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Патент USA US3054807

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7
United States Patent 0 M C6
,
3,054,191
Patented Sept. 18, 1962
1
2
3,054,797
perature range may be employed. We have found it pref
erable, for the majority of purposes, to utilize Raney
nickel as the hydrogenation catalyst. As previously
PROCESS FOR THE PREPARATION OF
S-AMINOHEXAHYDROPYRIMIDINES
Wilton 0. Bell, Monroe, La., and Albert E. Neckar, Terre
Haute, Ind., assignors to Commercial Solvents Corpora
tiou, New York, N.Y., a corporation of Maryland
No Drawing. Filed Oct. 11, 1961, Ser. No. 144,301
5 Claims. (Cl. 260-2564)
stated, the reaction can be effected at hydrogen pressures
ranging in excess of 500 pounds. We have found it pref
erable, however, to carry out the reaction at pressures
not in excess of 1,000-4,200 pounds for at higher pres
sures there is tendency to cleave the hexahydropyrim
idine ring. Also, as previously stated, temperatures rang
Our invention relates to the production of S-amino
ing from about 25 to about 100° C. are suitable for our
hexahydropyrimidines. More particularly it relates to an 10 reaction. However, we prefer to utilize temperatures of
improved process for producing S-aminohexahydropyrim
idines having the ‘following formula:
CH2
/
NHz
from about 70 to about 100° C. Solvents which can be
suitably utilized in the reduction procedure include the
lower aliphatic alcohols such as methanol, ethanol, etc.,
15 and the like.
vIn order to achieve a product having optimum color
characteristics and purity, it is preferable to cease hydro
genation on completion of the reaction which is indicated
by failure of additional hydrogen adsorption. After com
pletion of the reaction, the 5-aminohexahydropyrimidines
where R is lower alkyl and R1 is alkyl.
S-aminohexahydropyrimidines can be prepared by we
process described in US. Patent 2,3 87,043, issued to
can be puri?ed by ?rst separating the hydrogenation cata
lyst from the reaction mixture by ?ltration and then re
moving the solvent by distillation.
Murray Senkus. Brie?y this process consists of subject—
The following examples are offered to illustrate our in
ing a mixture of a S-nitrohexahyd-ropyrimidine, a nickel
However, it is not intended that the invention
hydrogenation catalyst and a solvent to liquid phase hy 25 ‘vention.
be limited to the speci?c materials set forth; rather, it is
drogcnation at pressures above 500 pounds and at tem
peratures ranging from about 25 to about ‘100° C. and
intended that all equivalents apparent to those skilled in
the art be included in the scope of the invention as de
fractionally distilling the resulting hydrogenation product
scribed in this speci?cation and the attached claims.
Example I
To a hydrogenation apparatus containing 500 m1. of
methanol and 10 grams of Raney nickel catalyst were
to recover the S-aminohexahydropyrirnidine.
S-aminohexahydropyrimidines produced by the above
described process are generally of poor color and purity.
Therefore, in order to obtain a product having acceptable
color characteristics and sufficient purity, it is necessary to
continuously added over a period of one hour, 240 grams
employ not only expensive distillation equipment but to 35 of S-nitro-l,3—bis(2-ethylhexyl)-5-methy1hexahydropyrim
use repeated distillation procedures. The need ‘for mul
idine. During the one-hour period, the resulting mixture
tiple distillations and the requirement of expensive and
was hydrogenated at approximately 1,000 pounds per
highly specialized equipment thus greatly increases the
square inch utilizing room temperature as the initial tem
cost of the ?nal product.
perature and gradually increasing the temperature to
We have now discovered an improved process whereby 40 about 70° C. At the end of the one-hour period, hydro
S-aminohexahydropyrimidines having the following for
genation was stopped. The reaction mixture was ?rst
?ltered to remove the catalyst and was then distilled at
atmospheric pressure at a temperature of 70° C. to re
move methanol. 197.5 grams of 5-amino-1,3-‘bis(2-ethyl
mula:
45 hexyl) -5~methylhexahydropyrimidine were collected. The
collected material had a color of Gardner 2.
