Germany patent specification No. 1,668,109 (November 2, 1972, Bayer) a
primary amine is reacted with phosgene in a mixture of an aqueous solution
of an inorganic base and a water-immiscible organic solvent, at temperatures
between -30C and +35C.
An improved variant of the above method is described in the
Federal Republic of Germany patent specification No. 1,809,173 (May 17, 1973,
Bayer). According to this method a very short contact time is applied,
i.e. the aqueous phase is contacted for a very short time with the organic
phase.
It is generally known from the literature that phosgene hydrolyzes
quickly in aqueous alkaline media (thus e.g. phosgene is removed from waste
gases by aqueous alkali), therefore the above two processes run with very
low yields, or they require very expensive automatic control means.
Several processes were disclosed for the preparation of diisocya-
nates and various polyisocyanates. The United~States patent specification
No. 3,923,732 (December 2, 1975, Olin Corp.) describes the preparation of
polyisocyanates by reacting the respective polyamines with phosgene in an
inert solvent. The disadvantage of this method is that only polyamines can
be applied as starting substances, and mixtures of polyisocyanates are
formed as products.
In the methods belonging to the second main group no phosgene is
applied for the preparation of isocyanates.
According to the method described in the German Democratic
Republic patent specification No. 1,154,090 (March 12, 1964, Bayer)
isocyanates are prepared by reacting a dialkyl urea with diphenyl carbonate.
The United States patent specification No. 3,423,448 (January
21, 1969, Sinclair ) discloses a method for the preparation of alkyl
isocyanates by reacting the respective alkylhydroxamic acids with thionyl
chloride.
According to the method described in the United States patent
specification No. 3,017,420 (January 16, 1962, Union Oil Corp.) isocyanates
1~3~
are prepared by reacting an alkali cyanate with an alkyl halide in dimethyl
formamide as solvent.
According to the method described in the United States patent
specification No. 3,076,007 (January 29, 1963, Union Carbide Corp.) ethylene
carbonate is reacted with an amine, and the resulting carbamate is converted
into the isocyanate at higher temperatures.
The United States patent specification No. 3,405,159 ~October 8,
1968, Merck ~ Co.) describes a method for the preparation of aliphatic
isocyanates by reacting an aliphatic amine with carbon monoxide at super-
atmospheric pressure, in the presence of a specially prepared palladium
phosphate catalyst.
An alternate method, utilizing carbon monoxide as reactant, is
described in the United States patent specification No. 3,523,963 (August 11,
1970, Olin Corp.). In this method carbon monoxide is reacted with an
aromatic nitro compound at superatmospheric pressure, in the presence of a
special catalyst.
According to the method disclosed in the United States patent
specification No. 3,493,596 (February 3, 1970, Universal Oil Products Co.)
isocyanates are prepared by oxidizing the respective organic isonitriles
with mercury oxide, in the presence of a metal porphyrine or a metal
phthalocyanine catalyst.
The United States patent specification No. 3,632,620 (January 4,
1972, Olin Mathleson) describes a method for the preparation of phenyl
isocyanate by reacting diphenyl carbodiimide with carbon monoxide under
superatmospheric pressure and at elevated temperature, in the presence of
a catalyst, such as palladium, rhodium, etc.
The majority of these latter methods utilizing no phosgene in the
preparation of isocyanates has the disadvantage that they require special
compounds with complicated structures as starting substances. Since such
compounds are generally not available on the market, they should be prepared
in a separate step, which requires extra investments and renders the process
- 5 -
1~3t;641
less competitive on industrial scale. Moreover, the use of phosgene cannot
be eliminated in some of the above processes, since a great number of the
starting substances can be prepared only from phosgene.
The yield of the above processes is generally unsatisfactory;
thus e.g. when carbon monoxide is applied as reactant, the isocyanate can
be prepared with a yield not exceeding 30-35%.
Now it has been found that the isocyanates of the general formula
(I) can be prepared more easily and more economically than before if the
respective amine of the general formula (II),
R - (NH2)n (II)
wherein R and n are as defined above, is reacted with a compound of the
general formula (III),
R'-0-C0-Cl (III)
wherein R' stands for chloromethyl, dichloromethyl or trichloromethyl
group, or with a mixture of such compounds, optionally in the presence of
phosgene.
