IN1
M.~Y
1-hCI1YL.iMII)O-I -DEOXY-D-GLUCITOL
content of the acetate (less than 7%) precluded the presence of additional acyl groups. Infrared spectm. Infrarrcl a1)sorption spectra wcre oht:rinrd with n Pcrkin-Elmer model 21 rc,cording sprctrophotonwtrr using a sodium chloridc prism.
Acknowledgment. The authors wish to thank Dr. Marion A. Buchanan for assistance with the
[CONTRIBUTION FROM THE
1583
gas chromatographic analyses and Mr. Lowell Sell for the infrared spectra reported in this paper. The authors wish to thank &* H. A* Schuette of the University of Wisconsin for a sample of authentic n-pentadeeanoic acid. APPLETON,WIS.
DEPARTMENT O F BIOCHEMISTRY, PURDUE
UNIVERSITY]
1-Acrylamido-1-deoxy-D-glucitol, 1-Deoxy-1-methacrylamido-D-glucitol and
Their Polymerization' ROY L. WHISTLER, HANS 1'. PANZER,
HUGH J. ROBERTS
AND
Received J u l y 8,1960 1-Acrylamido-1-deoxy-D-glucitol and 1-deoxy-1-methacrylamido-D-glucitol are synthesized from 1-amino-l-deoxy-Dglucitol (o-glucamine) and the appropriate acid anhydride. In an alternate synthesis acryloyl chloride replaces acrylic anhydride, and D-glucamine oxalate may replace the free hasc. The amides are relatively resistant to alkaline hydrolysis. Polymerization of the amides is initiated by high energy radiation, by decomposition of peroxidic or azo-type catalysts, and by redox catalyst systems. The polymers are water-soluble and form visrous solutions which gel with borate ion. Copolymerization of the amides with other vinyl monomers also occurs. 1-.4cetamido-l-deoxy-~-g~ucito~ is synthesized and characterized.
A small group of neutral synthetic high polymers receive industrial attention because of their hydrophilic nature. Among these are polyacrylamide, polyvinyl alcohol, and polyvinylpyrrolidone. A polymer of st ill greater hydrophilicity might consist of a hydrocarbon chain with a sugar unit attached to alternate carbon atoms. Such a structure might also evidence some polysaccharide-like characteristics. To examine these possibilities, work was undertaken to synthesize and polymerizc sugar-substituted vinyl monomers. A straight chain sugar might be expected to confer greater water solubility than tlie ring form of the sugar. Consequently, the monomcrs ehoscn were the N acryloyl and N-methacryloyl dcrivatives of 1amino-1-deoxy-D-glucitol (D-glucaminc), a commercially available sugar.* Both 1-acrylamido-1deoxy-D-glucitol (I) and I-dcoxy-1-methacrylamido n-glucitol (11)should produce polymers more wntrrsoluble than thc polymcr3.4 from p-vinylphcnvl glucoside (111) which is soluhlc only in the low molecular weight range. N-Acylation of n-glucamine occurs readily in methanol a t -10" to 0" using the acid anhydride as thc acylating agent. However, with commercial (1) Prcwntctl, in part, brforc t h c Division of Cnrboh,ytlratc Chc~mistrya t the 135th Mceting of thc Xmvricnn Chvmird Socicty, Boston, Mass., April 1959; Journal I'qic~r S o . 1 G ? 2 of the Purdur Agricultural Experiment St:ttion. ( 2 ) R. B. Flint and P. L. Salhcrg, U. S. Pat. 2,016,962 ( 1!):3,5); nvnil:il)l(~from Corn Protliic-ts Company, Nwv York,
N. Y. ( 3 ) 1%. I-l~lfcxicliand If.-J. Riifmmri, Cheni. Ber., 8 5 , 17.5 (l!)R%).
acrylic or methacrylic anhydrides, the N-acetyl derivative is produced simultaneously due to acetyl impurity. In an alternate synthesis of the acrylamide derivativc, acrylic anhydride is replaced by acryloyl chloride, which is easily prepared from brnzoyl chloride and acrylic acid15 and I)-gliican~inc may be replaced by its oxalic acid salt. Each of the N-acyl derivatives of D-glucamine is water-soluble, neutral, and nonreactive toward 0 CH3 /I I
H O
I
11
H- N- C- C=CH2
N-C-CH=CH,
I
I I HCOH I
HCH
HCH
I I
HCOH HOCH
HOCH
I I
I HCOH I
HCOH
HCOH
H7OH
HZCOH I
HzCOH
I
I1 P a C H = C € K 2 H HCOH 71-
I
HOCH
[
HC
I
HzCOH 111 ( 5 ) G. H. Stempel, Jr., R. P. Cross, and R. P. Mariella, J . A m . Cheni,. Sac., 72, 2299 (1950).
