U.S. patent number RE30,362 [Application Number 06/030,781] was granted by the patent office on 1980-08-05 for process for preparing polyvinylamine and salts thereof.
This patent grant is currently assigned to Dynapol. Invention is credited to Daniel J. Dawson, Richard D. Gless, Jr., Robert E. Wingard, Jr..
United States Patent |
RE30,362 |
Gless, Jr. , et al. |
August 5, 1980 |
Process for preparing polyvinylamine and salts thereof
Abstract
Poly(vinylamine salts of mineral acids are produced by reacting
acetaldehyde and acetamide at a mole ratio of 1:2-4 with acid
catalyst, cracking the ethylidene-bisacetamide which results into
vinylacetamide, polymerizing the vinylacetamide with a free radical
polymerization catalyst, and hydrolyzing the poly(vinylacetamide)
to the desired amine salts by contacting the polyvinylacetamide
with an aqueous solution of the corresponding mineral acid. This
product may be converted to the free amine, which in turn may
function as a precursor in the manufacture of certain polymeric
dyes and colorants.
Inventors: |
Gless, Jr.; Richard D.
(Oakland, CA), Dawson; Daniel J. (Los Altos, CA),
Wingard, Jr.; Robert E. (Palo Alto, CA) |
Assignee: |
Dynapol (Palo Alto,
CA)
|
Family
ID: |
21855991 |
Appl.
No.: |
06/030,781 |
Filed: |
April 17, 1979 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
520530 |
Nov 4, 1974 |
04018826 |
Apr 19, 1977 |
|
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Current U.S.
Class: |
525/509; 426/250;
525/351; 525/353; 525/369; 525/375; 525/377; 526/75; 534/561;
534/573; 534/DIG.3; 564/159; 564/215; 8/647 |
Current CPC
Class: |
C08F
8/44 (20130101); C09B 69/106 (20130101); C08F
8/44 (20130101); C08F 126/02 (20130101) |
Current International
Class: |
C08F
8/44 (20060101); C08F 8/00 (20060101); C09B
69/10 (20060101); C09B 69/00 (20060101); A23L
001/27 (); C07C 087/24 (); C08F 120/52 (); C08F
126/02 () |
Field of
Search: |
;260/583R,583P,583N
;526/12,47,310 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Ben-Ishai et al., Chemical Abstracts, vol. 64, 12592 (1966). .
Blance et al., Chemical Abstracts, vol. 65, 10695 (1966). .
Hart, J. Polymer Science, vol. 29, pp. 629 to 636 (1958). .
Michio et al., Chemical Abstracts, vol. 72, 22105b (1970). .
Noyes et al., J. Am. Chem. Soc., vol. 55, pp. 3493 to 3494 (1933).
.
Rath et al., Chemical Abstracts, vol. 59, 14131 (1965). .
Reynolds et al., J. Amer. Chem. Soc., vol. 69, pp. 911 to 915
(1947). .
Richter, Ber. Deut. Chem. Gesell., vol. 5, p. 477 (1872). .
Scheibler et al., Ber. Deut. Chem. Gesell., vol. 87, pp. 379 to 383
(1954)..
|
Primary Examiner: Higel; Floyd D.
Attorney, Agent or Firm: Benz; William H.
Claims
We claim:
1. A process for preparing poly(vinylamine) salt which comprises
the steps of: A. reacting at a temperature of from 20.degree. C. to
100.degree. C. acetaldehyde with from two to four stoichiometric
equivalents of acetamide in the presence of from 0.001 to 1.0 mole
per mole of acetamide of an aqueous mineral acid catalyst to yield
a vinylacetamide and ethylidene-bis-acetamide containing reaction
product,
B. neutralizing the aqueous mineral acid catalyst and heating the
vinylacetamide and ethylidene-bis-acetamide containing reaction
product to 150.degree. C. to 250.degree. C. for from 0.2 to 5 hours
in the presence of an inorganic nonacidic silicious oxide surface
catalyst to yield a decomposition product, said catalyst having a
surface area of at least about 1 m.sup.2 /g,
C. separating vinylacetamide from said decomposition product by
vacuum volatilization,
D. contacting with vinylacetamide at a concentration of from 10% to
50% by weight in a reaction medium selected from polar hydrogen
bonding liquids and nonpolar liquids with from 0.1 to 20 grams per
100 grams of vinylacetamide of a free radical initiator
polymerization catalyst at a temperature of from 25.degree. C. to
125.degree. C. for from 4 to 8 hours to yield
poly(vinylacetamide),
E. hydrolyzing said poly(vinylacetamide) by contacting it with from
1.05 to 3 equivalents of a mineral acid per equivalent of
poly(vinylacetamide) at a temperature of from .Badd..[.25.degree.
C. to 125.degree. C. for from 4 to 8 hours.]..Baddend.
.Iadd.60.degree. C. to 175.degree. C. for from 1 to 36 hours
.Iaddend.to yield the poly(vinylamine) salt of said mineral acid,
and
F. precipitating and recovering said poly(vinylamine) salt.
2. The process of claim 1, wherein in step B said catalyst is
celite and a reaction temperature of from 70.degree. C. to
200.degree. C. is employed.
