Phase-Transfer-Catalyzed Modification of Dextran Employing

Chapter 30

Phase-Transfer-Catalyzed Modification of Dextran Employing Dibutyltin Dichloride and Bis(cyclopentadienyl)titanium Dichloride 1

Yoshinobu Naoshima and Charles E. Carraher, Jr.

2

1

Department of Chemistry, Okayama University of Science, Ridai-cho, Okayama 700, Japan Department of Chemistry, Florida Atlantic University, Boca Raton, FL 33431

Downloaded by NORTH CAROLINA STATE UNIV on January 14, 2013 | http://pubs.acs.org Publication Date: December 22, 1988 | doi: 10.1021/bk-1988-0364.ch030

2

The modification of dextran was achieved employing dibutyltin dichloride and bis(cyclopentadienyl)titanium dichloride using the aqueous interfacial condensation system. The condensation was studied employing various phase transfer agent and as a function of reactant molar ratio. The parameters of percentage product yield and location of the maximum as the molar ratio of reactants is varied were employed to discern if the added phase transfer agents were functioning as a phase transfer agent. For condensations involving the titanocene dichloride, all of the employed phase transfer agents are believed to act as phase transfer agents when employing either sodium hydroxide or triethylamine as the added base. Further, triethylamine itself appears to act as a phase transfer agent. When the organostannane is employed similar results are obtained with the exception that the product percentage yields are generally less for systems employing triethylamine compared with systems employing sodium hydroxide. The roles of triethylamine for such systems is presently unknown. Carbohydrates are the most abundant, weight-wise, organic mater i a l available. Photosynthesis produces about 400 b i l l i o n tons annua l l y . The polysaccharides are generally composed of mono- and d i saccharide units. Dextran was chosen t o study f o r the following reasons. F i r s t , i t i s water soluble allowing three dimensional modification employing aqueous solution and c l a s s i c a l i n t e r f a c i a l condensation routes. Second, i t i s r e a d i l y available i n i n d u s t r i a l quantities. Third, i t i s available i n a range of molecular weight allowing product modif i c a t i o n t o be studied as a function of dextran chain s i z e . Fourth, i t i s generally considered t o be an under-utilized natural feedstock. Dextran i s the c o l l e c t i v e name of e x t r a c e l l u l a r b a c t e r i a l polyalpha-D-glucopyranoses linked largely by 1,6 bonds, with branching occurring a t the 1,2, 1,3 or 1,4 bonds. Physical properties vary 0097-6156/88/0364-0426$06.00/0 © 1988 American Chemical Society

In Chemical Reactions on Polymers; Benham, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1988.


30. N A O S H I M A A N D C A R R A H E R

Modification

of Dextran

427

according t o the amount and manner of branching, nature of endgroup, molecular weight and molecular weight d i s t r i b u t i o n , processing, etc. Dextran i s produced from sucrose by a number of bacteria the major ones being the nonpathogenic bacteria Leuconostoc mesenterodes and Leuconostoc dextranicum. As expected, the structure (and conse quently the properties) of the dextran i s determined by the p a r t i c u l a r s t r a i n that produces i t . Dextran i s the f i r s t microbial polysaccharide produced and u t i l i z e d on an i n d u s t r i a l scale. The potential importance of dextran as a s t r u c t u a l l y (and property) controlled feedstock i s c l e a r l y seen i n l i g h t of the recent emphasis of molecular b i o l o g i s t s and molecular engineers i n the generation of microbes f o r feedstock production. Dextran i s employed as pharmaceuticals (additives and coatings of medications), within cosmetics, as food extenders, as water-loss i n h i b i t o r s i n o i l w e l l d r i l l i n g muds and as the basis f o r a number of synthetic resins. Svenska Sockerfabriks Aktiebolaget f o r Aktiebolaget Pharmacia i n Sweden began large scale production of dextran about 1942 ( 1_). By 1947, Dextran Ltd. (East Anglia Chemical Co., England) began pro duction of dextran and i n 1949 Commercial Solvents Corp. (USA) began production (2,3). In 1952, the R. K. Laros Co. (3) began the enzymic production of dextran i n the presence of l i v i n g c e l l s . In an e f f o r t to standardize the dextran produced, by 1952, the majority of compa nies employed the L. mesenteroides NKRL B-512-(f) i n the production of dextran. The production of dextran involves mixing the appropri ate quantities of sucrose and enzyme under prescribed conditions. S o l u b i l i t y generally decreases with increase i n chain s i z e and extent of branching. The s o l u b i l i t y of dextran can be divided into four groups — those that are r e a d i l y soluble at room temperature i n water, DMF, DMSO and d i l u t e base; those that have d i f f i c u l t y d i s s o l v ing i n water; those that are soluble i n aqueous solution only i n the presence of base; and, those that are soluble only under pressure, a t high temperatures (> 100°C) and i n the presence of base. Dextran B-512 readily dissolves i n water and 6M, 2M glycine and 50% glucose aqueous solutions. Dextran B-512, dissolved i n water, approaches a form of compact s p h e r i c a l - l i k e h e l i c a l c o i l s (4-6). Streaming, birefringence meas urements indicate that the dextran has some f l e x i b i l i t y . The B-512 dextran shows a r e f r a c t i v e index increment, dn/dc, of 0.154 ml/g a t 436 mu i n water and an apparent radius of gyration i n water on the order of 2 χ 10 A. Branching occurs through about 5% of the units through the 1,3 linkage with about 80% of these branches being only one unit i n length. There e x i s t s a few, less than 1%, long branches i n B-512 dextran (6). Chemically dextrans are similar to one another. The a c t i v a t i o n energy f o r a c i d hydrolysis i s about 30-35 Kcal/mol (_5 ). The C-2 hydroxyls appear to be the most reactive i n most Lewis base and a c i d type reactions. A wide v a r i e t y of esters and ethers have been de scribed as well as carbonates and xanthates (2/8.)· a l k a l i n e solu t i o n , dextran forms a varying complex with a number of metal ions I

