Cellulose Chemistry and Technology - American Chemical Society

17 Electron Donor Properties of Tertiary Amines in Cellulose Anion Exchangers DOROTHY M . PERRIER and RUTH R. BENERITO

Downloaded by UNIV OF NORTH CAROLINA on October 26, 2015 | http://pubs.acs.org Publication Date: June 1, 1977 | doi: 10.1021/bk-1977-0048.ch017

Southern R e g i o n a l Research C e n t e r , N e w Orleans, L A 70179

The preparation and properties of diethylaminoethyl (DEAE) celluloses in which the tertiary amine groups are in the free amine form have been reported (1,2). Use of such groups within the cellulose matrix for the preparation of mono-quaternary ammonium ions and di-quaternary ammonium ions by reactions with alkyl halides and dihaloalkanes, respectively, has been reported (3). Recently, we have studied the use of cellulose anion exchangers in the preparation of exchangers having oxidation-reductionproperties, as well as anion exchange properties. Initially, the source of the reducing or oxidizing power resided in the anion, stabilized by the quaternary ammonium groups of the cellulose matrix. Cellulose exchangers in which the tertiary amine groups of DEAE cottons acted as ligands to Ni (II) and Cu (II) cations were also prepared and were found to be paramagnetic (4). This is a report of the possible use of the free electrons on the tertiary amine groups of DEAE cottons as the donor in formation of compounds with acceptor molecules. The 2,3,5,6-tetrachloro-p-benzoquinone was selected as one of the acceptor molecules because its reactions with triethylamine have been studied extensively (5,6). The other donor selected was tetracyanoethylene. Recently, the electron paramagnetic resonance of the adduct formed between TCNE and triethylamine has been reported (7). Experimental Reagents. The 2,3,5,6-tetrachloro-p-benzoquinone (chloranil), tetracyanoethylene (TCNE), and chloroform were reagent grade chemicals obtained from Eastman Organic Chemicals.* Absolute anhydrous methanol, reagent grade, was obtained from Matheson Coleman & Bell Manufacturing Chemists, tertiary butanol, Baker analyzed reagent, from J. T. Baker Chemical Co.; and anhydrous CuCl2 from the British Drug Houses Ltd.

244

In Cellulose Chemistry and Technology; Arthur, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1977.

17.

PERKIER AND B E N E R i T O

Tertiary Amines

245

Fabrics. The nonaqueous p r e p a r a t i o n s o f sodium c e l l u l o s a t e s i n f a b r i c form and t h e i r subsequent r e a c t i o n s a t room temperature with 3-chloroethyldiethylamine i n t - b u t a n o l t o form the f r e e amine forms o f d i e t h y l a m i n o e t h y l (DEAE) cottons o f v a r r y i n g n i t r o g e n contents have been r e p o r t e d (1,2). For a DEAE cotton o f a p p r o x i mately 2% N, c o t t o n sheeting T^Th o z / y d ) was r e a c t e d with a 1.25 M sodium methoxide s o l u t i o n , and the r e s u l t a n t sodium c e l l u l o s a t e was r e a c t e d f o r 2k h r w i t h a s o l u t i o n (k% by weight) o f 3-chloro ethyldiethylamine i n t-butanol. The adducts were formed by r e a c t i n g DEAE f a b r i c with a chloroform s o l u t i o n o f c h l o r a n i l o r TCNE i n a n i t r o g e n atmosphere. The y e l l o w green c h l o r a n i l adduct and the r e d d i s h brown TCNE adduct were washed s e v e r a l times i n CHCI3 before b e i n g analyzed.


