US 2656241 A
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Patented Oct. 20, 1853 UNITED STATES PATENT QFFICE FURTHER AMINIZED ANIINOALKYLATED CELLULOSES BY REACTING WITH ETH- YLENIMIN E Agriculture No Drawing. Application May 11, 1951; Serial No. 225,906
(Granted under Title 35, U. S. Code (1952),
see. 266) 6 Claims.
This invention may be manufactured and used by or for the Government of the United States of America for governmental purposes throughout the world without the payment to use of any royalty thereon.
This invention relates to cellulose derivatives which contain nitrogen in the form of amino groups and have ion-exchange properties which are not substantially altered by each used and regeneration.
The invention particularly relates to a process for producing a cellulose derivative which has a higher nitrogen content than that obtainable by the 2-aminoethylsulfuric acid process, which nitrogen is in a form more firmly bound than the nitrogen in compositions containing the same amount of nitrogen produced by the ethylenimine process.
One of the methods heretofore used to introduce amino groups involves the reaction of cellulose with an aminoalkylation agent such as a haloethylamino hydrohalide or with Z-aminoethylsulfuric acid in the presence of an alkali metal hydroxide. It has been well established that such reactions produce aminoalkyl cellulose ethers. Such aminoalkylated celluloses have proven to be resistant to the action of acids and bases. However, when more than about 1% nitrogen is so introduced, the others become more and more soluble in water, and the cellulosic fibrous character is lost in that cellulosic fabrics so treated become stiff and boardy.
Another method heretofore used to introduce amino groups involves the reaction of cellulose with imines such as ethylenimine. Chemists have been unable to conclusively establish whether all of the imine polymerizes upon the surfaces of the cellulosic fibers or whether some of it reacts to form aminoalkyl cellulose ethers. However, while up to about 10% nitrogen has in some manner been combined with, or on, cellulose by such a treatment, very little of the nitrogen is firmly bound. Even when the nitrogen content is low, upon treatment with aqueous acids or bases, a substantial amount of the amino nitrogen is lost.
The cellulosic derivatives containing amino groups and retaining a cellulosic fibrous character have been found to exhibit particularly valuable anion-exchange properties. Hoffpauir and Guthrie reported, J. Biol. Chem. 178, 207-212, that in the preparation of oilseed proteins, Aminized cotton fabric was the most satisfactory anion-exchange material for the preparation of protein, since a higher pH could be obtained with it and the ash and phosphorus content of the preparation were lower than that obtained with either of the commercial anion-exchange resins. The aminized cotton fabrics they used were pre pared by reacting cellulose with Z-aminoethylsulfuric acid in the presence of sodium hydroxide by the process of Patent 2,459,222 and contained 0.8% nitrogen.
We have found that while introducing additional amino groups by reacting an aminoalkylated cellulose with Z-aminoethylsulfuric acid in the presence of an alkali metal hydroxide, or introducing additional amino groups by reacting the composition produced by the reaction of cellulose with ethylenimine with additional portions of ethylenimine, tends to produce products which are soluble in water or easily decomposed by aqueous acids or bases; surprisingly, if an aminoalkylated cellulose is reacted with an alkylenimine, a totally diflerent type of product is produced. The product produced by this latter method retains a cellulosic fibrous character, and is more resistant to the action of aqueous acids 3 and bases than is a product containing a like amount of nitrogen produced by the ethylenimine method. It is therefore apparent that reacting an aminoalkylated cellulose with ethylenimine produces a different substance than is produced by retreating cellulose one or more times with either an aminoalkylating agent such as Z-aminoethylsulfuric acid or with an alkylenimine such as ethylenimine.
While the invention is not to be construed as being dependent upon the occurrence of a particular series of reactions, a possible explanation of the difference in the respective further aminized products is the following. Aminoalkylated celluloses contain aminoalkyl groups attached to the cellulosic nucleus by the relatively stable ether linkage. When the ethylenimine is in contact with cellulose it is reasonable that the polymerization of ethylenimine predominates, and the relatively soluble polyethyleneamine molecules form on the surfaces of the cellulosic material. 0n the other hand, when the ethylenimine is in contact with aminoalkylated cellulose, it is reasonable that the reaction of the amino groups of the cellulose derivative with the ethylenimine predominates, and the aminoethyl groups on the cellulosic nucleus are converted to poly(ethyleneamino) aminoethyl groups. The occurrence of the above series of reactions would account for the fact that the reaction of aminoretains a substantially unchanged"ion-exchangecapacity through at least four use and regeneration cycles.