Thus, this invention provides a process for the preparation of
isocyanate esters of the general formula (I), wherein n is one and R stands
for a straight-chained or branched Cl 10 alkyl, benzyl, cyclohexyl, phenyl,
halophenyl, methylphenyl or methoxyphenyl group, or n is two and R stands
for a hexamethylene, phenylene, methylenebis(phenylene), ethylenebis
(phenylene) or methylenebis( halophenylene) group, from amines of the
general formula (II), wherein R and n are as defined above, at a temperature
of -40C to l300C under a pressure of 0.2 to 200 atmospheres, Characterized
in that one or two amines of the general formula (II) are reacted with
a compound of the general formula (III), wherein R' stands for chloromethyl,
dichloromethyl or trichloromethyl group, or with a mixture thereof, fed into
the reaction mixture in liquid state.
The reaction can also be performed under atmospheric
`~ - 6 -
113~641
-- 7 --
or reduced pressure, it is preferred, however, to apply
superatmospheric pressure in the process. Depending on the
nature of the starting amine, the reaction can be performed
at temperatures of -40C to +300C. According to a preferred
method the reaction is performed in the presence of a
solvent or a solvent mixture. If desired or necessary~ 8
catalyst can be added to the mixture in order to promote
the reaction.
It is preferred to apply a chlorinated hydro¢arbon,
such as dichloromethane, chloroform, carbon tetrachloride~
chlorobenzene, etc., as solvent.
Of the catalyst applicable in the method of the in-
venbion activated carbon, metal chlorides (such as iron
chloride, zinc chloride~ etc.) on activated carbon, further_
more acid catalysts, primarily Lewis acids, are to be men-
tioned.
~he major advantage of the method according to the
invention i~ that the compounds of the general formula (III)
sre much more easy to handle than phosgene.
As known, phosgene is a gas above 8C, its volume
density is low, its solubility in the solvents apilied
decreases considerably with increasing temperature, further_
more phosgene dissociates at higher temperatures. On the
other hand, the compounds of the general formula (III) are
liquids~ thus their volume densities exceed that of phosgene
by orders oi magnitude~ their boiling points are close to
the boiling points of the solvents applied, and their solu-
bilities~ even at elevated temperatures, are more favourable
than that o~ pho~gene. The compounds of the general formula
(III) are more stable thermally than phosgene. It is a
1~3~6~:~
- 8 -
" , . .
particular ad~antage that the compounds of the general
formula (III) are good solvents for the isocyanates, thus
when applying a compound of the general formula (III) as
reactant~ isocyanate solutions of higher concentration than
the usual 17-17 w/w % can be prepared, which improves the
economy of bhe process.
Since the compounds of the general formula (III) are
liquids~ they can be ~ed easily, with a simple liquid pump,
into the reactors opeerting under superatmospheric pressure,
and their concentration can be maintained easily at the
value required in the reacbion. These tasks cannot be solved
in practice when utilizing gaseous phosgene as rsactant.
~ he compounds of the general formula (III~ have the
~urther advantage that their hydrolysis rates in alkaline
media are substantially lower than that o~ phosgene, thus
they can be applied in a broader pH rangeO
~ he non-reacted ¢hlorinated chloroformates, applied
in excess, can be decomposed thermally and/or catalytically
at the end of the reaction, thus they can be separated easily
from the crude isocyanate product.
In the known processes starting from an amine and
reacting it with phosgene under superatmospheric pressure
the reaction mixture is processed generally 90 that the mix-
ture is expanded and the individual components are separated
from each other under atmospheric pressure. ~he excess Or
phosgene and the gaseou~ hydrochloric acid are removed ~rom
the reaction mixture generally by passing an inert gas
through the solution of the crude isocyanate, and then the
solution is distilled in order to separate the isocyanate
from the solvent.
113ti6~1
_ 9 _
We have found that gaseous hydrochloric acid and
phosgene cen be removed from the reaction mixture more easily
if no pressure release and flushin~ i8 applied in the first
step of the separation, or if the first step of the separa-
tion i~ performed at a presaure even higher than that appliedin the reaction, and only the further steps of purification
(and, if required~ the recovery of the solvent) are performed
at lower pressures.
It has alsQ been found, unexpectedly, that if a mix-
ture of monochloromethyl chloroform3~e and trichloromethylchloroformate i9 reacted with an aromatic amine, diphenyl-
methane diisocyanate or polyphenyl-methylene polyi~ocyanates
are formed aa end-products. ~hese substance~ are widely
used~ es~ential material~ of the plastic industry.