3. The process of claim 1, wherein in step B said catalyst is high
surface area glass and a reaction temperature of 70.degree. C. to
200.degree. C. is employed.
4. The process of claim 3, wherein in step E, said mineral acid is
hydrochloric acid.
5. A process for preparing poly(vinylamine) which comprises
contacting said poly(vinylamine) salt of claim 1, step F, with not
less than a stoichiometric amount of an aqueous solution of a
strong base selected from the alkali and alkaline earth metal
hydroxides, thereby converting said poly(vinylamine) salt to said
poly(vinylamine).
6. The process of claim 5, wherein said strong base is an alkali
metal hydroxide.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a chemical process for forming
poly(vinylamine) salts .Iadd.of mineral acids.Iaddend., especially
poly(vinylamine hydrochloride), and in preferred embodiments
relates to further treating said poly(vinylamine) salts to yield
poly(vinylamine) and poly(vinylamine)-based polymeric colorants.
The invention also relates to the products of this process.
2. The Prior Art
Poly(vinylamine) salts, such as poly(vinylamine hydrochloride), are
desirable chemicals. Their primary use is as precursors of
poly(vinylamine). Being more stable than poly(vinylamine), they are
more easily shipped and stored with less precautions being needed
to prevent degradation. Poly(vinylamine) may be produced from
poly(vinylamine) salts by neutralizing with base. Poly(vinylamine)
itself is a linear polymer, which, because of its many active amine
groups, finds diverse applications, such as a cationic water
treatment resin and as a chemical intermediate. Unfortunately, it
has not found widespread commercial use. This is very likely
because an integrated overall process for its production has not
been provided by the art. Accordingly, it is an object of this
invention to provide a process for the preparation of this amine
and its precursor salts.
STATEMENT OF THE INVENTION
In its broadest aspect, this invention concerns a process for
preparing poly(vinylamine) salts. This process has the following
steps:
a. reacting acetaldehyde with at least two stoichiometric
equivalents of acetamide in the presence of a strong acid catalyst
to yield ethylidene-bis-acetamide;
b. decomposing the ethylidene-bis-acetamide in the presence of an
inorganic oxide surface catalyst under essentially neutral pH
conditions to yield a decomposition product;
c. separating vinylacetamide from this decomposition product;
d. contacting the vinylacetamide with a free radical initiator
under polymerization conditions to yield poly(vinylacetamide);
e. hydrolyzing this poly(vinylacetamide) with a mineral acid to
yield a poly(vinylamine) salt; and
f. precipitating and recovering the poly(vinylamine) salt.
The poly(vinylamine) salt product is a linear, uniform polymer
which has a molecular weight which can be controlled in the range
of from about 4,000 to about 1,000,000; which material, both as a
new material and as the product of a new process, represents
another embodiment of this invention.
In a further aspect, this invention concerns a process for
preparing poly(vinylamine). This process involves contacting
poly(vinylamine) salt, prepared by the above-described process, in
an aqueous medium with a base of sufficient strength and amount to
maintain the medium pH at about 10 or greater. The poly(vinylamine)
product which results is a linear polymer of molecular weight of
from about 3,000 to about 700,000, having repeating amine
functionalities, and represents another aspect of this
invention.
The amine product can be further treated and, in one preferred
aspect of this invention, is converted into a polymeric dye such as
by (1) adding to the amine groups of the poly(vinylamine) an
aromatic compound having an amine precursor functionality to form
an aromatic amine-substituted polymer product, (2) diazotizing the
aromatic amine substituents to form diazo groups, and (3) bonding
to the diazo groups an optical color coupler.
These poly(vinylamine) backbone dyes represent yet another aspect
of this invention.
BRIEF DESCRIPTION OF THE DRAWINGS
In the Detailed Description of the Invention, reference will be
made to the drawings which include 4 FIGS., each a schematic flow
diagram.
FIG. 1 illustrates a semi-batch embodiment of the invention as it
relates to the preparation of poly(vinylamine) salts;
FIG. 2 illustrates a modification of the process of FIG. 1,
enabling continuous operation;
FIG. 3 illustrates a method for hydrolyzing the salt to the free
amine;
FIG. 4 sets out a process for forming polymeric dyes from the free
amine.
DETAILED DESCRIPTION OF THE INVENTION
In the first step of the process of this invention, one mole of
acetaldehyde and two moles of acetamide are reacted to yield
ethylidene-bis-acetamide, ##STR1## Thus, stiochiometrically,
acetaldehyde and acetamide are employed in a ratio of 1:2.
