close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3079435

код для вставки
3,07,425
Patented Feb. 26, 1953
2
3,079,425
SYNTHESIS Girl‘ NITRATE ESTERS
George A. Mortimer, La Marque, Tex., assignor to Mon
santo Chemical Company, SLLouis, M0,, a corporation
of Delaware
No Drawing. Filed July 20, 1961, Ser. No. 1215,37 8
12 Claims. (Cl. 260-467)
water-cooled condenser attached to-a gas/train consistingv
of a Dry-Ice trap, an Ascarite tube and a mineral oil
bubbler vented to the atmosphere. The. ?ask was sub.—.
merged in a constant temperature bath'and charged with
22.60 g. (0.133 mole)» of silver nitrate and 75 ml. of‘
acetonitrile.
The stirrer was started and argon was passed
through the system overnight. The bath was then heated
to 40.0°i0.3" C. and 15.0 ml. (0.133 mole) of n-propyl
The present invention relates to the preparation of
chlorofor-mate was pipetted into the ?ask. The reaction
alkyl nitrates and more particularly to an improved 10 began immediately and was allowed to proceedfor about‘
method for preparing said nitrates from allcyl chloro'
28 hours.- At the end of that time, the reaction mixture
formates.
was ?ltered. The silver chloride precipitated was washed
The‘method of preparing nitrate esters from the corre
with a little acetonitrile, then triturated well with di~
sponding chloroformates has been described by Boshchan
chloromethanei and dried by suction prior to drying in a
in I. Am. Chem. Soc., 81, 3341 (1959). The reaction in 15 vacuum oven at 80° C. to give 16.94 g. or 89% of the.
general, however, is slow and yields in many cases are
theoretical possible in the reaction. A sample of the
low.
It has now been discovered that if this reaction is
carried out in the presence of amine catalysts, reaction
rates are appreciably increased and substantially. quanti~
tative yields are obtained.
According to the invention, alkyl nitrates are produced
by reacting alkyl chloroformates in a solvent medium with
a nitrate salt having a cation which will precipitate
chlorine practically quantitatively from the solvent in the
presence of an amine catalyst chosen from the group 25
consisting of tertiary alkyl amines, alkyl aromatic amines,
and heterocyclic amines.
Sui-table catalysts include, for
example, triethyl amine, trimethyl amine, tripropyl amine,
dimethyl aniline, pyridine, quinoline, isoquinoline, and
‘the like. The catalyst is employed in amounts from about 1% to about 30% by weight of the chloroformate. How
ever, the preferred amounts to be employed are in the
range from about 5 to about 15%.
Nitrate salts suitable for reacting with the alkyl chloro
formates include metallic nitrates such as those of silver,
copper, mercury, and lead and ammonium nitrate, with
silver nitrate being the preferred reactant.
Any organic solvent which will serve as an adequate
carrier for the reactants and does not react with them
can be employed as the reaction medium. For practical
purposes, those solvents in which the nitrate salts are
somewhat soluble are preferred, but it is not necessary
that the salts be completely soluble in the solvent. Ex
amples of solvents useful in the process of the invention
supernatant liquid prior to ?ltration was analyzed on a
gas chromatograph and found to consist essentially of
acetonitrile, n-propyl nitrate and unreactcd n-propyl
chloroforrnate.
Example 2
The reaction of Example 1 was run at room tempera
ture (25° C.) using the same proportions of reactants
but with the exception that‘ 2 ml. of pyridine wasadded
after the chloroformate was charged. Even before ad-.
dition of the pyridine could be completed, an extremely
vigorous evolution of gas occurred and a copious. pre
cipitation of silver chloride took place. Although re
action appeared to be complete in about 5 minutes, the
reaction mixture was stirred for one hour.
At the end
of that time, the supernatant liquid of the mixture was
analyzed using the gas chromatograph. No chloroe
formate remained and. all of the product except about
10% indicated to be n-propanol was n-propyl nitrate.
Example 3
The reaction of n~propyl chloroformate and silver ni
trate was carried out exactly as in Example 1 except that
the reaction temperature was maintained at —10°:5° C.
by means of a cooling bath. The reaction was ter
mlnated after 48.5 hours by suction ?ltration of the re
action mixture in the cold. The silver chloride precipi~
tate after washing and drying as in Example 1 amounted
to about 10.9% of the theoretical possible. The com
bined ?ltrate and washings were ?ash distilled in the cold
tetrachloride, and the like. The preferred solvent is 45 at 25 mm. Hg. An analysis of the distillate at 100° C.
acetoni-trile.
on the gas chromatograph showed it to be essentially the
Temperatures may be varied considerably. The re
same pro-duct as that obtained in Example 1, i.e., a mix
action occurs in two steps. The ?rst step results in the
ture
consisting essentially of acetonitrile, n-propyl nitrate,
formation of an alkyl nitratocarbonate. in the second
and
unreacted
n-propyl chloroformate. Only about 10%
step, the nitratocarbonate is decomposed to yield the
of the n-propyl chloroformate charged had been con
alkyl nitrate and carbon dioxide. The ?rst step may be
sumed. The distillate was then subjected to further dis
conducted at temperatures as low as —30° C. and at
tillation in a 40-cm. Vigreaux column and several fractions
temperatures below 15° C. results in the formation of the
were collected after the solvent was removed. The vapor
include acetonitrile, benzene, toluene, dioxane, carbon
nitratocarbonate without any appreciable decomposition.
