[CONTRIBUTION
NO. 66
FROM THE CHEMISTRY
LABORATORY O F THE
UNIVERSITY OF U T A H ]
A SYSTEM CORRELATING MOLECULAR STRUCTURE OF ORGANIC COMPOUNDS WITH THEIR BOILING POINTS. VI. T H E MONOHALOGEN DERIVATIVES OF T H E VARIOUS HYDROCARBONS CORLISS R. KINNEY Received March 1'7, 1941
The boiling points of the monohalogen derivatives of the various hydrocarbons may be calculated using the boiling point equation developed previously (1) and the boiling point numbers (b.p.n.'s) for the halogen atoms given in Table I and the b.p.n.'s given for the hydrocarbons (2). The equation, while empirical, permits the correlation of the structure of organic molecules with their boiling points, and consequently it may be used to predict the boiling points of compounds from their structures. The boiling points are calculated by substituting the molecular boiling point number (B.P.N.) into the boiling point equation B.P. = 230.14d/B.p.N. - 543
or they may be obtained directly from the table of values published earlier (3). The B.P.N. for a molecule is obtained by summing up the atomic and structural b.p.n.'s for the various atoms and structural groupings in the molecule as described before (2). The boiling point of a halogen derivative of a hydrocarbon depends not only upon the kind of halogen and the number of carbon and hydrogen atoms, but also upon the arrangement of the atoms. For example, primary, secondary, and tertiary halides have progressively lower boiling points. This property is accounted for by assigning appropriate b.p.n.'s to the halogens when occupying these characteristic positions. I n like fashion, the boiling point is affected by the arrangement of the carbon atoms, and these structural differences should be considered in obtaining a B.P.N. for a substance, using the b.p.n.'s already assigned (2). The calculation of the boiling points of 1-, 2-, 3-, and 4-iodo3-methylbutane demonstrates these points. __ B.P.N.
DERIVATIVE
I-Iodo-3-methylbutane 2-Iodo-3-methylbutane 3-Iodo-3-methylbutane 4-Iodo-3-methylbutane
3.2 3.2 3.2 3.2
'
+ 8 + 3.05 + 13.0 = 27.25 + 8 + 3.05 + 11.5 = 25.75 + 8 + 3.05+ 10.2 = 24.45 , + 8 + 3.05 + 13.0 = 27.25 1
i
B.P. (OBS'D)
149.6" 136.6' 125.1' 149.6'
~
~
148.2' 138.0' 127.2" 148.0'
The attachment of a halogen to an unsaturated carbon atom always lowers the boiling point. This behavior is characteristic and has been taken care of 111
112
CORLISS R. KINNEY
by assigning characteristic b.p.n.’s to the halogens when attached to doubly and triply bonded carbon atoms (Table I). This effect is shown by comparing TABLE I HALOGEN B.P.N.’s
1
TYPE
1. RCH2-X . . . . . . . . . . . . . . . . . . . . . . . . . . 2. R2CH-X., . . . . . . . . . . . . . . . . . . . . . . . . 3. RsC-X., .......................... 4. C=CHX ........................... 5. C=CXR ........................... 6. C-CX., . . . . . . . . . . . . . . . . . . . . . . . . . .
F
I
3.3 2.7 1 ?
C1
1
Br
7.5 6.5 6.0 7.0 6.0 5.0
I J
9.7 8.7 8.0 9.0 8.0 7.0
1
I ’
I
13.0 11.5 10.2 11.8 10.5 9.8
TABLE I1 BOILING POINTS OF THE CIS-TRANS ISOMERS B.P., ‘C.
1-Chloro-1-butene. ......................
cis trans
63.5 68.1
trans
2-C hloro-2-butene. ......................
{
cis trans
66.8 62.6
cis
1-Bromo-1-propene......................
1
cis trans
57.8 63.3
trans
1-Bromo-1-butene. ......................
cis trans
86.2 94.7
trans
2-Bromo-2-butene, ......................
cis trans
84.0 92.5
trans
1 -1odo-1-butene, ........................
cis trans
168.0 127.5
cis
2-chloro- and 3-chloro-1-butene, so chosen to avoid the complications of cistrans isomerism.
113
STRUCTURE AND BOILING POINT
B.P.N.