2

Chemical Analyses. Nitrogen contents o f a l l modified cottons were determined by the K j e l d a h l method and are r e p o r t e d as t o t a l m i l l i e q u i v a l e n t p e r gram o f f a b r i c (meq N/g f a b r i c ) . C h l o r i n e and metal i o n analyses o f adduct products were determined by G a l b r a i t h L a b o r a t o r i e s . I n f r a r e d a b s o r p t i o n s p e c t r a o f f a b r i c s were obtained on a P e r k i n Elmer 137 by the KBr d i s c method. R e f l e c t a n c e s p e c t r a i n t h e u v - v i s i b l e region were obtained on the V a r i a n Model 17 Spectrophotometer, with d i f f u s e r e f l e c t a n c e b a s e l i n e set at 90% transmittance f o r MgO i n the 250-700 nm range. Techniques o f e l e c t r o n emission spectroscopy f o r chemical analyses (ESCA) were a p p l i e d t o the DEAE cottons before and a f t e r t h e i r treatments with t h e e l e c t r o n acceptors. ESCA s p e c t r a were obtained on a V a r i a n IEE spectrometer, Model VIEE-15, t h a t had a Mg K X-ray source. S p e c t r a were obtained on samples o f f a b r i c . A l l b i n d i n g energies were given against a C^g l i n e o f 285.6 e l e c t r o n v o l t s (eV) as r e f e r e n c e . These s p e c t r a , analyzed t o y i e l d r e l a t i v e amounts o f n i t r o g e n o f d i f f e r e n t b i n d i n g e n e r g i e s , apply t o analyses o f surfaces only. A DuPont 310 curve analyzer was used t o r e s o l v e o v e r l a p p i n g peaks. Peak p o s i t i o n s are r e p o r t e d with a p r e c i s i o n o f ± .5 eV. The e l e c t r o n s p i n resonance s p e c t r a (ESR) o f the f a b r i c s were determined with a Varian i+502-15 spectrometer system equipped with a v a r i a b l e temperature accessory and a dual sample c a v i t y . a

Results and D i s c u s s i o n DEAE C o t t o n - C h l o r a n i l Adduct. T y p i c a l elemental analyses o f DEAE c o t t o n s , before and a f t e r r e a c t i o n s o f the amine groups with c h l o r a n i l o r with CuCl2, are given i n Table I . The c h a r a c t e r i s t i c b i n d i n g energies o f the Ν χ , Cl2p, and Cu2p e l e c t r o n s f o r the reagents and adducts are a l s o given. Included i n the t a b l e are corresponding data t o show e f f e c t s o f adding CuCl^ t o the DEAE c o t t o n - c h l o r a n i l adduct and o f adding c h l o r a n i l t o the DEAE c o t ton-CuCl2 adduct. 3



—

2

2

— 199. k

198.0

200. Τ 200.9

198.2

—• — 198.2

197.9

197.6

(eV)

96U.0

958.0

963.0

—

955.7

952.1

955.1

953.2

i s d i e t h y l a m i n o e t h y l c e l l u l o s e (DEAE) i n f r e e amine form i s adduct o f DEAE and c h l o r a n i l i s adduct o f 2 + CuClg i s DEAE + C u C l i s adduct o f k and c h l o r a n i l chloranil CuCl

398.9Î18]

2P

200.2

C 1

9^5.3

9^.7

9^.6

—

(eV)

"b - Bracketed number i s percentage o f t o t a l Ν o f each b i n d i n g energy

a - 1 2 3 k 5 6 7

7

— —

U00.2[9]

»*01. It [ 7 3 ]

5

6

399.3[20]

1*01.8[70]

k

39T.9[10]

399.3[3k]

kOQ.9[2l]

U01.7I39]

398.1[60]

3

b

eV)

398.3[l6]

l*00.l[l*0]

(

U00.3[28]

~

ls

1»01.6[56]

a

N

936.0

933.5

935.0

933. k

— —

—

—

1.86

2.10

2.02

2.02

Ν

B i n d i n g Energies (eV) o f E l e c t r o n s C h a r a c t e r i s t i c o f Elements i n C e l l u l o s e Exchangers

2

i

TABLE I .


cï

—

—

6.56

6.2k

6.28

.88

6.k9

5.16

k.l6

.86

Weight %

Cl

Anion

—

k.ll

— —

„+2 Cu

17.