n

(£). The b i o l o g i c a l properties of dextran again vary with s t r a i n . The B-512 i s d i g e s t i b l e i n mammalian tissues as the l i v e r , spleen, and kidneys, but not i n the blood ( 1_0 ). I t appears not t o stimulate


CHEMICAL REACTIONS ON POLYMERS


428

formation of antibodies i n man upon intravenous infusion ( 1_). On the other hand, subcutaneous i n j e c t i o n i n humans led to skin s e n s i t i v i t y and to the formation of p r e c i p i t a t i n g antibodies (1J_). Antibody f o r mation and p r e c i p i t a t i o n with antiserums decreases as chain length increases (Y\_,V2). Linear, water-soluble dextrans have many uses. One dextran i s employed i n viscous water-flooding f o r secondary recovery of petro leum with a potential market of about 2 x 1 0 tons per year. This dextran i s superior to carboxymethyl c e l l u l o s e when employed i n high calcium d r i l l i n g muds ( V3,J_4). These dextran-muds show superior s t a b i l i t y and performance at high pH and i n saturated brines (15-17). Other dextrans show good resistance to deterioration i n s o i l and the a b i l i t y to s t a b i l i z e aggregates (1_8) i n s o i l s . They can also be used i n binding collagen f i b e r s i n t o s u r g i c a l sutures (19). An underlying assumption i s that dextran i s a representative polysaccharide and that r e s u l t s derived from i t s study can be applied to other polysaccharides. Effected modifications are intended to occur throughout the dextran material rather than only at the sur face. This i s achieved by employing solutions containing dissolved dextran. Recently Carraher, Naoshima and coworkers effected the modifica t i o n of polysaccharides employing organostannanes and bis(cyclopentadienyl)titanium d i c h l o r i d e , BCTD (20-25). Here we report the modifi cation of dextran employing the i n t e r f a c i a l condensation technique using various phase transfer agents u t i l i z i n g BCTD and d i b u t y l t i n d i chloride, DBTD. Experimental Reactions were c a r r i e d out employing a one quart Kimex emulsify ing j a r placed on a Waring Blendor (Model 7011G) with a no load s t i r r i n g rate of about 20,000 rpm. The following organic chemicals were used as received (from A l d r i c h unless otherwise noted): b i s ( c y c l o pentadienyl)titanium d i c h l o r i d e , d i b u t y l t i n d i c h l o r i d e , 18-crown-6, dibenzo-18-crown-6, tetra-n-butylammonium hydrogensulfate (Tokyo Kasei Kogyo Co., Ltd., Japan), triethylamine (Wako Pure Chemical In dustries, Japan), and dextran (Wako Pure Chemical Industries; molecu l a r weight = 2 to 3 χ 10 ). In a t y p i c a l procedure, an aqueous solu t i o n of dextran containing a base and a phase transfer catalyst (PTC) was added rapidly s t i r r e d solutions of the organometallic d i c h l o r i d e i n chloroform. Repeated washings with organic solvent and water as s i s t e d i n the product p u r i f i c a t i o n . Elemental analyses f o r titanium and t i n were conducted employing the usual wet analysis procedure with HC10 . Infrared spectra were obtained using Hitachi 260-10 and 270-30 spectrometers and a D i g i l a b FTS-IMX FT-IR. EI mass spectral analysis was c a r r i e d out employing a JEOL JMS-D300 GC mass spectro meter connected with a JAI JHP-2 Curie Point Pyrolyzer. DT and TG analyses were performed employing a SINKU-RIKO ULVAC TGD-500M or a DuPont 990 TGA and 900 DSC. 4

Results and Discussion Structural characterization was based on s o l u b i l i t y , thermal and elemental analyses, and infrared and mass spectroscopies. Charac-



30.

NAOSHIMA AND CARRAHER

Modification

of Dextran

429

t e r i z a t i o n r e s u l t s were i n agreement with the product being composed of units, including unreacted u n i t s , as depicted i n Figures 1 and 2 and reported i n references 21_, _24 and 25. The investigation of the chemical modification of dextran t o determine the importance of various reaction parameters that may eventually allow the controlled synthesis of dextran-modified mater i a l s has began. The i n i t i a l parameter chosen was reactant molar r a t i o , since t h i s reaction v a r i a b l e has previously been found t o greatly influence other i n t e r f a c i a l condensations. Phase transfer c a t a l y s t s , PTC's, have been successfully employed i n the synthesis of various metal-containing polyethers and polyamines (for instance 26). Thus, the e f f e c t of various PTC's was also studied as a funct i o n of reactant molar r a t i o . Two parameters were employed i n evaluating i f an added PTC i s functioning as a PTC. These parameters were percentage y i e l d and p o s i t i o n of the maximum as the molar r a t i o of reactant i s varied. If PTC a c t i v i t y i s occurring, these parameters might vary as follows : a. d i f f e r i n g , normally enhanced y i e l d f o r systems employing an added PTC compared with the analogous systems omitting the PTC, and b. change i n the p o s i t i o n of the maximum i n percentage y i e l d . The maximizing of y i e l d as the molar r a t i o i s varied i s common f o r i e t e r f a c i a l systems (for instance 27-29). The molar r a t i o corresponding to the maximum y i e l d corresponds t o a favorable balancing of the ent r y of the reactants into the reaction zone. For a given set of r e actants t h i s maximin w i l l vary dependent on the s p e c i f i c reaction parameters. Thus factors that a f f e c t the r e l a t i v e transport factors w i l l a f f e c t the p o s i t i o n of the maximum whereas factors that do not a f f e c t these transport factors w i l l r e s u l t i n maximums occurring i n the same general area as the molar r a t i o i s varied. Increased y i e l d i s a l s o consistent with an increase i n the reactants reaching the r e action zone during the reaction. For the present study, y i e l d d i f ferences can be considered as r e l a t i v e measures o f transport f a c t o r s . A t h i r d , less dependable parameter that may be a measure of PTC a c t i v i t y i s percentage organometallin incorporation. Percentage i n corporation i s believed t o be less dependable f o r the following reasons. F i r s t , s t e r i c factors appear t o be c r i t i c a l f o r many analogous polymer modification of p o l y ( v i n y l alcohol) and polyethyleneimine (for instance 30-33). Second, f o r the current systems, only moderate differences i n percentage incorporation are found and these d i f f e r ences are believed t o be mainly due d i r e c t l y t o the difference i n molar r a t i o of reactant. As with most analogous cases involving polymer modification, generally high proportions of incorporation are found regardless of percentage y i e l d (for instance 30-33). Tables I-IV contain r e s u l t s as a function of i n i t i a l base, presence or absence of an added PTC, organometallin reactant and molar r a t i o of reactants. On a s t r i c t l y molar r a t i o of reactant s i t e s bas i s , the balancing of net quantity of reactants should occur a t an organometallic/dextran molar r a t i o of 3:2. The present studies are consistent with e a r l i e r studies that showed the maximums occurring away from t h i s 3:2 r a t i o . The values c i t e d i n Table V f o r reactant muximums should be considered only as general. Results contained i n Table I w i l l be u t i l i z e d t o i l l u s t r a t e how the parameters of percentage y i e l d and p o s i t i o n of the maximum of precentage y i e l d as reactant molar r a t i o i s varied might be employed t o indicate i f the added PTC



430


_3_

Bu

Bu

S n = 37°/o

Sn=41%

Figure 1. Possible structures of the tin-containing units.

Ti =17 %

Ti = 2 3 %

-Cp Ti-0-

-Cp Ti-0-

2

2

-Cp Ti-02

Λ 1

Cp

Ti = 23 %

° \ TiCpfX 1

Cp

Ti = 27°/·

Figure 2. Possible structures of the titanium-containing units.


30.

NAOSHIMA AND CARRAHER Table

I

.

Results for

as

funet ion

base

of Dextran

and amount

or

no

431

of

DBTD

trans fer

phase

PTC

T r i e t h y l amine Bu SnCl2

Yield

(mmo1)

(%)

2

a

29

29

0.05

29

29

0.14

0.11

28

37

38

0.14

0.28

41

37

4

0.07

1 .00

29

19

0.07

2 .00

28

22

3.00

19 7

water;Bu SnCl 2

B.

PTC

0.008

7

( 3 . OOmmol), in

2

TEA

(9.00mmol)

CHC1 ;30ι

50ml

None

None

0.015

12

4.00

(%)

PTC

None

0.50

(Dextran

Sn

Yield (g)

PTC


of

c o n t a i n i n g TBAHS

systems

catalyst, A.

a

Modification

3

37

28

0.035

a n d TBAHS

( 0 . 90mmol)

s e c . s t i r r i n g

in

50ml

time.)

NaOH 37

8

0.046

0.01

33

1 .00

57

21

0.14

0.05

27

28

2 .00

83

90

0.41

0.44

23

37

3 .00

4

94

0.025

0.70

39

25

4.00

0

0

(Ibid, and a.

above

90 s e c .

Yields

Table

except

Π .

employing

s t i r r i n g

based

saccharide

unit

for as

s y s terns

catalyst,

NaOH

0

(9.OOmmol)

in

-

place

of TEA

presence

of

Tables

, Π

I

function

a

containing

three

of

Bu Sn

units

2

per

a n d VI . base

a n d amount

18- c r o w n - 6

or

no

of

DBTD

phase

transfer

PTC

Triethylamine Bu SnCl 2

Sn

Yield

Yield

2

(mmo1)

(%)

(%)

(g)

None

None

PTC

0.50

16

7

0.02

0. 008

37

29

1 .00

37

19

0.09

0.05

29

29

2 .00

61

22

0.30

0.11

28

37

3.00

24

38

0.17

0.28

29

37

4

0.15

0. 035

28

37

None

PTC

15

4.00

( 3 . OOmmol),

(Dextran 50ml B.

0

t ime.)

on t h e

Results for

A.

30

0.50

water

TEA in

;Bu SnCl2 2

PTC

a n d 1 8 -• c r o w n - - 6

(9.OOmmol) 50ml

C H C 1 ! ; 30 s e c . 3

(0.90mmo1)

s t i r r i n g

time.)

in

NaOH 0.50

25

8

0 . 03

0.01

23

30

1 .00

82

21

0.20

0 . 05

29

28

2 .00

97

90

0 . 48

0.44

29

37

3 .00

98

94

0.73

0.70

27

25

0

0

4.00 (Ibid, and

above

90 s e c .

excep t

employing

s t i r r i ng

Source: Reproduced Longman.

0 NaOH

0

(6.OOmmol)

-

in

place

of TEA

t i me.)

w i t h p e r m i s s i o n from Ref . 34.

C o p y r i g h t 1987




432

Table

ΠΙ .

Results for

as

catalyst, A.

of

base

TBAHS

and

or

amount

no

phase

of

BCTD

transfer

PTC

2

T i C l

Y i e l d

2

(mmol)

Yield

b

(%)

Ti

(g)

(%)

PTC

None

PTC

None

PTC

0.50

ï~5

24

0.02

0.03

12

7~

1.00

78

56

0.19

0.14

12

9

None

2.00

77

67

0.38

0.33

18

12

3.00

69

46

0.51

0.34

17

21

1

0.28

0.01

21

4.00 (Dextran

28 (3.00mmol),

w a t e r ; C p

2

T i C l

2

in

TEA

50ml

(9.00mmol) CHC1 ;30 3

and

sec.

TBAHS

18

(0.90mmol)

s t i r r i n g

in

50ml

time.)

NaOH 0 .. 5 0

0

0

0

0

1. . 0 0

0

0

0

0

-

2.. 0 0

79

0

0.39

0

13

3,. 0 0

69

58

0.52

0 . 43

15

14

4,. 0 0

77

60

0.77

0.60

14

13

(Ibid, and b.

function

containing

Triethylamine C p

B.

a

systems

90

above sec.

Yields

except

based

saccharide

employing

s t i r r i n g

NaOH

(9.00mmol)

in

place

-

of

TEA

time.)

on

the

presence

unit

for

Tables

ΙΠ

of

three

and

Cp Ti 2

units

per

IV .


30.


Table

IV .

Results


for

as

catalyst, A.

a

systems

function

containing

base

and amount

18-crown-6

or

no

433

of

BCTD

phase

transfer

PTC

2

T i C l

Yield

2

(mmol)

Yield

(%)

Ti

(g)

PTC

(%)

None

PTC

None

PTC

0.50

5

24

5

0.03

~

1.00

4

56

0.01

0.14

12

None 7~ 9

2.00

16

67

0.08

0.33

15

12

3.00

25

46

0.18

0.34

17

21

1

0.38

21

18

4.00 (Dextran 50ml

39 O.OOmmol),

w a t e r ; C p

2

T i C l

TEA in

2

(9.00mmol) 50ml

0.01

and

CHC1 ;30 3

18-crown-6

sec.

s t i r r i n g

(0.90mmol)

in

time.)

NaOH 0.50

0

0

0

0

-

1 .00

0

0

0

0

-

-

2.00

0

0

0

0

-

-

3.00

80

58

9

14

4.00 (Ibid, and C.

of

of Dextran

Triethylamine C p

B.

Modification

above

90 s e c .

59 except

60 emp1oyi ng

s t i r r i ng

NaOH

0.59

0 . 43

0.59

0.60

( 6 . OOmmol)

in

-

13

15 pi ace

of

TEA

t i me.)

NaOH 0.50

0

0

0

0

-

1 .00

0

0

0

0

-

2 . 00

21

0

0.11

0

-

17

-

3.00

86

48

0.64

0 . 36

17

17

4.00

86

53

0.86

0.53

21

21

(Ibid, and

-

90

above s e c .

excep t

e m p 1 o y i n g NaOH

s t i r r i n g

( 9 . OOmmo1)

in

pi ace

of

TEA

time.)

Source: Reproduced w i t h p e r m i s s i o n from Ref. 34. C o p y r i g h t 1987 Longman.



434


Table OM

I n i t i a l

V

C p

2

2

SnCl

T i C l

"+"

2

2

0

not OM

a

of

PTC

results Maximum

PTC

Variation

Variation

TEA

TBAHS

+

+

1/3

NaOH

TBAHS

+

+

2/1

TEA

18-C-6**

NaOH

18-C-6

Maximum OM/Dextran*

+

2/1

+

0

3/1 2/1

TEA

DB-18-C-6***

+

+

NaOH

DB-18-C-6

+

0

3/1

TEA

TBAHS

+

+

>4/l

+

3/1

NaOH

TBAHS

TEA

18-C-6

+

1/3

NaOH

18-C-6

+

2/3

indicates

employing

Summary

Yield

Base

Bu

.

Added

that

PTC

a

with

v a r i a t i o n results

indicates

that

the

indicates

that

there

exists

obtained

trends

are

appears

between not

results

employing

a

obtained PTC.

similar. to

be

a

v a r i a t i o n ,

but

it

is

pronounced. is

•for

organometal1ic PTC

containing

**18-crown-6.

reactant. systems.

***dibenzo-18-crown-6.



30.


Modification

of Dextran

435

i s functioning as a PTC. F i r s t , percentage y i e l d s vary between systems employing an added PTC and those not containing an added PTC consistent with the addition of the PTC acting t o influence the transport of the reactants. Second, the maximums vary with respect to the presence or absence of the added PTC. For triethylamine (TEA) systems with tetra-n^-butylammonium hydrogensulfate (TBAHS), the percentage y i e l d maximum occurs near a DBTD/dextran r a t i o of 1/3; f o r the analogous systems except omitting the PTC, the maximum occurs around 3/3. For systems employing sodium hydroxide as the added base, the maximum occurs around 2/1 when the TBAHS i s present and around 3/1 when no PTC i s present. The r e s u l t s are consistent with TBAHS acting t o influence the transport of reactants. Results f o r other PTC's appear i n Table V and are consistent with PTC's functioning t o influence the transport of one or both of the reactants f o r the vast majority of the cases. Triethylamine i s believed t o act as a phase transfer agents (PTA) some i n t e r f a c i a l systems (for instance 26). The maximum percentage y i e l d s f o r the modification effected employing d i b u t y l t i n d i c h l o r i d e both occur around a 3/3 r a t i o (DBTD/ dextran; Table I) but with quite varying y i e l d s f o r systems employing 2 mmols of organostannane and greater. The approximate maximums (Table V) and y i e l d f o r PTC-containing systems vary with respect t o the nature of i n i t i a l l y added base (sodium hydroxide or TEA). With the exception of coincidence of the maximums f o r non PTC-containing systems, the evidence i s consistent with the presence of the TEA a f f e c t i n g the general outcome of the reaction. With most of the systems (Tables I, II) the percentage y i e l d s are lower when TEA i s employed. For these systems, i t i s not presently known i f TEA acts as a PTA or i n some other manner. The product of d i b u t y l t i n d i c h l o r i d e and TEA i s brown colored and not water soluble. The modified product i s white, eliminating the p o s s i b i l i t y that the product contains s i g n i f i c a n t portions of the simple organostannane-TEA product. For systems employing BCTD the s i t u a t i o n i s d i f f e r e n t . The maximums occur a t about 2/3 when employing TEA but no PTC and 4/3 when employing sodium hydroxide but no PTC. Again the maximums are dependent on the nature of the added base and added PTC. Yields vary but are not consistently lower when employing TEA compared with sodium hydroxide. I t i s possible that TEA may act t o influence the transport of one or both of the reactants f o r systems employing the organotitanium reactant. Addition of base i s intended t o serve two primary functions. F i r s t , t o act as a scavenger, n e u t r a l i z i n g hydrogen chloride e l i m i nated through condensation between the organometallic d i c h l o r i d e and dextran. Second, t o further activate, polarize the Lewis base f o r more ready attack a t e l e c t r o p h i l i c s i t e s . . Sodium hydroxide, a strong base, i s believed t o further polarize Lewis bases such as amines and hydroxyls whereas TEA does not provide t h i s added assistance t o as great of an extent (see £)· I t i s possible that t h i s further p o l a r i zation of the dextran-hydroxyl groups by the sodium hydroxide i s r e sponsible f o r the r e l a t i v e l y larger y i e l d s found compared t o systems employing TEA as the added base when DBTD i s used. I t i s possible that BCTD i s s u f f i c i e n t l y more reactive than DBTD such that additiona l p o l a r i z a t i o n of the hydroxyls by the hydroxide ion i s not s i g n i f i cant t o outcome of the reaction. While the terms phase transfer c a t a l y s t and phase transfer agent


436



are often employed interchangeably, the term PTA i s broader and i n cludes additives that become part of the o v e r a l l reaction product. In the present study, the TEA i s a PTA but not a PTC since i t has been found t o react with both of the metal-containing reactants. For the present products, TEA-containing moieties have been indicated em ploying both infrared and mass spectroscopies (24). An additional question concerns whether the location of the PTC has an e f f e c t on the reaction. Table VI contains r e s u l t s where 18crown-6 was added t o the either phase. I t appears that the i n i t i a l location of the 18-crown-6 has l i t t l e or no e f f e c t on the reaction.

Table

VI .

Results for

Bu

2

SnCl

the

as PTC

a

function

of

DBTD

(mmo1)

origi nal

1 ocat ion

Sn

Yield

Yield

2

and

1 8 - c r o w n -•6

(%)

(%)

(g)

Water

None

OR

8

20

25

0.01

0.025

0.03

30

37

23

1.00

21

75

82

0.05

0.19

0.20

28

29

29

None 0. 50

OR*

Water

OR

None

Water

2.00

90

91

97

0.44

0 . 45

0. 48

37

37

29

3.00

94

97

98

0.70

0.72

0.73

25

28

27

4.00

0

0

0

0

0

0

-

-

-

Dextran added

(3.OOmmol)

to

s t i r r i n g

s t i r r e d

and

s o d i u m h y d r o x i de

solutions

of

Bu SnCl 2

2

( 6 . OOmmol) in

50ml

iη

CHClg

50ml wi t h

water 90

:s e c .

time.

