Carbohydrate Sulfates - American Chemical Society

12 S u l f o n i c Acid a n d S u l f o m e t h y l - C o n t a i n i n g G r a f t C o - P o l y m e r s of X a n t h a n Gum I. W. COTTRELL, J. L. SHIM, and G. H. BEST

Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on March 23, 2016 | http://pubs.acs.org Publication Date: June 1, 1978 | doi: 10.1021/bk-1978-0077.ch012

Kelco Division of Merck & Co., Inc., 8225 Aero Drive, San Diego, CA 92123 R. A. EMPEY Kelco Division of Merck & Co., Inc.,P . O.Box 998, Okmulgee, OK 74447 Xanthan gum i s a h i g h m o l e c u l a r weight p o l y saccharide produced in a pure culture fermentation process by the microorganism Xanthomonas c a m p e s t r i s [1]. The structure of the polysaccharide is shown in Figure 1. As detailed in this figure, each repeating u n i t c o n t a i n s f i v e sugar u n i t s c o n s i s t i n g of two g l u c o s e u n i t s , two mannose u n i t s , and one g l u c u r o n i c acid unit. The main c h a i n of xanthan gum i s built up of ß-D-glucose u n i t s l i n k e d through the 1- and 4positions; i.e., the c h e m i c a l s t r u c t u r e of the main chain is identical to the c h e m i c a l s t r u c t u r e of cellulose. The s i d e c h a i n comprises the two mannose u n i t s and the g l u c u r o n i c a c i d u n i t . The t e r m i n a l ß - D - m a n n o s e unit is linked glycosidically to the 4 - p o s i t i o n of β-D-glucuronic a c i d , which i n t u r n i s l i n k e d glycosidically to the 2 - p o s i t i o n of ot-D-mannose. T h i s three– sugar s i d e c h a i n i s l i n k e d to the 3 - p o s i t i o n of every o t h e r g l u c o s e r e s i d u e i n the main c h a i n . A l s o , about h a l f of the t e r m i n a l D-mannose r e s i d u e s c a r r y a pyru vic a c i d r e s i d u e ketalically l i n k e d to the 4- and 6positions. The n o n t e r m i n a l D-mannose u n i t c o n t a i n s an a c e t y l group at the 6 - p o s i t i o n [2]. Xanthan gum was c o m m e r c i a l i z e d by K e l c o Company, now K e l c o D i v i s i o n of Merck & C o . , I n c . , i n 1964 and has found widespread u t i l i t y i n food and i n d u s t r i a l a p p l i c a t i o n s because of i t s unique p r o p e r t i e s . Attempts have been made to a l t e r the p r o p e r t i e s of xanthan gum by c h e m i c a l d e r i v a t i z a t i o n and m o d i f i c a t i o n . These d e r i v a t i v e s and m o d i f i c a t i o n s i n c l u d e d e a c e t y l a t e d xanthan gum [_3] , carboxymethy 1 e t h e r s [4.1 , c a t i o n i c d e r i v a t i v e s Γ 5 ,6] , p r o p y l e n e g l y c o l e s t e r s L Z L h y d r o x y a l k y l e t h e r s [8] , s u l f a t e s [9.] , and g r a f t c o polymers [10]. However, w i t h the e x c e p t i o n of d e a c e t y l a t e d xanthan gum, none of these d e r i v a t i v e s have been c o m m e r c i a l i z e d to d a t e .

0-8412-0426-8/78/47-077-193$05.00/0 © 1978 American Chemical Society

Schweiger; Carbohydrate Sulfates ACS Symposium Series; American Chemical Society: Washington, DC, 1978.


Figure 1. Structure of xanthan gum


12.

COTTRELL E T A L .

Xanthan

Gum

195


T h i s paper d e s c r i b e s the p r e p a r a t i o n of g r a f t c o p o l y m e r s o f x a n t h a n gum containing sulfonic acid g r o u p s a t t a c h e d by e i t h e r g r a f t c o p o l y m e r i z i n g acrylam i d e and 2 - a c r y l a m i d o - 2 - m e t h y l p r o p a n e s u l f o n i c a c i d (AMPSA) o n t o x a n t h a n gum, o r by sulfomethylating xanthan gum-polyacrylamide. T h e s e r e a c t i o n s a r e shown schematically in Figure 2. Results

and

Discussion

The s u l f o n i c a c i d and sulfomethy1-containing g r a f t c o p o l y m e r was p r e p a r e d by g r a f t i n g acrylamide (AM) and 2 - a c r y l a m i d o - 2 - m e t h y l p r o p a n e s u l f o n i c a c i d (AMPSA) o n t o x a n t h a n gum i n an a q u e o u s medium w i t h a eerie s a l t present (Figure 2). The r a t i o o f a c r y l a m i d e t o AMPSA was a d j u s t e d to give g r a f t polymers with v a r y i n g degrees of a n i o n i c c h a r a c t e r . A l s o , the r a t i o o f t o t a l monomer t o x a n t h a n gum was v a r i e d t o g i v e polymers with a range of v i s c o s i t i e s (Table I ) . Prel i m i n a r y s c r e e n i n g o f the p r o d u c t p o l y m e r from example 5 i n T a b l e I ( P o l y m e r I) h a s r e v e a l e d t h a t i t i s p s e u d o p l a s t i c , i s s t a b l e b e t w e e n pH 4^12, and e x h i b i t s a s y n e r g i s t i c v i s c o s i t y i n c r e a s e w i t h guar gum. E f f e c t o f pH and t e m p e r a t u r e on v i s c o s i t y and the shear-stress/shear-rate r e l a t i o n s h i p a r e shown i n F i g u r e s 3, 4, and 5, r e s p e c t i v e l y . These polymers a l s o p o s s e s s g o o d s a l t s t a b i l i t y , w h i c h makes them s u i t a b l e f o r o i l f i e l d u s e s , s u c h as f l o o d i n g and drilling. I n a d d i t i o n , t h e y c a n be u s e d i n o t h e r a p p l i c a t i o n s where t h i c k e n e d w a t e r i s d e s i r a b l e , such as t e x t i l e p r i n t i n g p a s t e t h i c k e n i n g , s l u r r y explosive f o r m u l a t i o n s , and c o a t i n g t e c h n o l o g y . The a f o r e m e n t i o n e d p o l y m e r was a l s o p r e p a r e d by i n t r o d u c i n g s u l f o n i c a c i d g r o u p s i n t o x a n t h a n gum by c o m b i n i n g g r a f t p o l y m e r i z a t i o n and c h e m i c a l modification techniques. F i r s t , polyacrylamide was grafted o n t o x a n t h a n gum a t 1:1 r a t i o by w e i g h t , t h e n t h e a m i d e f u n c t i o n was sulfomethylated with formaldehyde and s o d i u m m e t a b i s u l f i t e ( F i g u r e 2) [11] . P r e l i m i n a r y s c r e e n i n g of t h i s a n i o n i c polymer (Polymer II) has shown t h a t i t i s p s e u d o p l a s t i c ( F i g u r e 5 ) , has good high-temperature s t a b i l i t y ( F i g u r e 4 ) , and i s s t a b l e b e t w e e n pH 6 and 11 ( F i g u r e 3 ) . The p o l y m e r a l s o exh i b i t s a s y n e r g i s t i c v i s c o s i t y e f f e c t with guar gum. P o s s i b l e a p p l i c a t i o n s o f t h i s p o l y m e r a r e u s e as a d i s p e r s a n t and s t a b i l i z e r i n s l u r r i e s ; i n p e t r o l e u m recovery ( d r i l l i n g and f l o o d i n g ) , as an a n t i - s t a t i c f i l m f o r m e r ; and p o s s i b l y i n t e x t i l e s .


CARBOHYDRATE

196


1)

2

)

XANTHAN

GUM-POLY(ACRYLAMIDE-CO-AMPSA)

SULFOMETHYLATED

Figure 2.

Z N : AM

(1:1)

GRAFT

COPOLYMER

Polymerization reaction scheme


SULFATES

Schweiger; Carbohydrate Sulfates ACS Symposium Series; American Chemical Society: Washington, DC, 1978. 7.5 12 .5 16.7

42. 5 37.5 33. 3 25 16.7 12. 5 0

26 . 4 25.7 26.2 27.1 28.1 26.5 23.4

1.9

3.1

4.2

6.2

8.4

9.3

12. 5

10. 6

9. 3

8. 4

6.2

4.2

3.1

4

5

6

7

8

9

0

22

11

19 .2

4.2

2.1

3

10

11

22

18. 9

2.1

4.2

2

50

37. 5

33. 3

25

9

25

19.1

1.7

4.6

Weight (gm) copolymer

Content (%) 2-acrylamidoContent (%) 2-methylpropane Monomer sulfonic acid

340 200 250 230 300 290

350

250 250 300 300

50 50 50 50

340 350

50

250

480 500

66

50

480 520

66

50

480

Viscosity of Copolymer (1% KC1 solution)

520

V i s c o s i t y of Copolymer (distilled water)

66

Content (%) Xanthan gum

o f AMPSA and A c r y l a m i d e onto Xanthan Gum

1

Example

Acrylic Monomer Weight (gm)

of Graft Polymerization

Weight (gm) 2-acrylamido2-methylpropane Sulfonic Acid

Results

TABLE I


CARBOHYDRATE SULFATES

198


(CPS)

lOr

il

,

.

,

,

.

,

1

2

4

6

8

10

12

14

Ρ Η Figure 3.

Viscosity vs. pH for xanthan gum and both polymers

Figure 4.

Viscosity vs. temperature for xanthan gum and both polymers


COTTRELL E T A L .

Xanthan

Gum


10,

0.1

PO

SHEAR RATE

(sec-) 0.01

0.001

Ίο

-4-

loo

1000

SHEAR STRESS (dynes/cm ) 2

Figure 5. Low shear rate rheological properties of xanthan gum and both polymers. (These data were obtained using the Wells-Micro Brookfield Viscometer and the relaxation technique of Patton (12).)


CARBOHYDRATE

200

SULFATES

Experimental


Xanthan

Gum-Poly(aerylamide-co-AMPSA)

The s a m p l e s w e r e p r e p a r e d i n a 1000 m l r e a c t i o n v e s s e l equipped w i t h a n i t r o g e n i n l e t tube, a thermo m e t e r , a n d an a d d i t i o n f u n n e l . For the f i r s t three samples ( s e e T a b l e 1 ) , 500 ml o f a f e r m e n t a t i o n b e e r and 6.3 g o f t o t a l monomer ( a c r y l i c p l u s 2 - a e r y l a m i d o 2-methylpropane s u l f o n i c a c i d ) were combined. Examples 4-9 u s e d 500 ml f e r m e n t a t i o n b e e r a n d 12.5 g t o t a l monomer. E x a m p l e 10 c o m b i n e d 12.5 g o f 2 - a c r y l a m i d o 2-methylpropane s u l f o n i c a c i d a n d 500 ml o f f e r m e n t a t i o n beer. The monomer was d i s s o l v e d i n 50 ml w a t e r . The f e r m e n t a t i o n b e e r c o n t a i n e d 2.50 w e i g h t p e r c e n t o f X a n t h o m o n a s c a m p e s t r i s c o l l o i d , as d e t e r m i n e d by i s o p r o p y l a l c o h o l p r e c i p i t a t i o n o f c o l l o i d from a sample of the f e r m e n t a t i o n beer. The r e a c t i o n m i x t u r e was t h e n h e a t e d t o 7 5 ° C , w h i l e t h e r e a c t i o n v e s s e l was p u r g e d w i t h n i t r o g e n g a s f o r one h o u r . Thereafter, the r e a c t i o n v e s s e l was c o o l e d t o room t e m p e r a t u r e a n d 20 ml o f a c a t a l y s t s o l u t i o n d i l u t e d w i t h 50 ml o f w a t e r was a d d e d o v e r a p e r i o d o f 15 m i n u t e s w h i l e t h e c o n t e n t s were s t i r r e d . The c a t a l y s t s o l u t i o n was com p o s e d o f 0.1 Ν e e r i e ammonium n i t r a t e d i s s o l v e d i n 1 Ν n i t r i c acid. T h i s s o l u t i o n was made by d i s s o l v i n g 54.8 g o f e e r i e ammonium n i t r a t e i n 1 Ν n i t r i c a c i d and d i l u t i n g t o make 1 l i t e r o f s o l u t i o n . Following the a d d i t i o n o f the c a t a l y s t , s t i r r i n g o f the r e a c t i o n m i x t u r e was c o n t i n u e d f o r two h o u r s a t a r e a c t i o n t e m p e r a t u r e o f 20 t o 2 5 ° C , a f t e r w h i c h 2 g o f p - m e t h o x y p h e n o l d i s s o l v e d i n 50 ml o f i s o p r o p y l a l c o h o l w e r e added. T h e p r o d u c t was p r e c i p i t a t e d by t h e a d d i t i o n o f e x c e s s i s o p r o p y l a l c o h o l a n d was t h e n c o l l e c t e d a n d d r i e d a t 4 5 - 5 0 ° C f o r two h o u r s . The f i n a l w e i g h t s o f t h e p r o d u c t s a r e shown i n T a b l e I . V i s c o s i t y o f t h e c o p o l y m e r s was d e t e r m i n e d a t 1% by w e i g h t s o l u t i o n i n d i s t i l l e d w a t e r , u s i n g a B r o o k f i e l d L V F v i s c o m e t e r a t 60 rpm, No. 2 s p i n d l e . F o r p u r p o s e s o f c o m p a r i s o n , Xanthomonas c a m p e s t r i s c o l l o i d , w h i c h was o b t a i n e d d i r e c t l y f r o m t h e f e r m e n t a t i o n b e e r , h a d a v i s c o s i t y a t a c o n c e n t r a t i o n o f 1% by w e i g h t i n d i s t i l l e d w a t e r o f 840 cps. Sulfomethylated Polymer I I