PERRiER

AND B E N E R i T O

Tertiary Amines

247

Wet elemental analyses o f DEAE Cottons before and a f t e r r e a c t i o n with c h l o r a n i l showed that k meqs C l / g were added f o r every 3 meq N/g. The r a t i o o f meqs CI ions t o meqs o f organic c h l o r i n e per gram f a b r i c was 3/1 when the r e a c t i o n was c a r r i e d out i n nonpolar s o l v e n t s . ESCA s p e c t r a o f the c h l o r a n i l adducts were used t o estimate r e l a t i v e amounts o f nitrogens i n the DEAE cotton that had become more p o s i t i v e l y charged as a r e s u l t o f r e a c t i o n with c h l o r a n i l . The b i n d i n g e n e r g i e s , Eg.E., o f the N^ e l e c t r o n s observed i n the ESCA s p e c t r a o f nonaqueously prepared DEAE-cottons have been d i s cussed i n e a r l i e r reports (.3,8.). In f r e e amine groups, the E o f the N e l e c t r o n i s approximately 399 eV. Q u a t e r n i z a t i o n o f these f r e e amine groups with methyl i o d i d e t o form SR^ groups gives a spectrum e q u i v a l e n t t o Eg.E. of approximately **02.5 eV f o r the N , o r o f at l e a s t 3 eV higher than that f o r t h e f r e e amine n i t r o g e n . These d i f f e r e n c e s can be e a s i l y d i f f e r e n t i a t e d i n the ESCA s p e c t r a . However, t h e E o f the N electron i n some JR3H groups can d i f f e r from that o f the NR^ groups by o n l y 1 eV. Therefore, at times i t i s d i f f i c u l t t o d i f f e r e n t i a t e be tween t r u e quaternary nitrogens and those i n the h y d r o s a l t s o f t e r t i a r y amine. The N^g peak with Ε β o f 398.3 eV, c h a r a c t e r i s t i c o f r e l a t i v e l y negative n i t r o g e n i n f r e e t e r t i a r y amine groups o f DEAE cotton, was s t i l l present a f t e r r e a c t i o n with c h l o r a n i l , but i n a l e s s e r amount than i n the o r i g i n a l DEAE c o t t o n . In a d d i t i o n , N peaks with E E values o f i+00.6 and 1*01.6 eV were present. R e l a t i v e areas o f these peaks were used t o estimate t h a t 16% o f the t e r t i a r y amine groups o f the o r i g i n a l DEAE f a b r i c were unreacted. Based on ESCA and wet analyses, i t was concluded t h a t o f the Qk% r e a c t e d , three amine nitrogens r e a c t e d with one c h l o r a n i l molecule to y i e l d a product o f mole r a t i o s o f 3N/3C1/1 organic c h l o r i n e . The f o l l o w i n g i s one p o s s i b l e s t r u c t u r e (5.) f o r the product: s

B e E >


l s

l g

B # E #

l s

# Ε #

l s

B e

#

C H 2

3C1

5

where R i s (CellOC Η» — Ν — C = C — ) I Η Η Η

Ng and Hercules (£) used ESCA s p e c t r a t o support s t r u c t u r e s f o r various d o n o r - c h l o r a n i l adducts. Absence o f ESCA s h i f t s i n the s p e c t r a o f the adducts formed by weak donors such as hexamethylbenzene (HMB) with c h l o r a n i l , i n d i c a t e d nonbonding i n the ground s t a t e . A s h i f t i n the E g g o f the N electron o f e