DERIVATIVE
2-Chloro-1-butene 3-Chloro-1-butene
3.2 3.2
+ 7 + 1 . 5 + 6.0 = 17.7 + 7 + 1 . 5 + 6 . 5 = 18.2
I
56.8' 62.3"
~
58.5" 64.0"
Six pairs of cis and trans haloolefins and their boiling points a t atmospheric pressure were found in the literature (Table 11). In four cases, the trans isomer was reported as having a higher boiling point than the cis. This does not agree with the data obtained for those isomers whose structures have been determined with greater certainty, such as the esters of maleic and fumaric acids, the s-dihaloethylenes, etc., in which the cis isomer has the higher boiling point. For the majority of the haloolefins reported in the literature, which theoretically should exist in the two geometrical forms, no attempt was made to isolate the isomers. Consequently, new and accurate data are needed badly in this field. It appears likely that in certain cases the cis isomer is higher-boiling and in others, the trans. Until more reliable data have been obtained, a b.p.n. for this type of isomerism will not be assigned. The B.P.N.'s for the alicyclic halides are obtained by using the same b.p.n.'s for the halogens as for the analogous open chain derivatives. As an example, 1-chloro-1-methyleyclohexane may be used. 1 -Chloro-1-methylcyclohexane
+
+
Cyclohexane, less 2 hydrogen atoms, 6 X 0.8 10.0 2 . 7 . .. . . . . . . . . . . . . Methyl group attached to ring, 0.8 3.0. ......................... Chlorine, tertiary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B.P.N., calculated . . . . . . . ............................. B.P., calculated, . . . . . . . . ......................... B.P., observed.. . . . . . . . . . .........................
+
17.5 3.8 6.0 27.3 150.0' 149.5"
-
For those unsubstituted alicyclic halides which fit the formula, R(CH2),X, where R is a further unsubstituted alicyclic ring and n may be any integer including zero, unusually high boiling points are always observed. A similar observation was made for the similarly constituted dicyclo derivatives, R(CH2).R (4). This structure seems to affect the boiling point in quite a uniform manner. Also, the effect upon the boiling point is quite marked, as the following derivative, which is isomeric with the l-chloro-l-methyl-cyclohexane given above, shows. Chloromethylcyclohexane
+ +
Cyclohexane, less one hydrogen atom, 6 X 0.8 11 2 . 7 . . . . . . . . . . . . . . . 18.5 Methylene group, 0.8 2 . 0 . . . Chlorine, primary. . . . . . . . . . . . . B.p.n. for R(CH2), X structure,, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 B.P.N., calculated . . . . . . . . 30.3 B.P., calculated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.5' B.P., observed.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174.0'
+
114
CORLISS R. KINNEY
Characteristic b.p.n.'s are used for the halogens attached to the benzene and naphthalene rings (Table I). These b.p.n.'s give satisfactory results regardless of whether alkyl groups are attached to the aromatic ring or not and should be used for both types of compounds. This behavior is different from that observed for the corresponding alicyclic derivatives and possibly is accounted for in the unique effect of the aromatic rings on the boiling point. However, the exaltation of the boiling point is observed for all other halogen derivatives which fit the formula, R(CHZ),X, where R is an unsubstituted aryl radical and n is any integer other than zero. The following examples demonstrate these points. B.P.
B.P.N.
DERIVATIVE
1-Bromo-2-ethylbenzene (2-Bromoethy1)benzene
+
18 6.6 19 + 5.6
+ 9.2 = 33.8 + 9.8 + 1.5 = 35.9
201.1" 216.2"
-1
'
203.0' 217.5"
1
The boiling points of five halogen derivatives of biphenyl have been recorded in the literature. Two of these which are halogenated in the 4 position have high boiling points in a manner similar to that observed for the R(CH2),X compounds. Consequently for the 4-halobiphenyl derivatives the usual b.p.n. of 1.5 should be used as follows for 4-chlorobiphenyl: B.P.N.
19
1
+ 18 + 2.5 + 6 . 5 + 1.5 = 47.5
1
290.4'
291.2"
The atmospheric boiling points of a total of 437 monohalides were obtained from the literature and compared with the calculated values. None of the observed boiling points were discarded for any reason. For the total, the averTABLE I11 BOILING POINTDEVIATIONS A TYPE O F HALIDE
NO. O F H A L m E S
~
v
CALC'D, IRRESPECTIVE OF SIGN,
"c.
Fluorides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chlorides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bromides, . . . . . . . . . . . . . . . . . . . . . . . . . . . . Iodides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
26 182 157 72
4.08 4.09 5.63 5.50
DEVIATION ~ OF ~
CONSmEaLNG THE Av'' SIGN, QC.
f1.71 +O .80 +1.63 -0.43
1
%~o F ~ , p . t s ~ WITHIN rt10oc. OF CALC'D
88.4 90.6 84.1 86.1
Total, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
age deviation was 4.18" disregarding the sign and +0.91 taking the sign into consideration (Table 111). As might be expected, the best agreement was obtained with the fluorides and chlorides. However, there are many halides of all kinds for which the recorded boiling points are obviously out of line. These
~
TABLE I V HALIDESWHOSE OBSERVED BOILING POINTS DEVIATE MORETHAN&lO°C . FROM THE
CALCULATED B.P. TYPE OF HALIDE
(CALC'D).
"C.
B.P. (OZS'D).
C.
DEVIATION.
.
