Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
57~
~o-2379
LeA 21,183
--1--
PROCESS F3R THE P~EP~R~TION OF UREr~HANES
BACKGROUND OF TT~E IN~ENTION
. _ . _
The present invention relates to a process for the
preparation of urethanes (carbamic acid esters or carba-
5 mates) by the reac-tion of ureas with organic hydroxyl
compounds and carbon monoxide in the presence of molecu-
lar oxygen and of a catalyst system. ~he catalyst sys-
tem comprises at least one noble metal or at least one
noble metal compound and a quinoid compound or a compound
10 capable of being converted into quinoid compounds.
Organlc isocyanates are generally prepared on a
large scale by reactlon of the corresponding amines with
phosgene. Due to the high chlorine requirement and conse-
quent high energy costs for the preparation of phosgene,
lS a method for commercially producing organic isocyanates
that would not require the use of phosgene has long been
sought.
One approach taken in searching for a method for
phosgene free preparation of low molecular weight ure-
20 thanes is thermal cleavage. Numerous methods for thepreparation of urethanes which are capable of such
cleavaqe have been proposed. German Offenlegungsschriften
No. 2,908,250, No. 2,908,251 and No. 2,910,132 and U.S.
Patents 4,260,781 and 4,266,070 r for example, describe
25 the preparation of urethanes from primary amines, carbon
monoxide and organic hydroxyl compounds in the presence
of oxidizing agents. In U.S. Patent 4,266,070, the oxidl-
zing agents are quinones used in the absence of oxygen
and the catalysts used are carbonyl compounds. Such
30 carbonyl compounds are difficult to handle.
Another method for obtaining urethanes capable of
undergoing cleavage to form isocyanates is by reaction
Mo-2379
o~ N,N'-disubstituted ureas with compounds containing
hydroxyl groups and carbon monoxide in the presence of
suitable oxidizing agents. According to German Offenle-
gungsschrift No. 2,908,252, oxidizin~ agents useful in
this reaction are nitro comoounds or molecular oxygen,
alone or in combination wlth ni~ro compounds. This
reaction described in ~erman Offenlegungsschrift 2,908,252
proceeds in arcordance with the following general reaction
scheme (1):
o
10 Equation (1) 2 Rl-NH-C~NH-R + R -NO2 ~ 5 R OH + 3 CO
O O O
.. .. ..
2 Rl-N~-C-OR4 ~ 2 R2-NH-c-oR4 ~ R3-NH-c-oR ~ 2 H~O
wherein Rl, R , R3 and R4 represent alkyl or aryl
groups~
15 When molecular oxygen is used as the oxidizing agent, the
reaction takes place in accordance with the following
equation (Z):
o
Equation (2) R -NH-C-NH-R + 2 R -OH + CO ~ 1/2 2
,
Rl-NH-C-oR4 + R2-NH-C-oR4 + H20
From these equations it is readily seen that one disad-
vantage of usiny nitro compounds as oxidizing agents is
the formation of a mixture of urethanes which must be
25 separated (e.g. by distil]ation). ~litro compounds are
therefore useful oxidizing agents only when substituen-ts
Rl, R2 ~ R3 are identical because only then will the
formation of a mixture of urethanes be avoided. It is
rare, however, that both, the appropriate urea compound
30 and the nitro compound which corresponds to this urea
compond are simultaneously available for the reaction
on a large commercial scale.
Mo-2379
--3--
Aside from the nature of the oxidlzin~ agent, another
disadvantage of the process disclosed in German Offenle--
gungsschrift ~lo. 2,980,25~ lies in the ract that rela~
tively large quantities of inorganic or organic halides
5 must be used as cocatalysts. These halides are hiqhlv
corrosive. They also impair the process when carried out
on a commercial scale because they are largely insoluble
in the reaction environment.
SUMMA:RY OF THE INVE~TION
It is an ohject of the present invention to provide
;an imprcved p-~ocess for the production of urethanes.
It is another object of the present invention to
provide a process for the production of urethanes in
which very little, if any, insoluble and corrosive catalyst
15 is required.
These and other objects which will ~e apparent to
those skilled in the art are accompllshed by reacting a
urea having at least one hydrogen atom bonded to a urea
nitrogen atom, an organic compound containing at least
20 one hydroxyl group and carbon mono~ide in the presence of
molecular oxy~en and a catalyst system. The catalyst
system is made up of (i) a noble metal and/or a comPound
of a noble metal and (ii) at least one quinoid compound
having an oxidizing effect on the reactants resp.on oxi-
dizable catalyst components and/or atleast one compound capable of being converted into an
oxidizing quinoid compound under reaction conditions. The
catalyst system may also include tertiarv amines and/or
magnesium compounds and/or compounds of elements from
groups III A to V A and I }3 to VIII B of the Periodic
System of Elements. The reaction is generally carried out
at a temperature of from 100 to 300C and a pressure
from 5 to 500 bar.