Example 11 allows a comparison of the color character
istics of S-amino-l,3-bis(2-ethylhexyl)methylhexahydro
pyrimidine prepared according to Example I by the proc
wherein R is lower alkyl and R1 is alkyl having indus 50
ess of our invention with 5-amino~1,3-bis(2-ethylhexyl)
trially acceptable color characteristics and degrees of
S-methylhexahydropyrimidine prepared using the prior
purity can be produced without the necessity of repeated
and expensive puri?cation procedures. Thus, our new
j1 process represents a signi?cant economic advancement in
_,the production of S-aminohexahydropyrimidines.
Our invention consists essentially of incrementally add
ing the S-nitrohexahydropyrimidine to be reduced to a
art method. A comparison of the results shows the effec
tiveness of our process in producing a substantially color
55
less pure 5-amino~l,3-bis(Z-ethylhexyl)-5-methylhydro
pyrimidine.
Example II
A mixture consisting of 240 grams of 5-nitro-1,3-bis
mixture of methanol and hydrogenation catalyst and hy
drogenating the mixture while continuously maintaining
(Z-ethylhexyl)-5-methylhexahydropyrimidine, 500 ml. of
Generally, in carrying out our invention, any hydro
genation catalyst which is active within the aforesaid tem
approximately 1,000 pounds per square inch using room
temperature as the initial temperature. As the reduction
methanol, and 10 ‘grams of Raney nickel catalyst was
a temperature of from about 25 to about 100° C. and a 60 placed in a suitable hydrogenation apparatus and sealed.
pressure in excess of 500 pounds.
This mixture was then hydrogenated at a pressure of
1
3,054,797
a
3
4
.
proceeded, however, the temperature was gradually in
Now having described our invention, what we claim is:
1. In a process for the production of S-amino-hexa
creased to approximately 80° C. Hydrogenation was
continued for a period of about one hour at which time
hydropyrimidines of the formula:
adsorption of hydrogen had ceased. Upon cessation of
hydrogenation the reaction mixture was withdrawn from
the hydrogenation apparatus, the catalyst removed from
the solution by ?ltration, and the solution was distilled at
atmospheric pressure at 70° C. to remove methanol.
193 grams of 5-amino-1,3-bis(2-ethylhexyl)-5-methyl
hexahydropyrimidine were collected. The material had a
0
l0
N?a \R
wherein R is ‘lower alkyl and R1 is alkyl of improved
color ‘by subjecting a S-nitrohexahydropyrimidine to hy
Example III
drogenation in the liquid phase in the presence of a hydro
A portion of S-nitro-l,3-dibenzyl-S-methylhexahydro
genation catalyst at temperatures ranging from about 25
pyrimidine was subjected to hydrogenation following the
to about 100° C. and at pressures in excess of 500 pounds
vprocedure of Example I to obtain 5-amino-1,3-dibenzyl 15 the improvement which comprises incrementally intro
S-methylhexahydropyn'midine. The color characteristic
ducing the S-nitrohexahydropyrimidine into the liquid
of the material was similar to that shown in Example I.
phase hydrogenation reaction.
color of Gardner 8.
Example IV
2. The process of claim 1 wherein the S-aminohexa
A portion of S-nitro-1,3-diisopropylhexahydropyrim
20
ylhexahydropyrimidine.
'idine was subjected to hydrogenation following the pro
cedure of Example I to obtain 5-amino-l,3-diisopropyl
hexahydropyr-imidine. The color characteristic of the
material was similar to that shown in Example I.
Example V
V
A portion of vS-nitro-17,3,i-trimethylhexahydropyrim
hydropyrimidine is 5-arnino-1,3-bis (2-ethylhexy1)-5-meth
3. The process of claim 1 wherein the S-aminohexa
hydropyrimidine is 5-arnino—l,3-dibenzyl-5-methylhexahy
dropyrimidine.
25
V
4. The process of claim 1 wherein the S-arninohexa
hydropyrimidine is’ S-amino-1,3-diisopropylhexahydropy
Iimidine.
‘idine was subjected to hydrogenation following the pro
5. The process of claim 1 wherein the hexahydropy
cedure of Example I to obtain 5-amino-1,3,5-trimethyl 30 rimidine is 5-amino-1,3,S-trimethylhexahydropyrimidine.
* hexahydropyrimidine.
The color characteristic of the
No references cited.
material was similar to that shown in Example I.
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