Generally, however, it is preferred to use somewhat of an excess of
acetamide. Major excesses appear to offer no benefit, so suitably
the ratio is controlled between 1:2 and about 1:4. Reaction will
occur at ratios outside this range, for example, at ratios of less
than 1:2 or greater than 1:4, but such conditions are not
preferred. This reaction is carried out with stirring at elevated
temperature. Suitable temperatures are in the range of from about
20.degree. C. to about 100.degree. C. Acetaldehyde boils at about
20.degree. C. at atmospheric pressure, so, if temperatures above
about 20.degree. C. are desired, suitable superatmospheric
pressures must be employed or the reaction temperature must be
gradually raised as the acetaldehyde reacts. In a batch mode of
operation, the temperature will generally rise from the
acetaldehyde reflux temperature (20.degree. C.) to
60.degree.-75.degree. C. as reaction occurs. Thus, preferred
reaction temperatures are in the range of about 20.degree. C. to
75.degree. C. This reaction occurs at acidic pHs. Good results are
obtained when aqueous mineral acid, such as aqueous sulfuric or
hydrochloric acid is added in a catalytically effective amount such
as from about 0.001 to 1 mole of acid per mole of acetamide.
Preferably, from 0.002 to 0.1 mole of acid is added per mole of
acetamide. Larger amounts of acid may be employed, but, since they
are neutralized in the next step, offer no advantage.
In the second step, the ethylidene-bis-acetamide product is
thermally decomposed (cracked) to vinylacetamide. This cracking can
be carried out thermally, such as by heating the
ethylidene-bis-acetamide to about 150.degree. C. to 250.degree. C.
for from 0.2 to 5 hours, but preferably is carried out
catalytically. The use of a catalyst enables the cracking
temperature to be lowered into the range of from 70.degree. C. to
200.degree. C. Suitable catalysts include high surface area
inorganic solid materials, preferably of a silicous or oxidic
nature. As a general rule, nonacidic catalysts give best results.
(A nonacidic catalyst is one which by art-known tests such as
Hammett indicators gives a nonacidic reading.) Typical useful
catalysts include silicious catalysts such as diatomaceous earth,
fumed silica, chopped glass fiber, powdered glass, silica gel, and
fine sand. Acidic materials to be avoided include silica-alumina
hydrocarbon cracking catalysts and the like.
These catalysts should be employed in forms having surface areas of
at least about 1 m.sup.2 /g, preferably with surface areas of from
about 10 m.sup.2 /g to about 400 m.sup.2 /g. They may be added to
the reaction mixture as powders or pellets or could be employed as
a bed through which the reaction mixture is gradually passed.
Catalysts which give excellent results and are preferred include
diatomaceous earth of surface area 5 m.sup.2 /g to 20 m.sup.2 /g,
marketed under the trade name "Celite", and glass wool of surface
area 0.1 m.sup.2 /g to 1.0 m.sup.2 /g. Suitable reaction times for
the catalytic cracking step are from 0.2 hours to about 6
hours.
This step should be carried out under nonacidic conditions. This
means that the mineral acid present in the first step product must
be eliminated either by removal or by reaction with a neutralizing
amount of an acid acceptor. Suitable acid acceptors include alkali
metal and alkaline earth metal hydroxides, carbonates and
bicarbonates. Satisfactory results can be obtained with any of
these materials, so cost factors dictate a preference for sodium,
potassium and calcium hydroxides, carbonates and bicarbonates. The
carbonates are most preferred since they provide a buffering action
at or about the desired neutral pH's.
The vinylacetamide which is formed in this reaction step is more
volatile than the ethylidene-bis-acetamide feed material. It is
desirable to remove it by volatilization from the reaction mixture
as it is formed. This may be done by pulling a vacuum on the
reaction vessel during reaction. Water fed and/or formed during
neutralization and residual acetamides will also be volatilized. In
a batch operation, most of the water and acetamide will be carried
overhead first and can be isolated. In a continuous operation the
three materials would come overhead at once such that further
fractionation or crystallization or the like could be required to
segregate the vinylacetamide. It is not essential that the
vinylacetamide be completely purified. Vacuums of from about 1 mm
Hg to about 50 mm Hg are suitable to effect volatilization of the
vinylacetamide at the reaction temperatures. The
acetamide-containing vinylacetamide product melts at about room
temperature. Before it is polymerized, it optionally may undergo
purification treatment to remove acetamide. This treatment may take
the form of fractional crystallization, distillation, or passage
through a bed of resin of a cation exchange type such as the
styrene polymer based resins marketed by Rohm and Haas under the
trademark, Amberlite.RTM..
The vinylacetamide monomer, with or without purification treatment,
is polymerized. This polymerization is carried out in a liquid
reaction medium using a free-radical initiator catalyst. There are
two classes of suitable liquid media. Polar hydrogen bonding
liquids, like water and lower alkanols, are suitable and function
as solvents for the monomer and the polymer product. Non-polar
liquids, such as hydrocarbons, ethers, and ketones, are also
suitable, functioning as monomer solvents but not as solvents for
the polymer, such that the polymer forms a second phase. Lower
alkanols of from 1 to 5 carbons such as methanol, isopropanol,
n-butanol and the like, are preferred media, with isopropanol being
most preferred.
The amount of reaction media is generally selected to provide a
concentration of vinylacetamide monomer of from about 10% to 50% by
weight. Lower concentrations could be employed, but are not seen to
offer any significant advantage.
A free-radical initiator is employed as catalyst. Suitable
catalysts include the organic peroxides and other materials known
in the art for this purpose. A commonly available and thus
preferred catalyst is AIBN, 2,2;-azobis-(2-methylpropionitrile).
The amount of catalyst is not critical. Generally, amounts of from
0.1 gram to 20 grams of catalyst per 100 grams of vinylacetamide is
employed with additions of from 1 to 10 grams of catalyst per 100
grams of vinylacetamide being preferred.
The polymerization is carried out at a moderately elevated
temperature such as from about 25.degree. C. to about 125.degree.
C., with temperatures of from 50.degree. C. to 110.degree. C. being
preferred. The polymerization requires from about 4 to 8 hours to
complete, depending upon the exact temperature, catalyst, and
monomer concentration employed. Generally, the reaction will be
monitored by NMR or gas chromatography for unreacted monomer and
continued until no significant monomer remains, for example, less
than 5%, preferably less than 1%. Reaction medium is then removed
and the polymer is recovered by precipitation in a non-solvent.
Typical non-solvents include nonpolar organic liquids such as
ketones, ethers and hydrocarbons. Suitable non-solvents include
acetone, methylethylketone, methylisobutylketone, diethylether,
diisopropylether, hexane, cyclohexane, n-pentane, benzene, and the
like.
Following precipitation, the polymer product is recovered, washed,
and optionally dried.
In the next step, the poly(vinylacetamide) product is hydrolyzed to
poly(vinylamine) salt. This hydrolysis is suitably carried out in
water in the presence of a strong acid. At least one equivalent of
acid per equivalent of poly(vinylacetamide) should be used, such as
from 1.05 to 3 equivalents of acid per equivalent of polymer. Too
great an excess of acid can cause the hydrolysis product to
precipitate prematurely. Suitable acids include, for example,
hydrochloric, sulfuric, p-toluene sulfonic, trifluoroacetic and
hydrobromic acids, with hydrochloric acid being preferred. This
hydrolysis is carried out at elevated temperatures such as at the
reflux temperature of the solution (110.degree. C.) or temperatures
in the range of from about 60.degree. C. to 175.degree. C. and,
depending upon the temperature, requires from about 1 hour to about
36 hours, preferably 3 hours to 12 hours, to complete.
Following hydrolysis, the polymer salt can be recovered by further
acidifying to cause it to precipitate. This may be carried out by
adding additional acid to a concentration of 1 to 3 normal,
cooling, and isolating the precipitating polymer. The precipitated
polymer initially is a gum, but, upon drying forms a granular solid
of poly(vinylamine) salt, such as the hydrochloride or the like.
This product is a linear repeating polymer of the formula ##STR2##
wherein n is 50 to 10,000 so as to provide a molecular weight of
from about 4,000 to 800,000 and X.sup.- is the anion corresponding
to the acid employed in the hydrolysis.
The process may be halted at this point, yielding as its product
poly(vinylamine) salt. It also may be carried further, such as to
form the free amine. This conversion may be effected by contacting
the salt with an aqueous base such as an alkali metal or alkaline
earth metal oxide or hydroxide, at a pH of 10 or greater. Typical
useful bases include sodium hydroxide and potassium hydroxide.
Other basic materials may be used as well, but are not as
advantageous costwise. This neutralization may be carried out at
temperatures in the range of 15.degree.-50.degree. C. such as at
room temperature. This yields the polymeric free amine which may be
isolated and dried, if desired. The polyvinyl amine product is a
linear polymer. It is water soluble and has a formula ##STR3##
wherein n has a value of from 50 to 10,000 such that the polymer
has a molecular weight of from about 2000 to about 450,000.
One excellent use of the polymeric amine is in the manufacture of
polymeric azo and non azo colorants with the amine functionalities
being useful for attaching the chromophoric groups to the polymer
backbone.
In one preferred embodiment of this invention, the free amine is
directly converted into a polymeric dye precursor by a
"Schotten-Baumann" type reaction. In this reaction the polymeric
amine is formed and contacted with an aromatic compound containing
an amine precursor functionality and a sulfonyl chloride
functionality ##STR4## at relatively low temperatures (40.degree.
C. or less) and a pH of about 9-10. A typical reaction employs an
aqueous reaction solvent, preferably also containing some
water-miscible polar organic solvent such as tetrahydrofuran,
dioxane, dimethoxyethane, diglyme, isopropanol or t-butanol and
vigorous agitation.
Suitable aromatic compounds for use herein are n-acetylsulfanilyl
chloride ##STR5## benzenesulfonyl chloride, tosyl chloride,
p-bromobenzenesulfonyl chloride, p-nitrobenzenesulfonyl chloride,
methanesulfonyl chloride and p-n acetylnaphthalene sulfonyl
chloride ##STR6##
The concentration of polyamine in the solution should be maintained
at from about 1% to about 20%, preferably at concentrations of
about 5% to 15%, lower concentrations being uneconomic and higher
concentrations leading to poor reactions. As a rule, the aromatic
compound should be added gradually over a period of at least about
0.25 hours. During this addition, the pH should be monitored and
maintained between about pH 9 and 10. After the addition is
completed, the pH may suitably be raised somewhat, such as to
10-11, and the mixture stirred for an additional 0.5 to 4 hours.
The reaction which occurs is as follows in the case where
n-acetylsulfanilyl chloride is employed: ##STR7##
The product of this reaction may be isolated by stripping off the
organic solvent and filtering. It is useful as a precursor in the
formation of polymeric dyes. In this use, first it is contacted
with acid (generally a substantial excess of aqueous mineral acid
solution such as from 3-10 equivalents of acid per equivalent of
acetyl groups) to deacetylate it. The deacetylation is not a rapid
reaction, requiring about 6 hours at reflux temperature
(100.degree. C.). Higher or lower temperatures (200.degree. C. or
50.degree. C.) could be used if desired with accompanying changes
in reaction time. This deacetylation produces the polymer ##STR8##
wherein X.sup.- is the cation corresponding to the mineral acid
employed.
This product is next diazotized and coupled to form a dye.
Diazotization is carried out on the polymer solution at low
temperatures (0.degree. C. to about 35.degree. C.) in the presence
of a molar excess of nitrate, such as sodium nitrite, potassium
nitrite or the like. The diazotization is essentially
instantaneous, requiring only a minute or two to complete so that
reaction times of from about 0.1 minute to about 2 hours may be
used. After diazotization is completed, the solution is added to a
0.degree. C.-15.degree. C. chilled solution of a chromophoric
coupler at pH of about 13.0-13.5. This causes the desired azo dye
to form. Suitable couplers include the wide range of coupling
materials known in the art for forming azo dyes, including
Schaeffer's salt, ##STR9##
After coupling, the resulting solution is colored. It may be used
as such as a dye or colorant or it may be further processed to
isolate and/or purify the polymeric colorant component. These
colorants find a wide range of applications coextensive with
colorants of the prior art. They find a special application as
well, as nonabsorbable food colorants, because their size permits
them to be taken into the gastrointestinal tract and passed
therethrough with a minimum of absorption into the systemic
circulation. This assures that the products will have minimized
toxicity risk compared to monomeric colorant compounds which can be
absorbed through the gastrointestinal tract walls into the systemic
circulation.
The invention will be further described with reference to the
accompanying drawings.
Turning now to FIG. 1, a schematic flow diagram representing a
semi-batch embodiment of the process of this invention is there
depicted. Acetamide and acetaldehyde in a mole ratio of about 2-3
moles of acetamide per mole of acetaldehyde are charged to reactor
11 via conduits 12 and 14 respectively. Mineral acid (6 M sulfuric
acid) is charged to reactor 11 through conduit 15 in an amount of
0.05 equivalents per mole of acetaldehyde. The mixture is heated to
about 60.degree. C. by means not shown while stirring with agitator
16 driven by electric motor 17. After about 15 minutes, there has
been substantial reaction to form ethylidene-bis-acetamide,
CH.sub.3 --CH(NHCOCH.sub.3).sub.2. An acid acceptor or base, in
this case calcium carbonate, is added to reactor 11 via conduit 19
in an amount sufficient to neutralize the mineral acid present. A
high surface area, solid, inorganic oxide catalyst (Celite) is
added to the mixture via conduit 20. Stirring is continued and the
reaction temperature is raised to about 200.degree. C., causing the
ethylidene-bis-acetamide to crack, yielding vinylacetamide. A
vacuum is drawn on reactor 11, causing the vinylacetamide and
excess acetamide to volatilize and pass through conduit 21 to
condenser 22, where they condense and pass as a liquid through
conduit 24 to accumulator vessel 25. After the cracking is
completed and the vinylacetamide has been collected, waste is
withdrawn via conduit 26. Components of this waste stream,
including the acid neutralization products, catalyst, and any
further excess acetamide, may, if desired, be recovered. The
vinylacetamide and acetamide collected in vessel 25 may undergo
purification such as distillation, crystallization, or ion exchange
resin treatment if desired, by means not shown. The vinylacetamide,
with or without purification treatment, is passed via conduit 32 to
polymerization reactor 34, which is equipped with motor 35 and
agitator 36. A free radical-initiating polymerization catalyst is
added through conduit 37 along with a lower alkanol reaction
solvent such as methanol or isopropanol added through conduit 38,
and the reaction mixture is stirred at 65.degree. C. for 6 hours to
polymerize this vinylacetamide into poly(vinylacetamide), ##STR10##
This polymer product solution is then passed through conduit 39 to
precipitator 40, where it is continuously contacted with a flow of
non-solvent (acetone) supplied through conduit 41, to form a
suspension of solid polymer particles in the nonsolvent. Good
contact between the nonsolvent and the polymer product is assured
by disc agitator 42 driven by motor 44. This operation is carried
out at about 20.degree. C. The suspension is continuously passed
through conduit 45 to solid/liquid separator 46. Separator 46 can
take the form of a filter, a centrifuge, or equivalent means.
Liquid, consisting primarily of non-solvent (acetone), dissolved
residual acetamide, and lower alkanol reaction solvent is removed
via conduit 47 to means not shown either to effect disposal or
preferably recovery of its various components. Solid polymer
product passes through conduit 49 to hydrolysis reactor 50. Aqueous
hydrochloric acid in an amount of about two equivalents of
concentrated acid for each equivalent of vinylacetamide polymer is
added via conduit 51 and the mixture is agitated with agitator 52
(powered by motor 54) for about 6 hours while maintaining a reactor
temperature of about 110.degree. C. by means not shown. This
converts the vinylacetamide polymer to vinylamine hydrochloride
polymer. Additional hydrochloric acid (to 3 normal) is then added
to the reactor 50 via conduit 51 to precipitate the polymer. At
110.degree. C. the precipitated polymer is fluid and can be
isolated as a separate liquid phase alternatively. The two phases
are stirred while cooling to 30.degree. C. (to solidify the
polymer) and then continuously passed through conduit 56 to
solid/liquid separator means 57, which may be a centrifuge, a
rotary filter, a liquid stripper, or the like. In solid/liquid
separator 57 a liquid phase comprising a hydrochloric acid solution
is isolated and removed via conduit 59 optionally to recovery means
not shown and solid polyvinylamine hydrochloride is removed via
conduit 60. This solid polyvinylamine hydrochloride may be dried
and shipped to users or it may be further treated by means not
shown in FIG. 1 to yield further products.
FIG. 2 is a schematic flow diagram representing a section of an
embodiment of the process of this invention which permits continous
operation. In the embodiment of FIG. 2, the three steps which were
carried out batchwise in reactor 11 in FIG. 1 are carried out in
separate reaction zones. Reaction conditions and feeds are the same
as set forth in the description of FIG. 1, unless otherwise noted.
Acetamide, acetaldehyde, and sulfuric acid are continuously fed to
reactor 11 through conduits 12, 14 and 15 respectively and stirred
by motor 17 and agitator 16. The total liquid hourly space velocity
(LHSV) of the reactants into reactor 11 is about three reactor
volumes per hour. Reactor product, consisting primarily of
ethylidene-bis-acetamide, CH.sub.3 --CH(NHCOCH.sub.3).sub.2, is
continuously withdrawn and passed via conduit 18 to
neutralizer/mixer 11A where base (CaCO.sub.3) and Celite surface
catalyst are continuously added via conduits 19 and 20
respectively. These reactants are mixed by agitator 16A acting in
concert with motor 17A to yield a neutralizer/mixer product which
continuously withdrawn via conduit 18A and passed to reactor 11B.
Reactor 11B, stirred by agitator 16B and 17B, is maintained at a
temperature of about 200.degree. C.-225.degree. C. and an absolute
pressure of about 40 mm Hg and is of a size to yield a LHSV of
about one reactor volume per hour. These conditions effect cracking
of the ethylidene-bis-acetamide and volatilization of a
vinylacetamide product which is taken off as vapor through conduit
21, condensed in condenser 22, and continuously passed from the
reaction zone via conduit 24. This flow of vinylacetamide then may
be further treated in apparatus as shown in FIG. 1, with the
modifications that accumulator 25 may be omitted if desired and
that the passage of vinylacetamide to polymerization reactor 34 is
continuous. Similarly, in a continuous mode of operation, the
feeding of catalyst, the withdrawal of polymer product from reactor
34, its precipitation in precipitator 40, its isolation in
separator 46, its hydrolysis in reactor 50, and its final recovery
in separator 57 would all be carried out continuously.
As mentioned in the description of FIG. 1, it may be desired to
prepare poly(vinylamine hydrochloride) as the ultimate product of
this process. It may also be of interest to convert the
hydrochloride to the free amine, poly(vinylamine). This may be
carried out as shown in FIG. 3, which depicts in schematic flow
diagram a process for effecting this conversion. In FIG. 3, the
solid amine hydrochloride polymer, prepared such as in accordance
with FIG. 1, is passed through conduit 60 into reactor 61, where it
is stirred with aqueous base from conduit 62 (sodium hydroxide in
an amount of about 5 parts by weight of 10% NaOH per part of
polymer) for one hour at room temperature to yield the desired free
polyamine. The product is then passed via conduit 69 to ultrafilter
70 where sodium chloride, excess base, and other impurities are
removed and passed as a solution to waste or recovery via conduit
71. The poly(vinylamine) is removed through conduit 72 to dryer 73
where the poly(vinylamine) is isolated. Solid amine is removed via
conduit 75 to further processing, packaging or use as desired.
