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Патент USA US2409807

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Patented Oct. 22, 1946
‘ 2,409,806
William Shive, Urbana, 111., and Richard A. Glenn,
Mount Lebanon, Pa., assignors to Pittsburgh
Coke & Chemical Company, a corporation of
No Drawing. Application December 8, 1941,
Serial No. 422,187
5 Claims.
(Cl. 260—296)
' This invention relates to the synthesis of nico
timo compounds; and it comprises a method of
producing nicotinic compounds, such as nicotinic
acid and nicotinamide, directly from pyridine,
wherein pure pyridine is converted into substan
tially pure pyridine-B-sulfonic acid (also called
S-position. This is done in the present invention.
In the present invention, pyridine is ?rst sul
fonated. We have found that sulfonation of
pyridine may be practically confined to the 3
position by sulfonating with sulfur trioxide in
the absence of sulfuric acid,'with mercury as a
catalyst. The temperatures required are not
high, ranging from 170° to 300° C., and good sul
sulfonating with sulfur trioxide in a system sub
stantially free of water or sulfuric acid and in
fonation can be effected in, say, 3 to ‘6 hours.
the presence of mercury as a catalyst, a pyridine 10 The best yields, such as 90 per cent or more, are
‘ beta-pyridine sulfonic acid) advantageously by
3-sulfonate being then isolated and converted
into the nitrile of nicotinic acid (3-cyanopyridine
or beta-cyanopyridine) with a cyanide, and the
nitrile being hydrolyzed to furnish pure nicotin
amide or nicotinic acid; all as more fully herein
after set forth and as claimed.
Nicotinic acid is an essential, albeit an in?ni
generally obtained when operating at tempera
tures above 200° C., and with a substantial ex
cess of S03, such as 1.5 mols S03 per mol of
pyridine. Ratios from 1.2’ to 1.8 mols $03 per mol
When the sulfo~
nation reaction is completed, the excess S03 is
removed, as by precipitation with calcium car
15 of pyridine give good results.
bonate or barium carbonate, and the calcium or
tesimal, constituent of food. It forms part of
barium salt of beta-pyridine sulfonic acid is re
the vitamin B complex and is itself considered a
speci?c in various forms of- pellagra. A large
covered from the solution. This sulfonate is then
commercial demand has arisen for it for fortify
converted into the nitrile of nicotinic acid, 3
cyanopyridine, by direct treatment with a cya
ing cereal foods. For this purpose the nicotinic
nide, or advantageously by conversion into an
acid must be not only chemically pure but biologi
cally pure; that is, free from any substances
alkali metal sulfonate which is then treated with
having undesired effects on the human body. The 25 the cyanide. In either case, the S-cyanopyridine
obtained is readily hydrolyzed to obtain pure
presence of physiologically active impurities can
nicotinamide or nicotinic acid. Operating in
not be tolerated. Unfortunately, there is no food
this manner, with pure pyridine as the starting
sufficiently rich in nicotinic acid to warrant its
material, is easier and better than working with
extraction therefrom as a commercial proposition.
other materials and attempting to remove the
Nicotineamide is generally similar to nicotinic
impurities afterwards.
acid in its physiological reactions and uses, but is
In the sulfonation treatment, mercury and its
sometimes more desirable in that, even in similar
compounds, especially the sulfate, are the best
doses, it does not give the allergic reaction some
catalysts. Mercury can be removed from the
times produced by nicotinic acid.
reaction products as the sul?de, if desired, and
Nicotinic acid is pyridine carrying a carboxyl
the recovered sul?de can be added directly to
radical in the 3- or beta-position. Nicotineamide
the sulfur trioxide of a new batch to serve as
is the acid amide of this acid. As an academic
the catalyst.
proposition, the acid can be made by oxidizing any
In the present method, pyridine is sulfonated
pyridine derivative carrying a single substituent
in the beta- or 3-position, provided that the car 40 practically exclusively in the 3-position and the
reaction mixture is freed from excess (S03) and
bon in the 3- or beta-position is linked directly
to a carbon in the substituent. Unfortunately,
neutralized with lime, calcium carbonate, barium
again, there are few commercial materials having
carbonate, or baryta, as noted. The solution of
barium or calcium pyridine sulfonate thus ob
this structure which are available in su?icient
purity to warrant their direct use. Oxidation of ‘ 45 tained may be treated with I-IzS or sodium sul
?de to get rid of the mercury catalyst. It is not
necessary to remove the catalyst, but it may be
precipitated for recovery and reuse, if desired.
are not wanted.