e

l s

American Chemical Society Library 1155 16th St. N. W. Washington, D. C. 20036


CELLULOSE CHEMISTRY AND TECHNOLOGY

248

tetramethylphenylenediamine (TMPD) by +2 eV when i t r e a c t e d with c h l o r a n i l was a t t r i b u t e d t o formation o f S c a t i o n s t o the extent o f lh%. The s h i f t s i n the Εβ.Ε. o f the N e l e c t r o n s o f DEAE cottons on complexing with c h l o r a n i l were from +2 t o +3.5 eV. There was a decrease i n the E of C l e l e c t r o n s o f - 0 . 7 eV and an i n c r e a s e i n the i n t e n s i t y o f thP peak at approximately 198 eV c h a r a c t e r i s t i c o f CI" i o n s . Thus, some C l . e l e c t r o n s experience a s h i f t o f only - 0 . 7 eV (the organic c h l o r o a t o m s ) , and those going t o ions ( C l ~ ) a s h i f t o f - 3 . 0 eV. ESCA s p e c t r a o f the C and 0 e l e c t r o n s were a l s o s t u d i e d , but the s h i f t s i n the Ε o f these elements were not s i g n i f i cant. Even though the Ε o f the C electron in chloranil i s at 2 8 6 . 3 eV, i t s appearance"at 2 8 U . 6 eV i n the DEAE c o t t o n c h l o r a n i l complex i s e q u i v a l e n t t o that i n DEAE cottons. S i m i larly, Ε o f the 0, e l e c t r o n s o f 5 3 2 . 1 eV i n c h l o r a n i l , 531.9 i n the DEÂE* c o t t o n - c h l o r a n i l complex and 5 3 2 . 0 i n DEAE cotton were equivalent. Wet elemental analyses showed t h a t DEAE cottons coordinate 0 , 5 mm o f Cu ( I I ) f o r every meq Ν per g o f f a b r i c . The r a t i o s o f meqs amine nitrogen/mm Cu II/meqs Cl"* per g f a b r i c were 2 / 1 / 3 . In t h i s complex, the N-^ s p e c t r a showed t h r e e types o f n i t r o g e n s , as was the case i n the DEAE c o t t o n - c h l o r a n i l complex. As i n the s p e c t r a o f the other complex, a s m a l l percentage o f unreacted amine n i t r o g e n s was present as i n d i c a t e d by the E o f lowest v a l u e , approximately 398 eV. In the copper complex,'only 10$ o f the t e r t i a r y amines were unreacted. In donations o f e l e c t r o n s t o e i t h e r Cu ( I I ) ions or t o c h l o r a n i l , two types o f more e l e c t r o p o s i t i v e nitrogens are formed. The highest E , that a p p r o x i mating k02 eV, i s c h a r a c t e r i s t i c o f n i t r o g e n s in"quaternary ammonium i o n s . That peak o f intermediate E i s s i m i l a r t o the peak o f a n i t r o g e n i n a h y d r o s a l t o f a t e r t i a r y amine group, o r i t c o u l d be the r e s u l t o f a back donation i n the formation o f donor-acceptor bonds as when adducts are formed. The r a t i o o f nitrogens having the h i g h e s t Ε to n i t r o g e n s with intermediate B.E. A f o r the c h l o r a n i l ' c o m p l e x and 3 . 5 / 1 f o r the CuCl2 complex. When anhydrous CuCl2 i s r e a c t e d w i t h nonaqueous DEAE c o t t o n s , the complex formed gives ESCA s p e c t r a f o r the CU p, and CU^^ e l e c t r o n s s i m i l a r t o those observed with CuCl2 i n t h a t each E has a s a t e l l i t e at a h i g h e r b i n d i n g energy than the main peak. A d d i t i o n o f c h l o r a n i l to the DEAE c o t t o n - C u C l complexes lowers the E o f the C u e l e c t r o n s from 9 3 5 . 0 t o 9 3 3 . 5 eV without a f f e c t i n g i t s s a t e l l i t e , and lowers the E o f the C u ^ e l e c trons from 9 5 5 . 1 t o 9 5 2 . 1 and i t s s a t e l l i t e from 9 6 3 . 0 to 9 5 8 . 0 eV. ttese changes i n d i c a t e complexing o f Cu ( I I ) with added c h l o r a n i l . A d d i t i o n of C u C l t o the a l r e a d y complexed c h l o r a n i l o f the DEAE c o t t o n - c h l o r a n i l complex r e s u l t s i n the lower values o f 9 5 3 . 2 and 933.k eV f o r the E ^ values f o r the C u ^ and C^P'A e l e c t r o n s , but no s a t e l l i t e s are present. l s

B # E e

2

p

P

l

l s


β

s

E

Β β Ε β

l g

Β β Ε β

B e E

B

E

B # E #

Β β Ε β

E

w

a

s

2

2

/x

B # E >

2

B > E e

2

B e E #

2 p

2

B

E

2 p / y


17.