ZN: AM

(1:1) G r a f t

Copolymer

-

A g r a f t c o p o l y m e r i s p r e p a r e d by r e a c t i n g e q u a l p a r t s b y w e i g h t o f x a n t h a n gum a n d a c r y l a m i d e a c c o r d i n g t o t h e p r o c e d u r e g i v e n i n E x a m p l e 1 o f U. S. p a t e n t


12.

COTTRELL ET AL.

3,708,446. The r e s u l t i n g copolymer (1.44 g) i s d i s s o l v e d i n 100 ml d i s t i l l e d water i n a t h r e e neck, round bottom f l a s k (250 ml) f i t t e d w i t h a thermometer, s t i r r e r , and r e f l u x condenser. To t h i s s o l u t i o n i s added 0.95 g N a S 0 (0.005 m o l e ) , 0.80 g 50% NaOH (0.01 m o l e ) , and 0.81 g 37% CH2O (0.01 m o l e ) . The s o l u t i o n i s heated to 5 0 ° C and s t i r r e d at t h i s tempera ture for 3 hours. At the end of t h i s p e r i o d , the mixture i s c o o l e d to room temperature ( ^ 2 2 ° C ) , and the r e a c t i o n p r o d u c t i s r e c o v e r e d by a d d i t i o n of the s o l u t i o n to 2 volumes of i s o p r o p a n o l . The p r o d u c t i s d r i e d i n vacuo at 4 0 ° C and m i l l e d through a 60 mesh (U.S. standard) s c r e e n . The r e s u l t s of t h i s experiment are shown i n T a b l e I I . 2


201

Xanthan Gum

2

5

Table I I . The R e s u l t s of S u l f o m e t h y l a t i o n Gum-Acrylamide G r a f t Copolymer.

Y i e l d (g) T h e o r e t i c a l y i e l d (g) Y i e l d (%) Amide Groups Reacted (%) V i s c o s i t y (cps), 1% KC1 V i s c o s i t y (cps), 1%

of Xanthan

2.13 2.58 82.60 60.53 90 87 B r o o k f i e l d LVF Viscometer, 6 0 rpm

Abstract : Two n o v e l g r a f t copolymers of xanthan gum have been p r e p a r e d by g r a f t c o p o l y m e r i z i n g 2 - a c r y l a mido-2-methylpropane s u l f o n i c a c i d and a c r y l a m i d e onto xanthan gum and by g r a f t p o l y m e r i z i n g a c r y l a m i d e onto xanthan gum f o l l o w e d by s u l f o m e t h y l a t i o n . The p r e p a r a tion and p r o p e r t i e s of these two polymers are d i s c u s s e d. Literature 1. 2. 3. 4. 5. 6. 7. 8. 9.

Cited

Jeanes, A. R . , Pittsley, J. Ε . , and S e n t i , F . R . , J. A p p l . Polymer Sci. (1961), 5, 519-526. J a n s s o n , P. E., Keene, L., and L i n d b e r g , B., Carbohydrate Res. (1975), 45, 275-282. J e a n e s , A . R. and S l o n e k e r , J. H., U. S. Patent 3, 000, 790 (1961). Schweiger, R. G., U . S . P a t . 3,236,831 (1966). Schweiger, R. G., U . S . P a t . 3,244,695 (1966). Schweiger, R. G., U . S . P a t . 3,376,282 (1968). Schweiger, R. G., U . S . P a t . 3,256,271 (1966). Schweiger, R. G., U . S . P a t . 3,349,077 (1967). Schweiger, R. G., U . S . P a t . 3,446,796 (1969).


CARBOHYDRATE SULFATES

202 10. 11. 12.

P e t t i t t , D. J., U.S. Pat. 3,708,446 (1973). S c h i l l e r e t al., Ind. & Eng. Chem., p. 2132-2137 (1956). Patton, T. C., J. o f P a i n t Technology, (19 66), 38 (502), 656. 1978.


RECEIVED F e b r u a r y 6,


Carbohydrate Sulfates - American Chemical Society

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