Process for producing cyclic ureas

A process for producing a cyclic urea is provided. The process comprises reacting a diamine expressed by the formula (II) EQU R-HN-R'-NH-R (II) wherein R represents hydrogen atom or a lower alkyl group and R' represent dimethylene group, a lower alkyl group-substituted dimethylene group, trimethylene group, a lower alkyl group-substituted trimethylene group, tetramethylene group, a lower alkyl group-substituted tetramethylene group, but a case where R represents hydrogen atom and R' represent dimethylene group, a case where R represents hydrogen atom and R' represents a lower alkyl group-substituted dimethylene group and a case where R represent methyl group and R' represents dimethylene group are excluded, with phosgene in the presence of a dehydrochlorinating agent. In the process, the diamine is first converted to its hydrochloride, followed by reacting the hydrochloride with phosgene in water solvent while maintaining a pH of the reaction liquid in the range of 5.0 to 8.0 by said dehydrochlorinating agent to obtain a cyclic urea expressed by the formula (I) ##STR1## wherein R and R' are each as defined above.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a process for producing a cyclic urea by reacting 
a diamine with phosgene, which cyclic urea is expressed by the formula (I) 
##STR2## 
wherein R represents hydrogen atom or a lower alkyl group and R' 
represents dimethylene group, a lower alkyl group-substituted dimethylene 
group, trimethylene group, a lower alkyl group-substituted trimethylene 
group, tetramethylene group or a lower alkyl group-substituted 
tetramethylene group, but a case where R represents hydrogen atom and R' 
represents dimethylene group, a case where R represents hydrogen atom and 
R' represents a lower alkyl group-substituted dimethylene group and a case 
where R represents methyl group and R' represents dimethylene group are 
excluded. 
Cyclic ureas of the formula (I) such as 2-imidazolidinones, tetrahydro-2(b 
1H )-pyrimidines, hexahydro-2H-1,3-diazepin-2-ones, etc. are useful 
substances as non-protonic polar solvents and as an intermediate for 
pharmaceuticals, pesticides, etc. In particular, they are superior 
solvents for high-molecular compounds such as polyamides, polyvinyl 
chloride, polyvinyl alcohol, polystyrene, polyurethanes, phenol resins, 
etc. and also form complexes with many inorganic salts to dissolve therein 
and further are used as solvents for many organic reactions. 
2. Description of the Prior Art 
A process for obtaining 2-imidazolidinones by reacting diamines 
corresponding to 2-imidazolidinones of the above formula with phosgene has 
not yet been known, but a process for obtaining 
1,3-dimethyl-2-imidazolidinone which is a similar compound to the above 
cyclic ureas of the formula (I), with a yield of 13% by reacting 
N,N'-dimethyl-1,2-ethanediamine with phosgene in toluene solvent has been 
known (J. Chem. Soc., 1947, page 315). However, the present inventors 
carried out the reaction of N,N'-dimethyl-1,2-propanediamine with phosgene 
in toluene solvent according to the above process, but the yield of 
1,3,4-trimethyl-2-imidazolidinone belonging to the cyclic ureas of the 
formula (I) was less than 20%. 
Further, as the process for producing the above 
tetrahydro-2(1H)-pyrimidinones, a process of reacting N,N'-dimethyl-1, 
3-propanediamine with phosgene in toluene (J. Chem. Soc. page 315, 1947) 
and a process of reacting N,N'-bis (trimethylsilyl)-1,3-propanediamine 
with phosgene, followed by hydrolyzing the resulting 
tetrahydro-1,3-bis(trimethylsilyl)- 2(1H)-pyrimidinone (Chem. Ber. Vol. 
93, page 2813, 1960) have been known. 
However, as to the process of reacting N,N'-diamino-1,3propanediamine with 
phosgene in toluene, the present inventors followed the process, but the 
yield was less than 20%. Still further, according to the process of 
reacting N,N'-bis (trimethylsilyl)-1,3-propanediamine with phosgene, while 
the yield was 75%, it is necessary to obtain a silylating material so that 
the process is also not a process which can be carried out by directly 
reacting phosgene and also it is necessary to use an expensive silylating 
agent. 
