CA1199910A - Process for removing impurities from polyalkyleneoxy coloring agents - Google Patents

Abstract

Abstract Of the Disclosure A process is provided for removing impurities from a polyalkyleneoxy coloring agent, which comprises heating a crude reaction product containing the polyalkyleneoxy coloring agent and impurities to a temperature at which the crude reaction product separates into two liquid phases, one phase containing the coloring agent in relatively pure form and the other phase con-taining the impurities; and separating the phase containing the coloring agent from the phase containing the impurities.

Description

~` - ~ ~
case 1 ILIL¢~9 PROCESS FOR REMOVING IMPURITIES FROM
POLYALKYLENEOXY COLORI NG AGENTS

The present invention relates to a process for purifyiny ~olymeric coloring agents. More particularly the present inventio relates to a process for separating poly~eric alkyleneoxy coloring agents from impurities normally ~resent in a crude reaction pro-duct by means of ~he cloud point phenomenon.
Polymeric, alkyleneoxy, chromophoric group containing com-pounds have been known for manv years as disclosed in U. S.
Patent Number 3,157,633 to Ruhn Typically such compounds may be water soluble and they have accordingly ~een used extensively, as disclosed by Kuhn, as ugi-tive tints in the textile industry because they may be easily re-moved from textile fibers by scouring with aqueous solutions.
Recently, it has been discovered that certain polyalkyleneo compounds may advantageously be employed as colorina agents in resin svstems where the coloring agent may react with the resin and actually be bound to the resin by covalent bonding. Such coloring agents and methods for colorin~ resins are disclosed in U.S. Patent Number 4,284,72g filed March 31, 1980 to John P. Cross and ~.eorge H. Britton, JrO Un-fortunately, however, the methods known in the art for preparing ~olyalkyleneoxy compounds, as disclosed for instance in the Kuhn patent, have typically resulted in a reaction product being pro-vided in the form of an aqueous solution containing substantial amounts of water soluble impurities, e.g., inorganic salts, which may be detrimental in end use applications of the ty~e disclosed in the Cross et al. application, ~hat is where the~ are emploved as coloring agents. It, th~refore, would be hiqhly desirable to I

~ 39~

remove those impurities from the compositions before they are actually employed for their intended end use applications. Thus, the present invention is directed to a method whereby such im~
purities may be removed from pol~meric, polyalkyleneox~ coloring agents.
Accordlng to the present invention a process is provided for removing impurities from a polvalkyleneox~ coloring agent, which comprises heating a crude reaction product containing said polyalkyleneoxy coloring agent and impurities to a temperature at which the crude reac-tion product separates in-to two liquid phases, one phase containing said coloring agent in relatively pure form and the other phase containing said impurities; and separating the phase containing said coloring agent from the phase containing said impurities.
~he polyalkyleneoxy coloring agents oE the present inven-tion may be provided in the liquid or solid phase at ambient con-ditions of temperature and pressure. Preferred compounds accordinl J
to the invention ~.ay be characterized by the general formula:
R-(polymeric constituent-x)n where R is an organic dyestuff radical, the polymeric constituent is selected from polyalkylene oxides and coPolymers of polyalky-Lene oxides in which the alkylene moiety of the polymeric con-stituent contains 2 or more carbon atoms, and such polvmeric con-stituent has a molecular weight oE from about 100 to about 10,000;
n is an integer of from 1 to about 6; and x is selected from -OH, -NH2 and -SH. Preferred amongst the compounds of the abo~e formul ` are those wherein R is attached by an amino nitrogen to thepolymeric constituent. Compounds contemplated within this class are those wherein R is a nitroso, nitro, azo, including monazo, ~L~g99~ ~

diazo and triazo, diphenylmethane, triarylmethane, zanthene, acridene, methine, thiazole, indamine, azine, oxazine, or anthraquinone dyestuff radical~
A preferred method for preparing the polyalkyleneoxy coloring agents which may be purified according to the present invention is to first convert a colorless intermediate compound into the corresponding polyethyleneoxv compound and then ernploy the resulting compound -to produce compounds having chromophoric groups in the molecule. For instance, in the case of azo dye-stuffs, this may be accomplished bv reaeting a primary or secondary aromatic amine, preferably the former with ethylene-oxide, propyleneoxide or mixtures thereof aecording to proeedures well known in the art and then coupling the resulting eompound with a diazonium salt of an aromatic amine.
lS Some of the other classes oE dyestuffs such as the anthra-~uinones having ehlorine, bromine or iodine attached to the aromatie nucleus, may be reaeted with, for instance, exeess polyalkylene glyeol monoamine to produee the eorresponding seeondary amine.
~0 The polyethyleneoxy group can be introduced in other wat~s to produce the polyalkyleneoxty coloring agen-ts. For examPle, anthraquinone-2-carboxylic acid can be reacted with a molar excess of a polyethylene glycol ~aving a moleeular weight above about 1350, e.g., in the ~resence o~ p-toluene-sulfonic acid in a suit-able solvent, e.g., dioxane or nitro-benzene, to ,~roduee the eorresponding polvethvlene glyeol monoester of anthra~luinone-2-earboxylie acid. The reaction can also be conducted on other anthraauinone carboxvlic acids eontaining one or more additional ~ 9~l~

