Table 111. Observed Molar Polarizations, Molar Refractions, and Dipole Moments for Substituted Cinnamonitriles
X
F
c1
Br I CN
P?
RD
I*
a+
212.9 201.4 210.4 238.6 73.9
43.3 49.1 52.0 54.5 52.2
2.88 2.73 2.80 3.00 1.01
0.01 0.08 0.02 0.04
deviation of the dipole moment, expression
uU,
...
according to the
where ,u is the dipole moment and xi is the i t h slope (or intercept). LITERATURE CITED (1) DiCarlo, E. N., Smyth, C. P., J . Am. Chem. Soc. 84, 1128 (1962). (2) Dolter, R. J., Winch, B., Kissane, J., Junk, G., Howie, M., McFadden, P., Proc. Iowa Acad. Sci. 63, 391 (1956). ( 3 ) Kraus, K. W., Schulte, G. N., Dolter, R. J., Buenker, R. J., Plamondon, J. E., Koopman, D., Zbid., 71, 208 (1964).
RECEIVEDf o r review October 14, 1968. Accepted August 8, 1969. Work was supported by the National Science Foundation Undergraduate Research Participation Program.
Diesters from Trialkylacetic Acids and Glycols HENRY F. LEDERLE Olin Corp., New Haven, Conn.
06504
Diesters from trialkylacetic acids and the following glycols were prepared: straightchain cu,w-glycols, P,P-disubstituted propanediols, lower molecular weight polyethylene glycols, and 2,2,3,3,4,4-hexafluoropentanediol. Viscosities at 212 O, 1 O O O , and -40° F., ASTM viscosity slopes, and pour points were determined a n d compared.
T R I A L K Y L A c E T I C ( "neo") acids have recently become commercially available, and their structures have been described ( 6 ) . Their esterification requires more rigorous conditions than those employed for conventional acids. The esters a r e much more resistant toward both acid and base hydrolysis than conventional esters ( I 1, and the preparation and physical properties of several types of monoesters have been described ( 3 ) . The synthesis of diesters from straight-chain u,w-glycols, P,P-disubstituted propanediols, polyethylene glycols, and 2,2,3,3,4,4-hexafluoropentanediolis reported here. Viscosities, ASTM viscosity slopes between 212" and 100" F., and pour points were determined and compared. EXPERIMENTAL
S t a r t i n g materials were used as received. I n general, the method of Coopersmith et ul, ( 1 ) was used f o r the esterifications. Products of Type I11 and I V could be prepared by using toluene in place of xylene a s azeotroping agent. Instead of p-tolenesulfonic acid, products of Type I11 were prepared with sulfuric acid catalyst. When t h i s was the case, the catalyst was neutralized with an excess of solid calcium hydroxide, followed by filtration. This avoided contact with aqueous bases, which might have resulted in losses due to water solubility. Products of Type I1 were especially difficult to pre-
pare, Water formation usually stopped before the theoretical amount had azeotroped. When this occurred, the reaction mixture was cooled, additional catalyst was added, and azeotroping was resumed. If necessary, this procedure was repeated until the theoretical amount of water was obtained. Most products were obtained in analytical purity by vacuum distillation through a vacuum-jacketed Vigreux column, 5.5 inches long. Products of Type I11 were usually slightly yellow a f t e r one distillation and were redistilled. Most yields could be improved. Physical properties were determined by ASTM methods: kinetic viscosity by method D 445-65,ASTM slope between 212" and 100" F. by method D 341-43, and pour point by method D 97-57. Only one cooling bath, d r y ice-acetone, was used for t h e pour points. The approximate densities of Table IV were determined by weighing 10 ml. of the product in a graduated cylinder a t room temperature. DISCUSSION Diesters
from
Straight-Chain
glycols
(I, Table
I).
The first six products contained identical acyl groups (R, = R 2 ) . A t constant R, = R,, increasing the glycol chain length from z = 4 to z = 8 increased the viscosities, but gave lower ASTM slopes (runs 1 to 4). Increasing the glycol chain length from x = 4 to z = 10, while simultaneously decreasing the acid chain length, gave lower viscosities a t -40" F. and lower ASTM Journal of Chemical and Engineering Data, Vol. 15, No. 1, 1970
193
m m o m
mwwm
I l l 1
mmmm
0 9 009 009 009 0
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slopes ( r u n 5 ?is. run 1). However, when the glycol chain length became too long ( z = 12, run 6 ) , the ester crystallized at low temperatures. I n runs 7 t o 15, t h e acyl groups were different. The long-chain glycol with x = 12 again gave a relatively high pour point, b u t this could be overcome by increasing the difference in the acyl chain length ( r u n s 14 and 1 5 ) . Diesters from P$-Disubstituted Propanediols (11, Table 11).