Further, as a process for producing the above-mentioned 
hexahydro-2H-1,3-diazepin-2-ones, a process of obtaining 
hexahydro-2H-1,3-diazepin-2-ones by directly reacting 1,4-butanediamines 
with phosgene has not yet been known, but as an indirect process, a 
process of reacting N,N'-bis(trimethylsilyl)-1,4-butanediamine with 
phosgene and then hydrolyzing the resulting 
hexahydro-1,3-bis(trimethylsilyl)-2H-1,3-diazepin-2-one (Chem. Ber. Vol. 
93, page 2813, 1960) has been known. 
However, according to this process, it is necessary to obtain the silylated 
compound of 1,4-butanediamine in advance using an expensive silylating 
agent, and also the yield of the reaction of the diamine with phosgene 
(such a reaction with phosgene will be hereinafter referred to as 
"phosgenation reaction") is as low as 60% ; hence the process has not been 
commercially satisfactory. 
SUMMARY OF THE INVENTION 
The object of the present invention is to provide a process for producing a 
cyclic urea of the formula (I) by converting diamine to its hydrochloride, 
and thereafter reacting the hydrochloride with phosgene, with a high yield 
and at a commercially low cost. 
The present inventors have made extensive research on a commercial 
production process of a cyclic urea of the formula (I) from a diamine and 
phosgene, and as a result have found the following facts: 
It is known that usually processes using phosgene are carried out under a 
condition of absence of water to the utmost and also phosgene is easily 
hydrolyzed in an alkaline aqueous solution; thus the reaction of diamines 
with phosgene has been expected to require a large excess of phosgene. 
Surprisingly enough, however, it has been found that in the reaction of 
the above-mentioned diamines of the present invention with phosgene, 1.0 
to 1.5 times the theoretical quantity of phosgene is sufficient. Further, 
it has also been found that the yield of the objective product cyclic urea 
of the formula (I) is greatly improved in the presence of water solvent 
and a dehydrochlorinating agent as compared with those of the prior art. 
Still further it has been found that in the above case, when the pH at the 
time of the reaction is kept within a definite range i.e. 3.0 to 10.0 by 
the dehydrochlorinating agent in the presence of water, the yield is 
further improved. 
The present invention resides in a process for producing a cyclic urea 
which comprises converting a diamine expressed by the formula (II) 
EQU R-HN-R'-NH-R (II) 
wherein R and R' are each as defined above into its hydrochloride, followed 
by reacting the hydrochloride with phosgene in the presence of water and a 
dehydrochlorinating agent to obtain a cyclic urea expressed by the formula 
(I) 
##STR3## 
wherein R and R' are each as defined above. 
DESCRIPTION OF THE PREFERRED EMBODIMENT 
According to the present invention, since the reaction is carried out in a 
state where water is substantially present, that is, in water solvent, the 
hydrochloride of the diamine of the formula (II) successively formed by 
hydrochloric acid byproduced by the phosgenation reaction is not deposited 
at the time of the reaction, but it is dissolved in water so that the 
reaction can be carried out in a uniform state. Thus, it is possible to 
very easily control the pH at the time of the reaction. 
Further, since a dehydrochlorinating agent is simultaneously used at the 
time of the reaction, the dehydrochlorinating agent not only functions 
effectively for catching byproduced hydrochloric acid, but also when the 
reaction is carried out while the pH is kept in the range of 3.0 to 10.0, 
the objective product is obtained with a high yield which is unexpected 
from the prior art. The reason is that when a monocarbamyl chloride 
initially formed by the phosgenation reaction of the diamines is 
intermolecularly cyclized, it has become possible to inhibit formation of 
byproducts formed by the intermolecular reaction and byproducts of 
dicarbamyl chlorides of diamines, etc. through pH control. 
In the present invention, examples of the lower alkyl groups as defined for 
R and R' in the formula (II) are methyl, ethyl, propyl, butyl, etc. In the 
diamines of the formula (II) excluding, in the definitions thereof, a case 
wherein R represents hydrogen atom and R' represents dimethylene group, a 
case wherein R represents hydrogen atom and R' represents a lower alkyl 
group-substituted dimethylene group and a case wherein R represents methyl 
group and R' represents dimethylene group, concrete examples of the 
diamines are N,N'-diethylethylenediamine, N,N'-dipropyl-ethylenediamine, 
N,N'-dibutylethylenediamine, N,N'-dimethyl-1,2-propanediamine, N,N'-2- 
trimethyl-2, 3-butanediamine, N,N'-diethyl-1,2-propanediamine, etc. and 
these amines may be easily obtained from the corresponding alkyhalides and 
the corresponding alkylamines. 