As will be appreciated by those skilled in the art, a continuous
mode of operation could be easily effected in the processes of FIG.
3 by continuous feeding and removal of reactants and reaction
products.
In a preferred application of this invention, poly(vinylamine
hydrochloride) is converted to the free amine, which is in turn
used as a precursor in the production of polymeric dyes and
colorings. FIG. 4 depicts a schematic flow diagram of one
semi-batch embodiment of this preferred application.
Poly(vinylamine) hydrochloride), prepared such as is shown in FIG.
1, passes through conduit 60 to reactor 61. Aqueous base (NaOH) is
added via conduit 62. Solvent (THF) is added via conduit 71.
N-acetylsulfanilyl chloride is added via conduit 78. The relative
amounts of these materials are:
______________________________________ poly(vinylamine
hydrochloride) 1.0 equivalents aqueous base 2.0 equivalents
N-acetylsulfanilyl chloride 0.1-3.5 equivalents solvent sufficient
to yield a 1-50% by weight emulsion
______________________________________
The mixture is maintained at a temperature of about
0.degree.-30.degree. C. and is stirred by agitator 64 and motor 65
for about 2 hours. The pH is maintained at pH 9-10 by base
addition. This causes the free amine to form and serially react
with the NH acetylsulfanilyl chloride in a Schotten-Baumann type
reaction to yield the polysulfonamide compound ##STR11##
The reaction mixture is passed through conduit 66 to solvent
stripping column 72 where THF is taken overhead and removed via
conduit 74, preferably for recycle to conduit 71. The removal of
solvent causes the polysulfonamide to precipitate and form a
slurry. This slurry is passed through conduit 75 to separator 67
where an aqueous liquid phase containing residual solvent, polymer,
and sulfonic acid salt and neutralization products is removed via
conduit 69 optionally to component recovery apparatus not shown.
Solid polysulfonamide is isolated in separator 67 and passed via
conduit 70 to deacetylation reactor 79 where it is stirred by
agitator 80 and motor 81 at 100.degree. C. for 2-14 hours with 3-20
equivalents of dilute aqueous hydrochloric acid supplied through
conduit 82. The reaction product, a solution of the deacetylated
polymer ##STR12## then is passed via conduit 84 to diazotization
reactor 85 where sodium nitrite (1.0 moles per equivalent of
polymer) is added via conduit 89 and stirred by agitator 86 and
motor 87 for 1/2 hour at 15.degree. C. to form a solution of the
diazotized polymer. ##STR13## This solution is passed through
conduit 90 to dye coupling reactor 91 and is stirred by agitator 92
and motor 94 with a dye coupler, such as Schaeffer's salt,
previously added via conduit 95. About 1.1 moles of coupler per
equivalent of polymer is employed. After about one-half hour of
stirring at about 10.degree. C., a polymeric dye is formed having a
structure ##STR14##
This material is water soluble, so that the reaction product is a
solution. The solution could be used as a colorant without further
treatment. More commonly, however, it is purified to remove
deacetylation products, excess sodium nitrite, unreacted dye
coupler and the like. In one embodiment, this purification is
effected by passing the solution via conduit 96 to dialysis unit 97
where these impurities are dialyzed into water supplied through
conduit 99 and removed via line 100 either to waste or preferably
to recovery means not shown. The purified solution of dye may then
be passed, if desired, via conduit 101 to concentration means 102,
where water is removed via conduit 104 and a concentrated solution
of dye or (if concentration means 102 takes the form of a dryer)
solid dye is recovered and removed via conduit 105. As with the
other batch processes here-illustrated, it can be readily seen to
modify this semi-batch reaction scheme to yield a continuous
process if desired.
The invention is further described by the following Examples. These
are merely to illustrate the invention and are not to be construed
as limiting its scope, which is instead set forth by the appended
claims.
EXAMPLE I
A. Preparation of Vinylacetamide
To 462 g of acetamide (technical) was added 12.45 ml of 6 M aqueous
sulfuric acid followed immediately by 168 ml (3 moles) of
acetaldehyde (90.sup.+ %). This mixture was stirred and heated
until the internal temperature reached 70.degree. C. (9 minutes).
After another minute of heating, the 95.degree. C. clear solution
spontaneously crystallized, causing a temperature rise to
106.degree. C. The reaction product, ethylidene-bis-acetamide, was
not separated. Heating and stirring were continued for another 5
minutes and a mixture of 60 g calcium carbonate (precipitated
chalk) and 30 g soft glass powder was added. The resulting mixture
was heated to cracking temperature and distilled at 40 mm Hg
(200.degree. C. bath temperature). When the internal temperature
reached 160.degree. C. (0.5 hr.), the receiver was changed. After
another 1.7 hr, the distillation was almost over, the stirrer was
stopped and the heating continued. Slow distillation continued for
another hour and was then stopped. The first distillation fraction
was 95.9 g of water and acetamide. The second fraction was 466 g of
orange oil and crystals. NMR indicated this mixture to contain 195
g vinylacetamide (76% yield), 217 g acetamide, and 54 g
ethylidene-bis-acetamide.