1554
VOL. 2G
WHISTLER, PASZER, .4ND ROBERTS
TABLE I N-ACYLATED-D-GLUCAMINES Acyl Group
Carbon, yo Calcd. Found
Hydrogen, % Calcd. Found
Nitrogen, % Calcd. Found
~
CHZ:CH.COCHs:C(CHa).COCHaCO--"
45 95 48 18 43.04
45.98 48.31 41.43
7.28 7.68 7.68
~
6.95 7.61 7.54
M.P., '
~~
5.95 5 62 6.27
~
5.67 5.64 6.41
[a1*,"
RI
~~~
120-121 160-161 126-127
-2G.3(4.0, H20) -22.4(3.8,H20) -20.3 (2.9,H20)*
0.39 0 50 0.28
The elemental analysis was performed on a sample isolated by preparative papcr chromatography which contained b At 25".
1.93y0rwidiie on ignition.
TABLE I1 YIELDSOF POLYMERS. ?& A'-Acryl VI-D-gliwnmine( I ) 0 . l M Monomer 0 5 M Monomer Slow Fast Slow Fast Persulfate-bisulfite (HtO) Chlorate-sulfite (H20) Benzoyl peroxide (DMF) ru,a'-.4zoisohiityronitrile ( D M F )
95 63 17 68
78 71 87 91
89 54
52 56
72 79
N-Methacr).loyl-D-gliicamine (11) 0 . ldf hlonomer 0 5dkfMonomer Slow Fast Slow Fast
0
19 67 0 0
83 64
47 0
0
35 70 17" $8"
27 61 31° 29"
Saturated solution of monomer.
ninhydrin. Their infrared spectra show major absorption bands at 3.0 p (broad), 3.33-3.45 p , 6.1-6.2 p, and 6.4-6.5 w , corresponding respectively t,o E-H and 0-H stretching (superimposed) , C-H stretching, amide I and amide I1 vibrations. A C=C absorption band is present at 6.03-6.04 p in I and 11, but absent in the Ai-acetyl derivative. A lack of absorption bands in the 5.7-5.8 p region shows the absence of ester carbonyl groups. These data, together with the element'al analyses (Table I), establish that the compounds are the expected N-acyl derivat,ives of D-gliicamine. It was of interest tJoinvestigate the susceptibility of these amides t,o alkaline hydrolysis. Both unsaturated amides are resistant to weak base, while in strong base I1 hydrolyzes slowly, and I hydrolyzes somewhat more rapidly, although still more slowly than the N-acetyl derivative (Fig, 1). The order of susceptibility of these molecules to basecatalyzed hydrolysis is in accord with the expected effects of resonance stabilization by the double bond and steric hindrance by the a-methyl group. In preliminary experiments it was found t'hat saturated aqueous solutions of compounds I and I1 are polymerized t,o viscous solritions by nltrnviolet and gamma irradiation, and t'o insoluble gels by ammonium pcrsulfate. It was also observed during attempts to purify crude monomer that peroxides present in et'hyl et'her can ca,talyze the polymerization of compound I. To invcst'igate the effects of different' chcJmical initiators under various condit ions, two factorial ~xpcriment~s were performed. I n the first, a 2j factorial, both monomers were polymcrizcd in aqueous solution with t,wo redox systems, at. t'wo lcvcls of monomer concentration, two lcvcls of initiator concentration, and t'wo cnmhinations of tcmperature and time. The polymcrs w r r isolated, the yields (per cent of nionomcr
I
I
40r
i
$
6W 30L 5
20
J
0
a
* = IO 0
0 0
20
40 60 HOURS
80
IO0
Fig. 1. Rates of hydrolysis of N-acyl derivatives of D-glucamirie, 0.2M in 2.34.U sodium hydroxidc solution a t 25".
converted to isolable polymer) measured, and their limiting viscosity numbers determined. The lower level of initiator concentration gave no polymcr. Jn the second factorial experiment both monomers were a t the same two concentration levels, but with dimethylformamide as solvent, and a single concentmtion of two thermal decomposition type catalysts was used with two appropriate combinations of time and temperature. The time and temperature combinations, while necessarily different for the two experiments, were chosen to permit a relatively slow and a,relatively rapid polymerization rate in each case (Tables I1 and 111).
MAY
I-ACRYLAMIDO-~-DEOXY-D-GLUCITOL
1961
TABLE I11 LIMITING. VISCOSITY NUMBERS OF POLYMERSO NN-Acryloylu-glucamine Slow Fast Persulfate-bisulfite
36.5
24.9
10.0 13.5
9 5
17.3
12.9
Methacryloyln-glucamiue Slow F a s t 38.1
24.9
(H20)
Chlorate-sulfite (H&) Benzoyl peroxide
(DMW
a,a'-Azoisobutyronitrile (DMF)
7.5
8.4 22.5b
7.0 0.8b
23.4b 10.1*
-
0 Monomer concentration 0.5211. Rhcre polymer was obtained from experiments with monomer concentration a t 0.1211, the viscosity numbers were too low for accurate measurement. * Saturated solution of monomer.
On subjection of the data from each experiment to analysis of variance it is observed that the major factors affecting the yield are the nature of the monomer, the nature of the initiator, and the concentration of the monomer. Compound I1 gives lower yields than compound I in all instances except those where the chlorate-sulfite redox system is the initiator. With the chlorate-sulfite system none of the factors tested has significant effect on yield. However, compound I gives significantly higher yields with persulfate-bisulfite than with chlorate-sulfite, while the reverse is true for compound 11. Benzoyl peroxide and a,a'-azOisobutyronit,rile (AIBN) produce higher yields from 0.5M monomer solutions than from 0.1M solutions and, while persulfate-bisulfite shows the same effect with compound 11, the reverse is true with compound I. There is also some indication of an interaction between the thermal decomposition type initiators and the polymerization conditions. Thus, a,a'-azoisobutyronitrile appears to give higher yields at the slower rate of decomposition while benzoyl peroxide may produce higher yields a t the more rapid decomposition rate. As expected, high limiting viscosity numbers are obtained when the higher monomer concentrations are coupled with the slower polymerization rate. The persulfate-bisulfite initiator system gives higher viscosity numbers than does the chlorate-sulfite system, while no significant difference in viscosity is observed between polymers initiated by benzoyl peroxide and those initiated by ala'-azoisobutyronitrile. When the two monomers are polymerized under the same conditions, the observed differences in limiting viscosity numbers are not statistically significant. However, additional replications of the experiment might show a significant interaction between monomers and polymerization conditions. That is, when polymerized with either benzoyl peroxide or ala'-azoisobutyronitrile at the slower rate, compound I1 may give polymers with higher viscosity numbers than those obtained from com-
1586
pound I, while a t the more rapid rate this effect may be reversed. All of the polymers represented in Table I11 have small limiting viscosity numbers. However, when concentrated aqueous solutions of monomer are polymerized with persuifate-bisulfite a t O", polymers having viscosities comparable to those of some of the natural and synthetic gums are obtained (Table IV). These polymers are apparently cross linked, since in water they are extensively hydrated but not completely dtissolved. The presence of one mole of N-acetyl-D-glucamine per mole of N-acryloyl-D-glucamine in such a polymerization mixture suppresses the cross linking and results in soluble polymers with limiting viscosity numbers of 250 to 400.sThe osmotic molecular weight of one of these polymers, [q] = 250, is 3.1 X TABLE IV COMPARATIVE VISCOSITIES" OF 1% GUMSOLUTIONS AT 25" Gum
cps.
Locust bean gum Methylcellulose Gum tragacanth Carrageenan Poly(N-acryloyl-D-glutamine)* High-viscosity sodium carbosymethy lcellulose Gum karaya Sodium alginate Guar gum
100 150 200 300 650 1200 1500 2000 3300
~~
Table, except for poly(N-acryloyl-D-glutamine), taken from A . M. Goldstein and E. N. Alter, in Industrial Cums, R. L. Whistler, ed., Academic Press Inc., New York, 1959, p. 337. Obtained by polymerization of a 5070 solution of monomer in water containing ammonium persulfate (0.01M) and sodium bisulfita (0.0511.1) a t 4' for six hours. Viscosity measured with a Brookfield viscometer a t 90 r.p.m.
Poly(N-acryloyl-Pglucamine) displays a high tolerance for electrolytes (Table V). The addition of sodium borate to a concentrated solution of poly(N-acryloyl-D-glucamine) causes the solution to set to a rigid gel. This behavior is characteristic of polysaccharides containing adjacent hydroxyl groups in the cis position and is due t o cross linking.7 Since adjacent cis hydroxyls are found on Cq and Cg, and on Ca and Cs of the D-glucsmine moiety, it is not surprising that this polymer reacts in the same manner. EXPERIMENTAL
Chromatoyraphy. Chromatography was conducted a t 25' on Whatman No. 1 (analytical) and Whatman No. 3MM (preparative) papers by the descending technique with 1-butano1:ethanol:water 40: 11:19 as solvent. The silver (6) A limiting viscosity number of 470 waa found for the highly viscous, natural gum, guaran. (7) R. L. Whistler and C. L. Smart, Polysaccharide Chemistry, Academic Press Inc., New York, 1953, p. 296.
158G
WHISTLER, PANZER, AND ROBERTS
TABLE V ELECTROLYTE TOLERANCE OF POLY( N-ACRY LOY I.-D-GLUCAMINE) ~~
Electrolyte hcctic acid Aluminum potassium sulfate, Alz( S04)3.KzSO4.24HzO Aluminum chloride Ammonium chloride Ammonium sulfate Calcium chloride Chromium chloride, CrCl&H20 Hydrochloric acid Mercuric chloride Phosphoric acid Potassium chloride Potassium hydroxide Potassium iodide Potassium sulfate Sodium bicarbonate Sodium borate, Na2B407.10H~0 Sodium carbonate Sodium chloride Sodium hydroxide Sodium nitrate Sodium nitrite Sodium phosphate monobasic, NaHzPOa.HZ0 Sodium phosphate dibasic Sodium phosphate tribasic, NaaP04.10H20 Sodium sulfate Sodium sulfite Sodium thiosulfate Zinc chloride Zinc sulfate, ZnSOc7H20
~~
Concentration of Electrolyte (yo) with Which a 2y0 Polymer Solution Is Compatiblea
80 Saturated 25 25 25 25 Saturated 37 Saturated 85 25 25 25 Saturated Saturated Saturated 25 25 25 25 25 25 25 25 Saturated Saturated 25 20c 25
Each concentration shown is the maximum concentration tested, unless noted. b Maximum concentration tested was 100%. Precipitate was fibrous. Maximum concentaration tested was 25y0. One drop of hydrochloric acid was nddcd t o dissolve zinc oxychloride. Precipitate formed slowly upon standing. 0
nitrate reagent of Trevelyan, Procter, and Harrison8 was used to develop the spots. D-Glucamine. D-Ghcamine ( 1-amino-1-deoxy-D-glucitol) \vas obtained from Corn Products Co., Argo, Ill., either as the crude base (about 85y0 pure) or as the crystalline osalate. The crude base was purified by means of the dicylidene derivative according to the method developed by Kagan, Rebenstorf, and Heinselmane for D-galactamine. .4m.p. of 182-183" was found for salicylidene-D-glutamine. D-Glucamine melted at 126-127' and had a specific rotation, [Culy,of - 8 . O O . D-GIucamine oxalate was converted to the free base by thc passage of a 5-10y0 aqueous solution through a column of Amberlite IRA-400 (OH)lDfollowed by concentration of the effluent under reduced pressure at 40-50' to about one (8) W. E. Trevelyan, D. P. Procter, and J. S.Harrison, N n h r e , 166, 444 (1950). (9) F. Kagan, M. A. Rebenstorf, and R. V. Heinzelman, .I. Am. Clienz. Soc., 79,3541 (1957). (10) Product of Rohm & Haas Company, Resinous
Products Division, Philadelphia, Pa.
VOL.
26
fifth the original volume, addition of five volumes of ethanol, and refrigeration. The semisolid mass which formed was freed from most of the excess mother liquor by suction filtration with a thin sheet of rubber clamped over the funnel. The cake was washed with ether and dried under vacuum; m.p. 128'. N-Acylation of D-glucamine. D-Glutamine was N-acylated by treatment with acrylic or methacrylic anhydride in cold methanol (method A) or by treatment with acryloyl chloride in cold aqueous potassium carbonate solution (method B). Method A : A suspension of 0.138 mole (25 g.) of finely powdered D-glucamine in 250 ml. of absolute methanol was chilled to - 10" in an ice-methanol bath, and 0.276 mole of acrylic or methacrylic anhydride, freshly distilled under reduced pressure to remove inhibitor, was added. The solids dissolved with stirring while the temperature rose to about 0". Stirring was continued until precipitation of the amide began, usually for 30 to 60 min., and the solution was left a t 0" overnight. The product was filtered through an ice-cold fritted glass funnel, washed with ether and vacuum-dried over calcium chloride. With commercial acrylic or methacrylic anhydride the product of method A was a mixture of the desired amide and the N-acetyl derivative. Separation by chromatography on paper or on a Celite" column gave l-acetamido-l-deoxyn-glucitol identical in melting point, optical rotation, R y value and infrared spectrum with that synthesized from Dglucamine and acetic anhydride by method A. Fractional distillation of commercial methacrylic anhydride under reduced pressure yielded pure methacrylic anhydride which gave a 92% yield of N-methacryloyl-D-glutamine by method A. Method B: A mixture of 0.2 mole (36 g.) of D-glucamine and 0.01 mole (0.69 g.) of sodium nitrite in 100 ml. of 2M potassium carbonate solution was warmed on a steam bath until solution was complete, then cooled to 3-4'. Twotenths mole (18 ml.) of acryloyl chloride6 was added dropwise with stirring so that the temperature did not exceed 10'. After all of the acryloyl chloride was added, stirring was continued for 30 min. at 4O, then for 1-2 hr. while the mixture was allowed to come to room temperature. Finally the mixture was allowed to stand at room temperature overnight. The contents of the flask was washed into a large beaker with 1 1. of 99.5% ethanol. After thorough mixing the suspension was filtered by suction. The precipitate, consisting of salts and unchanged D-glucamine, was washed on the filtcr with 100 ml. of 90% ethanol, then discarded. To the combined filtrate and washings was added 1 1. of ethyl ether. After standing a t 0-5" overnight the mixture was filtered, the filtrate mixed with an additional 3800 ml. of ethyl ether, and again held a t 0-5' overnight. The white crystals which formed were collected on a filter, washed with ether and dried under vacuum; yield, 28 g. (60%) of chromatographically pure N-acryloyl-D-glutamine. After recrystallization from ether-ethanol-water the melting point mas 120-121'. l-Acrylamido-l-deoxy-~-glucitol from D-glucamine oxalate. A mixture of 0.1 mole (45 g.) of D-glucamine oxalate and 0.005 mole (0.35 g.) of sodium nitrite in 67 ml. of 364 potassium carbonate solution was warmed on a steam bath until solution was complete, then cooled at 3-4'. Twotenths mole (18 ml.) of ncryloyl chloride was added dropwise with stirring so that the temperature did not exceed 10'. After all of the acryloyl chloride was added, stirring was continued for 30 min. at 4O, then for 1-2 hr. while the mixture was allowed to come to room temperature. Finally the mixture was allowcd to stand a t room temperature overnight. The clear liauid was decanted from the residue in the reaction flask. The residue was washed four times with 250( 11) Diatomaceous silica, a product of Johns-Manville, New York, N. Y.
M A Y -1961
~-ACRYLAMIDO-~-DEOXY-D-GLUCITOL
mi. portions of 99.5% ethanol, then discarded. The washings were combined with the decanted liquid, thoroughly mixed, and the suspension was filtered by suction. Thc precipitated snlts were washed on the filter with 100 ml. of 90% ethanol, then discarded. To the combined filtrate a i d washings was added 300 ml. of ethyl ether and the mixture allowed to stand overnight a t 0-5". The white crystals which formed were collected on a filter, while the yellowish sirup adhering to the bottom of the container was discarded. The filtrate was mixed with an additional 1500 ml. of ethyl ether and again held a t 0-5" overnight. The second crop of white crystals was collected on a filter and combined with the first to yield 15-18 g. of crude N-acryloyl-Dglucamine. Chromatography of the crude product showed the prcsence of several very slow moving impurities, one of which corresponded in R , value to D-glucamine. The crude material was dissolved in water and treated batchwise with Dowex 50W-X4 (H+).l2 The resultant solution was stabilized by the addition of O . O l ~ csodium nitrite and evaporated under reduced pressure a t room temperature or below. The solid was dissolved in a minimum of water, the solution mixed with ten volumes of ethanol and ten volumes of ether, and the mixture refrigerated; yield, 12-14 g. (52-60%) of chromatographically pure N-acryloyl-D-glucamine. Alkaline hydrolysis of the amides. Solutions of 0.1 g. of each amide in 50 ml. of 0.2M sodium hydroxide solution were thermostated a t 25.0'. Aliquots were removed periodically and titrated with standard hydrochloric acid. The composition of the hydrolysis mixture was also examined chromatographically from time to time. Hydrolysis was negligible over several weeks. Solutions of 4 mmoles (0.9-1.0 g.) of each amide in 20 ml. of 2.34M sodium hydroxide were thermostated a t 25.0" Periodically 1-ml. aliquots were removed, neutralized with 1 ml. of 2.34M hydrochloric acid, and diluted to 50 or 100 ml. A 1-ml. aliquot was analyzed for n-glutamine by the following modification of Danielson's 1,2-naphthoquinone4-sulfonate method13 for the colorimetric determination of amino acids. To 1 ml. of D-glucamine solution (0-2 pmole) was added 5 ml. of Clark and Lubs p H 7.8 borate buffer,I4 and 1 ml. of freshly prepared 0.5Tc sodium 1,2-naphthoquinone-4sulfonate soliltion. The solutions were mixed, heated in a boiling water bath for 15 min., and chilled in a cold water bath for 5 min. One milliliter of acid formaldehyde reagent13 was added, followed by 1 ml. of a 2.5% solution of sodium thiosulfate pentahydrate and 6 ml. of water. The solutions were mixed and after 15 min. the optical densities were measured a t 480 mp (Beckman B spectrophotometer, 1-cm. cells). A reagent blank correction was made and the concentration of D-glUCamine obtained from a standard curve prepared simultaneously. Polymerization by -,+radiation. A solution of 0.5 g. of N-acryloyl-D-ghcamine (or N-methacryloyl-D-glutamine) in 10 ml. of oxygen-free distilled water in a sealed test-tube was exposed to the y-radiation from a cobalt-60 source for 1 hr. a t 21'. The sample received a total dose of 22,500 roentgens. A viscous, tacky solution was obtained. The addition of methanol resulted in the precipitation of a white, amorphous solid which was isolated, washed with methanol and ethyl ether, and dried under vacuum. Polymerizations with persulfate. To 10 ml. of a saturated solution Of N-acryloyl-D-glutamine (or N-methacryloyl-Dglucamine) in oxygen-free water was added 1 mg. of ammonium persulfate. The clear solution was maintained a t (12) A product of The Dow Chemical Company, Midland, Mich. (13) I. S. Danielson, J. Bid. Chem., 101, 505 (1933). (14) w. M. Clark, The Determination of Hydrogen Ions, 2nd ed., Williams & Wilkins Company, Baltimore, Md., 1925, p. 107.
1587
25" for 12 hr. There resulted a stiff gcl which swelled but did not dissolve in water. To a solution of 2.2 g. of N-acryloyl-D-glucamine in 16.8 g. of hot, oxygcn-free watcr was nddcd 20 mg. of potassium persulfate. The solution was heated a t 80" for 6 hr. A viscous solution was obtained which was dilutcd with water and dialyzcd. Thc water-soluble polymer had a limiting viscosity number, [ V I , of 140 in 0.5M sodium nitratc solution. Polymerization with redox catalyst systems. Thirty-two 18 X 150 mm. test tubes were charged with monomer as follows: Tubes 1-4, 9-12: 235 mg. mole) of N-aCrylOyl-Dglucamine. Tubes 5-8, 13-1G: 1175 mg. (5 X lo-$ mole) of N-acryloyl-n-glucamine. Tubes 17-20, 25-28: 249 mg. ( mole) of h'-methacryloyl-D-glucamine. Tubes 21-24, 29-32: 1245 mg. (5 X 10-8 mole) of N-methacryloylD-glucamine. Oxygen was removed by placing the tubes in a vacuum dcsiccator and repeatedly evacuating and filling the chamber with nitroeen. Solvent was added to each tube a5 follows (oxygcn-frec water was used throughout): Tubes 1-8, 17-24: 10 ml. of water. Tubes 9, 10, 13, 14, 25, 2G, 29, 30: 10 ml. of 0.1% acetic acid. Tubcs 11, 12, 15, 16, 27, 28, 31, 32: 10 ml. of 1% acctic acid. After solution of the monomer was complete, oxidizing agents were added to each tube as follows: Tubes 1, 2, 5, 6, 17, 18, 21, 22: 1 ml. of 0.0228% mole) ammonium persulfate solution. Tubes 3, 4, 7, 8, 19, 20, 23, 24: 1 ml. of 2.28Yc (10-5 mole) ammonium persulfate solution. Tubes 9, 10, 13, 14, 25, 26, 29, 30: 1 ml. of 