Note: Descriptions are shown in the official language in which they were submitted.
The conventional method ~or the manufacture of carbamic
acid esters of relatively high molecular weight is to synthesize
~ - chlorocarbonic acid esters from the corresponding relatively
- hig~ molecular weight alcohols by phosgenation followed by
aminolysis of these esters.
This expensive method of manufacture can be replaced by
. R reaction of lower aliphatic carbamic acid esters with rela~
tively high molecular weight alcohols. In U.S. Patent
Specification 2,934,549, S. Beinfest et al. describe a process
o~ this type, and propose the use of aluminum alcoholat~es as
- catalysts.
- It has now been found? surprisingly, that low molecular
weight alkyl titanates are substantially more active catalysts
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than the- aluminum alcoholates for esterification reactions of
this type. When using alkyl titanates it generally proves
possible, under otherwise identical conditions, to shorten the
reaction times to half, and in many cases to one-tenth, of the
time required when using aluminum alcoholates.
Usin~ the new method according to the invention, it is
also not necessary to employ an excess of lower aliphatic car-
bamic acid esters, as is described in Examples 1 and 5 - 7 of
U.S. Patent Specification 2,934,559. Thus, in the trans-
esterification of ethyl carbamate with 1,5-pentanediol, des-
cribed in Example 6 of U.S. Patent Specification 2,g~4,559, it
proved possible~ when using the method according to the inven
tion, to increase the yield from 68.5% to 91% in spite of
reducing the amount of carbamic acid ester from 1.~ molesto one
mole equivalent. The reaction time was reduced from 4 hours
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to 1~ hours.
In the case of the trans-esterification with relatively
high molecular weight polyglycol ethers, -the method according to
U.S. Patent Specification 2,934,559, using aluminum alcoholate as
the catalyst, proves even more disadvantageous since, for example,
when using a polyglycol of molecu:Lar weight 1,000 the reaction time
must be increased by more than 20 hours in order to achieve 70% con-
verslon.
Accordingly, the invention relates to a process for the
manufacture of a carbamic acid ester of a relatively high boiling
alcohol selected from alkanols and alkanediols, their oxalkylation
products, and the oxalkylation products of trihydric or tetrahydric
aliphatic alcohols, said relatively high boiling alcohol having a
boiling point of above 190C, which comprises transesterifying one
mole of C2-C5-alkyl carbamic acid ester with one mole of said
relatively high boiling alcohol in the presence of a Cl-C4-alkyl
titanate as a catalyst and distilling off from the reaction mixture
the lower alcohol resulting from the carbamic acid ester.
By relatively high-boiling alcohols there are essentially
to be understood alkanols or alkanediols, their oxyalkylation pro-
ducts and the oxyalkylation products of trihydric or tetrahydric
aliphatic alcohols which at normal conditions have a boiling point
above 190 and above of the low molecular weight carbamic acid esters
employed.
The reaction temperature, in the reaction according to
the invention of low molecular weight carbamic acid esters with
relatively high-boiling alcohols is in general set to from
about 80 to 210C at pressures of from about 25 to 760 mm Hg.
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i The reaction temperature depends on the boiling point of the
; alcohol liberated and on the structure of the relatively high-
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boiling alcohol. Whilst, for example, polyethylene glycols
of molecular weigh-t up to about 300 undergo trans-esterification
even at atmospheric pressure and temperatures of from about 160
to about 180C, it is necessary, when employing relatively high
molecular weight polyethylene glycols, to use reduced pressure
of, for example, 100 to 300 mm Hg. Lower pressures are alsv
o~ advantage if the reaction can be carried out at low reaction
temperatures. In the trans-esterification reaction according
to Ihe invention, the reaction temperatures and pressures to be
used are limited by the boiling point of the low molecular
weight carbamic acid esters employed. When using carbamic
acid ethyl ester, for eæample, these limits are 180C at a
pressure of 760 mm Hg or, for example, 140C at a pressure of
240 mm Hg. Preferably3 the reaction is carried out at
~emperatures of about 140 - 160 and pressures of 100 to 240
mm Hg, provided the reactants permit this.
Relatively high boiling alcohols which can be used for
the trans-esterification reaction according to the invention
are, above all, aliphati~, saturated monohydric or polyhydric
alcohols or ether-alcohols which have a boiling point, under
the reaction conditions, above that of the low molecular weight
carbamic acid ester employed. The boiling point of the
relatively high-boiling alcohols should be above 190C &nd
preferably above 210C. Relatively high-boiling aîcohols
which may be used in particular are alcohols, above all so-
called fatty alcohols with about 8 to 20 carbon atoms~ for
example cctyl alcohol, dodecyl alcohol 7 stea~yl alcohol or c~tjl
alcohol, and their reaction products with about 1 to 5C moles
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of ethylene oxide~ or of ethylene oxide and propylene oxide,
~- for example pentaethoxy-dodecanol and tetrapropoxy-heptaethoxy-
- octadecanol, as well as alkanediols with 2 to 5 carbon atoms in
~ . .
the reaction products of these alkanediols or of trihydric and
.,
tetrahydric alcohols, such as pentaerythritol or glycerol, with
about l to 200 moles of ethylene oxide, or of ethylene oxide and
propylene oxide. Preferred examples of such relatively high-
boiling alcohols which may be mentioned are ethylene glycol~
diethylene glycol, polyethylene glycols wi-1;h molecular weights
of 150 to about lO,000, and also propylene glycol, butylene
glycol,pentane-1,5-glycol,..
In view of the possible use of the reaction products
according to the invention as plasticizers for cellulose art
icles, polyethylene glycols with molecular weights of from
about 200 to 5,000 are preIerentially employed for the trans-
esterification reaction.