In the present invention, using these diamines as a raw material, the 
corresponding 2-imidazolidinones expressed by the formula (I) such as 
1,3-diethyl-2-imidazolidinone, 1,3-dipropyl-imidazolidinones, 
1,3-dibutyl-2-imidazolidinone, 1,3,4-trimethyl-2-imidazolidinone, 
1,3,4,4,5-pentamethyl-2-imidazolidinone, 
1,3-diethyl-4-methyl-2-imidazolidinone, etc. are obtained. 
Further, concrete examples of diamines of the formula (II) wherein R 
represents a hydrogen atom and R' represents trimethylene group or a lower 
alkyl group-substituted trimethylene group are 1,3-propanediamine, 
N,N'-dimethyl-1,3-propanediamine, N,N'-diethyl-1,3-propanediamine, 
N,N'-dipropyl-1,3-propanediamine, 
N,N'-bis(1-methylethyl)-1,3-propanediamine, 
N,N'-dibutyl-1,3-propanediamine, 2,2-dimethyl-1,3-propanediamine, 
N,N',2,2-tetramethyl-1,3-propanediamine, etc. These 1,3-propanediamines 
may be easily obtained by reaction of 1,3-dihalopropanes with ammonia or 
the corresponding monoalkylamines or the like reaction. 
In the present invention, using these amines as a raw material, it is 
possible to obtain the corresponding cyclic ureas of the formula (I) such 
as tetrahydro-2(1H)-pyrimidinone, 
tetrahydro-1,3-dimethyl-2(1H)-pyrimidinone, 1,3-diethyl- 
tetrahydro-2(1H)-pyrimidinone, tetrahydro-1,3-dipropyl-2(1H)-pyrimidinone, 
tetrahydro-1,3-bis(1-methylethyl)-2(1H)-pyrimidinone, 
1,3-dibutyl-tetrahydro-2(1H)-pyrimidinone, 
tetrahydro-5,5-dimethyl-2(1H)-pyrimidinone, 
tetrahydro-1,3,5,5-tetramethyl-2(1H)-pyrimidinone, etc. 
Further, concrete examples of diamines of the formula (II) wherein R 
represents hydrogen atom or a lower alkyl group and R' represents 
tetramethylene group or a lower alkyl group-substituted tetramethylene 
group are 1,4-butanediamine, N,N'-dimethyl-1,4-butanediamine, 
N,N'-diethyl-1,4-butanediamine, N,N'-dipropyl-1,4-butanediamine, 
N,N'-dibutyl-1,4-butanediamine, 2,5-dimethyl-2,5-hexanediamine, etc. These 
1,4-butanediamines may be easily obtained by reaction of 1,4-dihalobutanes 
and ammonia or the corresponding monoalkylamines or the like reaction. 
In the present invention, using these diamines as a raw material, it is 
possible to obtain the corresponding cyclic ureas expressed by the formula 
(I) such as hexahydro-2H-1,3-diazepin-2-one, 
hexahydro-1,3-dimethyl-2H-1,3-diazepin-2-one, 
1,3-diethylhexahydro-2H-1,3-diazepin-2-one, 
hexahydro-1,3-dipropyl-2H-1,3-diazepin-2-one, 
hexahydro-1,3-dibutyl-2H-1,3-diazepin-2-one, 
hexahydro-4,4,7,7-tetramethyl-2H-1,3-diazepin-2-one, etc. 
In the present invention, the diamines are first converted into their 
hydrochlorides followed by reacting them with phosgene. In the process of 
carrying out the reaction while keeping the pH within a range of 3.0-10.0, 
it is advantageous to feed the diamines in the form of their 
hydrochlorides from the beginning of the reaction. 
When the diamines are used in the form of their hydrochlorides, if 
hydrochloric acid is used in an equivalent quantity and the resulting 
diamine dihydrochlorides are fed, the pH at the beginning of the reaction 
is about 3 and even if the resulting dihydrochlorides are phosgenated, the 
reaction rate is very low. 