Mo-2379
S'7~
DETAILED DESCRIPTION OF THE INVEN~ION
~ he present invention relates ~o a process for the
preparation of urethanes by reactinq an unsubstituted or
substituted urea containin~ at least one hydrogen atom
5 attached to a urea ni-trogen atom with an organic compound
containing at least one hydroxyl group and carbon monoxi.de
in the presence of molecular oxygen and a catalyst system.
The catalyst syste~ is made up of (i) at least one noble
metal and~or a compound of a noble metal of the Eighth
10 Sub-group of the Periodic System of Elements, and (ii)
at least one quinoid compound having an oxidizing action
and/or at least one compound capable of being converted
into an oxidizing quinoid compound under the reaction
conditions~
Suitable ureas are any organic compounds having at
least one structural unit of the formula
H - N - CO - N -
in which the free valencies are saturated by hydrogen
a-toms or by organic substituents whieh are preferably
20 inert under the reaction conditions. Examples oE such
ureas include urea itself or substituted ureas corre
sponding to the formulae (I), (II), (III):
H O X H X3 H O
~ ~ 5
N-C-N N---C- ,N N C-N X
25 ~1 x2 ~ X4 ~ Xl
(I) (II) (III)
in which Xl, X2, and X3 (which may be the same or differ-
30 ent) represent hydroqen or any organie group which is
inert under the reaction conditions, such as aliphatic
hydrocarbon groups havinq from 1 to 4 earbon atoms or
Mo-2379
--5--
aromatic hydrocar~on groups ha~ing from 6 to 10 carbon
atoms. The di~alent substituent X4 and the two nitrogen
atoms of the urea group together form an a-t least 5-
membered heterocyclic ring having at least one (prefer-
5 ably 2 to 6) carbon atoms arranged within the ring andoptionally hetero atoms additionally present in the ring.
The divalent substituent X5 forms a heterocyclic ring
(preferably 5- or 6- membered) with one of the nitrogen
atoms of the urea group as rlng member, and in addition
10 to at least two carbon atoms axranged within the ring i-t
may ha~e other hetero atoms arranged within the ring.
All oE the substituents Xl through X may be substi-
tuted or interrupted by difunctional groups. Sui-ta~le
substituents or difunctional groups include halogen atoms,
15 keto groups, sulfoxide groups, sulfone g~oups, ether groups,
carboxylic acld esters and nitro groups. Other urea grouPs
may also be functional groups, i.e.one molecule of the
starting urea may contain more than one urea group. If
these additional urea groups are of the type depicted in
20 general formulae I, II, or III, they are also converted
into urethane groups in accordance with the present inven-
tion. If the urea starting material contains one or more
amino groups, these amino groups are also converted into
urethane groups under the reaction conditions described
25 in German Offenlegungsschrift No. 3,0~,982. The molecu-
lar weights of suitable urea starting materials generally
range from 60 to 600.
The urea compound used as the starting material is
preferably a urea correspondlng to formula (I) and/or (II)
30 which is sy~metrically substituted. It is particularly
preferred to use N,N'-disubstituted ureas of formula ~I)
in which the two su~stituents are identical groups,
particularly Cl C4-al~yl groups or a phenyl group. Unsub-
stituted urea is also suitable.
Mo~2379
~2~'7~
--6--
Specific examp].es of suitable urea s-tarting materials
include: urea, N-tert.-butylurea, N,N dimethvlurea,
N,N'-dimethylurea, N-phenyl-N,N'-dimethyl-urea, tris
(2-chlorophenyl)-urea, 6-nitxo-1-naphthylurea, 3~amino-
5 4-methyl-phenylurea, 2-imidazolidinone, 1,4-butylene-bis-
urea, N,N-pentamethylene-urea, N,N'-bis-(2-furyl)-urea,
l-oxa-6,8-diazacyclododecanone-7, and N,N'-2,2'-bipheny-
lene urea. Preferred urea star-ting materials include:
urea, N,N'-dimethylurea, N,N'-dicyclohexyl-urea, N,N'-
10 diphenylurea, N,N'~bis-(p-tolyl)-urea, ~,N'-bis-(2-amino-
phenyl)-urea, N,N'-bis-(4-nitrophenyl)-urea and N,N'-
bis-(4-chlorophenyl)-urea. N,N'-dimethylurea and ~,N'-
diphenylurea are particularly preferred.
The hydroxyl group-containing starting material may
15 be any organic compound containing hydroxyl groups, in
particular a monohydric or higher hydric alcohol or a
monohydric or higher hydrlc phenol. Compounds which are
saturated monohydric aliphatic alcohols in the molecular
weight range of from 32 to 300 containing primary hydroxyl
20 groups or monovalent phenols with a maximum molecular
weight of 300 are particularly preferred.
The alcohol starting material may be any straight
chained or branched monohydric or polyhydric alkanol,
alkenol, cycloalkanol, cycloalkenol or aralkyl alcohol.
25 These alcohols may contain inert substituents. Suitable
inert substituents include halogen atoms, sulfoxide groups,
sulfone groups, nitro groups, carbonyl groups and carbox~
ylic acid ester groups. ~lcohols having ether bridges are
also suitable. Specific examples of suitable alcohols are:
30 Methanol, ethanol, n-propanol, isopropanol, n-butanol, n-
pentanol, n-hexanol, cyclohexanol, benzyl alcohol, chloro-
ethanol, ethylene glycol, diethylene glycol, propylene
glycol, dipropylene glycol, glycerol, hexanetriol and
trimethylolpropane. Monohydric aliphatic alcohols having
35 from 1 to 6 carbon atoms are particularly preferred.
Mo-2379
--7--
Suitable phenols include: phenol, 2-isopropox~-
phenol, 7-hydroxy-2, 2-dimethyl-2,3-dihydrobenzofuran, the
isomeric chlorophenols, cresols, ethylphenols, propyl-
phenols, bu~ylphenols or higher alkylphenols, pyrocate-
5 chol, 4,4' dihydroxy-diphenylmethane, bisphenol-A, anthra~
nol, phenanthrol, pyroyallol, phloroglucinol or 8-quino~
linol. Preferred mononuclear phenols having up to 12
carbon atoms and dinuclear phenols having up to 18 carbon
atoms are preerable.
In carrying out the process accoxding to the inven-
tion, the hydroxyl group-containing starting material is
generally used in a quantity such that from 2 to 200,
preferably from 2 to 100 mol of hydxoxyl groups are pre-
sent for each mol of urea groups of the urea star-ting
15 material present in the reaction mixture. Since relatively
inexpensive hydroxyl compounds which are liquid under the
reaction conditions are generally used, they are preferably
used in excess within the ranges mentioned. The excess
hydroxyl compound then serves as the reaction medium
(solvent).
Carbon monoxide is also used as a reactant in the
process of the present invention. This starting material
is generally used in a quantity such that from 0.5 to 30
mol of carbon ~onoxide is present for each mol of urea
25 group in the urea starting material. If primary amlno
groups are also to be converted into urethane groups
(according to German Offenlegungsschrift No. 3,046,982),
at least one additional mol of carbon monoxide must be
provided for each mol of amino group to be reacted.
The oxidizing agent used in the present invention
may be molecular oxygen in the pure form or in the form
of a mixture with an inert gas such as nitrogen, carbon
dioxide, or preferably aix. In the presence of molecular
oxygen, oxycarbonylation takes place (i.e., the reaction
35 proceeds as shown in equation (2)) or, in the case of
Mo-2379
~a~s~7~
symmetrically su~stltuted urea starting materials, the
reaction may proceed in the manner shown in equation (3):
H ~ H
Equation (3) R -N-C-N-Rl + 2 R4-oH ~ CO + l2 2
H O
2 R -N-C-oR4 + H2O
It ls readily seen from this equatlon, that 1/2 mol of
carbon monoxide and l/4 mol of molecular oxygen are re-
quired ror each urethane group formed in tha described
10 reaction. Molecular oxygen is generally used in a
quantity ranging from approximately stoichiometric to
approximately 5 times the stoichiometric amount (based
on the urea groups to be reacted). If the hydroxyl group
containing starting material used is sensltive to ox~di-
15 zing agen-ts, it is often advisable to use the oxy~en
oxidizing agent in less than the equivalen~ quantity,
(based on the urea groups of the urea starting material).
It may therefore be appropriate to use oxygen in a quan-
tity which is only 60 to 100% of the equivalent quantity
20 when hydroxyl group-containing starting materials which
are sensitive to oxidation are used. In such cases where
less than a stoichiometric quantity of oxygen is used, the
loss in yield due to use of such a lesser amount is much
smaller than the loss due to formation of unwanted
25 oxidation productsO Moreover, when subequivalent quan-
tities of oxygen are used,unreacted starting materlals
may be easily recovered and used again whereas alcohol
destroyed by unwanted oxidation reactions cannot be
recovered.
The oxidizing agent employed in the present invention
may in principle be any inorganic, largely ionic compound
which has an oxidizing action, particularly salt-type
compounds of metals in higher valency stages. Organic
Mo-2379
.
oxidizing agents, in particular quinones, are also suitable
in principle. All of these oxidizing agents are, however,
less suitable than oxygen. Organic nitro compounds are
no-t suitable oxidizing agents in the process of the
5present in-~ention.
The process of the present invention must be carried
out in the presence of a catalyst sys-tem. This catalyst
system is made up of (i) at least one noble metal and/or
at least one compound of a noble metal of the Eighth
lOSub-group of ~he Periodic System of Elements and (ii)
at least one quinoid compound having an oxidizing action
and/or at least one compound capable of being convertecl
into an oxidizing quinoid compound under the reaction
conditions.
Catalyst component (i) may be either a noble metal
of the Eighth Sub-group of the Periodic Sys~em or a som-
pound of such a metal. It is particularly advantageous to
use a noble metal compound which is soluble in the reac-
tion mixture, such as a chloride, bromide, iodide,
20chlorine complex, bromine complex~ iodine complex, ace-
tate, acetyl acetonates or other soluble noble metal
compounds. Preferred noble metals are palladium, ruthen-
ium and rhodium. Palladium is particularly preferred,
especially in the form of soluble palladium chloride or
25 palladium acetate.
Preferred concentrations for catalyst co~ponent
(i) are generally from 3 to 1000 ppm (preferably from 5
to 100 ppm), calculated as noble metal and based on the
whole reaction mixture, including any solvent used.
30 Although higher concentrations o noble metal could be
used, such concentrations are uneconomical due to
possible loss of noble metal, particularly since they do
not increase the yield o urethane.
Catalyst component (ii) is a quinoid compound
Mo-2379
q ~
--10--
havlng an oxidi~ing action and/or a compound capable of
being con~erte.d into an oxidizing quinoid compound un~er
the reaction conditions. By "quinoid co~pounds" are ~eant
compounds such as those described in "The Chemistry o~ the
5 Quinoid Compounds" Parts I and II (~ondon, Wiley 1974,
Publishers: Patai) frequently manufactured e.g. as dyes or
dye precursors. ~ny quinoid compound is in principle
suitable for use as catalyst component (ii) i~ it is
capable of oxldizing the noble metal present in ca-talyst
10 component (i) from the ~ero oxidation state to a positive
oxidation state under the reaetion conditions o~ the pre-
sent invention. Preferred quinoid compounds are those
which are eapable of converting palladium (a particularly
pre~erred metal) from zero oxidation state to its ~2 oxi-
15 dation state.
Instead of such quinoid eompounds, compounds capableo~ being converted into sueh quinoid compounds may be
used as catalyst component (ii). That is, eompounds
whieh are converted into sueh a quinoid eompound by an
20 oxidation reaction (brought about by the oxidizing agent
~sed in the process of the present invention), or by
solvolysis or an elimination reaction may be used as
eatalyst component (ii).
Suitable quinoid catalyst components (ii) include:
25 ortho- and para-quinones; multinuclear quinones; and
heterocyclic quinones in a substituted or unsubs-titu-ted
form; imino, N-al~yl- or ~-arylimino deri~atives of these
quinones,e.~. o-tetrachlorobenzoquinone/ p-tetrachloro-
benzoquinone, 2,5~dichloro-3,6-dihydroxy-p-benzoquinone,
30 2-chlorophenyl-1,4-benzoquinone, 2,3-dichloronaphthoqui-
none, anthraquinone, l-chloroanthraquinone, 7-chlo~ro-4-
hydroxy 1,10 anthraquinone, 1-nitroanthraquinone~2-
carboxylic acid, 1,5-dichloroanthra~uinone, 1,8-dichloro-
anthraquinone, 2,6-dichloroanthraquinone, 1,4-dihydroxy-
35 anthraquinone, acenaphthenedione, 5,7-dichloro-lH-indol-
Mo-2379
5'7~3
--11--
2,3-dlone, indi~o or 1,4-dihydro-2,3-quinoxalinedione.