The proce~s of the invention can be conducted either
batchwi~e or continuou~ly~ utilising apparatuses commonly
applied in the chemi¢al industry.
It i9 preferred to perform the reaction in a con-
tinuous way in a pre~surized tube reactor, by; feeding the
2 ~ reacbants into the reactor with a liquid pump.
Ib is also preferred bo use in the reactor a filling
with great surface area. As ~illing e.g. the activated
carbon catsly~t itself, or a support impregnated with a
cataly~t (iron chloride, zinc chloride, etc.) can be used.
~he process of the invention is elucidated in detail
by the aid of the following non-limiting ~xamples.
Exam~le 1
20 ml/min. of a 31.1 w/w % carbon tetrachloride solu-
tion of butylamine and 20.0 ml/min. of a 52 w/w % carbon
tetrachloride ~olution of dichloromethyl chloroformate are
113~6~
-- 10 --
fed simultaneously into a tube reactor operatig at 180C and
50 atm. pressure. ~he mixture leaving the reactor i9 fed
continuously into a gas/liquid separator connected to the
reactor, where 289 ml of a carbon tetrachloride solution
5 containing 24.2 w/w % of butyl isocyanate is separated from
the ga~eous substances.
After removing the solvent from the solution 94 g of
butyl isocyanate are obtained, thUs the yield is 95 %.
Exam~le 2
20.0 ml/min. of a 31.1 w/w % carbon tetrachloride
solution of butylamine and 20.0 ml/min. of a 52 w/w % carbon
tetrachloride solubion of dichloromethyl chloroformate are
fed simultaneously inbo a tube reactor operating at 130C and
5 atm. pressure. 300 ml of a liquid reaction mixture are
15 separated from the gaseou~ subsbances in the gas/liquid ~epa-
rator~ and the liquid is ied into a column filled with
activated carbon at 150C under reduced pressure; The carbon
tetrachloride solution of butyl isocyanate which leaves the
column is separated and purified in the usual manner to obtain
20 92 g (94 %) of butyl isacyanateO
20.0 ml/min. of a 31.1 w/w % carbon tetrachloride
solution of but;srlamine and 20.0 ml/min. of a 60.3 w/w % carbon
tetrachloride solution of trichloromethyl chlorofo~mate are
25 fed simultaneously into a tube reactor operating at 180C and
50 atm. pres3ure. 280 ml of a carbon tetrachloride solution
containing 24.4 w/w % of butyl isocyanate are separated from
the gaseous products in the gas/liquid separator connected to
the reactor. ~b~e sol~ent is separated from the solute in the
usual manner to obtain 93 g (94.5 %) of butyl isocyanate.
1~3~6~L~
Exam~le 4
20.0 ml/min. of a 31.1 w/w % carbon tetrachloride
solution of butylamine and 20.0 ml/min. of a 60.3 w/w % carbon
tetrachloride solution oi triohloromethyl chloroformate are
fed simulta~eously into a tube reactor operating at 120C
and 5 atm. pressure. 300 ml of a liquid reaction mixture are
separated from the gaseous products in the continuously
openating gas/liquid separator~ and the liquid mixture is fed
into a column filled with activated carbon impregnated with
zinc ¢hloride. ~his ¢olumn operates at 200C under atmospheric
pressure. ~he product i9 separated from the solution leaving
the column to obtain 94 g (95 %) of butyl isocyanate.
ExamPle S
- One proceeds as described in Example 4 with the
difference that dichloromethane is applied as solvent. After
separating the product from the solvent 91 g ~93.5 %) of
butyl isocyanate are obtainedO
ExamPle 6
One proceeds as described in Example 4 with the
difference thst chloroform is applied as solvent. After se-
parating the product from the solvent 92 g (g4 %) of butyl
isocyanate are obta~ned.
ExamPle 7
One proceeds as described in Example 4 with the
difference that chlorobenzene is applied as solvent. AfOer
separating the product from the solvent 94 g (95 %) of butyl
isocysna~e are obtained.
Exsm~le 8
One proceeds as described in Example 4 with the
difference that o-dichlorobenzene is applied as solv~ntO
113
-- 12 --
After separating the product from the solvent 94 g (95 %) of
butyl i~ocyanate are obtained.