The calcium or barium pyridine sulfonate is then
An object achieved in the present invention is
the provision of a method of producing pure nico 50 reacted with sodium or potassium carbonate or
sulfate, if desired, to convert the alkaline earth
tinic acid or pure nicotinamide, using pyridine
compound to an alkali metal sulfonate. The dry
itself, free from any other pyridine compound, as
pyridine-3-sulfonate of alkali or alkaline earth
a source material. There are ample supplies of
metal is recovered, and is mixed with sodium or
pure pyridine available, and it can be converted
potassium cyanide, or advantageously a mixture
into nicotinic acid by attaching a carboxyl in the
any other than a 3-, or beta-side chain does not
give nicotinic acid, and does give impurities that
of the two, and heated so as to give a progressive,
of cyanide in the reaction mixture increase the
rather slow evolution of 3-cyanopyridine, which
yield of 3-cyanopyridine.
comes off as a vapor and is condensed. We‘ have
The B-cyanopyridine prepared as above was
found that the rapid removal of B-cyanopyridine
hydrolyzed to nicotinic acid by using concen
trated hydrochloric acid, re?uxing for 12 hours.
asit is formed increases the yield. Prompt re
moval of 3-cyanopyridine may be effected by
operating under reduced pressure, or by the use
The B-cyanopyridine was thus converted with an
almost theoretical yield (95 per cent) to nicotinic
acid hydrochloride. The hydrochloride was freed
both. Quick removal is particularly useful in
from excess hydrochloric acid by evaporating to
the later stages of the reaction. Better yields 10 dryness. The crude nicotinic acid was separated
are obtained by not carrying the temperature of
from the dried mass by adding approximately 2
the mixture of the pyridine-3-‘su1f0nate and the
mols sodium acetate per mol of nicotinic acid
cyanide or cyanide mixture to such a point as
and then adding sufficient water to effect solution
to effect complete fusion. We have found 3<i0° to
at about 90° C. On cooling and standing, crude
380° C. a satisfactory temperature range. Such 15 nicotinic acid separated and was removed by
precautions lessen or avoid the formation of res
inous products, which result in lowered yields.
The nicotinic acid was puri?ed by two recrys
In a speci?c embodiment of this invention, 100
tallizations from water; that is, by adding suf
of a stream of inert gas, such as nitrogen, or
parts by weight of sulfur trioxide and 1.8 parts
?cient boiling water to eifect solution at approx
by weight of mercuric sulfate were placed in a 20 imately 90° C. and cooling the batch to about 5°
reaction vessel and 60 parts by weight of pure
C. The nicotinic acid was removed by ?ltration
anhydrous pyridine were added slowly to the
and the above process repeated. By this method
vessel during one hour. During the addition of
an 85 per cent theoretical yield, on the 3-cyano
the pyridine, the vessel and its contents were
pyridine, of pure nicotinic acid (having a melting
cooled from time to time, since the reaction 25 point of 236 to 2365’ C.) was obtained. An
developed a great deal of heat. Such cooling is
increased yield was obtained by reworking the
not usually necessary when the temperatures do
mother liquor obtained above.
not exceed 250° C. After the pyridine addi
In a further speci?c embodiment, barium
tion was complete, the mixture was heated for 6
pyridine-3-sulfonate prepared as described above,
hours under re?ux at about 230° 0., care being 30 was converted to the sodium salt by treating with
taken to avoid the entry of atmospheric mois
sodium sulfate. With 50 parts by weight of this
ture into the system. Upon cooling the reaction
sodium salt in ?nely powdered form were mixed
mixture, a thick viscous liquid was obtained,
25 parts by weight of'sodium cyanide and 25 parts
which was poured into 2000 parts by weight of
by weight of potassium cyanide. The mixture
water and neutralized with barium carbonate. 35 was heated slowly at a rate and at a tempera
The excess S03, converted to H2504 by dilution
ture sufficient to produce a steady evolution of
with water as above described, was ‘thus con-_
verted to an insoluble salt and was removed by
volatile material (which was condensed and col
lected) but insui'?cient to produce white clouds,
?ltration. The soluble barium pyridine-3-sul
which characterize overheating. The latter stage
fonate was decolorized with decolorizing carbon, 40 of the heating Was carried out under reduced
although this is not a necessary part of the proc
pressure to assist in removing the 3~cyanopyri
ess. Mercury can now be removed by precipi
tating it as the sul?de, using HzS or NaHS‘ as
The distillate was puri?ed in a conven
tional manner to yield 13 parts by weight of
S-cyanopyridine, a yield of 45 per cent of theo
a reagent, and ?ltering‘to recover the HgS, which
is then added to a fresh batch. The ?ltrate was 45 retical, based on the sodium pyridine-S-sulfonate.