0.0106% mole) sodium chlorate solution. Tubes 11, 12, 15, 16, 27, 28, 31, 32: 1 ml. of 1.06% (10-6 mole) sodium chlorate solution. The tubes were flushed with nitrogen, stoppered, and brought to the desired polymerization temperatures by immersing all odd-numbered tubes in an ice-water bath and all even-numbered tubes in a water bath thermostated a t 30'. When temperature equilibrium was established, reducing agent was added to each tube a t 30-second intervals: Tubes containing 10-7 and mole of ammonium persulfate received 1 ml. of 0.005270 ( 5 X IO-* mole) and 1 ml. of 0.52% (5 X 10-6 mole) sodium bisulfite solutions respectively. Tubes containing 10-7 and 10-6 mole of sodium chlorate received 1 ml. of 0.0378% (3 X 10-7 mole) and 1 ml. of 3.78% ( 3 X 10-6 mole) sodium sulfite solutions respectively. All tubes were immediately restoppered. The different acetic acid concentrations were selected to maintain a pH of 4.1 in the chlorate-sulfite system and a pH below 5.5 in the persulfate-bisulfite system. Thirty minutes after addition of the reducing agent, the contents of the even-numbered tubes were poured into about 200 ml. of methanol containing 1 mg./ml. of anhydrous sodium acetate to precipitate the polymers. Twelve hours after the addition of the reducing agent to the odd-numbered tubes, the polymers formed therein were isolated similarly. No polymers were obtained from either redox system a t the lower concentrations of the initiators. The polymers were collected on fritted glass filters, washed with methanol, redissolved in water, and thoroughly dialyzed against deionized water. The dialyzed solutions were concentrated under reduced pressure to a volume of about 30 ml. for measurement of viscosity. Yields were calculated directly from the concentration of these solutions by drying aliquots on Celite at 100' under vacuum. High viscosity poly(N-acryloyl-D-glutamine) was obtained by polymerization of a mixture of N-acryloyl-D-glucamine and N-acetyl-n-glucamine, which contained 54yC of the acryloyl derivative, and had been prepared from wglucamine and commercial acrylic anhydride by method A. To a cold (0") solution of 10 g. of the mixture in 10 ml. of oxygenfree water was added 22.8 mg.of ammonium persulfate and 5.2 mg. of sodium bisulfite. The solution was maintained a t 0" for 12 hr. A stiff sirup resulted. The polymer was shaken overnieht with 1 1. of water. The resultant solution was thoroughly dialyzed, filtered from a small amount of
1588
VOL.
WRIGHT AND H A R T M A "
insoluble material through coarse fritted glass covered with a layer of Celite, concentrated to about 300 ml. under reduced pressure and freeze-dried. The polymer had a limib ing viscosity number, [?I, of 410 in water. Polymriznlion with ben'oyl perozide and a,a'-azoisobutyroniirile ( A I B N ) . Sixteen 18 X 150 mm. test tubes were charged with monomer as follows: Tubes 1, 5, 9, 13: 235 mg. ( mole) of N-acryloyl-D-ghcamhe. Tubes 2, 6, 10, 14: 1175 mg. (5 X lo-* mole) of N-acryloyl-m glucaminp. Tubes 3, 7, 11, 15: 249 mg. mole) of Nmethacryloyl-mglucamine. Tubes 4, 8, 12, 16: 1245 mg. (5 X lo-' mole) of N-methacryloyl-D-glucamine. Air was rcplaced with nitrogen by flushing as described above, 9 ml. of dimethylformamide ( D M F ) was added to each tube, and the tubes were stoppered. The N-acryloylD-glucamine dissolved readily but the methacryloyl compound was less soluble. Tubes 1-4 and 9-12 were placed in an oven a t 60" for 30 min. Solution was still incomplete in tubes 4 and 12. Initiator was added to each of these eight mole) tubes as follows: Tubes 1-4: 1 ml. of 2.4% benzoyl peroxide in dimethylformamide. Tubes 9-12: 1 ml. of 1.6% (lo-' mole) a,&-azoisobutyronitrile in dimethylformamide. The stoppered tubes were then heated a t C O O for 48 hr. Complete solution of the methacryloyl compound in tubes 4 and 12 did not occur. Initiator was added to the remaining eight tubes in a like manner: Tubes 5-8 received 1 ml. of 2.4% benzoyl peroxide in dimethylformamide. Tubes 13-16 received 1 ml. of 1.6% a&-azoisobutyronitrile in dimethylformamide. These tubes were immersed in a boiling water bath for 30 min. during which time the methacryloyl compound in tubes 8 and 16 did not completely dipsolve. After 30 min. the tubes were chilled in cold water. The polymers were only slightly soluble in dimethylformamide and usually precipitated aa n sticky mws. They were trituratcd with methanol, collected on filters, dissolved in water, and dialyzed. The resultant solutions were concentrated under reduced pressure to a volume of about 30 ml. for mertsiirem&ntof viscosity. Yields were calculated as described above.