Polymeric quinoid compounds such as those described
by H.G. Cassidy and R.~. Kun in "Oxida~ion-P~eductio~ Poly-
mers" (Polymer Reviews Vol~ 11, Interscience Publ. New
5 York 1965) are also suitable as catalyst component (li).
Preferred quinoid compounds are those which are
substituted with one or more electron-accepting substituent
such as chlorine, bromine, cyano-, nitro-, carboxylic acid
or sulfonic acid groups because such substituents increase
10 the capacity fQr oxidation. Quinoid comPounds containing
N-aryl or N-alkyl substituents are also particularly
effective. Examples of particularly preferred quinoid
compounds include: o-tetrachlorobenzoquinone, p-tetra-
chlorobenzoquinone, 2,5-dichloro-3,6-dihydroxy-p-benzo-
15 quinone, 2,3-dichloro-1,4-naphthoquinone, 7-chloro-4-
hydroxy-1,10-anthraquinone, 1,5~dichloroanthraquinone,
1,8-dichloroanthraquinone and 2-(N-phenylamino)-3-chloro-
1,4-naphthoquinone.
Quinoid precursors which are suitable as catalyst
20 component (ii) include ketals of the above-described
corresponding quinoid catalyst components and hydrogenated
forms of these quinoid components (particularly the corre-
sponding hydroquinones). Aromatic amines and polynuclear
aromatic compounds substituted e.g. by sulfonic acid, car-
25 boxylic acid, nitro or cyano ~roups or such materialswhich already contain a keto group in the ring system are
also converted into quinoid catalyst components (ii)
under the oxidizing reaction conditions.
Suitable precursors of quinoid catalyst components
30 (ii) include the hydroquinones and ketals of the above-
mentioned quinones, 5-amino-2~(phenylamino)-benzene sul-
fonic acid, 5-amino-2-[(4-chlorophenyl)amino]-benzene
sulfonic acid, 4,4'-diamino-(1,1' biphenyl)-3,3'-disul-
fonic acid, 2-aminobenzene sulfonic acld and benzanthrone-
Mo-2379
-~c~s~
3-carbonitrile.
Catalyst component (ii) is ~enerally added to the
reaction system at a concentration of from 0.1 wt % to 5
wt %, preferably concentrations of from 0.5 to 3 wt ~,
5 ~based on the -total quantity of reaction mixture including
any solvents used). The catalyst system used in the pres-
ent invention may also contain certain metal compounds and/
or tertiary amines as addi~ional components.
These optional catalyst components include magnesium
10 compounds (particularly inorganic or organic salts of
magnesium) and compounds of elements of the Third to Fifth
Main Group and/or First to ~ighth Sub-group of the
Periodic System of Elements which are capable of under-
going a redox reaction under the reaction conditions.
15 Such catalyst components are preferably compounds of metals
of atomic numbers 12, 22 ko 23, 41, 47, 58 and 92 which
compounds are at least partially soluble in the reaction
mixture. Particularly p~eferred optional catalyst com-
ponents are the acetates, nitrates and chlorides of chro-
20 mium, manganese, cobalt, copper, cerium and magnesium~optionally in the form o-f hydrates or amine complexes of
these metal salts. Oxides of the metals enumerated above
may also be used as catalyst components in combination
with activating chlorides, e.g. ammonium chlorides. If
25 these catalyst components are used, they are generally
added in 1 to 10 times the molar quantity (based on cata~
lyst component (i)). The catalyst component may be
used in a quantity of up to 0.1 wt ~ (based on the total
weight of the reaction mixture including any solvents
30 used).
When present in the catalyst system, -tertiary
amine catalyst components act as complex formers for the
oxidized form of catalyst component (i) and for any
optional catalyst component of the type described above
Mo-2379
5'~
-13-
if -the complex forming action of the starting compounds
present in the reaction mixture is not sufficient for
these purposes. Any tertiary amines, i.e. amines which
contain aliphatically, cycloali.phatically, araliphaticalïy
5 and/or aromatically bound tertiary amino groups or
tertiary amino groups which form part of a heterocyclic
ring are appropriate to the present invention. Examples
of suitable tertiary amines include triethylamine,
diisopropylmethylamine, cyclohexyldiethylamine, triphenyl~
10 amine, N,N-diethyl-aniline, N-phenyl-piperidine, pyri-
dine, quinoline, 1,4-diaza-(2,2,2)-bicyclooctane and
pyrimidine. Triethylamine, N,N-diethyl-aniline and
pyridine are preferred -tertiary amine catalyst components.