then evaporated to dryness. A yield of barium
This nitrile was then hydrolyzed‘ in the conven
salt of pyridine-3-sulfonic acid amounting to 90
per cent of theoretical was thus obtained.
In other speci?c operations using similar pro
tional manner to nicotinic acid.v ’
In another speci?c embodiment of the inven
tion, illustrating the production of nicotinamide,
portions of reagents, a yield of 75 per cent was 50 10 parts of 3-cyanopyridine produced as described
obtained by heating for 9 hours at 200°; a yield
hereinabove were dissolved in 72 parts of‘ con
of'96 per cent was obtained by heating for 6
centrated sulfuric acid and allowed to stand for
hours at 225° C. ; a yield of nearly 100 per cent
12 to 15 hours. The reaction mixture was then
was obtained by heating for 5 hours at 230° C.;
poured into about 200 parts of water, and the
and a yield of 90 per cent was obtained by heat 55 sulfuric acid was neutralized with excess am
ing for 6 hours at 2'50-260° C. These and other
monium hydroxide. The resulting basic mixture
runs indicate that the optimum temperature for
was extracted several times with ether. The
this sulfonation is about 225° to 235° C.
ether solution was concentrated by evaporation
A mixture of 40 parts by weight of barium
and allowed to stand for a time, whereupon one
pyridine-B-sulfonate, prepared as described and 60 part of nicotinamide crystallized out. The melt
ing point of the crude amide was 120° C.
11 parts by weight of potassium cyanide, was
In a further embodiment, 10 parts of 3-cyano
heated slowly at atmospheric pressure to incipi
pyridine were dissolved in 36 parts of cold sul
ent fusion in a still, and heating was continued
furic acid and the mixture was allowed to stand
until no more volatile material Was produced,
even on strong heating. The distillate, 3-cyano 65 for 16 hours at room temperature. The reaction
mixture was poured into 250 parts of ice water,
pyridine, was condensed and collected and dis
and rendered basic by‘ adding excess ammonium
solved in ether, and the ether solution was washed
hydroxide. The basic solution was then heated
with dilute caustic soda solution. The caustic
to about 70° C., and extracted several times with
solution was then separated and the ether solu
benzene. Evaporation of the benzene yielded on
tion was washed and dried. The solvent was
part of nicotinamide.
distilled off, leaving the solid nit-rile or 3-cyanopy
In the foregoing examples, “parts” are parts
ridine. This was recrystallized from petroleum
by weight, unless otherwise indicated. The nico
ether, yielding 5 parts by weight of pure beta
tinamide obtained is highly useful therapeuti
cyanopyridine, M. P. 48° C‘. Higher proportions 75 cally, as previously noted, but may be readily
hydrolyzed into nicotinic acid if desired, since
it is a product of the partial hydrolysis of 3-cyanopyridine.
X being selected from the group consisting of
alkali metals and alkaline earth metals and re
covering the 3 cyano pyridine thus formed.
By the term “free of H20” or “in the substan2. The process according to claim 1 wherein
tial absence of H20” as used in the claims, we 5 the mixture is heated at a temperature of 340°
mean free from H2O as such or combined with
to 380° C.
S03 in the form of H3804.
What we claim is:
X is
1. The process of producing 3 cyano pyridine
by heating a, mixture of potassium cyanide and 10 X is
sodium cyanide with a pyridine sulfonic acid salt
of the following formula
X is
The process according to claim 1 wherein
The process according to claim 1 wherein
The process according to claim 1 wherein
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