Thus, when the amines are used in the form of their hydrochlorides, it is 
preferred to react these in the form close to monohydrochlorides obtained 
by reacting hydrochloric acid in a quantity less than equivalent, and if 
the dihydrochlorides are fed from the beginning, it is preferred to carry 
out dehydrochlorination in advance with the dehydrochlorinating agent to 
make the pH 3 or more, followed by phosgenation reaction. 
Further, if the diamines are fed as they are and reacted, the pH at the 
beginning of the reaction becomes 11 or more; thus it is preferred to add 
hydrochloric acid in advance of the phosgenation reaction to make the pH 
10 or less, followed by the reaction. 
Water is used as the solvent in the present invention. It may be placed in 
the reactor in advance or introduced together with the dehydrochlorinating 
agent, e.g. dropwise introduced in the form of an aqueous solution of an 
alkali metal compound. The quantity of water used has no particular 
limitation, but a quantity enough to keep a uniform reaction is preferred 
and 0.5 to 50 times by weight, preferably 3 to 30 times by weight the 
weight of the diamines. 
Preferable examples of the dehydrochlorinating agent used in the present 
invention are alkali metal compounds such as NaOH, KOH, Na.sub.2 CO.sub.3, 
K.sub.2 CO.sub.3, etc. or tertiary amines such as aliphatic tertiary 
amines, e.g. trimethylamine, triethylamine, etc., aromatic tertiary amines 
e.g. dimethylaniline, diethylaniline, etc., and heterocyclic tertiary 
amines e.g. pyridine, methylpyridine, pyradine, etc. If no 
dehydrochlorinating agent is used, the raw material itself becomes an 
agent for catching byproduced hydrochloric acid so that it is difficult to 
further advance the reaction. The reaction temperature in the present 
invention has no particular limitation, but it is preferred to carry out 
the reaction at a temperature in the range of 0.degree.-70.degree. C. 
The quantity of the dehydrochlorinating agent used in the present invention 
varies depending on the pH range at the time of the reaction, and for 
example if the reaction is carried out in a pH range close to neutrality, 
the quantity is suitably determined so as to correspond to the quantity of 
byproduced hydrochloric acid and that of hydrochloric acid consumed at the 
time of feeding. Further, the quantity of phosgene is sufficient to be 1.0 
to 1.5 times its stoichiometrical quantity relative to the diamines, i.e. 
1.0 to 1.5 times by mol the mols of the diamines. 
A usual preferred embodiment of the process of the present invention is as 
follows: 
Water and a diamine are added into a reactor equipped with a 
phosgene-blowing tube, a dropping funnel, an electrode for pH measurement, 
a thermometer, a reflux condenser and a stirrer. Hydrochloric acid is 
added to make the pH of the fed solution about 3 to 10, followed by 
introducing phosgene through the phosgene-blowing tube while agitating the 
solution at a suitable temperature, and at the same time dropwise adding a 
dehydrochlorinating agent through the dropping funnel, to thereby keep the 
pH of the reaction liquid at 3.0 to 10.0, preferably 5.0 to 8.0, purging 
unreacted phosgene by nitrogen gas after completion of the blowing and the 
dropwise addition, and taking out the objective product in a conventional 
manner such as extraction and/or distillation, etc.

The present invention will be described in more detail by way of Examples 
and Comparative examples. 
EXAMPLE 1 
Water (100 ml) and N,N'-dimethyl-1,2-propane-diamine (20.4 g, 0.20 mol) 
were placed in a 300 ml glass flask equipped with a phosgene-blowing tube, 
a dropping funnel, a thermometer, a reflux condenser and a stirrer, and on 
the other hand, 20% NaOH aqueous solution (84.0 g, 0.40 mol) was placed in 
the dropping funnel. Phosgene was blown in the flask through the 
phosgene-blowing tube with stirring at a rate of 10 g/hr. for 2 hours 
while the inner temperature of the flask was kept at 20.degree. C. At the 
same time, 20% NaOH aqueous solution was dropwise added through the 
dropping funnel over 2 hours. After completion of the blowing and dropwise 
addition, aging was carried out at 20.degree. C. for one hour. A sample 
was taken from the resulting reaction mass and the quantity of 
1,3,4-trimethyl-2-imidazolidinone was determined according to gas 
chromatography. The production yield was 78.9%. 