D u r r and coworkers (2) reported high thermal stabilities for similar esters. Based on pour points and viscosities a t -40" F., Type I1 has relatively poor low-temperat u r e fluidity. ASTM slopes a r e relatively high. This probably results from lack of free rotation and chain flexibility caused by bunching of the alkyl substituents near the carboxyl groups. One product, r u n 18, had a low pour point, but this was achieved only because its molecular weight was lower than the other products of Type 11. Diesters from Polyethylene Glycols (111, Table 111). Where comparisons between compounds of similar molecular weights a r e available ( r u n s 22, 23, 25, and 2 6 ) , the ester from the longer-chain polyethylene glycols had lower ASTM slopes and pour points. The ether oxygens apparently contribute increased chain flexibility. MacPhail ( 4 ) has recently described several closely related esters. Diesters from 2,2,3,3,4,4-Hexatluoropentanediol (IV, Table IV). Viscosities increase a s the acyl groups become larger.
While r u n 27 still had good low-temperature fluidity, runs 28 and 29 became progressively worse. ASTM
slopes were relatively high. The approximate densities increased with increasing fluorine content. Snead and Gisser ( 5 ) have demonstrated superior thermal and oxidative stability f o r related esters. Comparison of Types I to Iv. If one considers diethylene glycol a s a pentanediol in which the center methylene group has been replaced by an ether oxygen, a comparison between t h e various pentanediol esters of neodecanoic acid ( R = CBHI9) can be made. Based on pour points and viscosities a t -40" F., the best low-temperat u r e fluidity was obtained by Type I , followed by Types 111, IV, and I1 (runs 2, 23, 28, and 1 6 ) . LITERATURE CITED (1) Coopersmith, M., Rutkowsky, A. J., Fusco, S. J., Ind. Eng. Chem. Prod. Res. Develop. 5, 46 (1966). ( 2 ) Durr, A. M., Meador, W. R., Thompson, C. E., Preprints of Papers, Division of Petroleum Chemistry,
ACS, Vol. 8, No. 3,49 (1963). (3) Lederle, H. F., Ind. Eng. Chem. Prod. Res. Develop. 7, 94 (1968). ( 4 ) MacPhail, A. C. B. ( t o Shell Internationale Research Maatschappij N. V,), Brit, Patent 1,091,457 (May 6, 1968). ( 5 ) Snead, J. L., Gisser, H. (to United States of America), U. S. Patent 3,189,644 (June 15, 1965). ( 6 ) Wickson, E. J., Moore, R. R., Hydrocarbon Process. Petrol. Refiner 43, 185 (1964).
RECEIVEDfor review March 10, 1969. Accepted November 4, 1969.
Selective Hydrogenation of the Double Bond in Unsaturated Aliphatic Isocyanates ROBERT J. KNOPF Chemicals and Plastics Research and Development Department, Union Carbide Corp., South Charleston, W. Va.
25303
Unsaturated aliphatic isocyanates were hydrogenated selectively in high yields to their saturated counterparts over palladium or platinum catalysts at ambient temperatures and low pressures (10 to 40 p.s.i.). Continued reduction beyond the point of theoretical hydrogen uptake resulted i n a gradual loss of isocyanate content with concomitant formation of the appropriately substituted formamide and symmetrical urea. Catalyst activity apparently was destroyed during this sluggish secondary reaction, because hydrogen uptake ceased a t relatively low levels of conversion of the isocyanate function.
AS PART of a program directed toward utilizing the double bond in olefinic isocyanates a s a selective reaction site, we decided to explore t h e possibility of catalytically hydrogenating various unsaturated aliphatic mono- and diisocyanates to their saturated counterparts, a s illustrated f o r the diisocyanate case by Equation 1. This transformation was of interest to u s academically a s 196
Journal of Chemical and Engineering Data, Vol. 15, No. 1, 1970
%% rg'b an example of a novel selective reaction of olefinic isocyanates and commercially a s a potential route to certain polymer-forming diisocyanates whose olefinic precursors were more readily accessible.