PERKIER AND B E N E R i T O

Tertiary

Amines

249

The DEAE cotton-chloranil product was paramagnetic. A typ i c a l ESR spectrum obtained at room temperature i s shown i n Figure 1. The singlet i s not characteristic of a free electron on a nitrogen, which would generate a t r i p l e t . The g value of 2.0059 was found i n the study. Thus far, very l i t t l e research has been carried out on single crystals formed by charge transfer for D A" reactions i n the solid state. With chloranil as the acceptor of electrons from tetramethylphenylene-diamine (TMPD) rather than from a triethylamine group, i t was found that the hyperfine s p l i t t i n g of the ESR signal changed with time. The absence of a t r i p l e t characteristic of a radical cation i n such complexes has been explained i n several ways (10). In the pure crystals of TMPD-chloranil, the D ion was ab sent and i t was presumed that both the D ions and A"" ions were present, but i n small concentrations in a predominantly molecular l a t t i c e . The components of the g-term gave an average g value of 2.0052 similar to that obtained i n this study for the DEAE cotton-chloranil complex. Comparisons of IR spectra of DEAE cottons before and after reaction with chloranil were made to gain evidence of reaction. New and strong bands at 6.3 μ characteristic of N Rl^ groups, and those bands characteristic of conjugated C=C groups at 6.2 and 6.6M were evident i n the spectra of the fabrics containing the DEAE cotton-chloranil adducts. In addition, there were also weak bands at 5·95μ, characteristic of C=0, and bands at 7. and 10.lu characteristic of C-Cl groups. Visible reflectance spectra of the cottons containing the DEAE cotton-chloranil adducts were compared with those of the DEAE cottons and of known products of chloranil. The DEAE cot tons absorb only in the 280-300 nm range. Chloranil absorbs at 285 nm; i t s adduct with triethylamine absorbs i n i t i a l l y i n the 320-380 nm region, but at longer wave lengths (380, 1+35, 787 nm), on standing. Its sodium salt absorbs at 1*25 and 1*52 nm. Ab sorption spectra of aliphatic amines and chloranil have been thoroughly investigated (.5,11). It has been shown that the semiquinone anion, (CgCl^O") i s responsible for absorption at 1*26 and 1*52 nm. After long standing, the yellowish solution, as well as the solid green adduct formed between triethylamine and chloranil, absorb at 380, 1*35, 770, 393, 1*1*0, and 889 nm. It is not surprising therefore that our DEAE cotton-chloranil com plex formed on the fabric absorbed throughout the 300-750 nm region. The fabric adduct is dark green in nonpolar solvents and a lighter green i n polar solvents. Foster also reported that the solid adduct formed between triethylamine and chloranil showed a strong ESR single line absorption. Examination of redox powers of the fabrics containing the chloranil adduct showed that the product i s a good reducing re agent. Nitroblue tetrazolium i n the presence of CN can be reduced


+

+

++

+



250


by the adduct but not by the o r i g i n a l c h l o r a n i l o r DEAE c o t t o n used s e p a r a t e l y . The DEAE c o t t o n - c h l o r a n i l r e a c t i o n must have r e s u l t e d i n some c r o s s l i n k i n g between c e l l u l o s e c h a i n s , because the products were i n s o l u b l e i n cupriethylenediamine. DEAE Cotton-TCNE Adduct. Nitrogen analyses o f DEAE cottons before and a f t e r r e a c t i o n with TCNE by the Kjedahl method showed that two meqs N/g o f cotton were added f o r each meq N/g o f cotton i n the o r i g i n a l DEAE c o t t o n . A DEAE c o t t o n (l.hh meq N/g) con t a i n e d k.29 meq N/g a f t e r TCNE treatment, f o r example. T h i s i n d i c a t e s r e a c t i o n o f 2 amino n i t r o g e n groups o f DEAE cotton with one TCNE t o y i e l d t h e f o l l o w i n g product:

(C H ) 2

NC I ©

CellOH C N I 4

2

5

2

®NC H 0Cell / 2

4

P = c /

\ CN

2CN

Data i n Table I I show the Eg.E. values f o r the C i , 0 i , and Ν χ e l e c t r o n s from a l l f a b r i c s and o f the C l p ^ and C l ^ and o f the Cu2p'/j. and C u _ ^ e l e c t r o n s , when these elements were present. As p r e v i o u s l y r e p o r t e d , DEAE f a b r i c s c o n t a i n about 30% o f the n i t r o gens i n a somewhat more p o s i t i v e form than that i n the f r e e amino groups. Probably i n the p r e p a r a t i o n o f DEAE c o t t o n s , some f r e e amine nitrogens r e a c t with excess 3-chloroethyldiethylamine o r an organic s o l v e n t or a proton. The E values f o r elements i n TCNE are a l s o i n c l u d e d . The ESCA s p e c t r a o f the N e l e c t r o n s again showed three d i f ferent E g v a l u e s . The r a t i o o f r e l a t i v e amounts o f h i g h e s t t o intermediate peaks f o r t h i s complex was 1/1. The intermediate peak i n t h i s case i s a combination o f amino n i t r o g e n s that became more e l e c t r o p o s i t i v e during r e a c t i o n and TCNE n i t r o g e n s t h a t be came more negative. I n i t i a l l y i t was assumed t h a t the lowest B.E * 397.7 eV was due t o the CN i n combination w i t h _ f r e e amino n i t r o g e n s . However, r e p o r t e d values f o r E^^g^ o f t h e CN are questionable (12). T h e r e f o r e , the CN ions o f * t h e DEAE cotton-TCNE adduct were exchanged f o r CI by use o f excess NaCl s o l u t i o n . Analyses o f the N spectra f o r Ε values o f 1+01.3, 399.1 and s

2

s

2

2

B # E e

l g

e E

E

o i

l g

β E


8

In Cellulose Chemistry and Technology; Arthur, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1977. c

289.3^ sn

TCNE —

1+00.2

—

2

DEAE-CuCl -TCNE i s the C u C l 2

complex subsequently t r e a t e d with TCNE

—

2

—

398.1[11]

397.9[10]

397.8[31]

397.7[l+6]

DEAE i s d i e t h y l a m i n o e t h y l cotton i n the f r e e amine form DEAE-TCNE i s DEAE f a b r i c complexed with tetracyanoethylene DEAE-TCNE-c11ci2 i s DEAE complexed f i r s t with TCNE and then t r e a t e d with C u C l DEAE-CUCI2 i s the complex formed with C U C I 2

(#) i s width at h a l f height °[#] i s r e l a t i v e percentage o f t o t a l Ν

b

a

2

—

398.8[28]

1+01.7[6l]

198.1(2.7)

532.7(2.1)

285.3(3.0)

DEAE-CuCl -TCNE

285.3

399.3[20]

1+01.8[70]

198.2(U.1)

532.7(2.3)

2

399.0[35]

399.1[26]

285.3(2.7)

DEAE-CuCl

1+01.3[26] U01.6[3l+]

—

197.9(3.5)

[i+o] 3 9 8 . 1 [ 6 0 ]

532.3(2.2)

1+01

Is

285.0(2.7)

2

197.6(2)

2P

DEAE-TCNE-CuCl

532.0(2.2)

C 1

532.2(2.3)

b

°ls

285.3(3.0)

ls

DEAE-TCNE

C

o f Treated F a b r i c s

281*.6(2.7)

8,

B i n d i n g Energies (eV) o f E l e c t r o n s i n Elements

DEAE

Fabrics

TABLE I I .