•Organ i c.

Literature Cited 1. Gronwall, A. Dextran and Its Use in Colloidal Solutions; Academic Press, New York, 1957. 2. Mfg. Chemist 1952, 23(2), 49. 3. Chem. Eng. 1952, 59, 215(Sept.) and 240(Dec.). 4. Oene, Η. V.; Cragg, L. H. J. Polymer Sci. 1962, 57, 175. 5. Antonini, E.; Bellelli, L.; Bruzzeni, A.; Caputo, A.; Chiancone, E.; Rossi-Fanelli, A. Biopolymers 1964, 2, 35. 6. Bovey, F. J. Polymer Sci. 1959, 35, 167 and 183. 7. Baker, P. J. Dextrans; Academic Press, New York, 1959.



30.


Modification

of Dextran

437

8. Flodin, P. Dextran Gels and Their Applications in Gel Filtration; Halmatd, Uppsala, 1962. 9. Rowe, C. E. Ph. D. Thesis, Univ. Birmingham, 1956. 10. Fischer, E.; Stein, E. Dextranases; Academic Press, New York, 1960. 11. Kabat, E. Bull. Soc. Chim. Biol. 1960, 42, 1549. 12. Hehre, E.; Sugg, J.; Neill, J. Ann. Ν. Y. Acad. Sci. 1952, 55, 467. 13. Monaghan, P; Gidley, J. Oil Gas J. 1959, 57, 100. 14. Dumbauld, G.; Monaghan, P. U. S. Patent 3,065,170, 1962. 15. Mueller, Ε. Z. Angew. Geol. 1963, 9, 213. 16. Owen, W. Sugar 1952, 47(7), 50. 17. Owen, W. U. S. Patent 2,602,082, 1952. 18. Novak, L.; Witt, E.; Hiler, M. Agr. Food Chem. 1955, 3, 1028. 19. Novak, L. U. S. Patent 2,748,774, 1956. 20. Carraher, C. E.; Giron, D. J.; Schroeder, J. Α.; Mcneely, C. U. S. Patent 4,312,981, 1982. 21. Naoshima, Y.; Hirono, S.; Carraher, C. E. J. Polymer Materials 1985, 2, 43. 22. Carraher, C. E.; Gehrke, T. G.; Giron, D. J.; Cerutis, D.; Molloy, Η. M. J. Macromol. Sci.-Chem. 1983, A19, 1121. 23. Carraher, C. E.; Burt, W. R.; Giron, D. J.; Schroeder, J. Α.; Taylor, M. L.; Molloy, H. M.; Tiernan, T. O. J. Appl. Polym. Sci. 1983, 28, 1919. 24. Naoshima, Y.; Carraher, C. E.; Hess, G. G. Polym. Mat. Sci. Eng. 1983, 49, 215. 25. Naoshima, Y.; Hirono, S.; Carraher, C. E. Polym. Mat. Sci. Eng. 1985, 52, 29. 26. Mathias, L. J.; Carraher, C. Ε., Eds. Crown Ethers and Phase Transfer Catalysis in Polymer Science; Plenum Press, New York, 1984. 27. Morgan, P. W. Condensation Polymers:By Interfacial and Solution Methods; Wiley, New York, 1965. 28. Millich, F.; Carraher, C. Ε., Eds. Interfacial Synthesis, Vols. I and II; Dekker, New York, 1977. 29. Carraher, C. E.; Preston, J., Eds. Interfacial Synthesis, Vol. III; Dekker, New York, 1982. 30. Carraher, C. E.; Tsuda, Μ., Eds. Modification of Polymers; American Chemical Society, Washington, D. C., 1980. 31. Carraher, C. E.; Moore, J. Α., Eds. Modification of Polymers; Plenum Press, New York, 1983. 32. Carraher, C. E.; Feddersen, M. F. Angew. Makromolekulare Chemie 1976, 54, 119. 33. Carraher, C. E.; Ademu-John, C.; Fortman, J. J.; Giron, D. J.; Turner, C. J. Polymer materials 1984, 1, 116. 34. Naoshima, Y., Applied Organometallic Chemistry 1987, 1, 245-249. RECEIVED October

30, 1987


Phase-Transfer-Catalyzed Modification of Dextran Employing

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