EXAMPLE 2 
Reaction was carried out in the same manner as in Example 1 except that 
N,N'-dimethyl-1,2-propanediamine was replaced by 
N,N'-2-trimethyl-2,3-butanediamine (26.1 g, 0.20 mol), followed by 
analysis. As a result the production yield of 1,3,4,4,5- 
pentamethyl-2-imidazolidinone was 76.7%. 
EXAMPLE 3 
Reaction was carried out in the same manner as in Example 1 except that 
N,N'-dimethyl-1,2-propanediamine was replaced by 
N,N'-diethyl-1,2-propanediamine (26.1 g, 0.20 mol), followed by analysis. 
As a result the production yield of 1,3-diethyl-4- 
methyl-2-imidazolidinone was 77.3%. 
EXAMPLE 4 
Reaction was carried out in the same manner as in Example 1 except that 20% 
NaOH aqueous solution was replaced by triethylamine (40.5 g, 0.40 mol), 
followed by analysis. The production yield of 
1,3,4-trimethyl-2-imidazolidinone was 71.4%. 
EXAMPLE 5 
Water (100 ml), N,N'-dimethyl-1,2-propanediamine (20.4 g, 0.20 mol) and 36% 
hydrochloric acid (30.4 g, 0.30 mol) were placed in a 500 ml glass flask 
equipped with a phosgene-blowing tube, a dropping funnel, an electrode for 
pH measurement, a thermometer, a reflux condenser and a stirrer. 
On the other hand, 20% NaOH aqueous solution (168.0 g, 0.80 mol) was placed 
in the dropping funnel. Phosgene was blown in the flask with stirring at a 
rate of 10 g/hr. over 2 hours while the reaction temperature was kept at 
20.degree. C. under cooling. At the same time, 20% NaOH aqueous solution 
was dropwise added over 2 hours while the pH of the reaction liquid was 
controlled to 7.0.+-.0.3. 
After completion of the blowing and dropwise addition, the inside of the 
system was purged with nitrogen gas at a rate of 20 min. for 20 minutes. 
A sample was taken from the resulting reaction mass and the quantity of 
1,3,4-trimethyl-2-imidazolidinone was determined according to gas 
chromatography. The production yield was 91.3%. 49% NaOH aqueous solution 
was added to the reaction-completed liquid to make it alkaline, followed 
by twice extracting the resulting material with 1,2-dichloroethane (150 
g/once), separating the resulting oil layer and distilling it to obtain 
1,3,4-trimethyl-2-imidazolidinone (b.p. 133.degree.-135.degree. C./20 
torr)(21.8 g). 
COMATIVE EXAMPLE 1 
Toluene (100 ml) and N,N'-dimethyl-1,2-propanediamine (20.4 g, 0.20 mol) 
were placed in a 300 ml glass flask equipped with a phosgene-blowing tube, 
a thermometer, a reflux condenser and a stirrer. Phosgene was blown in the 
flask through the phosgene-blowing tube with stirring at a rate of 10 
g/hr. for 2 hours while the inner temperature of the flask was kept at 
20.degree. C., followed by aging the resulting material at the same 
temperature for one hour. A sample was taken from the resulting reaction 
mass and the quantity of 1,3,4-trimethyl-2-imidazolidinone was determined 
according to gas chromatography. The production yield was 18.3%. 
EXAMPLE 6 
Water (100 ml) and N,N'-dimethyl-1,3-propanediamine (20.4 g, 0.20 mol) were 
placed in a 300 ml glass flask equipped with a phosgene-blowing tube, a 
dropping funnel, a thermometer, a reflux condenser and a stirrer, and on 
the other hand, 20% NaOH aqueous solution (84.0 g, 0.4 mol) was placed in 
the dropping funnel. 
Phosgene was blown in the flask through the phosgene-blowing tube with 
stirring at a rate of 10 g/hr. for 2 hours while the inner temperature of 
the flask was kept at 20.degree. C. At the same time, 20% NaOH aqueous 
solution was dropwise added through the dropping funnel over 2 hours. 
After completion of the blowing and dropwise addition, the resulting 
material was aged at 20.degree. C. for one hour. 
A sample was taken from the resulting reaction mass and the quantity of 
tetrahydro-1,3-dimethyl-2(1H)-pyrimidinone was determined. The production 
yield was 77.1%. 