Example 9
20.0 ml/min of a 31.1 w/w % carbon tetrachloride
solution of butylamine and 20.0 ml/min. of a 41.1 w/w % carbon
tetrachloride solution of monochloromethyl chloroformate are
fed ~imultaneously into a tube reactor operating at 150C
and 40 atm. pressure. The reaction mixture exiting the re-
actor i9 distilled under superatmospheric pressure. In this
step 310 ml of a solution containing 20.9 w/w ~0 of butyl
isocyanate are separated from the gaseous substance~O ~he
product is separated from the solvent and then purified to
obtain 91 g (92 %) of butyl isocyanate.
ExamPle 10
20.0 ml/oin. of a 31.1 w/w % carbon tetrachloride
solution of butylamine and 2000 ml/min. of a carbon tetra-
chloride solution containiDg 30.3 w/w % of phosgene and
30.3 w/w % of trichloromethyl chloroformate are fed simul-
taneously into a tube reactor operating at 180C and 50 atm.
pressure. ~he mixture which leaves the reactor is passed
through a column filled with activated carbon; thIs colum~
operates at 200C and 5 atm. pressure. ~hereafter 300 ml o~
a solution containil~g 24 w/w % of butyl isocyanate are se-
- parated from the gaseous substances in the gas/liquid se-
parator. ~he product is separated from the solvent and thon
purified to obtain 93 g (94.5 %) of butyl isocyanate.
ExamPle 11
A solution of 198 g of trichloromethyl chloroformate
in 200 ml of carbon tetrachloride, 73 g of butylamine and
200 ml of a 10 w/w % aqueous sodium hydroxide solution are
11366~L:l
-- 13 --
fed into a raund-bottomed flask of 1000 ml capacity,
equipped with a stirrer, a thermometer, a droppiDg funnel
and a reflux co~denser. The reaction mixture is stirred at
-20C for 2 hours, a~d then the aqueous phase is separated.
~he organic phase is dried, evaporated, and the vapours are
passed through a column filled with activated carbon, operat-
ing at 120& . The carbon tetraehloride solution of butyl
isocyanate i~ separated then from the gaseous substances~
the solvent is distilled off, and the residue i9 purified in
the usual manner to obtain 96.5 g (97.5 %~ o~ butyl isocyanate.
Ex~m~le 12
One proceed~ as described in ~xample 11 with the
difference that 270 ml of a 20 w/w % aqueous sodium carbonate
solution i9 substituted for the aqueous sodium hydroxide
solubion. 96 g (97 %) of butyl isocyanate are obtained.
Example 13
73 g of butylamine, 198 g of trichloromethyl chloro-
iormate and 200 ml of a 10 w/w ~ aqueous sodium hydroxide
solution are fed into a round-bottomed flask of 1000 ml
capacity~ equipped with a stirrer and a thermometer. The
reaction mixture i8 stirred at -20C for 3 hours, thereaiter
101 g of triethylamine are added, and the mixture i9 stirred
at -20C for additional 2 hours. The aqueous phase is separat-
ed and the organic phase is distilled. 96 g (96 %) of
butyl isocyanate are obtained.
Exam~le 14
198 g of trichloromethyl chloroformate, 73 g of
butylamine~ 200 ml of o-dichlorobenzene and 200 ml of a
10 w/w % aqueous sodium hydroxide solution are fed into a
round-bottomed flask of 1000 ml caE>acity, equipped with a
~l36~
-- l* --
stirrer~ A thermometer and a droppi~g funnel. ~hq reaotion
mixture i~ sbirred at -20C for 3 hours~ thereafter the
organic phase is separated and dried.
10.9 g of tetramethylammonium chloride are added to the
organic phase~ and the mixture is boiledO When the evolution
of phosgene and hydrochloric acid ceases~ bhe solvent i8
removed from the crude reaction mixture to obtain 96 g (96 %)
of butyl isocyanateO
ExamPle 15
20.0 ml/min. of a 10.23 w/w % carbon tetrachloride solu-
tion of methylamine and 20.0 ml/min. of a 6003 w/w ~ oarbon
tetrachloride solution of trichloromethyl chloroformate are
fed simultaneously into a tube reactor operating at 160C
and 50 atm. pressure. ~he product i8 separated ~rom the
resulting mixbure in the usual way and thelpuri~ied to
obtain 51.3 g (90 %) of methyl isocyanate.