—

935.9

963.0 955.1 91+1*.6 9 3 5 . 0

952.1+ 9 3 2 . 9

—


252

397.Τ eV f o r a DEAE cotton-TCNE complex, before and a f t e r exchange with CÏ i o n s , give r e l a t i v e peak areas o f 1/1/2 before and 1/1/1 a f t e r e x t r a c t i o n . Use o f Nal r a t h e r than NaCl t o exchange CN ions from another piece of_the same DEAE cotton-TCNE adduct r e s u l t e d i n o x i d a t i o n o f some Ϊ t o f r e e I . Nevertheless, r a t i o s o f peak areas were changed t o 1/1/0.5. I t was shown that the E o f the CN was that o f the lowest o f the three values observed f ô r * N spectra. On the assumption that only the unreacted (:NR^) groups were r e s p o n s i b l e f o r the peak o f lowest E a f t e r exchange with excess N a l , i t was c a l c u l a t e d that the number o f nitrogens quatern i z e d ( c h a r a c t e r i z e d by highest Ε ) was twice t h a t l e f t as unreacted t e r t i a r y amines ( c h a r a c t e r i z e d by lowest E ). This information, together with wet analyses o f DEAE cotton and the DEAE cotton-TCNE complex, showed that f o r every amino Ν i n the DEAE cotton t h a t reacted, one n i t r o g e n from the TCNE remained i n the bound o r organo fo_rm ( Ε β = 399.1), and 1.5 nitrogens from the TCNE were i n the CN form." *Thus, the r a t i o o f amine nitrogens reacted/bound CN/CN was c a l c u l a t e d t o be 2/2/3. These data show that 70$ o f the amino nitrogens o f DEAE cotton were quaternized by TCNE and t h a t most were i n the highest e l e c t r o p o s i t i v e s t a t e , because the r a t i o o f nitrogens i n highest t o intermediate Eg was 10/1 compared t o 3.5/1 f o r the DEAE cotton-CuCl2 complex* and 2/1 f o r the DEAE c o t t o n - c h l o r a n i l complex. The increase o f +3 eV i n the E o f the N electrons o f DEAE cottons on r e a c t i o n with TCNE, and the decreases o f -1.1 and -2.5 eV i n t h e E^ o f the N- e l e c t r o n s o f TCNE, are i n d i c a t i v e of a strong r e a c t i o n between tee donor and acceptor i n which amino nitrogens become quaternized and the cyano groups bound t o the e t h y l e n i c carbons are l e s s e l e c t r o p o s i t i v e than i n the o r i g i n a l TCNE. A d d i t i o n o f anhydrous CuCl2 DEAE cotton-TCNE adduct r e s u l t e d i n a small a d d i t i o n o f Cu ( I I ) t o the f a b r i c , but the B.E. values f o r the Cu2 >/ and C u 2 % were at 952.U and 932.9 eV, r e s p e c t i v e l y . These ESCA s h i f t s were -2.7 and -2.0 eV from those observed with the DEAE cotton-CuClp complex. In a d d i t i o n , n e i t h e r s a t e l l i t e was present when the Cu ( I I ) was added t o the DEAE c o t ton-TCNE complex. A l s o , when TCNE was added t o t h e DEAE cottonC u C l complex, a small a d d i t i o n o f n i t r o g e n was obtained and only the main C u 2 ^ p e a k o f Ε a t 935.9 eV was observed. 2

B > E

lg

B E


β E

B e E >

< Ε >

E

B e E >

l s

E

t

o

t

n

e

E

p

A

p

2

p

β E

The DEAE cotton-TCNE*adduct was a l s o paramagnetic, g i v i n g a s i n g l e t i n i t s ESR s p e c t r a . In Figure 2 i s a t y p i c a l spectrum obtained at room temperature. The"g-value was 2.0032. This ESR s i n g l e t i s not c h a r a c t e r i s t i c o f an e l e c t r o n on the Ν o f the c a t i o n o r o f a f r e e e l e c t r o n on an anion formed by a charge t r a n s f e r complex. Stamires and Turkevich (7.) were able t o obtain an 1 1 - l i n e spectrum by r e a c t i n g TCNE with t r i e t h y l a m i n e i n c h l o r o form. The 11 l i n e s with a separation o f about 1.6 gauss and an i n t e n s i t y r a t i o o f l/U/10/l6/19/l6/10/U/l, were a t t r i b u t e d t o the anion r a d i c a l formed by the capture o f one e l e c t r o n by TCNE. The g-value o f the center o f the complex was close t o that o f a f r e e


Tertiary

Amines


PERRiER AND B E N E R i T O

Figure 2. ESR signal of a DEAE cotton after its reaction with tetracyanoethylene (TCNE) in chloroform