chromophoric or other non-interfering groups in the molecule. An aromatic amine, e.g., aniline or nuclear suhstituted aniline, can be reac-ted with a ~olyethylene glycol as described above under pressure at a -temperature of about 220C to 230C, preferably in the presence of iodine or a copper or sodium hal.ide as a ca-talyst.
The resulting amine, e.g., the polyethylene glycol substituted aniline, can then be coupled with the usual diazonium salts, e.g., H acid, to produce a diazo polyalkyleneoxy coloring agent.
An aromatic bromo compound, e.g., 2-bromoanthraquinone, can be reacted with polyethylene glvcol in -the presence of sodium at 150C to produce the corresponding anthra~uinone polyethylene glv-col ether. A nitrophenol, e.g., p-nitrophenol, can be reac-ted with polyethylene glvcol in the same manner to produce the p-nitrophenol polyethy]ene glycol ether. I'his compound can then be reduced by any of the me-thods well known in the art for re-ducing aromatic nitro groups, e.g., 2inc and acetic acid, hydrogen and catalyst, to produce the corresponding p-amino compound which can then be dia~otized and coupled with a suitable aromatic com-pound, e.g., "H" acid, to produce a polyalkyleneoxy coloring agent ~0 which may be purified according to the present invention.
Typically, all of the above procedures for preparing ~oly-meric, alkyleneoxy, chromo~horic group containing compounds may result in the compound being produced in a crude reac-tion mixture containing substantial amounts of impurities in the form of by-products produced during the svnthesis of the desired compound.
These materials are generally wa-ter soluble, e.g., inorganic salts, as is the chromophoric group containing compound makiny separation based on differiny solubilitY ~uite difficult if not impossible.
~rheir pr ence, furthermore, is undesirable ln a colorinq aqent 11~991(~

product desiqned, for instance, for incorporation into urethanes by the formation of covalent bonds because they may interfere with the polymerization reaction. Until the present invention, further more, no fully satisfactory method has been available for the re-moval of such impurities from the reaction mixture. It has now been discovered, however, that by makiny use of a rather unus-lal property of these compounds a simple, and effective separation of the compounds from impurities ~resent in the crude reaction mixtur may be accomplished. The separation is accomplished by simply heating the crude aqueous reaction mixture at least to the cloud point. On passing the cloud point, the crude reaction mixture separates into two phases - one phase containing the colorant and a second aqueous phase containing substantial amounts of impuritie such as water solub:le sa:lts. 'l'he two phases may then be separated by any of the means known in the art. Additional water may be added to the colorant containing phase and the separation may be repeated one or more times to further purify the colorant.
The following examples illustrate the invention but are not to be construed as a limita-tion thereof. The ~arts and percentage are all by weiyht unless otherwise specified.
PREPARATION I
__ Ethylene oxide was bubbled into warm aniline under nitroyen until two molar e~uivalents of ethylene oxide were consumed~ Ther was thus produced N,N-dihydroxyethylaniline, which solidified on coolin~ to room temperature.
Similarly, meta-toluidine was treated with ethylene oxide producinq N,N-dihydroxyethyl-m-toluidlne.
PREPI~RATION II
______ .
Five hundred forty-three grams (3 moles) oE N,N-dihydroxy-ethylanil e and 2.S qrams pota~]um hydroxlde wer- placed in a l~L99910

2 liter stainless steel ~ressure reator e~uinped with an agitator gas inlet tube and vent. Af~er purgincj wi-th nitrogen, the reactor and contents were heated at 100C under vacuum and held on temper-ature for 0.5 hours. The vacuum was bro~en with nitrogen and the reactor was heated to 150C. Ethylene oxide was added through the inlet tube until eight eauivalents were consumed. ~fter ?ost reacting for 30 minutes, the mixture was subjected to vacuum for 30 minutes, then cooled to room tem~erature. The thus produced intermediate:
~ (CH2CH2-ot5H
~ -N
~CH2CH2 Ot5H
was an amber, freeflowing liquid.
PREPARA'rION III
The method of Preparation II was followed, using ~1,N-dihydroxyethyl-m-toluidine and enough ethylene oxide to add eight moles. The product was -the formula:

~ ~ ~(cFl2cH~-~tsH

(CH2CH2 O~5H
and was a liquid at room temperature.
EXAMPLE I
To a 2 liter glass reactor was charged aniline (47.9 grams, 0.52 moles), which was cooled to 0C. Hydrochloric acid (16:l grams) was added dropwise with stirring, and the resulting mix-ture cooled to 0C. Sodium nitrite (40.3 grams, 0.58 moles) was dis-solved in wa-ter (80 milliliters) and added dropwise to the aniline solution while maintaining the temperature helow 5C. ~1hen 11999~0 addition was complete, the mixture was stirred for 30 minutes and excess nitrite was confirmed by sta-cch-iodide paPer~ Sulfamic acid was added i~n portions until excess ni-trite was consumed.
In another reactor, the intermediate of Pre~aration III
(282 grams, 0.52 moles) was charged. ~ solution of sodium acetate (29.6 grams, 0.36 moles) in water (51 milliliters) was prepared.
The previously prepared aniline diazonium solution was added in portions using the sodium aceta-te solution to maintain the pH of the coupling bath at 4-5. rremperature was maintained below 10C.
'I'he mixture was DOS t-stirred for one hour after addition of dia-zonium salt was complete.
The mixture was poured into a beaker and heated to 95C
on a steam bath. The colorant formed a layer on top of the solution and was decanted. 'L'he thus isoLated material, a dark liquid, was treated with an equal volume of water and heated to 35C whereupon the formation of two phases again occurred. This time the colorant formed a layer on the bottom. The aqueous layer was decanted and discarded. The colorant was again treated with water and two phases formed by heating to 95C. Tlle aqueous layer ~0 was decanted and discarded.
After removing vola-tile componen~s at 85C and 2 m~Hg vacuum to 99.4 percent nonvolatile, a yellow colorant was ob-tained:

~ ~ 3 N /
(Cil2CH2-Ot5H

1~99~310 EXAMPLE II
In a manner similar to Example 1, aniline and the e-thoxy-lated intermediate of Preparation II were coupled glving a yellow colorant of the structure:

~ ~ ~ /(CH2CH2-O~5H
(CH2CH2-Ot5EI

EXAMPLE_III
In a manner similar to Example I, 2-amino-5-nitroanisole and the intermediate o:E Preparation III were coupled givinq a red colorant:

O - ~ W =W ~ 2 2 tS

CH3 (CH2cH2-~5H

EXAMPLE IV
Using the methods described in U. S. Patent 4,137,243, a colorant was prepared from quinizarin and a diamlne of molecular weight 230 derived from a polypropylene oxide. The resulting viscous blue colorant has the structure CH3 C1~3 H ~ ~ (CH2-C~I-Otl 6CH2CH-NH2 \., ~d ( 2 H Otl 6CH2CH NH2 ~ 9~3 EXAMPLE V
_ Using standard procedures, 2-amino-6-methoxvbenzothiazole was dia~otized with nitrosylsulfuric acid and coupled with the intermediate of Preparation III at a pH of 2. After a procedure similar to that of Example I, a red colorant was obtained:

CH30 S (CH2CH2-O~5H
: CH3 EXAMPLE VI
__ Exam~-le of Incor~~oration into_a FLexible PoLyester E~olvurethane Foam ,~
To a mixture of a pol~ester ~olyol of hydrox~$71 number 46 (100 grams), water (3.6 yrams), a silicone based emulsifier (1.3 grams), stannous octoate (0.4 grams) and ter-tiarv amine catalyst (0.3 grams) was added 0.1 gram (0.1 ph~) of the yellow . single component li~uid reactive coloring agent of Example I.
The mixture was stirred for 30 seconds to ensure a homogeneous mixture. Toluene diisoc~7anate (45.7 grams) was added and mixing continued for 5 seconds whereupon the Eoam began to rise. After foam rise was completed (about 3 minutes), the foam was post-cured for 8 minutes in a 120C oven. The ~thus produced foam was butter vellow in color.
EXAMPLE VII
_. _ Incorporation into a PolYurethane Film A urethane prepolvmer was prepared from :lO4 grams of a polyDrop~lene glycol of molecular weight 2000, 22.5 grams of _g_ ~39g~

toluene diisocyanate, 3.2 grams of the red coloring agent of Example III. To 30 grams of the prepolymer was added 7 drons of dibutyltin dilaurate and the resulting mixture was cast as a 40 mil fi.lm on ~olyte-trafluoroethylene. A:Eter curing at room temneratllre overnight, a tough, ~lexib]e "~eep red film ~as obtained.
r AMPLE VIII
Inco~ration into an E~oxy To a mixture of 58 grams of an epoxy resin derived from bis-phenol A with weight per epoxy of about 185 to 192, 54 grams of methyltetrahydrophthalic anhvdride and 0.66 grams of a tertiary amine catalvst was added 1 dro~ of the hlue coloring agent of Example IV. After curing at 110C, a clear blue resin was obtained.
1 5 _XAMP LE I X ~
Example of Incor~oratio_ i.nto a Polyester Polyurethane Foam A mixture of a polydiethylene adipate (equivalent weight . 1066, 50 grams), N-ethylmorpholi.ne (0.9 grams), N,N-dimethyl-hexadecylamine (0.05 grams), a mixture of nonionic and anionic surfactants and the coloran~ of Rxample I ~0.25 grams) was blended until the components were homogeneous. To this mixture was added toluene diisocyanate (22,3 grams) and mixing was con-tinued for 5 seconds. The mixture was poured into a container and allowed to rise forming a ~ellow flexi.ble urethane foam.
E A~1PLE X
Example of Incorporat.ion into a Reaction In~ection Molding _ _) Fo _ ulation A mixture was prenared of an acrylonitrile and styrene modified polyol (equivalent weight 2000, 42.5 grams), a mixture of sho dlols (equivalent weiqht ~8, 7.5 grams), meth~lene 11~99~0 chloride (1.0 grams), dibutyltin dilaurate (1 drop) and 0.25 gra~s of the colorant of Example V. 'I'he mixture was blended until homogeneous. To this mixture was added a modified diphenyl-methane diisocyanate (equivalent weight 147, 26.6 grams) and blending continued for 5 seconds to ensure homogeneity. AEter approximately 15 seconds the mixture rapidly tripled its volume and cured. The thus formed polymer was deep violet in color.
Upon slicing, it was evident that the color was distributed evenly throughout the structure.

Claims (7)

WHAT IS CLAIMED IS:

1. A process for removing impurities from a polyalky-leneoxy coloring agent, which comprises heating a crude reaction product containing said polyalkyleneoxy coloring agent and im-purities to a temperature at which the crude reaction product separates into two liquid phases, one phase containing said coloring agent in relatively pure form and the other phase con-taining said impurities; and separating the phase containing said coloring agent from the phase containing said impurities.

2. The process of Claim 1 wherein said polyalkyleneoxy coloring agent is a reactive coloring agent.

3. The process of Claim 1 wherein said polyalkyleneoxy coloring agent is selected from compounds characterized by the general formula:
R-(polymeric constituent-x)n where R is an organic dyestuff radical; the polymeric constituent is selected from polyalkylene oxides and copolymers of polyalky-lene oxides in which the alkylene moiety of the polymeric con-stituent contains 2 or more carbon atoms and such polymeric con-stituent has a molecular weight of from about 100 to about 10,000;
n is an integer of from 1 to about 6; and x is selected from -OH, NH2, and -SH.

4. The process of claim 2 wherein R is attached by means of an amino nitrogen to the polymeric constituent.

5. The process of Claim 2 wherein R is selected from nitroso, nitro, azo, including monazo, diazo and triazo, di-phenylmethane, triarylmethane, zanthene, acridene, methine, thiazole, indamine, azine, oxazine, or anthraquinone dyestuff radical.

6. A process for removing impurities from a polyalky-leneoxy coloring agent, which comprises converting a colorless intermediate compound into the corresponding polyalkyleneoxy compound; employing the resulting compound to produce compounds having chromophoric groups in the molecule in a crude reaction mixture containing impurities; heating the crude reaction mixture to a temperature at which the crude reaction product separates into two liquid phases, one phase containing said coloring agent in relatively pure form and the other phase containing said impurities; and separating the phase containing said reactive coloring agent from the phase containing said impurities.

7. The process of Claim 6 wherein said polyalkyleneoxy coloring agent contains an azo group as the chromophoric group, said colorless intermediate compound is an aromatic amine selected from primary or secondary amines; said aromatic amine is reacted with an alkylene oxide selected from ethylene oxide; propylene oxide and mixtures of ethylene oxide and propylene oxide; and the resulting compound is coupled with a diazonium salt of an aromatic amine.