Low molecular weight carbamic acid esters which can be
.
used are the alkyl carbamates containing 2 to 5 carbon atoms,
such as carbamic acid methyl ester, ethyl ester, propyl ester,
isopropyl ester and butyl ester, or mixtures of the said car-
bamates.
Suitable alkyl titanates are above all those with 1 to
carbon atoms. For example, methyl titanate, ethyl titan-
ate or isopropyl titanate can be employed. m e concentra-
tion o~ the alkyl titanates to be used in the trans-esterification
process according to the invention can va~y within wide limits5
i-t should be optimized in each particular case. Preferably,
O.OOl to about O.l mole of the alkyl tit~na-te is employed per
mole of the relatively high-boiling alcohol.
- To carry out the trans-esteri~cation according to the
invention, the two components, namely the carb~mic acid ester
and the relatively high-boiling alcohol are advantageously
employed in about the equivalent ratio. The reaction time
for the trans-esterification according to the invention depends
above all on the nature of the relatively high-boiling alcohol
used and on the reaction conditions employed. In most cases,
~ a reaction time of about 1 - 2 hours suffices; however, in
order to achie~e as far-reaching a trans-ecterification as poss-
ible, this will in general be followed by a post-reaction
period of about 2 - 4 hours.
- The carbamic acid esters of relatively high-boiling
alcohols obtained according to the invention can be used as
plasticizers for fibers and films of natural and regenerated
cellulose and as agents for rendering synthetic fibers hydro-
philic. Reaction of the carbamic acid esters according to
~he invention ~ith formaldehyde gives products which possess
groups which are reactive towards cellulose and can be used as
reactive plasticizers for cellulose fibers and films.
Example 1:
200 g (1 mole) of a polyethylene glycol of molecular
weight 200, together with 178 g (2 moles) of carbamic acid
ethyl ester and 2 g of ethyl titanate are heated to 160 - 180C
in a four-necked flask equipped with a distillation a-t-tachmen~
thermometer, stirrer and heater. Hereupon, 82 g of ethanol
(1.78 moles) distil off in the course of 2 hours. Poly-
ethylene glycol(200) bis-carbamic acid ester is obtained ~n a
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yield of 258 g (89~' of theory).
Example 2
500 g (0.5 mole) of a polyethylene glycol of molecularweight 1,000 together with 89 g (1 mole) of carbamic acid ethyl
ester and 2 g of isopropyl titanate are heated under a pressure
of 200 mm Hg to 140 - 150C whilst stirring and the ethanol
~ormed is collected in a cold trap. A~t;er as little as 90
minutes' reaction time, 41.5 g (90% of theory)'of the alcohol
ha~e distilled over.'In the course of a further 40 minutes'period
of heating, a further 45 g of ethanol are obtained. 530 g
of polyethylene glycol(l,OOQ) bis-carbamic acid ester are
obtained, corresponding to a conversion of 97.7%.
Example 3
135 g (0.5 mole) of octadecyl alcohol together with 51.5
g (0.5 mole) of carbamic acid isopropyl ester and 1 g of iso-
propyl titanate are heated under a pressure of 300 ~m Hg to
150 - 155C, whilst stirring. Hereupon, 29 g of isopropanol
distil off in the course of 75 minutes. Carbamic acid octa-
, -
decyl ester is obtained in a yield of 136 g (99% of theory) and
with a melting point of 93 - 94C (after recrystallization from
ethanol).
Exam~le 4
31 g (0.5 mole) of ethylene glycol and 89 g (1 mole) of
carbamic acid ethyl ester are heated together with 2 g of iso-
propyl titanate. Using an external temperature of 180 -
195C, 41 g of ethanol hereupon distil off in the couuse o~ 6
hours t~Lrough a descending condenser.
After'recrystallization from eth~-lol) 55 g o~ ethylene
,
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glycol bis-carbamic acid ester are obtained, corresponding to
a yield of 74%.
Example 5
1,000 g (0.2 mole) of a polyether-alcohol of molecular
weight 5,000, obtained by reacting 1 mole of pentaerythri-tol
with 20 moles of propylene oxide and 80 moles of ethylene oxide,
are heaied together with 35.6 g (0.4 mole) of carbamic acid
ethyl ester and 2 g of isopropyl titanate to 150C under a pres-
sure of 300 mm Hg. m e 18.2 g of eth~nol which hereupon
distil off in the course of 6 hours and are collected in a cold
trap correspond to a conversion of 98% based on the carbamic
acid ethyl ester employed.
Example 6
` 500 g (0.5 mole) of a polyethylene glycol cf molecular
weight 1,000, 117 g (1.0 mole) of carbamic acid butyl ester and
1.3 g (0.05 mole) of ethyl titanate are heated under a pressure
140 mm Hg to 150 - 160C, whilst stirring- Hereupon~ 65g of~uta-
ncl distil off, in the courseof3hours,anda~ collected, ~ a adescending
condenser, in an ice-coo'ed receiver. This corresponds to
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a conversion of 88~.
Polyethylene glycol(l,000) bis-carbamic acid ester is
` obtained in a yield of 548 g.
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338 g (0.4 mole) of a reaction product of 1 mole of
dodecyl alcohol with 15 moles of ethylene oxide are heated
together with 47 g (0.4 mole) of butylurethane ~nd 2 g o~ iso-
propyl titanate ~nder a pressure of 140 mm Hg to 150 160C,
whilst stirring. After 2 hours, the pressure is reduced to
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60 mm Hg. Hereupon, 31.7 g of alcohol distil over,
in which 26 g (82% of theory) of butanol were found by gas
chromatography. m is corresponds to a conversion of ~8%.
- The yield of carbamic acid ester of ethoxylated dodecyl
alcohol is 320 g (90% of theory).
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