254

CELLULOSE

CHEMISTRY

A N D

TECHNOLOGY

e l e c t r o n . The g-value o f the s i n g l e t spectrum obtained i n our adduct was l e s s than that obtained with the DEAE c o t t o n - c h l o r a n i l adduct. The IR s p e c t r a o f DEAE cotton-TCNE adducts on the f a b r i c give strong absorption bands a t h ,6\i > c h a r a c t e r i s t i c o f C=N, and at 5 . 9 5 and 6 . 1 μ c h a r a c t e r i s t i c o f C=N groups. The strong bands at 6 . 2 and 6.7\i were i n d i c a t i v e o f conjugated double bonds. These marked d i f f e r e n c e s i n s p e c t r a a f t e r DEAE cotton had been t r e a t e d with TCNE i n d i c a t e d s t r o n g r e a c t i o n between donor and acceptor. The redox powers o f TCNE were a l s o d i f f e r e n t a f t e r i t was r e a c t e d with DEAE cotton. TCNE, a good o x i d i z i n g reagent alone, was a l s o an e f f e c t i v e o x i d i z i n g reagent when complexed with DEAE c o t t o n . A f t e r r e a c t i o n with DEAE c o t t o n , the r e s u l t a n t f a b r i c was a per oxide generator, i t f l u o r e s c e d , and i t produced chemiluminescence. Summary I n t e r a c t i o n s between t e r t i a r y amine groups o f DEAE cottons as an η type o f donor, D, and TCNE o r p - c h l o r a n i l as the π type of acceptor, A, were l a r g e enough t o produce products with absorp t i o n s i n the u v - v i s i b l e range that were not c h a r a c t e r i s t i c o f the i n d i v i d u a l components, and t o produce e l e c t r o n t r a n s f e r s i n the ground s t a t e r e s u l t i n g i n paramagnetic p r o p e r t i e s o f the D-A com p l e x w i t h i n the c e l l u l o s e matrix. ESR data i n d i c a t e d absence o f unpaired e l e c t r o n s l o c a t e d on n i t r o g e n atoms o f the amine groups and suggest transformation o f outer (π ) D-A complexes t o i n n e r (σ) D A or D A type complexes. ESCA s p e c t r a were used i n conjunction with wet analyses t o support proposed s t r u c t u r e s f o r the products. Acknowledgement The authors express t h e i r a p p r e c i a t i o n t o Mr. Oscar Hinojosa f o r ESR s p e c t r a .

Literature Cited 1. Berni, Ralph J . , Soignet, Donald Μ., and Benerito, Ruth R., Textile Res. J., (1970), 40, 999. 2. Soignet, Donald Μ., Berni, Ralph J., and Benerito, Ruth R., J. Appl. Polymer Sci., (1971),15, 155. 3. Perrier, Dorothy M. and Benerito, Ruth R., J. Appl. Polymer Sci., (1975),19, 3211. 4. Perrier, Dorothy M. and Benerito, Ruth R., J. Appl. Polymer Sci., (1976), 20, 000. 5. Foster, R., Rec. Trav. Chim., (1964), 83, 711. 6. Mulliken, Robert S., J. A. C. S., (1952), 74, 811. 7. Stamires, Dennis N. and Turkevich, John, J.A.C.S., (1963), 85, 2557. 8. Soignet, Donald M., Berni, Ralph J., and Benerito, Ruth R., Anal. Chem., (1974), 46, 941.



17.

PERRIER AND BENERITO

Tertiary Amines

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9. Ng, Kung T. and Hercules, David Μ., J.A.C.S., (1974), 97, 4168. 10. Foster, R., "Organic Charge-Transfer Complexes," p. 269, Academic Press, New York, 1969. 11. Shah, Salish B. and Murthy, A. S. N., J. Phys Chem., (1975), 70, 322. 12. Siegbahn, Kai, Nordling, Carl, Faklman, Anders, Nordberg, Ragnar, Hamrin, Κjell, Hedman, Jan, Johansson, Guirilla, Bergmark, Torsten, Karlson, Sven-Erik, Lindgren, Ingvar, and Lindberg, Bernt, "ESCA Atomic, Molecular and Solid State Structures Studied by Means of Electron Spectroscopy," Almquist and Wiksells AB, Stockholm, 1967. *Mention of companies or commercial products does not imply recommendation by the U. S. Department of Agriculture over others not mentioned.


Cellulose Chemistry and Technology - American Chemical Society

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