chromatographs of the fractions analyzed were identical
At temperatures from 15° C. upward, decomposition of 55 to that of the distillation feed.
the intermediate sets in as soon as it is formed and this
Example 4
reaction may be conducted at temperatures as high as
150° C. Preferably, the reaction is conducted by carrying
The reaction of Example 3 was repeated except that
out the ?rst step at temperatures in the range from about
2.0 m1. of pyridine was added to the reaction mixture.
-20° C. to about 15° C. with a gradual warmup in the 60 Temperature was controlled at —l'7°i2° C. After a
reaction mixture after the salt is precipitated therefrom,
employing temperatures anywhere in the range from 15°
total reaction period of 3 hours which included the hour
required for introducing the n-propyl chloroformate, an
C. to 150° C.
aliquot of the reaction mixture liquid was withdrawn and
The invention is illustrated in the following examples
which, however, are not to be construed as limiting it in
analyzed at 100° C. on a gas chromatograph. Again,
the same major constituents were found to be present,
the acetonitrile solvent, n-propyl nitrate, and unreacted
n-propyl chloroforma-te, the amount of the latter indi
Example 1
cating that 60% of this starting material had been con
sumed. The Ascarite tube showed no weight gain
The reaction vessel employed was a 200-ml., three 70 indicating that n-propyl nitratocarbonate was not decom
any manner whatsoever.
necked ?ask ?tted with a stirrer, a gas entry tube and a
posing in the reaction mixture, although it did decom
___
3,079,
3
pose to carbon dioxide and n-propyl nitrate when
chromatographed.
.
6. An improved process for the production of n-propyl
nitrate which comprises reacting n-propyl chloroformate
and silver nitrate in acetonitrile as a solvent medium in
the presence of pyridine in an amount from about 5%
reaction mixture then showed in addition to the aceto 5 to about 15% by weight of the chloroformate at a tem
perature in the range from about 15° C. to about 150° C.
nitrile band only a single peak corresponding to n-oropyl
The reaction mixture was allowed to warm to room
temperature overnight. A vapor chromatogram of the
nitrate.
The n-propyl chloroformate had been converted
essentially quantitatively to the corresponding alkyl
nitrate.
Example 5
Triethyl amine was employed as a catalyst in this ex
periment. The reaction paralleled that of Example 1 in
all respects except that 2.0 ml. of triethyl amine was
7. An improved process for the production of alkyl
nitrates which comprises reacting an alltyl chloroformate
and silver nitrate in a solvent medium in the presence of
a tertiary amine chosen from the group consisting of
heterocyclic amines, alkyl amines and alkyl aromatic
amines at a temperature in the range from about -20° C.
to about 15 ° C. and thereafter heating said reaction mix
ture to a temperature in the range from about 15° C. to
added with the reactants and the reaction temperature
about 150° C.
was somewhat lower, being controlled at about 32° x, 15
8. The process of claim 7 wherein said solvent medium
Samples were withdrawn after reaction periods of 5 and
30 minutes, respectively, and subjected to analysis in a
is acetonitrile.
‘
9. The process of claim 7 wherein said amine is present
gas chromatograph. The same products were obtained
in an amount from about 1% to about 30% by weight of
as were obtained in Example 1 but at an accelerated rate
20 said chloroformate.
of reaction.
10. The process of claim 8 wherein said amine is
What is claimed is:
1. An improved process for the production of alkyl
nitrates which comprises reacting an alkyl chlorcformate
pyridine.
.
11. The process of claim 8 wherein said amine is tri
ethyl amine.
and silver nitrate in a solvent medium in the presence
12. An improved pr cess for the production of n-propyl
of a tertiary amine chosen from the group consisting of 25
heterocyclic amines, alkyl amines and alkyl aromatic
nitrate which comprises reacting n-propyl chloroformate
amines at temperature in the range from about 15° C.
and silver nitrate in acetonitrile as a solvent medium in
the presence of pyridine in an amount from about 5% to
to about 150° C.
about 15% by weight of the chloroformate at a tempera
2. The process of claim 1 wherein said solvent medium
30 ture in the range from about ~20° C. to about 15 ° C.
is acetonitrile.
and thereafter heating said reaction mixture to a tem
3. The process of claim 1 wherein said amine is present
in an amount from about 1% to about 30% by weight of
perature in the range from about 15° C. to about 150° C.
said chloroformate.
4. The process. of claim 2 wherein said amine is
References Cited in the ?le of this patent
35
pyridine.
5. The process of claim 2 wherein said amine is tri
ethyl amine.
Boshchan: I. Am. Chem. Soc, 81, 3341 (1959).
Vona et al.: I. Am. Chem. Soc, 81, 1095-9 (1959)
Документ
Категория
Без категории
Просмотров
0
Размер файла
285 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа