Chloride elimination and ultraviolet bands in dichloroprotoanemonin/methyl methacrylate copolymer

Chapman, D. A.

Li, G. T. C.

Winston, A.

English

NASA Technical Reports Server

I 1  " 
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SEQUENCE DISTRI3VJION STUDIES OF DICHLOROPROTOAWONIN a 
METHYL METHACRYLATE COPOLYMERS 
A. Winston, D. #. Chapman and G. T, C. Li. 
Department of Chemistry, West Virginia University 
Morgantown, West Virginia 26505 
Polymerization of l,3-diene type monomers to give polymer units whioh 
spontaneously undergo an elimination reaction is a convenient means for 
preparing polymers having a high degree of conjugated unsaturation in the 
main chain. 
such a monomer as it readily forms 1,4-addition copolymers with methyl 
methacrylate, styrene, etc., and under suitable conditions ydergoes a 
rapid dehydrohalogenation to give conjugated DCPA residues, 
possible addition and elimination reactions are shown in scheme A, 
Dichloroprotoanemonin (DCPA) (I) is an excellent example of 
The various 
Scheme A: 
I 
TT 
I11 V 
We reported earlier2 that the DCPA residues consist almost entirely of 
Structures I1 and 111 are ruled out on the basis that structures Iv and V. 
one equivalent of HC1 is eliminated per equivalent of DCPA that enters the 
copolymer. The presence of structure IV from 1,4-elimination is confirmed 
by infrared absorption at 1770 cm-l for the conjugated lactone carbonyl 
group, and by ultraviolet absorption at Xmax 300 m)l for the three double, 
bond conjugated system. An additional infrared bond at 1800 emo1 is con- 
sistent with the non-conjugated carbonyl group, and suggests the presence 
of structure V from 1,2-elimination of hydrogen chloride. 
Several additional DCPA-MMA copolymers were prepared for the purpose of 
confirming the previous results on chloride elimination and for further 
spectral studies, These copolymerizations, Nos, 3, I t ,  5 are reported in 
Table 1 and compared with the previously reported data for Nos. 1 and 2, 
The good agreement between the amount of chloride eliminated as H C 1  and the 
amount remaining in the copolymer confirms the previous observation that 
half of the chloride is eliminated on copolymerization of DCPA with methyl 
may be attributed to errors introduced by the inability to isolate Con- 
pletely all of the copolymers formed, 
possess, in addition to the intense band at 300 ap~, a weak band at 368 9, 
B Figure 1, Whereas the band at 300 m)f is readily attributable to the three 
E double bond conjugated system of structure IV, the band at 368 mfl indicates 
that more extended conjugated structures may be present. These structures 
1 I I  
B t e  c u u .  
Q C  
0 0  
- -  
v) - -  I methacrylate, The slightly high values for the percent chloride eliminated 
u 
0 ! z  " G = m  
Ultraviolet spectral studies have revealed that DCPA-MMA copolymers E a .  2 2 :  
3 L i  
L -  .o = 
L L L  
3 0  
I 2 
" .^ 
https://ntrs.nasa.gov/search.jsp?R=19680013732 2020-03-12T08:56:04+00:00Z
A . .  
are very possibly DCPA residue diads ( V I )  which, having a six double bond 
conjugated system, would be expected t o  absorb at  about the  observed 
position. 
1 
0 
VI 
If t h i s  is the  case, the absorption band at 368 nyf, being w e l l  resolved 
from the 300 
dist r ibut ion i n  th'is system, 
band, would provide a means f o r  measuring the diad sequence 
I n  the case of DCPA-styrene copolymers, d i s t i nc t  absorption peaks above 
300 my. are completely lacking, Figure 2. Since copolymers of styrene with 
cycl ic  monomers are usually highly al ternat ing,  the probabili ty fo r  diad 
formation i n  such cases is re la t ive ly  low and, hence, the absence of a band 
a t  about 368 mp for  the DCPA-styrene copolymers supports the proposal that 
this band is due t o  DCPA residue diad sequences, 
and since Beer's l a w  held over the concentration range involved, the values 
were converted t o  absorbance f o r  O.l$ solutions, Table 2. 
values against copolymer composition, Figure 3 ,  sham that the absorbance I 
consistently increases with each increase i n  the  DCPA residue i n  the COpOl-' 
p e r .  This r e su l t  is conpatable with the  increasing probabili ty of diad 
formation with increasing DCPA content. A plo t  of t h e  absorbance at 368 " ~ f  
against  the actual  diad concentration should give a s t ra ight  l i n e  if  the  
diads were r ea l ly  responsible f o r  t h i s  band, 
function3 f o r  diad formation had t o  be determined from the  reac t iv i ty  ra t ios .  
The data f o r  the  calculation of the reactivity r a t io s  are reported i n  Table 
3 and the feed copolymer compositions are l o t t e d  i n  F i  yre 4. Solution of 
t he  copylmer equation by the Fineman-Ross,8 M~o-Lewis, and curve f i t t i n g  
methods provided the reac t iv i ty  r a t io s  listed i n  Table 4. 
w a s  used i n  the  calculation of the copolymer composition curve, Figure 4, 
and the number dis t r ibut ion function, Table 5. In  the calculation of the 
number dis t r ibut ion function the feed composition responsible f o r  each of 
the copolymers was required, However, the feeds actually employed i n  the  
copolymerization reactions were unsatisfactory f o r  this purpose because the 
constant passage of nitrogen through the system for HC1 removal caused 
appreciable amounts of both monomers t o  be volat i l ized,  thus changing the 
feed composition. 
would have provided the various copolymer compositions obtained, were 
calculated from the copolymer compositions by means of the reac t iv i ty  ra t ios ,  
From the effective feed compositions and the reac t iv i ty  r a t io s ,  the number 
dis t r ibut ion functionsand f i n a l l y  the DCPA diad concentrations were call 
culated, Table 5. 
The absorbance a t  max 368 mp was measured for  the  various copolymers, 
A p lo t  of these 
However, i n  order t o  prepare t h i s  p lo t ,  the  number dis t r ibut ion 
The average value 
For this reason the effect ive feed compositions which 
A plot  of t h e  diad concentration again& the  absorbance i s  shown i n  
Figure 5. 
proposal that the band at  hmax 368 
residues i n  the copolymer, 
where the quantity used for  the  measurement of the  sequence is  clear ly  
resolved from that of the isolated unit. 
The reasonably s t ra ight  l i ne  produced supports w e l l  the or ig ina l  
i s  due t o  &ads sequences of DCPA 
This  particular system is  one of the  few cases 
3 . .I ". 
A simila,r treatment of the 300 m ) ~  band of the isolated DCPA conjugated 
uni t ,  s t ructure  IV, has not yet  afforded consistent resu l t s ,  However, since 
the  dis t r ibut ion between 1,4- and 1,Z-elimination t o  give structures IV and 