ExamPle 16
20.0 ml/min. of a 39.2 w/~ ~ carbon tetrachloride solu-
tion of aniline and 20.0 ml/min. of a 60.3 w/w % carbon tetra-
¢hloride solution o~ tri¢hloromethyl chloroformate are fed
simulta~eously into a tube reactor operating at 180C and
50 atm. pressure. ~he producb is separated from the crudo
rea¢tion mixture in the usual way and then purified to ob-
tain 133.4 g (96 %) of phe4yl isocyanate.
Exam~le 17
20.0 ml/min. of a 44.2 w/w ~ carbon tetrachloride ~olu-
tion o~ m-chloroaniline and 20.0 ml/min. of a 60.3 w/w %
carbon tetrachloride solution of trichloromethyl chloroformate
are fed simultaneously into a tube reactor operating at
180C and 60 atm. pressure. 310 ml of a carbon tetrachloride
1~3~i64~1
solution containing 33.7 w/w % of m-chlorophenyl isocyanate are separated
from the gaseous substances in the gas/liquid separator. Thereafter the sol-
vent is removed from the mixture to obtain 142.3 g (93%) of m-chlorophenyl
isocyanate.
Example 18
20.0 ml/min. of a 40 w/w % carbon tetrachloride solution of cycl~o-
hexylamine and 20.0 ml/min. of a 60.3 w/w % carbon tetrachloride solution of
trichloromethyl chloroformate are fed simultaneously into a tube reactor op-
erating at 170C and 50 atm. pressure. 320 ml of a carbon tetrachloride
solution containing 33 w/w % of cyclohexyl isocyanate are separated from the
gaseous substances in the gas/liquid separator. Thereafter the solvent is
removed from the mixture to obtain 136 g (94%) of cyclohexyl isocyanate.
Example 19
20.0 ml/min. of a 42 w/w % carbon tetrachloride solution of hexa-
methylene diamine and 40.0 ml/min. of a 60.3 w/w % carbon tetrachloride solu-
tion of trichloromethyl chloroformate are fed simultaneously into a tube re-
actor operating at 140C and 50 atm. pressure. 430 ml of a carbon tetrachlor-
ide solution containing 28.5 w/w % of hexamethylene diisocyanate are separ-
ated from the gaseous by-products. The solvent is removed in the usual way
to obtain 156 g (94%) of hexamethylene diisocyanate.
Example 20
20.0 ml/min. of a 45 w/w % carbon tetrachloride solution of tol-
uylene diamine (containing 65 w/w % of 2,4-isomer and 35 w/w % of 2,6-isomer)
and 40.0 ml/min. of a 60.3 w/w % carbon tetrachloride solution of trichloro-
methyl chloroformate are fed simultaneously into a tube reactor
~1366~1
-- 16 _
operating at 190C and 50 atm. pressureO 440 ml of a solution
containing 29 w/w % of toluylene diisocyanate are separated
from the gaseous by-products in the gas/liquid separator.
The solvent is removed in the usual way to obtain 165 g (95 ~)
of toluylene diisocyanate.
Example 21
10.0 ml/min. (7.3 g/min.) of butylamine snd 30.0
ml/min. of trichloromethyl chloroformate are fed simultaneously
into a tube reactor operating at 150C and 5 atm. pressure.
The mixture which leaves the reactor is fed into a column
filled with activated carbon, operating at 180C and 5 atm.
pressure. Thereafter the gaseous substances are removed in
the gas/liguid separator, and the crude product i~ distilled.
91 g ~92 %) of butyl isocyanate are obtained.
Example 22
20.0 ml/min. of a 40 w/w % carbon tetrachloride
solution of 4,4'-diphenyl~ethane diamine and 20.0 ml/minO o~
a 60.3 w/w % carbon tetrachloride solution of trichloromethyl
chloroformate are fed simultaneously into a tube reactor
?0 operating at 130C and 50 atm. pressureO 320 ml of a solution
containing 16.6 w/w % of 4~4~-diphenylmethane diisocyanate
are separated from the gaseous by-products. ~he solvent is
removed from the solution in the usual way and the product
is purified to obtain 70 g (74 %) of the diisocyanate.
ExamPle 23
20.0 ml/min. o~ a 39.16 w/w % carbon tetrachloride
solution of aniline and 20.0 ml/min. of a 41.4 w/w ~ carbon
tetrachloride solution o~ monochloromethyl chloroformate are
fed ~imultaneously into a tube reactor operating ab 130C
and 50 atm. pressure. ~he gaseous by-products are separated,`
113Çi~
-- 17 _
and the resulting solution which contains phenyl isocyanate
and 4,4'-diph~nylmethane diisocyanate is distilledO 12 g
(9 %) of phenyl isocyanate and 67 g (89 %) of 4,4'-diphenyl-
methane diisocyanate are obtained.
Example 24
20.0 ml/min. of a 39016 w/w % carbon tetrachloride
solution of aniline and 20.0 ml/min. of a carbon tetrachlor-
ide solution containing 20.~2 w/w % of monochloromethyl
chloroformate and 30.15 w/w % of trichloromethyl chloroformate
are fed simultaneously into a tube reactor operating at
130C and 50 atm. pressure. ~he gaseous by-products are re-
moved in the gas/liquid separator, and then the solvent i8
removed from the resulting carbon tetrachloride solution of
phenyl isocyanate and 4,4'-diphenylmethane diisocyanate.
The residue is purified in the usual way to obtain 14 g
(10 %) of phenyl isocyanate and 64.7 g (85 %) of 4,4'-di-
phenylmethane diisocyanate.
ExamPle 25
- 20.0 ml/minO of a carbon tetrachloride solution
contai~ing 12.1 w/w % of butylamine and 36 w/w % of aniline
and 22.0 ml/min. o$ a solution containing 69 w/w % of tri-
chloromethyl chloroformate snd 29 w/w % of monochloromethyl
chloroformate are fed simultaneously into a tube reactor
operating at 170C and 50 atm. pressure. ~he gaseous by-
products are removed in the gas/liquid separator to obtain
8 solution which contains butyl isocyanate, phenyl isocyanate
and 4~4'-diphenylmethane diisocyanate.
~he solvent is evaporated, and the isocyanates
are separated from each other by distillation. 34 g (94 ~)
of butyl isocyanate~ 9 g (10 %) of phenyl isocyanate and
1~36~
_ 18 -
92 G (86 %) of 4,4'-diphenylmethane diisoc~anate are obtained.
ExamPle 26
,
20.0 ml/min. of a 31.1 w/w % carbon tetrachloride solu-
tion of butylamine and 20.0 ml/min. of a 60.6 w/w % carbon
tetrachloride solution of trichloromethyl chloroformate are
fed simultaneously into a tube reactor operating at 150C
and 5 atm. pressureO ~he mixture which leaves the reactor is
passed through a column filled with activated carbon, operat-
ing a~ 180C and 5 atmO pressure. Therea~ter the mixture i~
fed into a gas/liquid separator operating at 80C and 5 atm.
pressure, and 73 g of pure, dry, gaseous hydrochloric acid
are lead off from the separabor in every 10 minutes. ~he
liquid phase is expanded and distilled at atmospheric pressure,
and the phosgene-containing carbon tetrachloride solution i8
recirculated into the column filled with activated carbon.
The product is purified to obtain 93 g (94 %3 of butyl iso-
¢yanate.
Exam~le 27
One proceeds as described in Example 26 with the
difference bhat o-dichlorobenzene is applied as solventO
92 g ~93 ~) of butyl isocyanste are obtained.
Example 28
One proceeds as described in Example 26 with the
difference that the reactants are fed directly into the column
filled with activated carbon, operating at 180C and 5 atm.
pressure. 92.5 g (93.5 %) of butyl isocyanate are obtained.
Example 29
One proceeds ss described in ~xample 26 with the
difference that 20.0 ml/min. of a 31 w/w % carbon tetrachlor-
ide ~olution o~ butylamine~ 2000 ml/min. o~ a 30.3 w/w %
113~i6~1
-- 19 -- .
carbon tetrachloride solution of trichloromethyl chloroformate
and 20.0 ml/min. of a 30.4 w/w % carbon tetrachloride solu-
tion of phosgene are fed simultaneously into the tube reactor
operating at 150C and 5 atm. pressure. After one hour the
feeding oi the phosgene solution is cut off~ and the carbon
tetrachloride solution of phosgene, obtained in the distilla-
tion at atmospheric pressure, is recirculated into the tube
reactor. 94 g (95 %) of butyl i~ocyanate are obtained.
