INDUSTRIAL A N D ENGINEERING CHEMISTRY
August 1948
TABLEV. EFFECTOF ASSIGNEDPROBABILITY VALUESFOR INTRAMOLECULAR LINKAGE ON UNSATURATION-REACTION TIME RELATION (When intralinks are assumed to contribute nothing to the network) C" t k n 220 25 C/25 5500 5 0 112 49 c/49 7 38 144 cj144 12 19 289 C/289 17 17 324 C/324 18 220 5478 24.9 C/24.9 5 0.001 112.5 48.7 C/48.7 7 38.5 142.4 C/142.4 12 19.3 284 4 C/284.4 17 17.2 318.5 W318.5 18 5280 220 24 C/24 5 0.01 114.5 46.1 C/46.1 7 41.2 128.2 C/l28.2 12 21.7 242.8 C/242.8 17 19.6 268.9 C/268.9 18 23 C/23 5060 220 5 0.02 117.4 43.1 c/43.1 7 45.1 112.3 C/112.3 12 25.8 196.5 C/196.5 17 28.7 213.8 C/213.8 18 4620 220 21 c/2 1 5 0.04 124.2 37.2 c/37.2 7 57.3 12 80.6 C/80.6 44.4 104 C/104 17 44.4 104 C/104 18 4400 220 20 c/20 5 0.05 128.3 34.3 c/34.3 7 64.8 C/64.8 67.9 12 76.1 57.8 C/57.8 17 89.0 49.0 (749.0 18 Adjusted SO that curves all start a t point t = 220; n = 5.
If increasing probability values are assigned to k in Equation 6, as shown in Table V, a series of curves departing from the ideal expression t = c/n2 will be obtained. Their characteristics are illustrated in Figure 17. When a value of about 0.5 has been
1517
assigned to k , the curves begin to bend backward as unsaturation reaches the higher levels of this series; this indicates a point of diminishing returns has been reached with reference to polymeric unsaturation. No such phenomenon was observed in this series of experiments, nor has any been reported in the literature. Two possible conclusions may be drawn from these observations: either the probability of intramolecular links is small with the Butyl ranges of unsaturation or intramolecular links contribute to the cross-linked network. ACKNOWLEDGMENT
The author is indebted to C. W. Haemel: and his staff for the layout and construction of the finished graphs and to F. P. Baldwin for valuable consultations during the course of this work. LITERATURE CITED
(1) Baldwin, F.P., unpublished data. (2) Baldwin, F. I?., Turner, L. B., and Zapp, R. L., IND. ENQ. CHEM.,36,791(1944). (3) Farmer, E. H., Rubber Chem. Technol., 15,765 (1942). (4) Farmer, E. H., and Shipley, F. W., J . Polymer Sci., 1, 293 (1946). ( 5 ) Flory, P. J., IND.ENG.CHEM.,38,417 (1946). (6) Flory, P. J., J. Am. Chem. SOC.,63,372 (1943); Rubber Chem. Technol., 16,493(1943). (7) Flory, P. J., and Rehner, J., Jr., J . Chem. Phus., 11, 521 (1943). (8) Reh'ner, J., Jr., laboratory data. (9) Rehner, J., Jr., and Grey, Priscilla, IND.ENG.CHEM.,ANAL.ED., 17,367(1945). (10) Rehner, J., Jr., and Holowchak, J., IND. ENG.CHEM.,ANAL.ED. 16, 98 (1944); Rubber Chem. Technol., 17,738 (1944). (11) Treloar, L. R.G., Trans. Faraday Soc., 36, 538 (1940);Rubber Chem. Techno!., 13,795(1940). RECEIVED October 17, 1946. Presented, in part, before the Division of Rubber Chemistry at the 110th Meeting of the AMERICAN CHEMICAL SOCIETY. Chicago, Ill.
Synthesis of Substituted Furans J
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ITHOUT prior knowledge of its chemistry, the graphical ormula of furan might give the impression that its properties would resemble those of butadiene, divinyl ether, and the hybridized cyclic type commonly known as benzenoid. The graphical structure is $pod in the sense that examples can be found in the literature of all three types in the reaction of furans. There is ample evidence for the butadiene structure in furans. The diene syntheses of the Diels-Alder type are so common among furans containing saturated substituents, that Johnson and his collaborators have recommended the reaction for preparation of identifying derivatives. The laboratories of Reichstein (39) and of Johnson (4%') have proved also that hydrogen cyanide adds 1,4to furfuryl chloride; at least this is the most reasonable explanation for the formation of 2-methyl-5-cyanofuran. H-C-C-H
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