Diluent-Gel Point Relationships for the Reaction of Tetra-(β-carboxyethyl)-cyclohexanone with...
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3006 NOTES Vol. ii Diluent-Gel Point Relationships for the Reaction of Tetra-(p-carboxyethy1)-cyclohexanone with Di- ethylene Glycol BY IRVING \VALTCHER AND IRVISG MILLER' RECEIVED DECEMBER 11, 1954 In his basic investigation of gel points, Flory? found that the experimental values for the extent of reaction at which gelation occurred, the critical extent of reaction, were higher than the values pre- dicted from his theoretical analyses for such sys- tems. He ascribed the discrepancy to the small amount of intramolecular reaction which occurs, this reaction not contributing to the formation of infinite networks. Stockmayer and Wei1324 have used the dilution principle as a means of excluding the error due to the intramolecular reaction. They reasoned that since the cyclization reaction assumes more impor- tance at higher dilutions, a series of gel points ob- tained at increasing dilutions in an inert solvent should show ever increasing values for the extent of reaction at which gelation occurs. Using the system pentaerythritol-adipic acid and dimethoxytetra- ethylene glycol as the inert diluent, they plotted the extent of reaction at the gel point as a function of the volume of the system and found the observed points to fall on a straight line which when extrapo- lated to zero volume, a so-called "infinite concen- tration," gave a value for the critical extent of re- action equal to 0.578 in excellent agreement with the predicted value of 0.577. This then appears to be a device for eliminating the error due to cy- clization reactions. During the course of some work on polyesters, we had occasion to use this same technique on the system tetra-(~-carboxyethyl)-cyclohexanone5 and diethylene glycol,6 and using dimethoxytetraethyl- ene glycol7 as the diluent. The data of Table I were obtained by use of the falling sphere method for observing the gel point and by titrating unre- acted carboxyl groups to follow the extent of reac- tim. The values for the critical extent of reac- (1) The material presented was taken from the h1.S. thesis of I. (2) P. J. Flory, THIS JOURSAL, 68, 3083 (1941). 13) W. H. Stockmayer, "Advancing Fronts in Chemistry." Reinhold (4) I,. L. Weil, doctoral dissertation, Columbia University, 1945. 13) Prepared according to H. A. Bruson and T. W. Riener, THIS (0) Distilled Eastman Kodak Cu product. >filler, 1952, Pub]. Carp., New York, N. Y., 1945, p. 01. .IIJUKNAL, 64, 2850 119-1?) Ansul Chemiral Co and di.itilled from sotliiini, 1) I). tion, Flory's'' pc, were plotted as a function of the volume of the system. The points were found to fall 011 a straight line, enabling extrapolation to zero volume, the intercept giving a value for pc of 0.585 as compared with the calculated value of 0.577 from the Florp equation. TABLE I POLYCOSDENSATIOS OF EQUIVALEST QUANTITIES OF TETRA- LOHEXASOSE ASD rjIETHYLESE GLY- COL .4T 110.8' USING UIRIETHOXYTETRAETIIYLES& GLYCOl. AS SOLVENT' '( l'/L.ob,C ,k 1,; v/l',lb,r fir 19.8 1.25 0.042 70. i :3 ,41 i) 74.i 4i.9 1.92 .(ii5 i(i.0 4.I(i .ii4 57.5 2.35 .fig1 79.4 4 80 78ii 7O.i 3.41 ,743 ( ' All reactions catalyzed by p-toluenesulfonic acitl. h V/ I ' o = volume of polymer + solvent/volume of poll-mer. Specific volume of equivalent quantities of tetra-(p-car- boxyethy1)-cyclohexanone and diethylene glycol = 0.837 cc./g.; specific volume of dirnethoxytetraethylene glycol = 1.071 cc./g. The critical extent of reaction should be inde- pendent of temperature and values of pc = 0.5S5 at 110.8' and pc 0.582 at 136" bear this out. Lye looked for a possible effect on the value for the gel point caused by the degree of coiling aiitl uncoiling of the polyester molecule being formed. It might be expected that the tightly coiled m(Jl?- cules found in poor solvents would participate in relatively more intramolecular reaction than ex- tended chains found in good solvents. Xcetoplie- none was chosen as the second solvent and at I 1O.S" it is a poorer solvent for the polyester than is di- methoxytetraethylene glycol. Duplicate experi- ments at comparable dilutions gave p, values of 0.738 and O.i-1-0 for acetophenone and O.TU and 0.745 for dimethoxytetraethylene glycol. The divergence in the above values for pc in the two solvents appears to fall within the limit of es- perimental error involved in determining the points. It should be noted that although acetophenone is :i poorer solvent for the polyester than is dimethoxy- tetraethylene glycol, there is considerable doubt as to whether it can be classified as a solvent poor enough to lead to the tightly coiled molecules we were after. CHEMISTRY DEPARTMENT STATE L-XIVERSITY OF SE\Y YORK COLLEGE OF FORESTRY SVRACVSE 10, SETY YORK Solvent, Solvent,
Transcript of Diluent-Gel Point Relationships for the Reaction of Tetra-(β-carboxyethyl)-cyclohexanone with...