The above mentioned tertiary amines may also be used as
15 metal salt complexes of catalyst component (i) and some of
the optio~ally used catalyst components. I catalyst
component (i) and/or an optional catalyst component is
used in an oxidic form, it is generally advantageous to
actlvate it by using the tertiary amines in the form of
20 hydrochlorides. The op-tional tertiary amine catalyst
component is generally used in a quantity of up to 10
wt %, preferably from 0.2 to 3 wt % (based on the total
reaction mixture including any solvents used) bu~ larger
quantities may be employed.
The process of the present invention may be carried
out in the presence or absence of solvents. The hydroxyl
group-containing starting material which is preferably
used in excess may act as solvent but inert solvents may
also be used. Such inert solvents may constitute up to
30 80 wt % of the whole reaction mixture. The quantity of
solvent used, whether it be excess hydroxyl compound or
an inert solvent, must be calculated so that the heat of
the exothermic reaction of urethane formation can be
dissipated without greatly increasing the temperature.
Mo-2379
5~
-14-
The process of the present invention is therefore generally
carried out uslng a concentration of urea startiny
material of from 5 to 30 wt %, preferably from 5 to 20
wt ~ (based on the whole reactlon mixture including the
5 solvent).
Suitable solvents are those which are inert ~ith
respect to the reactants and the catalyst system such as
aromatic, cycloaliphatic and aliphatic hydrocarbons,
optionally su~stituted with halogens. Specific examples
10 of such solvents are benzene, toluene, xylene, chloro-
benzene, dichlorobenzene, trichloroberzene, chloronaph-
thalene, cyclohexane, methylcyclohexane, chlorocyclohexane,
methylene chlori~e, carbon tetrachloride, tetrachloro
ethane, trichlorotrifluoroethane and similar compounds
15 as well as tertiary amines.
The reaction temperature in -the process of the
present invention is generally from 100 to about 300C,
preferably from 100 to 250C and most preferably from 140
to 220C. The pressure which ~ould be adjusted to ensure
20 that a liquid phase is always present, is ~enerally from
5 to 500 bar, preferably from 30 to 300 bar. The reaction
time required for quantitative conversion varies from a
few minutes to several hours, depending upon the starting
materials employed.
The process of the present invention may be carried
out batchwise or continuously. It is advantageous to
select a solvent in which the produc-t of the process
(urethane) is easily soluble. After release of the pres-
sure from the reaction medium and cooling to a temperature
30 in the region of 50C to 80C, catalyst components
(i), (ii) and optional metal catalysts (including in some
cases the complex form of tertiary amine catalysts) pre-
cipitate substantially completely in many solvents.
In some cases, it is advantageous to concen-trate the reac-
35 tion mixture by evaporation -to 70-50% of the ori~Jinal
Mo-2379
~2~
-15-
volume in order to precipi-tate the catalyst. The catalyst
mixture may then be separated from the solution containing
urethane by filtration or centrifuging. If precipita-
tion of the catalyst components is not possible, they mav
5 be ~ecovered as r~sidue from a process such as dlstillation.
The catalyst components separated by one of the
methods mentioned above can in most cases be returned to
the process and reused although they are in a chernically
changed form. ~f -the catalyst component (ii) contained
10 halogen, the catalyst mixtures obtained after the reaction
will have a lower halogen content. These catalysts may
then contain chemically bound nitrogen as a result of
reactions with the urea starting material.
Depending upon the nature o the starting materials
15 and on the reaction conditions primary amines may be li-
berated by side reactions from the urea starting material
or from the urethane obtained as produc-t of the process.
These primary amines together with excess hydroxyl grou~-
containing material may generally be removed from the
20 product mixture by distillation and returned to the process
after the addition of fresh starting rnateri.als. According
to German Offenlegungsschrift No. 3,046,982, when amines
formed by such side reactions are reacted with the same
catalyst systems and under the same reaction conditions,
25 the urethanes which are obtained from the urea starting
material by the process of the present invention are
obtalned. Any losses in yield due to side reactions are
thereore very slight if these by-products are returned
to the reaction environment.
The urethanes obtained as products of the ~rocess
of the present invention are generally the least volatile
constituents of the product mixtures aside from the cata-
lyst components (i), (ii) and optional metal catalysts.
After removal of the more volati]e constituents of the
Mo-2379
3~'7
- 1 6 -
product solution, the product urethane may be purified
or separated f~om the catalyst components either by further
distillation (which should in most cases be carried out
under vacuum), by extraction or crystallization. Any
5 tertiary amine catalyst used in the pro~ess is generally
distilled off with the more volatile constituents or with
solvent and may be returned to the reaction environment
unless it is bound by complex foxmation with a metal
catalyst componen-t.
The products of the process of the present invention
(urethanes) are suitable or use as pesticides or as
intermediate products for the preparation of pesticides.
They are also suitable as starting materials for the pre-
paration of the isocyanates on which they are based.
15 These isocyanates are prepared by thermal cleavage of the
urethane in accordance with techniques known to those in
the art.
The process of the present invention is illustrated
by the following Examples but the invention is not limited
20 to the conditions given in these Examples.
EXAMPLES
Most of the experiments described below were
carrled out in an enamelled 1.3 l steel autoclave to
exclude any catalytic effect from the metal of the wall~
25 Some experiments were carried out in a 0.7 1 refined steel
autoclave. The urethane yields, (calcuiated on the basls
of equation (2)) are based on the amount of urea used un-
less otherwise indicated and are given in terms of mol ~.
The amine yields, in particular the aniline yields (when
~0 diphenylurea, which is particularly preferred, was used as
the urea starting material) which are the result of side
reactions, were calculated on the basis of the following,
theoretical equation (4):
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. ~
~ t3~7
Equation (4)
H ~ H
~ N-C-N ~ 2 ~ ~ NH2 + C2
5 ~his equation serves only as a basis for the calculation
and in no way represents the actual mode of forma-tion of
the amine or aniline.
Exam~les 1 to
The procedure in each of these examples was as
lO follo~s:
531.9 g of a mixture having the composition described
below were introduced into an enamelled 1.3 l refined
steel autoclave. The mixture was made up of 94 ppm of
a noble metal chloride (see ~able 1 for the specific com-
15 pound), 188 ppm of copper (II) acetate monohydra-te,
81.4 w-t ~ of ethanol, 16.9 wt ~ of N,N'~diphenylurea (DPH)
and 1.6 wt % of p-tetrachlorobenzoquinone. 100 bar of
carbon monoxide and 25 bar of air were then forced into
the autoclave at room temperature. The reaction mixture
20 was heated to 180C with stirring and left to react at
this temperature for one hour.
After the reaction mixture had cooled to room tem-
perature, the pressure was released and a second, similar
reaction phase ~as carried out with a fresh mix-ture of
25 carbon monoxide and air. A total of about 1.3 oxidation
equivalents (based on DPH) was introduced in the form cf
atmospheric oxygen. The resul-ts shown in Table l were
obtained from gas chromatographic analysis. Example 6
is a comparison example carried out without catalyst
30 component (i) of the pxesent invention.
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57~
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Table l
Example Catalyst Yield ln mol %
No. component Phenyl
_ _ _ _(i) urethaneAniline
l PdC12 77.7 10.0
2 RuC13 72.2 12.4
3 RhCl3 63.~ 12.6
4 IrCl3 56.5 17.2
PtC12 54~9 44.0
6 -- 48.2 47.0
.
Example 7 (Comparison example)
The procedure was the same as that used in Examples
1 to 5 with the exception tha~ the catalyst system of the
lS present invention was omitted. 523 g of a mixture of
82.8 wt % of ethanol and 17.2 wt % of DPH were used.
49.8 mol % of phenylurethane and 48.2 mol % of aniline
were obtained.
Examples 8 to 16
__ _
The procedure used ~as that descxibed in Example 1.
532 g of a mixture of the following composition: 81.~
wt % of ethanol, 16.9 wt % of DPH, 38 ppm of palladium
acetate, 188 ppm of copper (II) acetate monohydrate and
1~6 wt % of a compound corresponding to catalyst compo-
25 nent (ii) were introduced into the autoclave and reacted.In Examples ~ to ll, catalyst component (ii) was a qui-
noid compound; in Examples 12 to 16 the catalyst compo-
nent was the precursor of a quinoid compound. The resul-ts
oE these reactions are given in Table 2.
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Unable to recognize this page.
5~q~
-2~-
EXample 17 (Comparison example)
The procedure was the same as that used in Example
8 with the exception that the copper (II) acetate mono-
hydrate and qulnoid were omitted. 40.3 mol % of phenyl
5 urethane and 10.6 mol % of aniline were produced.
Example 18
The procedure was the same as was used in Example
9 bu-t without the addition of copper (II) acetate mono-
hydrate. 64.8 mol % of phenyl urethane and 18.8 mol % of
lO aniline were produced. Compared with Example 9, this
Example shows that although the copper catalyst component
is not essential to this inven-ti.on, i-t may improve the
yield.
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Example 19 (Comparison Example)
The procedure was the same as that used in Example
8 except that the mlxture was reacted under 125 bar of
nitrogen for l hour at each stage rather under a carbon
monoxide/air mixture. 40 mol % of phenylurethane and
52 mol % of aniline were o~tained.
Example 20
286.5 g of a mixture of the following composition
were introduced into a 0.7 1 refined steel autoclave:
37.6 wt % of ethanol, 43.8 wt %6 of o-dichIorobenzene,
16.9 wt % of DPH, 1.6 wt % of 2,3-dichloro-1,4-naphtho-
quinone, l90 ppm of copper (II) acetate monohydrate
and 38 ppm of palladium ace~ate. A gas mixture of 100
bar of C~ and 25 bar of air was forced into the autoclave
(i.e. about 0.86 oxidation equivalents ba~ed on DPH were
introduced in the form of atmospheric oxygen). The
reaction mixture was reacted for one hour at 180~C with
stirring. 73 mol % of phenylurethane and 24 mol % of
aniline were obtained~ The phenylurethane yield based
on oxygen was about 85 mol -6.
Example 21
286.S g of a mixture of 81.5 wt % of methanol,
16.9 wt 6 of DPH, 1.6 wt % of 2,3-dichloro-1,4-naph~
thoquinone, 190 ppm of copper (II) acetate monohvdrate
and 38 ppm of palladium acetate were reacted in the same
manner as in Example 20. 66 mol g6 of O-methyl-N-phenyl-
urethane and 18 mol % of aniline were obtained. The
urethane ~ield based on oxygen was about 100 mol 6.
Example 22
263.7 g of a mixture having the following composi-
tlon were introduced into a 0.7 1 refined steel autoclave:
88.5 wt % of phenol, 8.8 wt g6 of N,N'-dimethylurea
(DMH), 2~7 wt 6 of p-tetrachlorobenzoquinone, 180 ppm of
copper acetate monohydrate and 18 ppm of palladium
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~13;~5"7~
-22--
acetate. The mixture was reacted for two ona-hour inter-
vals at 180~C with a gas mixture of 100 bar oE carbon
monoxide and 25 bar of air wlth stirring. 33.5 mol % of
N methyl-O-phenylurethane was obtained.
S ExamPle 23 (Comparison Example)
This Example shows that in comparison with Example
22, a reaction carried out in the absence of air as
oxidizing agent, although possible, results in a sub-
stantially lower urethane yield. The procedure was the
same as -~hat in Example 22 but 125 bar of nitrogen were
forced inio the autoclave instead of the CO/air mixture.
8 mol % of urethane was obtained.
Example 24
284 g of a mixture having the following composltion
were introduced into a 0.7 1 refined steel autoclaveo
73.8 wt % of o-dlchlorobenzene, 8.2 wt % of DMH, 16.4 wt %
of 2-propanol, 1.6 wt % of p~tetrachlorobenzoquinone,
164 ppm of copper (II) acetate mono~ydrate and 41 ppm of
palladium acetate. A gas mixture of 100 bar of CO and
25 har of air was forced into the autoclave (i.e. about
0.65 oxidation equivalents based on DMH was introduced
in the form of atmospheric oxygen). 26 mol % of N-
methyl-carbamic acid isopro~yl ester was obtained. The
yield based on oxygen was about 40 mol %.
Example 25
220 g of a mixture having the following composition
were introduced into a 0.7 1 refined steel autoclave~
91.1 wt % of ethanol, 6.8 wt ~ of urea, 2.1 wt % of
2,3-dichloro-1,4-naphthoquinone, 250 ppm of copper (II)
acetate monohydrate and 50 ppm of palladium acetate.
The reaction was carried out in the manner described in
Example 1. 42 mol % of ethylcarbamate was obtained.
Example 26
220 g of a mixture having the following composi-
tion were introduced into a 0.7 1 refined steel autoclave:
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87.3 wt % of ethanol, 10.7 wt ~ of N,N,N'-trimethylurea,
2.0 wt % of 2,3-dlchloro-1,4-naph-thoquinone, 240 ppm of
copper (II) acetate monohydrate and 48 ppm of palladium
acetate. The reaction was carried out in the manner
indicated in Example 1. 30 mol ~ of N-methyl-carbamic
acid ethyl ester and 34 mol. % of N,N-dimethyl-carbamic
acid ethyl ester were obtained. Approxima-tely 60
mol % of the N,N,N'-trimethylurea remained unreacted.
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