EXAMPLE 7 
Reaction was carried out in the same manner as in Example 6 except that 
N,N'-dimethyl-1,3-propanediamine was replaced by 1,3-propanediamine (14.8 
g, 0.20 mol), followed by analysis. As a result, the production yield of 
tetrahydro-2(1H)-pyrimidinone was 76.8%. 
EXAMPLE 8 
Reaction was carried out in the same manner as in Example 6, except that 
N,N'-dimethyl-1,3-propanediamine was replaced by 
N,N'-diethyl-1,3-propanediamine (26.0 g, 0.20 mol), followed by analysis. 
As a result the production yield of 1,3-diethyltetra- 
hydro-2(1H)-pyrimidinone was 73.3%. 
EXAMPLE 9 
Reaction was carried out in the same manner as in Example 6 except that 
N,N'-dimethyl-1,3-propanediamine was replaced by 
N,N'-dibutyl-1,3-propanediamine (37.2 g, 0.20 mol), followed by analysis. 
As a result, the production yield of 1,3-dibutyl- 
tetrahydro-2(1H)-pyrimidinone was 71.9%. 
EXAMPLE 10 
Reaction was carried out in the same manner as in Example 6 except that 
N,N'-dimethyl-1,3-propanediamine was replaced by 
2,2-dimethyl-1,3-propanediamine (20.4 g, 0.20 mol), followed by analysis. 
As a result, the production yield of tetrahydro-5,5- 
dimethyl-2(1H)-pyrimidinone was 75.5%. 
EXAMPLE11 
Reaction was carried out in the same manner as in Example 6 except that 
N,N'-dimethyl-1,3-propanediamine was replaced by 
N,N',2,2-tetramethyl-1,3-propanediamine (26.0 g, 0.20 mol). As a result, 
the production yield of tetrahydro-1,3,5,5-tetramethyl-2(1H)-pyrimidinone 
was 73.9%. 
EXAMPLE 12 
Reaction was carried out in the same manner as in Example 6 except that 20% 
NaOH aqueous solution was replaced by triethylamine (40.5 g, 0.40 mol), 
followed by analysis. As a result, the production yield of 
tetrahydro-1,3-dimethyl-2(1H)-pyrmidinone was 70.4%. 
EXAMPLE 13 
Water (100 ml), N,N'-dimethyl-1,3-propanediamine (20.4 g, 0.20 mol) and 36% 
hydrochloric acid (30.4 g, 0.30 mol)were placed in a 500 ml flask equipped 
with a phosgene-blowing tube, a dropping funnel, an electrode for pH 
measurement, a thermometer, a reflux condenser and a stirrer. On the other 
hand, 20% NaOH aqueous solution (168.0 g, 0.80 mol) was placed in the 
dropping funnel. 
Phosgene was blown in the flask through the phosgene-blowing tube with 
stirring at a rate of 10 g/hr. for 2 hours while the reaction temperature 
was kept at 20.degree. C. under cooling. At the same time, 20% NaOH 
aqueous solution was dropwise added over 2 hours while the pH of the 
reaction liquid was controlled to 7.0 .+-.0.3. After completion of the 
blowing and dropwise addition, the inside of the system was purged with 
nitrogen gas at a rate of 20 l/min. for 20 minutes. 
A sample was taken from the resulting reaction mass and the quantity of 
tetrahydro-1,3-dimethyl-2(1H)-pyrimidinone was determined according to gas 
chromatography. The production yield was 90.7%. 40% NaOH aqueous solution 
was added to the reaction-completed liquid to make the pH value in the 
vicinity of 12, followed by twice extracting the resulting material with 
1,2-dichloroethane (150 g/once), separating the resulting oil layer and 
distilling it to obtain tetrahydro-1,3-dimethyl-2(1H)-pyrimidinone (a 
fraction of b.p. 93-94.degree. C./5 torr)(21.8 g). 
COMATIVE EXAMPLE 2 
Toluene (100 ml) and N,N'-dimethyl-1,3-propanediamine (20.4 g, 0.20 mol) 
were placed in a 300 ml glass flask equipped with a phosgene-blowing tube, 
a thermometer, a reflux condenser and a stirrer. Phosgene was blown in the 
flask through the phosgene-blowing tube with stirring ate of 10 g/hr. for 
2 hours while the inner temperature of the flask was kept at 20.degree. C. 