Example 30
20.0 ml/min. o~ a 10.23 w/w % carbon tetrachloride
solution of methylamine and 20.0 ml/minO of a 60.3 w/w %
carbon tetrachloride solution of trichloromethyl chloroformate
are fed into a tube reaotor operating at 150C and 5 atm.
pressure. ~he mixture which leaves the reactor i~ fed into
8 reactor filled with activated carbon, operating at 180C
and 5 atm. pressure. ~hereafter the mixture is fed into a
8? arator operabing at 80C and 5 atm. pressure~ and 22 g
(6.6 litres) of dry~ gsseous hydrochloric acid are led ofi
from the separator. ~he mixture is then expanded and distilled
at atmospheric pressure. The phosgene-containing carbon
tetrachloride solution is recirculated into the reactor
filled with activated carbon~ and the product is purified.
82.55 g o~ a product consisting of 70 w/w ~ of methylcarbamoyl
chloride and 30 w/w % oi methyl isocyanate are obtained~
thus the conversion is 97.6 %.
Example 31
20.0 ml/min. of a 43 w/w % carbon tetrachloride
solution oi hexylamine and 20~0 ml/min. of a 60.3 w/w %
carbon tetrachloride solution of trichloromethyl chloroformate
are fed simultaneously into a tube reactor operabing at
il3
- 20 -
180C and 50 atm. preasure; 300 ml of 9 mixture ~of n-hexyl
isocyanate and carbon tetrachloride sre obtained after
separating the liquid from the gaseous substances in the
llquid/gas separator. ~his mixture is distilled to obtain
101.9 g (91 %) of n-hexyl isocyanate.
ExamPle 32
20.0 ml/min. Or a 23.4 w/w % carbon tetrachloride
so~ution of iaopropylamine and 20.0 ml/min. of a 60.3 w/w %
car~Qn tetrachloride solution of trichloromethyl chloroformate
are fed aimultaneously into a tube rea¢tor filled with granulsr
activ~ted csrbon, operating at 220C and 50 atm. pressure.
The mix~ure which leaves the reactor is fed continuously
into a gss/liquid separator, where 2~0 ml o~ a carbon tetra-
chloride solution containing isopropyl isocyanabe are ob-
tained. ~his ~olution is di~tilled to obtain 68.4 g (94 %)
of isopropyl i~ocyanate.
Exam~le 3~ `
~ solution of 44.6 g of 4-chloro-4'-amino-biphenyl
in 200 ml o~ dichloromethane and 200 ml of a 20 w/w % di-
chloromethane solution Or trichloromethyl chloroformate are
red continuously~ within 10 minutes into a tube reactor
operating at 120C and 5 atm. pressure. ~he mixture which
lea~es the reactor is sub~ected to separation, and the 350 ~1
Or the ~olution obtained i~ distilled. 23 g (90 %) of
4-chloro-biphenyl-4'-isocyanate are obtaincd.
Exam~le 34
20.0 ml/min. of a 37.8 w/w ~ chlorobenzene solution
of p-toluidine and 20.0 ml/min. of a 41 w/w % chlorobenzeDe
solution Or trichloromethyl chloroformate are fed continuou~ly
into a tube reactor filled with activated carbon~ operati~g
1~36~
at 180C. The mixture which leaves the reactor is fed into a gas/liquid sep-
arator, and the separated 360 ml of liquid are distilled. 98.6 g (93%) of
4-methylphenyl isocyanate are obtained.
Example 35
20.0 ml/min. of a 46 w/w % o-dichlorobenzene solution of 4-ethyl-
aniline and 20.0 ml/min. of a 60.3 w/w % o-dichlorobenzene solution of tri-
chloromethyl chloroformate are fed simultaneously and continuously into a
tube reactor operating at 150C and 5 atm. pressure. The mixture which
leaves the reactor is expanded and fed into a gas/liquid separator to obtain
380 ml of a solution, which is then distilled. 102 g (88%) of 4-ethylphenyl
isocyanate are obtained.
Example 36
20.0 ml/min. of a 22.9 w/w % carbon tetrachloride solution of p-
anisidine and 20.0 ml/min. of a 60 w/w % carbon tetrachloride solution of
trichloromethyl chloroformate are fed simultaneously and continuously into
a reactor operating at 180C and 50 atm. pressure. The mixture which leaves
the reactor is separated, and the solution is distilled to obtain 102.6 g
~86%) of 4-methoxyphenyl isocyanate.
Example 37
20.0 ml/min. of a 43.2 w/w % chlorobenzene solution of m-phenylene
diamine and 30.0 ml/min. of a 65 w/w % o-dichlorobenzene solution of tri-
chloromethyl chloroformate are fed simultaneously and continuously into a
tube reac~or operating at 150C and 5 atm. pressure. 460 ml of a liquid
are separated in the gas/liquid separator, and then the liquid is distilled
to obtain 106 g (91.6 %) of m-phenylene diiso-
1~l3~69~
cyanate.