[CONTRIBUTION FROM
THE
26
Measureme7 t of viscosily. Viscosities were determined in aqueous solution a t 25.0' using an Ubbelohde viscometer in which dilutions of 25:30, 25:35, 25:40, and 25:45 were made by the successive addition of 5-ml. portions of water to a 25-ml. aliquot of the original solution. The concentrations of the undiluted polymer solution were determined by drying on Celite a t 100" in a vacuum oven. Limiting vis[?] = lim ? - ?o/?oC, were calculated cosity CdO
without application of density or kinetic energy corrections, which were negligible. Measurement of molecular weight. The osmot,ic molecular weight of one of the polymers waa determined in 0.1 molar sodium chloride solution using the Stabin-Immergut modificstion16 of the Zimm-Myerson17 osmometer with gelcellophane membranes's and redistilled toluene as the manometric liquid. A value of 3.1 X 106 was found. Electrolyte tolerance of poly(N-acryloyGD-glucamine). To 10 g. of electrolyte solution 2-3 drops of a 2% solution of poly(N-acryloyl-D-glucamine) were added, and the solution was observed for precipitation of the polymer.
Acknowledgment. The authors thank the National Science Foundation and the Corn Industries Research Foundation for grants in partial support of this work. LAFAYETTE, IND. (15) International Union of Pure and Applied Chemistry, Report on Nomenclature in the Field of Macromolecules, J . Polymer Sci., 8 , 257 (1952). (16) J. V. Stabin and E. H. Immermt. J . Polvmer Sn'.. 14; 209 (1954). (17) B. H. Zimm and I. Myerson, J . Am. Chem. Soc., 68, 911 (1946). (18) Kindly supplied by Dr. R. H. Marchessault, American Viscose Corp., Marcus Hook, Pa. -
I
CHEMICAL RESEARCH DEPARTMENT, ATLASPOWDER CO.]
Catalytic Isomerization of the Hexitols ;D-Glucitol, D-Mannitol, L-Iditol, and Galactitol LEON WRIGHT
AND
LUDWIG HARTMANN
Received July 11, 1960 A study has been made of the catalytic isomerization, in aqueous solution, of D-glucitol, nmannitol, and kiditol over the temperature range 130' to 190'. A t 170' and 1900 p.5.i.g. hydrogen the quasi-equilibrium 2 D-glucitol D-mannitol kiditol is established after three to four hours in the presence of nickel-kieselguhr catalyst. T o a first approximation, the equilibrium concentrations of the hexitols are: 41.4 f 2.5 wt. % D-glucitol, 31.5 f 2.4 wt. % D-mannitol, and 26.5 f 2.3 wt. $& biditol. The presence of hydrogen is necessary for isomerization to occur; however, the extent of isomerization is virtually independent of hydrogen presRure over the range 650 to 2600 p.5.i.g. This may he a surface saturation (completion of a monolayer) effect. Isomerization occurs in alkaline solution, but is inhibited in mildly acid solutions. A mechanism is proposed, involving catalytic dehydrogenation of R hexitol followed by alkali catalyzed isomerization of the relstcd aldoand ketohexoses via 1,a-enediol intermediates. Hydrogenation of the hexose mixture completes the reaction scheme. A small amount of secondary isomerization of D-glucitol to galactitol(1-2%) and of D-mannitol and kidjtol to Dttaljtol(2%) occiirs under these conditions. Catalytic isomerization of galactitol at 170" and 1900 p.5.i.g. hydrogen yields two major products, DL-glucitol and Dbtalitol, and two minor products, allitol and Dkmannitol. During this work the hexaacetyl derivatives of Dktalitol and Dbmannitol, and the tribenzylidene derivative of m-talitol were prepared for the first time. ~
+
I n recent years, the catalytic isomerization of polyhydric alcohols has been reported by several investigators.
A series of papers on the hydrogenolysis of carbohydrates by von Rudloff, Tulloch, Perlin, Francis, and Gorin1-6 is of particular interest in that
(1) E. von Rudloff and A. P. Tulloch, Can. J . Chem., 35, 1504 (1957).
(1958).
(2) P. A. Gorin and A. S. Perlin, Can. J . Chem., 36, 661