The further aminization processiof ,thisrinyenetion can be suitably applied to any form of an' aminoalkylated cellulose, for example to;am;ino.,- alkylated cotton, aminoalkylated,alpha-cellulose, aminoallgvlated viscose rayon, and-'the-like. PIB: ferred starting materials, comprise an aminoethylated cellulose containing from about 0.5 to 1.8% nitrogen; and suchstarting -materialsare preferably furtheram-inized according toour-invention until they-contain from about 2'to 5% nitrogen.
A" preferred-embodiment of the invention is in the-furtheraminizationof aminoalkylated cotton' cellulose in the form of yarn, particularlywhen the yarn'is treated assuch or while-made up into a fabric. However, in general, any oftheaminoalk-ylated celluleses can'be further-aminized by the process of the invention'in theform of-raw-fibers, sliver; or in-a disintegratedor powdered form;
The reaction is preferably conductedfbvcontacting the aminoalkylated cellulose with the vapors of 'ethylenimine at a temperature below the decomposition temperature of the cellulosic material; However; in-the further: aminization of-certain aminoalkylated'celluloses; the alkylenimine can'be'dissolved'in a solventinert to the aminoalkylatedcellulose and" the reaction con-'- ducted in solution, for example in a solution containing an imine such as N-cetyl ethylenimine in benzene, toluene; xylene, or other liquid hydrocarbons.
Ethylenimine is the preferredalk-ylenimine for employment inthe processof; the invention; However, alkylenimines such as-2 methylethylenimine,- 2,2-dimethylethylenimine and, in general; the homologsof ethylenimine can suitably be employed.
The reaction'can beeonducted at any temperature from aboutroom-temperature to-the-decomposition temperature of the cellulosic -material. However, temperatures of from ab'outfaf) -to-106 C. constitute-a preferred range of temperatures for employment in the process of the invention;
In conducting the process: inthe-preferred manner, i; e., in contacting-the aminoalkylated' cellulose withgthe vapors of theimine, it is-preferred to employ less than an equal: part of weight of ethylenimine. The use ofainounts-ofi from about 10: to" based upon .theweightof the: aminoalkylated cellulose have; been: found to b particularly suitablewhere the. cellulosici material is placed in an evacuated; chamber-a which the imine is. allowed to. evaporate.
Where it is desired, to produce a; product; hav ing arelatively high nitrogen content, theyreace tion is -preferabl-yaccomplished in ,several ,steps, contacting the aminoalkylated .cellulosewiththe preferred amount of imineimeach step.
The time. necessary to accomplish a given degree of furtheraminization, of course varies ,-wide- 1y. depending upon the temperature; and amount.
a ing atotal of 3. times.
of imine used. In general it has been found desirable to employ temperatures below about 100 C. and times of greater than about 6 hours for each treatment.
The following examples are presentedto illustrate in detail certain phases of the invention. However, as it is apparent that other materials, reactions, conditions.. and operative steps can be used, the: scope ofthe invention is defined by the appended claims, and the invention is not to -be construed asgbeing limited to the particular substancesgorronerations recited in the examples.
Example 1 The fabric was now placed in a vacuum cham-.
ber heated to. C? After-the.- chamoer had-been evacuated, ethylenimine was-introduced'dropwise into .the' chamber through an: addition tube. in
such awaythat it"vaporized 311.0808. The weight of ethylenimine used was 16 percent of the weight of "the fabric- After i the. fabric hadareactecl for tlhreeidays.- with the ethylenimine vapor, it was remoyed: and analyzed; It had an anion-exchange capacity of.1260:.milliequivalents per kg.
and anitrogen'contentzof-2i59 percent. After it hadbeen .used 201166-1130 remove: hydrochloric acid from: dilute aqueous solution, being regenerated with dilute ammonium hydroxide solution. it had;
an anion-exchange capacity of .1206 and a nitrogencontent of;2.l4.upercent.. After it. hadbeen used .four. times to removehydrochioric acid-fromdilute. aqueous-solutiomit had. an anion-exchange capacity-pf 1140::milliequivalentsper. leg. andia nitrcgenpontent ofz 2;.2'l percent;. some of: the.
fabric; wasboiledxfor. 61. hours; with 2 percent sodium :hydroxide solution. After this it had an anion-exchange- ;capacity'o-f :1560-. and-a nitrogen content 1 of 1.95 i percent.