A sample was taken from the resulting reaction mass and the quantity of 
tetrahydro-1,3-dimethyl-2(1H)-pyrimidinone was determined. The production 
yield was 17.6%. 
EXAMPLE 14 
Water (100 ml) and N,N'-dimethyl-1,4-butanediamine (23.2) g, 0.20 mol) were 
placed in a 300 ml glass flask equipped with a phosgene-blowing tube, a 
dropping funnel, a thermometer, a reflux condenser and a stirrer, and on 
the other hand, 20% NaOH aqueous solution (84.0 g, 0.40 mol) was placed in 
the dropping funnel. Phosgene was blown in the flask through the 
phosgene-blowing tube with stirring at a rate of 10 g/hr. for 2 hours 
while the inner temperature of the flask was kept at 20.degree. C. At the 
same time, 20% NaOH aqueous solution was dropwise added through the 
dropping funnel over 2 hours. After completion of the blowing and dropwise 
addition, the resulting material was aged at 20.degree. C. for one hour. A 
sample was taken from the resulting reaction mass and the quantity of 
hexahydro-1,3-dimethyl-2H-1,3-diazepin-2-one was determined. The 
production yield was 78.9%. 
EXAMPLE 15 
Reaction was carried out in the same manner as in Example 14 except that 
N,N'-dimethyl-1,4-butanediamine was replaced by 1,4-butanediamine (17.6 g, 
0.20 mol), followed by analysis. As a result, the production yield of 
hexahydro-2H-1,3-diazepin-2-one was 80.1%. 
EXAMPLE 16 
Reaction was carried out in the same manner as in Example 14, except that 
N,N'-dimethyl-1,4-butanediamine was replaced by 
N,N'-diethyl-1,4-butanediamine (28.9 g, 0.20 mol), followed by analysis. 
As a result, the production yield of 1,3-diethyl- 
hexahydro-2H-1,3-diazepin-2-one was 75.7%. 
EXAMPLE 17 
Reaction was carried out in the same manner as in Example 14, except that 
N,N'-dimethyl-1,4-butanediamine was replaced by 
N,N'-dipropyl-1,4-butanediamine (31.7 g, 0.20 mol), followed by analysis. 
As a result, the production yield of 
hexahydro-1,3-dipropyl-2H,3-diazepin-2-one was 72.7%. 
EXAMPLE 18 
Reaction was carried out in the same manner as in Example 14 except that 
N,N'-dimethyl-1,4-butanediamine was replaced by 
N,N'-dibutyl-1,4-butanediamine (34.5 g, 0.20 mol). As a result, the 
production yield of 1,3-dibutyl-hexahydro-2H-1,3-diazepin-2-one was 72.3%. 
EXAMPLE 19 
Reaction was carried out in the same manner as in Example 14 except that 
N,N'-dimethyl-1,4-butanediamine was replaced by 
2,5-dimethyl-2,5-hexanediamine (28.9 g, 0.20 mol), followed by analysis. 
As a result, the production yield of 
hexahydro-2H-4,4,7,7-tetramethyl-2H-1,3-diazepine-2-one was 75.2%. 
EXAMPLE 20 
Reaction was carried out in the same manner as in Example 14, except that 
20% NaOH aqueous solution was replaced by triethylamine (40.5 g, 0.40 
mol), followed by analysis. As a result, the production yield of 
hexahydro-1,3-dimethyl-2H-1,3-diazepin-2-one was 71.4%. 
EXAMPLE 21 
Water (100 ml), N,N'-dimethyl-1-4-butanediamine (23.2 g, 0.20 mol) and 36% 
hydrochloric acid (30.4 g, 0.30 mol) were placed in a 500 ml glass flask 
equipped with a phosgene-blowing tube, a dropping funnel, an electrode for 
pH measurement, a thermometer, a reflux condenser and a stirrer. 
On the other hand, 20% NaOH aqueous solution (168.0 g, 0.80 mol) was placed 
in the dropping funnel. Phosgene was blown in the flask with stirring at a 
rate of 10 g/hr. over 2 hours while the reaction temperature was kept at 
20.degree. C. under cooling. At the same time, 20% NaOH aqueous solution 
was dropwise added over 2 hours while the pH of the reaction liquid was 
controlled to 7.0.+-.0.3. After completion of the blowing and dropwise 
addition, the inside of the system was purged with nitrogen gas at a rate 
of 20 l/min. for 20 minutes. 