V is not known a t  present, accurate concentration values of s t ructure  IV 
cannot be determined. Also, the contribution of the  diad t o  the absorbance 
at 300 is not known, although a t  the  low diad concentrations t h i s  factor  
i s  probably negligable, 
EXPERIMENTAL 
Dichloroprotoanemonin was prepared through the  reaction of sodium tri- 
chlora etate with succinic anhydride according t o  the  method of Winston and 
Sharp.8 The white c rys ta l l ine  compound was purified by sublimation at  95OC 
(1 mm) , mp 97.5%. Elemental. analyses were performed by Gailbraith Labora- 
t o r i e s ,  Knoxville, Tennessee. Ultraviolet spectra were recorded on the 
Bausch and Lomb Spectronic 505 using 1.0 cm, cells (dioxane solutions). 
Copolwerization Procedure 
The copolymerizations were carr ied out in a three neck f lask  fitted 
To the ref lux condenser was connected a tube leading t o  a t r a p  
with a reflux condenser and a gas i n l e t  tube a tending  t o  the  bottom of the  
f lask,  
containing a known volume of standard sodim hydroxide solution. 
polymerization, nitrogen gas, dr ied by a previous passage through concen- 
t r a t ed  sulfur ic  acid, was introduced through the i n l e t  tube i n  order t o  
sweep the hydrogen chloride in to  t h e  standard base solution, 
termination of the polymerization, the excess base was t i t r a t e d  with standard 
hydrochloric acid, 
constant temperature bath. 
caused the polymers t o  precipi ta te ,  
precipi ta t ions from acetone-methanol and were dried under reduced pressure 
f o r  two days, 
t h a t  they were free of DCPA and solvent impurities, 
,and elimination dataare 'reported i n  Table 3. 
During the  
I 
A t  the 
The temperature of polymerization was  held at 650 by a 
Addition of methanol t o  the  reaction mixture, 
The polymers were pruified by three 
Examination of the NMR spectra of t h e  copolymers indicated 
The copolymerization 
Determination of Reactivity Ratios 
Solutions of DCPA and m e t h y l  methacrylate i n  benzene were polymerized 
at 650 i n  sealed tubes. 
t he  color of the reaction mixture changed from colorless t o  golden-orange, 
Copolymers formed from the 0.05-0.4 mole f ract ion DCPA feeds were pre- 
c ip i ta ted  from methanol. 
DCPA feeds f a i l e d  t o  precipi ta te  on addition of methanol, the  unreacted 
residual  methyl methacrylate and solvents were evaporated on a rotary 
evaporator a t  room temperature, 
out of the  polymer at  95O/1 mm, 
amount of benzene and repreoipitated from ligroin.  The polymers were 
collected,  washed, and dried under reduced pressure. The copolymers were 
then analyzed f o r  chlorine and the  copolymer compositions were calculated 
on the  basis  of one chlorine per DCPA residue, Table 3, 
During the polymerization time of from 4-6 hrs. 
Since copolymers from above 0.40 mole f ract ion 
The residual lactone monomer w a s  sublimed 
The residue was then dissolved i n  a small  
ACKNOWIZDGMEXT 
P a r t i a l  support of t h i s  work by NASA (Grant NsG-533) is  grateful ly  
acknowledged. 
Y 
REFERENCES 
1, 
2. 
A, Winston and G. 11. C. L i ,  J. Polymer Sci. , s, 127 (1967), 
A .  Winston and D. A ,  Chapman, Preprints of the  IUPAC International 
Symposium on Macromolecular Chemistry, Brussels-Louvain, June 12-16, 
1967, No. 1/6; J, Polymer Sci. ,  i n  press, 
3. G, Goldfinger and T. Kane, J, Polymer Sci,,  2, 462 (1948). 