In -Order to obtain: an. evf nz higher QJIiGIIrBLichange. capacity. the fabric wastrea-ted a second time=with ethylenimine- ,-by the. method 1 described,
above. The ionrexchan e capacity-was now 2070 milliequivalents. per and theni-trcgen content was-4.63 percent- After it had been usedonce. toremove hydrochloric acid from. dilute aqueous solution, being regenerated with dilute ammonium hydroxide solution, it had an anion-exchange capacity of1830'and'a. nitrogen content of 3.63 percent; After d'cycles as an anion-exchanger its capacity was 1830 milliequivalents per kg; and
its nitrogencontent was -S-J7'T-percent; After boiling-with sodium hydroxide solution as previously described its anion excha-nge capacity M mill-iequivalents per Kg; and itsnitrogen content. was-2:79 percent;
. nitrogen content was 1.58 percent. After boiling.
with sodium hydroxide solution as previously described, the values -were. 900 and. 1.39 respectively,
Thisfabric was again put. throughthe part of.
theprocess. using,zraminoethylsulfu-ric. acid, ,make
It .now had an anion.-
exchange capacity of 1290 and a nitrogen content of 1.97 but was stiff and boardy and beginning to lose its fabric structure. After boiling with sodium hydroxide solution as previously described, the values were 1050 and 1.55 respec tively.
For comparative purposes some of the original untreated fabric was cured with sodium hydroxide solution alone to give a control fabric and this was then processed with ethylenimine only at the 16 percent level as previously duscribed. The anion-exchange capacity was 770 milliequivalents per kg. and the nitrogen content was 2.20 percent. After it had been used once to remove hydrochloric acid from dilute aqueous solution, being regenerated with dilute ammonium hydroxide solution, it had an anion exchange capacity of 570 and a nitrogen content of 1.09 percent. After 4 regeneration cycles the values were 520 and 1.03 respectively. After boiling with sodium hydroxide solution as described previously the values were 380 and 0.75 respectively. When the control fabric was processed twice with ethylenimine alone at the 16 percent level as previously described the values were 1310 and 3.38 respectively, but these fell to 950 and 1.70 after one use and to 890 and 1.65 after four regeneration cycles. After boiling with sodium hydroxide solution as previously described the values were 680 and 1.26 respectively.
A summary of the ion-exchange capacity of the materials made in the above examples is given in the following table:
AESA represents Z-aminoethylsuliuric acid and Imine represents ethylenimine.
Example 2 Coarse cotton bagging was put through the Z-aminoethylsulfuric acid process 5 times using a solution composed of 65 parts water, 25 parts sodium hydroxide and 10 parts 2-aminoethylsulfuric acid. This was to determine how high an anion-exchange capacity could be reached by this process alone. The anion-exchange capacity was 1210 milliquivalents per kg. and the nitrogen content was 1.71 percent. The fabric was, however, stiff and boardy and beginning to show signs of going into solution. It was now processed with the vapor of ethylenimine at the 16 percent level in a manner similar to that described in Example 1. The anion-exchange capacity was now 2700 and the nitrogen content 5.00 percent.
Having thus described our invention, we claim:
1. A process for the production of a cellulosic anion-exchange material which comprises further aminizing an aminoethylated cellulose containing from about 0.5 to 1.8% nitrogen by reacting it with the vapors of ethylenimine until the reaction product contains from about 2 to 5% nitrogen.
2. The process of claim 1 in which the aminoethylated cotton cellulose further aminized is in the form of a fabric.
3. The process of claim 1 in which aminoethylated cellulose is further aminized by subjecting the aminoethylated cellulose to a series of further amim'zation treatments using about 15%, by weight, of ethylenimine vapors and a temperature of about 70 C. in each treatment.
4. A process of producing an ion-exchange fabric which even after use and regeneration for at least four cycles has an ion-exchange capacity of at least about 1400 mini-equivalents, and which possesses cellulosic fibrous character comprising: reacting aminoethylated cotton fabric containing 0.5 to 1.8% nitrogen with ethylenimine until the fabric contains from 2 to 5% nitrogen, the aminoethylated cotton being one obtained by treating cotton fabric with aminoethylsulfuric acid and sodium hydroxide.
5. The process of claim 4 in which the ethylenimine is in the form of a vapor.
6. The process of claim 4 in which the ethylenimine is dissolved in an organic solvent.
GEORGE L. DRAKE, JR. JOHN D. GUTHRIE.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,097,120 Fink et a1 Oct. 26, 1937 ,45 ,222 Guthrie Jan. 18, 1949