1082
HARRY WIENER
RI 0 -2 -1 0 -2 -3 -3 -4 -3 0 -4 -3
'C .
0.0 -6.6 0.0 -1.8 +0.3 -11.1 -2.9 0.0
71.7 78.3 69.1 73.9 68.8 80.2 72.0 70.1 73.5 69.9 66.3 78.7 68.1 76.9 69.8 71.5 72.1 74.6 72.1 72.6 70.1 78.6 71.1 74 .G
-3.1 +0.2 f3.8
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-
-1
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,
+2.0 -6.8 f0.3 -1.4 0.0 -2.5 0.0 -0.5 -2.0 -6.5 A1 .o -2 5 -5.0 -0.5 -4.0 t3.5 +6.0 il.5 -0.0 t5.0 +2.3
,
~
~
! ~
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~
,
-1r.l
i2,6 68.1
68.6 66.1 i0.6 s1.1 67.1 69. G
71.7 78.9 69.1 73.9 69.3 81.2 71.9 70.1 73.6
70.5 66.3 78.3 68.0 78.i 69.7 72.2 72.1
1
,
0.0 -0.6 0.0 0.0 -0.5 - 1.o +o. 1 0.0 -0.1 -0.6 0.0 +0.4 +0.1 -1.8 +0.1 -0.7 0.0
72.2
-0.1
70.6
+0.5
78.0
'
-0.9
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G8.0
10.1
65.9 70.8 m.4
+0.2 -0.2 1 0 7
\\ itli molecular structure by a method similar to that applicable to the thermal properties is not clear. The fact, however, that this can be done with good agreement between (Aculated and experimental values makes it likely that the differences betneen the 7-alues of other optical properties, taken at two different n-n\-e lengths, may also be correlated by this method. I n particular, this pro-
1088
HARRY X-IESER
cedure may prove t o be useful in correlating absorption spectra and molecular structure of hydrocarbon isomers. TABLL 6 Predicted m l u e s o j surface tensmL, specijic di spc 1 ~ i o i i ,and critacal solutaon temperature of ~lOi1~J?i~,S
.I!!.,
/L-Sonallc-. . . . . . . . . . . . . . 2-Methgloctaiie. . . . . 3-Methyloct ane . . . ., , ., -l-~lethyloctanc, . . . . . . . 3-Ethylheptane, . . . . . . . , . .
4-Etlij-lheptane . . .
.
.,
d.
9S.i 9Y.6 96 .o 98.2 97.5 97.7 !J9.5 !J7. 7 !ib . 7 0 8 . ,5
.
2 >2-Diiiiethylheptaii1. 2,3-Dimetli~lheptaiie 2,4-Dinietli?.lhept:ilie.. . 2,5-Diiiiethylheptane 2 , G-Dimethylhept aiie . 3,3-Dimethglheptane 3 4-Diiiietli?.lheptaiir 3,5-Dimct Iiylhcpt niir 4.4-Dimetliylhept~ne 2-~Ieth3-1-3-ethglhe~~~i~~ % - ~ l e t h ? . l - - l - e t h v l h e ~ ~. ~. i i P 3 - ~ l e t h ? - l - 3 - e t h ? . l h e .~.~ ~ i i ~ 3-~ietli~l-4-etliyllies3llc 2,2.3-Trimet hylhesaiie 2 2,4-Triiiiei liyllic~xiiir 2.2.5-TrimcLt liylhrsaiic~ 2.3.3-Triiiiet h\-lhez;~iic 2,:3,4-TriiiiethylIiesaiic~ 2,3,5-TriiiietIiylhczaiic 2 . 4 .-L-T~imctli~-llii~saiic. 3.3.4-Triii~ethyllicsa1ie. . 3 . 3-Diet h \- I pr ii t a i i r 2.2-Dim~tliyI-~i-cth?.ipc.llt iiii( 2.3-Diiiiet hvl &et 1ivlr)ciit aiit' . . 2 . 4 - D i i i i e t t i \ - l - 3 - ~ t l i ~ l ~ ~ c. 1 .i .t ~ . ~~~t~ 2 . 2 . 3 . 3-Tetranieth~l~,ciitaiic, . . . . . . 2 . 2 . 3 . 1 - T e t r a l i i e t h ~ ; l ~ ~ r i i .~ a i, i ~. . . . . . 2 >2,4,4-Tctramrthylpentnne , . , . . . . . . . 2 , 3 , 3 , 4 - T ~ t r a i ? iiiylpeiitaiie. ~t . , ... .. . . ..
99.2 0S.I 97. I 97 .!i
~
,
9 6 . (1 !I5 0
:is
-6
97.0 05.2 06,s 95.5
:i4
-4 0 -6
701.0 95.3
:XI
32 :36
-4
'C,
dynes,'cm.
22.9 22.0 22.5 , 22.2 ' 22.7
1
~
22.4
20.5 22.4 21.3 21.6 21.1 21.8 22.9 .- -I ,. , ]
21.5 23.0 23.3 21.9 20.0 19.G 22.7 "3.0 21, *5 20,s 23.5 24.6 22.4 24.3 22.7 23.7 22.1 18.0 24.0
'
74.9 76.S 75.3 76.0 74.5 75.1
79.9
' -75.1
I
~
,
1i.s
77.2 78,: ;ti .-I 73.7
-IJ.X
76.4 72.9 72.2 75.6 so . 3
sl.s 73.5 72.0
-- .o
I I -,
rh.4 71.3
GS.7 74.1
69.3 73.5 70 . ii 74.7 84.9 70.0
CRITIC.11, SOLUTIOT T1:JlPERATURE IS ANILI\'L:
The critic*al rolntion temperaturc in aniline has been i i d t o a. considerable extent as an indication of the composition of hydrocarbon mixtures. Within a single groiip of paraffin ieomerb, thi. property closely obeys equation 2 . Estension to the entire +rir. of allxmes lends to the somewhat more complicated e c p i t ion :
PHYSICAL PROPERTIES A S D XOLECULAR STRUCTURE O F ALKANES
(14.4 - 1 . 3 n ) l p
1089 (9)
The observed yalues of the critical solution temperature in aniline, given in table 5. are those determined by TT'ibaut (12), except for two paraffins, 3-methylhexane and 3-ethylpentane, which were not prepared by TTibaut and for which the older values of Edgar and Calingaert are given ( 2 ) . The average experimental uncertainty is estimated a t &0.25"C. The average deviation between calcclated and observed values is i0.34"C. PHYSICAL PROPERTIES O F THE S O S 1 X E S
In table G predicted values of the surface tension, specific dispersion, and critical solution temperature of the thirty-five nonanes, calculated from equations 4, 8, and 9 are listed. The average probable error of the predicted s-alues may be estimated a t 1 0 . 3 d p e s / c m . in surface tension, i0.6nil. g. in specific dispersion, and &O.T"C. in aniline point. SUMMARY
Simple empirical equations, permitting the calculation of physical properties of the allianes from their molecular structure, are proposed. The properties correlated are the surface tensions of the nornial allianes, the difference in surface tension betveen any branched-chain alkane and its normal isomer, and the difference in specific dispersion and aniline point betn-een branched-chain and normal alkanes. Comparison n-ith experimental data from the literature shows that the average deviations of the calculated from the observed values are of the order of the experimental uncertainties in all cases. Predicted values of these three physical properties for the nonanes are given.