3006 NOTES Vol. i i
Diluent-Gel Point Relationships for the Reaction of Tetra-(p-carboxyethy1)-cyclohexanone with Di-
ethylene Glycol BY IRVING \VALTCHER AND IRVISG MILLER'
RECEIVED DECEMBER 11, 1954
In his basic investigation of gel points, Flory? found that the experimental values for the extent of reaction a t which gelation occurred, the critical extent of reaction, were higher than the values pre- dicted from his theoretical analyses for such sys- tems. He ascribed the discrepancy to the small amount of intramolecular reaction which occurs, this reaction not contributing to the formation of infinite networks.
Stockmayer and Wei1324 have used the dilution principle as a means of excluding the error due to the intramolecular reaction. They reasoned that since the cyclization reaction assumes more impor- tance a t higher dilutions, a series of gel points ob- tained a t increasing dilutions in an inert solvent should show ever increasing values for the extent of reaction a t which gelation occurs. Using the system pentaerythritol-adipic acid and dimethoxytetra- ethylene glycol as the inert diluent, they plotted the extent of reaction at the gel point as a function of the volume of the system and found the observed points to fall on a straight line which when extrapo- lated to zero volume, a so-called "infinite concen- tration," gave a value for the critical extent of re- action equal to 0.578 in excellent agreement with the predicted value of 0.577. This then appears to be a device for eliminating the error due to cy- clization reactions.
During the course of some work on polyesters, we had occasion to use this same technique on the system tetra-(~-carboxyethyl)-cyclohexanone5 and diethylene glycol,6 and using dimethoxytetraethyl- ene glycol7 as the diluent. The data of Table I were obtained by use of the falling sphere method for observing the gel point and by titrating unre- acted carboxyl groups to follow the extent of reac- t im. The values for the critical extent of reac-
(1) T h e material presented was taken from the h1.S. thesis of I.
( 2 ) P. J . Flory, THIS JOURSAL, 68, 3083 (1941). 13) W. H. Stockmayer , "Advancing F ron t s in Chemistry." Reinhold
(4) I,. L. Weil, doctoral dissertation, Columbia University, 1945. 13) Prepared according t o H. A. Bruson and T. W. Riener, T H I S
(0) Distilled Eastman Kodak C u product.
>filler, 1952,
Pub]. Carp. , N e w York, N. Y . , 1945, p. 01.
. I I J U K N A L , 64, 2850 119-1?)
Ansul Chemiral C o and di.itilled from sotliiini, 1) I).
tion, Flory's'' pc, were plotted as a function of the volume of the system. The points were found to fall 011 a straight line, enabling extrapolation to zero volume, the intercept giving a value for pc of 0.585 as compared with the calculated value of 0.577 from the Florp equation.
TABLE I POLYCOSDENSATIOS O F EQUIVALEST QUANTITIES OF T E T R A -
LOHEXASOSE A S D r j IETHYLESE GLY- COL .4T 110.8' USING UIRIETHOXYTETRAETIIYLES& GLYCOl.
AS SOLVENT'
' ( l ' / L . o b , C ,k 1 , ; v/l',lb,r fir
19 .8 1 .25 0.042 7 0 . i :3 , 4 1 i) 74.i 4 i . 9 1.92 . ( i i5 i ( i . 0 4 . I ( i .ii4 57.5 2 . 3 5 .fig1 7 9 . 4 4 80 78ii 7 O . i 3 . 4 1 ,743 (' All reactions catalyzed by p-toluenesulfonic acitl.
h V / I'o = volume of polymer + solvent/volume of poll-mer. Specific volume of equivalent quantities of tetra-(p-car-
boxyethy1)-cyclohexanone and diethylene glycol = 0.837 cc./g.; specific volume of dirnethoxytetraethylene glycol = 1.071 cc./g.
The critical extent of reaction should be inde- pendent of temperature and values of pc = 0.5S5 a t 110.8' and pc 0.582 a t 136" bear this out.
Lye looked for a possible effect on the value for the gel point caused by the degree of coiling aiitl uncoiling of the polyester molecule being formed. I t might be expected that the tightly coiled m(Jl?- cules found in poor solvents would participate in relatively more intramolecular reaction than ex- tended chains found in good solvents. Xcetoplie- none was chosen as the second solvent and a t I 1O.S" it is a poorer solvent for the polyester than is di- methoxytetraethylene glycol. Duplicate experi- ments a t comparable dilutions gave p, values of 0.738 and O.i-1-0 for acetophenone and O . T U and 0.745 for dimethoxytetraethylene glycol.
The divergence in the above values for pc in the two solvents appears to fall within the limit of es- perimental error involved in determining the points. It should be noted that although acetophenone is :i poorer solvent for the polyester than is dimethoxy- tetraethylene glycol, there is considerable doubt as to whether i t can be classified as a solvent poor enough to lead to the tightly coiled molecules we were after. CHEMISTRY DEPARTMENT STATE L-XIVERSITY OF S E \ Y YORK COLLEGE OF FORESTRY SVRACVSE 1 0 , SETY YORK
Solvent , Solvent ,