Example 38
400 ml of o-dichlorobenzene and 130 ml of trichloromethyl chloro-
formate are introduced into a round-bottomed flask of 2500 ml capacity,
equipped with a stirrer, a reflux condenser and a thermometer. Thereafter
1000 ml of a 21 w/w % o-dichlorobenzene solution of 4,4'-diamino-dibenzyl
are added to the mixture with stirring, whereupon the temperature of the re-
action mixture raises above 100C. The resulting mixture is stirred at
130C for 4 hours and then processed by fractional distillation. 201 g
(94.8%) of 4,4'-dibenzyl diisocyanate are obtained.
Example 39
400 ml of o-dichlorobenzene and 100 ml of trichloromethyl chloro-
formate are introduced into a round-bottomed flask of 2500 ml capacity,
equipped with a stirrer, a reflux condenser and a thermometer. 1000 ml of
a 27 w/w % o-dichlorobenzene solution of methylenebis-~o-chloroaniline) are
added to the mixture with stirring, whereupon the temperature of the reac-
tion mixture raises above 100C. At the end of the addition the mixture is
stirred at 130 C for 4 hours and then distilled. 230 g (90%) of 3,3'-di-
chloro-diphenylmethane-4,4'-diisocyanate are obtained.
Example 40
210 g of ignited sodium carbonate and 100 ml of o-dichlorobenzene
are introduced into a round-bottomed flask of 2500 ml capacity, equipped
with a stirrer and a thermometer. 100 ml of a 30 w/w % o-dichlorobenzene
solution of trichloromethyl chloroformate are added to the mixture under
cont1nuous stirring and intense cooling (at -40C) within
- 22 -
,........................ '
3~
- 23 -
one hour. The,reaction mixture i~ stirred then for one furthar
hour at 0-20C, thereafter the mixture is filtered and the
filtrate i9 distilled to obtain 26 g (92 %) of methyl i80-
cyanate.
ExamPle 41
One proceeds as described in Example 4 with the
difference that act$vated oarbon impregnated with 0.5 w/w %
of ferric chloride i8 applied as catsly~tO 91 g (92 %) Or
butyl isocyanate are obtained.
10 ' ExamPle 42
On0 proceeds as described in Example 4 wibh the
diYference that sctivated carbon impregnated with 0.5 w/w %
of aluminium chloride is applied as cabalyst. 89 g ~(90 %) of'
butyl isocysns'te are obtai~ed.
ExamPle 43
One proceeds as described in Example 15 wibh the
difference that the reactor is operated at 250a under a
- pressure of 5 atmospheres. 53 g (93 %) of methyl isocyanate
are obtained.
ExamPle 44
20.0 ml/min. of a 31.1 w/w % o-dichlorobenzene 801u-
tion of butylamine and 20.0 ml/min. of a 60 w/w % solutien
of trichloromethyl chloroformste are fed simultaneously and
continuously, through a pre-heater~ into a tube reacbor
filled with activated carbon, operati~g at 300& . ~he mixture
which leaves the reactor is passed through a separator~ and
the separated liquid is distilled. 83 g (85 %~ of butyl iso-
cyanate are obtained.
Example 45
20.0 ml/min. of a 36.8 w/w ~ o-dichlorobenzene solu-
L
tion of benzylamine and 20.0 ml/min. of a 30 w/w % solution of trichloro-
methyl chloroformate are fed simultaneously and continuously, by means of a
high-pressure liquid pump, into a tube reactor operating at 180C and 200
atm. pressure. The mixture which leaves the reactor is expanded, passed
through a gas/liquid separator, and the separated liquid is distilled. 92 g
(86%) of benzyl isocyanate are obtained.
Example 46
20.0 ml/min. of a 33.6 w/w % o-dichlorobenzene solution of aniline
and 20.0 ml/min. of a 60.5 w/w % o-dichlorobenzene solution of trichloro-
methyl chloroformate are fed simultaneously and continuously into a reactoroperating at 120C and 0.2 atm. pressure. The product is removed continu-
ously from the reactor by distillation, and the crude product is purified by
fractional distillation. 120 g ~86%) of phenyl isocyanate are obtained.
_ 24 -