B. Polymerization of Vinylacetamide
A red-brown solution of 460 g of vinylacetamide, 557 g acetamide,
and 123 g ethylidene-bis-acetamide, (one-half of five combined
vinylacetamide preparations in accord with part A) in 570 ml
methanol was filtered through 250 g of Amerilite.RTM. IRC-50 ion
exchange resin over an eight hour period. The column was rinsed
with 1,000 ml methanol. The combined column eluant was stripped to
its original volume of 1,667 ml, treated with 7.75 g of AIBN
polymerization catalyst (1 mole %), deoxygenated, and stirred under
argon at 65.degree. C. for 15 hours to polymerize. Solid polymer
was precipitated from the resulting very thick solution by addition
to 15 liters acetone. The polymer was collected by filtration,
washed with acetone and dried in a vacuum oven (80.degree. C.) for
2 days to afford 459 g of crude poly(vinylacetamide) contaminated
with acetamide as a yellow, semi-granular solid having molecular
weight of 200,000 as determined by Gel Permeation Chromatography,
using demethylformamide as eluent and polystyrene as standards.
C. Hydrolysis of Poly(vinylacetamide) to Poly(vinylamine
hydrochloride)
The crude poly(vinylacetamide) obtained in part B (459 g) was
dissolved in 1,000 ml water with heating. Concentrated hydrochloric
acid (1,000 ml) was added and the resulting dark brown solution was
stirred and heated at a gentle reflux (97.degree.-106.degree. C.)
for 19 hours. A precipitate formed and was redissolved by addition
of 200 ml water. Reflux was continued and over the next 8 hours
1,000 ml water was added in several portions to maintain solubility
of the polymer. After a total of 27 hours at reflux, the polymer
was precipitated by the addition of 1,000 ml concentrated
hydrochloric acid. The mixture was cooled to 18.degree. C. and the
thick polymeric gum isolated by decantation and dried under vacuum
at 50.degree.-75.degree. C. with occasional pulverization for 40
hours to give 332 g of poly(vinylamine hydrochloride) as a brown
granular solid (77% yield from vinylacetamide, 59% from
acetaldehyde).
D. Conversion of Poly(vinylamine hydrochloride) to Sulfonamido
Adduct
70.0 G of the poly(vinylamine hydrochloride) of part C was added
with 0.7 liters of water to a 5 liter stirred flask. Water was
added to a volume of 7.0 liters. The pH was raised from 2.5 to 10.0
by addition of 2.5 M NaOH. Then 350 ml of tetrahydrofuran was added
to yield a solution of the free amine.
Next, 308 grams (1.5 equivalents) of N-acetylsulfanilyl chloride
was added slowly, pH being controlled at 9.0-9.5 by NaOH addition.
700 Ml of THF was added to maintain a solution. Additional NaOH was
added to carry the pH to 10.5-11.0. THF was stripped off under
vacuum. A precipitate formed and was collected and found to be the
polymer ##STR15## This reaction was repeated three times, yielding
a total of about 840 g of product.
E. Hydrolysis
The individual products of the four runs of part D were
hydrolyzed.
To a flask was added one of the reaction products, 1.7 liters of
water, and 440 ml of conc. hydrochloric acid. The mixture was
refluxed for 6 hours to yield a solution of the amine ##STR16## As
a precaution, the reflux was continued overnight. (This reaction
was repeated with each product of part D.)
F. Diazotization and Coupling
One of the solutions of part E containing 1.0 equivalents of
polymer and 6.0 equivalents of hydrochloric acid was cooled to
15.degree. C. 211 Ml of 5 N NaNO.sub.2 was added with stirring. The
mixture was stirred for 30 minutes. The solution was then
transferred to a solution of 249 g (1.15 equivalents) of
Schaeffer's salt in 6 liters of water and 8 equivalents of NaOH at
a temperature of about 10.degree. C. (maintained by ice addition).
This solution was stirred for 30 minutes. NaOH was added to pH 12
and a solution of the polymeric Sunset Yellow colored dye,
##STR17## was obtained. Water and low M.W. impurities were then
removed to yield the dye as a dry powder.
EXAMPLES II-V
A second product of part E of Example I was diazotized with
NaNO.sub.2 as set forth in part F of Example I. The resulting
solution was divided into several portions and treated with a
variety of coupling agents.
In Example II, a solution containing 0.29 equivalents of diazo
groups was treated with 143 g of pyrazolone T and after treatment
under the conditions of part F of Exaple I yielded 109 g of a
polymeric tartrazine colored dye.
In Example III, R salt was the coupling agent such that the final
dye had a formula ##STR18##
In Example IV, Chicago acid was the coupling agent such that the
final dye was ##STR19##
In Example V chromatropic acid was the coupling agent such that the
final product was
* * * * *