A sample was taken from the resulting reaction mass and the quantity of 
hexahydro-1,3-dimethyl-2H-1,3-diazepin-2-one was determined according to 
gas chromatography. The production yield was 91.2%. 49% NaOH aqueous 
solution was added to the reaction-completed liquid to make the pH a value 
in the vicinity of 12, followed by twice extracting the resulting material 
with 1,2-dichloroethane (150 g/once), separating the resulting oil layer 
and distilling it to obtain hexahydro-1,3-dimethyl-2H-1,3-diazepin-2-one 
(a fraction of b.p. 94-95.degree. C./4 torr) (24.1 g). 
COMATIVE EXAMPLE 3 
Toluene (100 ml) and N,N'-dimethyl-1,4-butanediamine (23.2 g, 0.20 mol) 
were placed in a 300 ml glass flask equipped with a phosgene-blowing tube, 
a thermometer, a reflux condenser and a stirrer. Phosgene was blown in the 
flask through the phosgene-blowing tube with stirring a rate of 10 g/hr. 
for 2 hours while the inner temperature of the flask was kept at 
20.degree. C. 
A sample was taken from the resulting reaction mass and the quantity of 
hexahydro-1,3-dimethyl-2H-1,3-diazepin-2-one was determined according to 
gas chromatography. The production yield was 15.3%. 
EXAMPLE 22 
Water (100 ml) and N,N'-diethyl-ethylenediamine (11.6 g, 0.1 mol) were 
placed in a 300 ml 4-neck-flask equipped with a reflux condenser, a 
thermometer, a dropping funnel, a phosgene-blowing tube and a stirrer, and 
on the other hand, triethylamine (20.2 g, 0.2 mol) was placed in the 
dropping funnel. Phosgene was blown in the flask through the 
phosgene-blowing tube with stirring at a rate of 10 g/hr. for one hour 
while the flask was kept at 20.degree. C. At the same time, triethylamine 
was dropwise added through the dropping funnel over one hour. After 
completion of the blowing and dropwise addition, the resulting material 
was aged at 20.degree. C. for one hour. A sample was taken out from the 
reaction mass and the quantity of 1,3-diethyl-2-imidazolidinone was 
determined. The theoretical yield was 76.6%. 
EXAMPLE 23 
Water (100 ml), N,N'-diethylethylenediamine (23.2 g, 0.2 mol) and 36% 
hydrochloric acid (30.4 g, 0.3 mol) were placed in a 500 ml flask equipped 
with a reflux condenser, a thermometer, a dropping funnel, a 
phosgene-blowing tube, an electrode for pH measurement and a stirrer. On 
the other hand, 20% NaOH aqueous solution (168.0 g, 0.8 mol) was placed in 
the dropping funnel. Phosgene was blown in the flask with stirring at a 
rate of 10 g/hr. for 2 hours while the reaction temperature was kept at 
20.degree. C. under cooling. At the same time, 20% NaOH aqueous solution 
was dropwise added over 2 hours while the pH of the reaction liquid was 
controlled to 7.0.+-.0.3. After completion of the blowing and dropwise 
addition, the inside of the system was purged with nitrogen gas at a rate 
of 20 l/min. A sample was taken out from the reaction mass and the 
quantity of 1,3-diethyl-2-imidazolidinone was determined. As a result, 
unreacted N,N'-diethylenediamine (1.2 g, conversion 94.8 g) and 
1,3-diethyl-2-imidazolidinone (25.6 g, selectivity 95.2%) were present. 
48% NaOH aqueous solutionw as added to the reaction-completed liquid to 
make the pH a value in the vicinity of 10, followed by twice extracting 
the resulting material with 1,2-dichloroethane (150 g/once), separating 
the resulting oil layer and distilling it to obtain 
1,3,diethyl-2-imidazolidinone (a fraction of b.p. 146-149.degree. C./20-25 
mm Hg) (24.5 g). 
EXAMPLE 24 
Reaction was carried out in the same manner as in Example 22 except that 
N,N'-diethylethylenediamine was replaced by N,N'-dipropylethylenediamine 
(14.4 g, 0.1 mol) followed by analysis. As a result, 
1,3-dipropyl-2-imidazolidinone was formed with a theoretical yield of 
70.0%.