4. M, Fineman and S. D. ROSS, J. Polymer Sci., 5, 259 (1950). 
5. F. R, k y o  and F. M. Lewis, J, Am. Chem, Soc., 66, 1594 (1944). 
6. A, Winston and J. C. Sharp, J. Am. Chem, Soc., 88, 4196 (1966). 
Table 1 
Copolymerization of Dichloroprotoanemonin (MI) with 
Methyl Hetnacrylate (IJrZ) 
Copolymer No. 
Mole Fract. 141 i n  Feed 
\?t. Feed (g) 
'Jol. Benzene (ml) 
React Time (hr) 
W t .  Copolymer (g) 
CX i n  Copolymer ($1 
Total C 1  i n  Copolymer ( g )  
Total C 1  Eliminated (g) 
C l  Eliminated ($1 
DCPA i n  Copolymer (%I 
Mole Fract,  DCPA i n  Copolymer 
1 
0.20 
5.. 63 
0 
6.0 
1.33 
3.27 
0.043 
0.049 
53.3 
11.8 
0.094 
2 3 
0.20 0.20 
5.65 5.65 
5 0 
603 1.7 
2.23 122 
2.96 1.60 
0.066 0,020 
0.076 0.025 
53.5 55.6 
T917 5,8 
0.086 0.036 
4 
0.20 
5-65 
0 
6 s  
.I 
1.86 
I 
6.74 
0.053 
Table 2 
Ultraviolet  Absorption Data f o r  DCPA-MMA 
Copolymers at 368 ny. in Dioxane 
5 
0.44 
6.28 
15 
18 
0.505 
6.76 
0.0341 
0,0350 
50.5 
24.4 
0,202 
4 L .5- -  Copolymer No. 1 2 3 
Copolymer Conc. (g/ l )  1.096 1,550 1.630 1.912 0.916 
Absorbance at 368 mp 0,421 0,451 0.155 0.245 1.358 
Absorbance (adjusted t o  O,lOO$ .: * 
s o b .  0.3% 0,291 0,095 Oil28 1.48 
* Mole Fract. 
DCPA i n  feed 
f 1 
0.05 
0.1 
0.2 
0 , 4  
0.5 
0.6 
0.7 
0.8 
0.3 
009 
Table 3 
Feed Copolymer Composition Data f o r  the 
DCPA (Ml)-MNA( (M2) System 
Conversion C1 A n a l . ,  
f! $ 
41.7 
350 2 
12.1 
2.4 
3.3 
7.1 
11.4 
2.7 
2.9 
4.2 
Mole fract, 
DCPA i n  
Copolymera 
Fl 
0.06 
- 
0.08 
0.13 
0.20 
0.32 
0.36 
0.51 
0.23 
0,60 
0.69 
7.74 
10 53 
11.51 
18.19 
15.85 
2030 
a. Calculated on the basis  of one chlorine per DCPA residue, 
Table 4 
Reactivity Ratios for 
DCPA (Mi) - MMA (Mz) copolymerization 
Method 
Fineman-Ross 
Mayo-Lewis 
Curve F i t t ing  
Average 
r 2  
0,16 + 0,15 
0.16 2 0.15 
- rl 
1.44 0,21 
1.45 2 0.45 
1.42 0,115- ~. 
1.43 2 0.45 
- 
Table 5 
Calculation of the Diad Concentration of the 
DCPA - MMA Copolymers 
Copolymer Wo. 1 2 3 4 5 
Feed Composition I .  
Gopolymer Cotrpo sit ion 
_. (14ole Fract, DCPA) 
(Mole Fract, DCPA)‘ 0.139 0.1.26 0.052 0.077 0.305 
Number Distribution Function 
f o r  DCPA Diads (N) 0.0243 0,0220 0.0086 0.0131 0.0612 
Diad Conc. (.%) 0,144 O,ll8 0,0250 0.0442 0.745 
0.094 0,086 0.036 0.053 0,202 
* I “  
a. Effective feed composition as calculated from the copolymer 
composition and the  react ivi ty  ra t ios .  
*: . .  I 
$ 
Fig, 1, Ultraviolet 
. spectrum of DCPA-MMA 
copolymer. 
Pig, 2. Ultraviolet 
s p e c t m  of DCPA-Styrene 
copolymer. 
'1.6 
1.2 
1.0 
0.8 
0.6 
0.4 
0.2 
0 
J 
0 2 4 6 8 10 12 14 16 18 20 22 24 26 . 
Corroentration of ~ C P A  i n  Copomer, $ 
Rblation between the concentration of DCPA residues Fig, 3. 
i n  the copolymer and the jabsor%ance a t  368 np f o r  O& . 1 I, 
solutions. 
" ,  
, i. , 
1.6 
1.4 
1.2 
81.0 
8 
2 
$0.8 
0.6 
P 
4 
0.4 
0.2 
F1 
.8 
.7 
,6 
.1 
Fig, 4. Feed-copolymer composition plot for DCPA 
(Q) = MMA (M2). 
0.16 r2 = 3 ~ 4 3 .  
The curve is drawn for rl = 
t 
0.2 0.3 0.4 0.5 . 0.6 0e7 0 0.1 
’ j  Diad Concentration in Copolymer, $ 
Fig. 5. , Relation between the DCPA diad concentration in 
the copolymer and the absorbance at 368 ny for 0.1s 
solutions, 1 
. ” - -  
1 


Sequence distribution studies of dichloroprotoanemonin-methyl methacrylate copolymers

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