Nov., 1946
THERMODYNAMICS OF STYRENE AND ITS METHYL DERIVATIVES
2213
[CONTRIBUTION FROM THE CHEMISTRY DEPARTMENT, UNIVERSITY OF CALIFORNIA]
The Thermodynamics of Styrene and its Methyl Derivativesf BY CHARLES
w.BECKETT~ AND KENNETH s. PITZER3
This value was obtained from the following: the heat content function at 298.16"K. in Table I, the heat of vaporization4 (10.50 * 0.10 kcal./mole at 298.16'K.), the heat of formation of liquid styreneJs and the heat contents of graphite and hydrogen a t 298.16°K.9 Combining the above value of AHf: for styrene with that for ethylbenzenes gives A€$ equal to 26.42 * 0.40 for the dehydrogenation of ethylbenzene to styrene. If this is combined with the heat TABLE I content functions of these compounds6 and with CALCULATED THERMODYNAMIC PROPERTIES OF STYRENEthat of h y d r ~ g e nthe , ~ heat of dehydrogenation at IN THE IDEALGASEOUS STATE, CAL./DEG. MOLE 355'K. is 28.38 * 0.40 kcal./mole as compared to (He -(Pthe value, 28.56 * 0.25, from hydrogenation Temp., OK. cp H : ) / T &)/T S data.1° 82.48 16.72 65.76 298.16 29.18 Equilibrium constants for the dehydrogenation 65.86 82.65 16.79 300 29.35 of ethylbenzene, calculated from the free energy 92.35 21.07 71.28 38.32 400 functions using A@ equal to 26.42, are about 25 101.76 25.32 76.44 45.94 500 per cent. less than the experimental constants 110.70 29.28 81.42 600 52.14 at 360 to 495' published recently by Ghosh.11 119.14 32.93 86.21 700 B7.21 This discrepancy is near the estimated limits of 127.03 90.82 800 €11.40 36.22 error in and ( p - Z ) / T . Since experi95.26 134.48 €14.93 39.22 900 mental details were not given, the uncertainty of 141.49 41.95 99.54 1000 67.92 the observed equilibrium constants cannot be ap148.09 44.44 103.66 70.48 1100 praised. 154.31 46.70 107.61 72.66 1200 Methyl Styrenes.-The thermodynamic func111.44 160.20 48.77 74.54 1300 tions of some of the methyl styrenes were esti165.79 50.67 115.13 1400 7'6.16 mated by the method of increments.6q6 Thus, the 171.09 52.42 118.68 1500 77.57 entropy of p-methylstyrene is tainty of these values is estimated to be about 0.5 S (p-methylstyrene) = S (styrene) S (#-xylene) cal./deg. mole a t the lower temperatures. It may - S (toluene) R In 2 be somewhat larger at the higher temperatures. These calculated values agree fairly well with the and that of trans-P-methylstyrene is meager amount of independent data available. S (truns-,%methylstyrene) = S (styrene) S (trans-2The single observed heat capacity given by Scott butene) and Mellors' is C: = 35.83 and C: cor. = 36.16 - S (propylene) R In 2 a t 100'. The calculated value a t this temperaThe equations for the other properties have the ture is 35.91 * 0.50. same form except that the last term, R In 2, is The heat of formation of styrene at OOK. in the omitted in the heat content function and heat ideal gaseous state is capacity. This term is merely an adjustment of AH,;; = 40.34 * 0.30 kcal./mole the symmetry number. The estimated properties for m-methylstyrene (1) This work wis performed at the University of California as are the same as those given for p-methylstyrene expart of the work of the American Petroleum Institute Research cept that the quantity R In 2 is added to S and to Project 44 on the "Collection, Analysis, and Calculation of Data on the Properties of Hydrocarbons" with headquarters at the National -(F" @)/Tin order to take into account the Bureau of Standards. lower symmetry number of the meta compound. (2) Research Associate on the American Petroleum Institute ReThis is in accord with the small difference, apart search Project 44. (3) Associate Supervisor on the American Petroleum Institute Refrom the symmetry numbers, between properties search Project 44. of meta and para xylenes.' (4) K. S. Pitzer. L. Guttman and E. F. Westrum. Jr., THIS In the preceding paper4 are given the data necessary to calculate the thermodynamic properties of styrene in the perfect gas state. By making use of the increments for the addition of a methyl group to toluenes or to propylene6 one may estimate values for the methyl styrenes. Styrene.-The thermodynamic properties of styrene, calculated from data given in the preceding paper,4 are shown in Table I. The uncer-
a
+ +
+ +
-
JOURNAL, 68, 2209 (1946). ( 5 ) K. S. Pitzer and I). W. Scott, ibid., 66, 803 (1943);
W. J. Taylor, D . D. Wagman, M. A. Williams, K. S. Pitzer and F. D. Rossini. J . Research Nafl. Bur. Sfandards, #, 95 (1948). (6) J. E. Kilpatrick and K. S. Pitrer, J . Research. N d l . B w . Standards, 87, 163 11946). 17) R. B. Scott and J. W. Mellors, ibid., 84, 243 (1946).
(8) E. J. Prosen and F. D. Rossini, ibid., 84, 69 (1945). (9) D. D. Wagman, J. E. Kilpatrick, W. J. Taylor, K. S. P i t z u and F. D. Rossini, ibid., 84, 143 (1846). (10) M. A. Dolliva, T. L. Gresham, G. B. Kistiakoasky and W. E. Vaughn, THDJ o m A L , 6% 631 (1937). (11) J. C. Ghoah, S. Ran Das Guha and A. N. Roy, Cuncnf Sci., 14, 269 (1846).
RICHARD13. 'I'I!KNEK.\NU ARTIIUKC. COPE
321'1
The method of increments is a fairly reliable approximation for these compounds. The over-all uncertainty of these estimates may exceed one cal./deg. mole, but the uncertainty of their differences probably is much less. The method of increments, however, is not reliable for the other methyl derivatives in which steric effects are large and specific in character. A consideration of these steric effects indicates TABLE I1 ESTIMATED THERMODYNAMIC PROPERTIES OF #-METHYLSTYRENE IN THE IDEAL GASEOUS STATE, CAL../DFG. MOLE Estimates for the 0-,m-, a- and cis-@-methylstyrenesare the same except that R In 2 (1.4) should be added t o the entropy and th.e - (F - Hi)T function of m-methylstyrene.
Temp., OK.
298.16 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
(Ho
-
ct
&)/T
34.7 34.9 44.8 53.5 60.7
20.3 20.3 25.2 30.0 34.6 38.8 42.'6 46.1 49.3 52.2 54.9 57.3 59.6 61.6
66.8 71.8 76.1 79.8 82.9 85.6 87.9 89.9 91.6
-
-(P &)/T 71.4 71.5 78.1 84.2 90.1 95.8 101.2 106.4 111.4 116.3 120.9 125.4 129.7 133.9
[CONTRIBUTION FROM THE
S 91.7 91.9 103.3 114.3 124.7 134.5 143.7 152.5 160.7 168.4 175.7 182.7 189.3 195.5
Vol. 68
TABLE I11 ESTIMATED THERMODYNAMIC PROPERTIES OF trans-& METHYLSTYRENE IN THE IDEALGASEOESSTATE, CAL./ D E G . MOLE Temp., OK.
298.16 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
34.9 35.1 45.2 54.0 61.2 67.2 72.2 76.4 80.0 83.1 85.8 88.1 90.0 91.7
(HO I&/T
-(P-
19.9 20.0 25.1 30.0 34.6 38.9 42.7 46.'2 49 5 52.4 55.1 57.5 59.8 61.8
71.0 71.1 77.6 83.7 89.6 95.3 100.7 105.9 111.0 115.8 120.5 125.0 129.4 133.5
S
&)/T
90.9 91.1 102.6 113.7 124.2 134.1 143.4 152.2 160.4 168.2 175.5 182.5 189.1 195.4
that the properties of o-methyl, a-methyl and cis-0-methylstyrene are about the same as those given for 9-methylstyrene. This estimate is considered the best one possible at this time.
Summary Thermodynamic properties of styrene were calculated. Estimates were given for the properties of the various methyl styrenes. BERKELEY,
CALIF.
DEPARTMENT OF CHEMISTRY, MASSACHUSETTS INSTITUTE
RECEIVED JUNE 24, 1946
OF TECHNOLOGY]
~-(Dialkylaminomethyl)-2-phenyl-4-quinolinemethanolswith 8-Amino or Hydroxy Substituents BY RICHARD B. TURNER AND ARTHURC. COPE King and Work2 have reported that the simple quinine analogs, a-(dialkylaminomethyl)-4quinolinemethanols (I),are suppressive agents for certain forms of avian malaria. These compounds are less active and less toxic than 8-aminoquinolines of the Plasmochin type (II), which have a different mode of action on the malaria parasite.a In the search for superior antimalarial drugs sponsored by the Committee on Medical Research, it was considered of interest to investigate the properties of compounds containing both CY(dialkylaminomethyl)-4-quinolinemethanol and 8(1) The work described in this paper was done under a contract, recommended by the Committee on Medical Research, between the Office of Scientific Research and Development and the Massachusetts Institute of Technology. (2) King and Work, J . Chem. Soc., 1307 (1940); 401 (1942); see Kaufmann, B e l . , 46, 1823 (1913); Rabe, Pesternack and Kindler. i b i d . , 60, 144 (1917). (3) Pharmacological and clinical characteristics of the various classes of antimalarial drugs will be described in a forthcoming monograph by the Survey of Antimalarial Drugs.
amino groups. Earlier work had shown that a 2phenyl substitutent greatly enhances antimalarial activity in 4-quinolinemethanols and diminishes it in 8-aminoq~inolines.~ Both series of drugs (I CHOHCHzNRs I
ci"i \ LN' I
I
and 11) include highly active compounds which do not contain the 6-methoxy group present in quinine and Plasm~chin.~ This paper reports the synthesis of &amino King-Work types, 111, which contain a 2-phenyl substituent and are unsubstituted in the 6 position. The corresponding 8-hydroxy com-