"C
~~~
Fluoride 1. Fluoromethane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ............................... 3. 3.Fluoro-1-propene. . . . . . . . . . . . . . . . . . . . .. Chloride 1. 2.Chloro-2-methylheptane. . . . . . . . . . . . . . . . . . . . . . . . 2. l-Chloro-2-methyl-2-butene ....................... 3. 3-Chloro.2-methylenepentane . . . . . . . . . . . . . . . . . . . . . 4 . 1-Chloro-2.hexene. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. l.Chloro.2-butyne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. (1-Chloro-1-methylethyl)cyclopropane. . . . . . . . . . . . 7. (1-Chloro-1.methylpropyl)cyclopropane. . . . . . . . . . . 8 . 3-Chloromethyl.l,1,2.trimethylcyclopentane . . . . . . 9. 2.Chloro.l-methyl.4-(l.methylethyl)cyclohexane . . ........... 10. 1-Chloro-1 -phenylethane. . . . . . 11. 1.Chloromethyl-4-methylbenzene. . . . . . 12. Chlorohexamethylbenzene., ...................... 13. l.Chloro.1-phenylethene . . . . . . . . . . . . . . 14. l-Chloro.2.phenyl.2-methylethene . . . . . . . . . . . . . . . . . 15. l.Chloro.2.(4-mcthylphenyl)ethene . . . . . . . . . . . . . . . . 16. 3-Chloroacenaphthene. . . . . . . . . . . . . . . . . . . . . . . . . . . . 17. 5.Chloro.l,2,3,4-tetrahydronaphthalene. . . . . . . . . . Bromide 1. 2-Bromo.3,3-dimethyl-l-butene. . . . . . . . . . . . . . . . . . . 2. l-Bromo-3-rnethyl-2.butene. . . . . . . . . . . . . . . . . . . . . . . 3. 2-Bromo-3-methyl-2-bu ..... ........... 4. 1-Bromo-2-pentene 5. 1-Bromo-3-ethyl-2-pent 6. 1.Bromo.l-hexene . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. 1-Bromo-1 -heptene. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. 1-Bromo-1 -octene. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. Z.Bromo.1,5-hexenyne. . . . . . . . . . . . . . . . . 10. 1-Bromo-2-propyne .................... 11. 1-Bromo-1 -methylcyclopropane. . . . . . . . 12. (1-Bromo-1.methylethyl)cyclopropane. . . . . . . . . . . . . 13. 1-Bromo-1 .(1-methylethyl)cyclopropane. . . . . . . . . . 14. (1.Bromo-1-methylpropy1)cyclopropane. . . . . . . . . . . 15. (1-Bromo-1-ethylpropyl)cyclopropane. . . . . . . . . . . . . 16. 1.Bromo-1-cyclohexene. . . . . . . . . . . . . . . . . . . . . . . . . . 17. 2.Bromo-l.methylcycIohexane . . . . . . . . . . . . . . . . . . . .
18. l.hIethyl-2.(bromomethyl)benzene . . . . ...... 19. 1-;\lethyl-4-(bromomethyl) benzene . . . . . . . . . . . . . . . ........... 20. 4-Bromo-3-isopropyl-1-methylbenzene., 21. 6.Bromo-3-isopropyl-1-methylbenzene. . . . . . . . . . . . 22. l-Bromo-l-(3-methylphenyl)ethene.~~. ............ 23. 1-(4-Bromophenyl).l.propene . . . . . . . . . . . . . . . . . . . . . ... 24 . 6-Bromo-l,2,3,4-tetrahydronaphthalene., 25. 3-Bromoacenaphthene. . . . . . . . . . . . . . . . . . . . . . . . . . . .
...
-100.6 -48.8
-13.2
-78.0 -32.0 +1 . 0
$22.6 $16.8 f14.2
161.2 102.4 110.6 131.8 93.0 113.0 138.4 187.3 207.6 180.7 188.4 300.9 180.9 203.7 201.9 296.3 236.8
145. Odec 117.5 122.0 121.0 82.5 132.5 151.5 175.0 182.5 194.0 201.0 285.0 199.0 214.0 223.0 309.0 250.0
-16.2 +15.1 $11.4 -10.8 -10.5 +19.5 +13.1 -12.3 -25.1 +13.3 $12.6 -15.9 +18.1 $10.3 +22.1 +12.7 $13.2
115.3 123.3 107.2 135.3 176.1 150.0 172.9 194.4 136.2 76.4
139.5 99.0 119.0 123.5 153.0 139.0 162.0 179.0 148.0 89.0 99.5 152.5 174.0 167.5 186.5 165.0 158.0 216.5 219.0 224.0 225.0 242.0 240.5 238.5 335.0
$24.2 $24.3 4-11.8 -11.8 -23.1
84.8
131.3 131.3 155.4 175.3 154.9 172.1
205.5 205.5 235.2 235.2 216.2 227.3 254.5 306.6
-11.0 -10.9 -15.4 +11.8
f12.6 +14.7 $21.2 +42.7 +12.1 f11.2 +10.1 -14.1 +ll.O +13.5 -11.2 -10.2 +25.8 +13.2 -16.0 +28.4
116
CORLISS R. KINNEY
TABLE IV-Concluded B.P. TYPE OF HALIDE
(OBS'D),
DEViATION,
"C.
C.
128.0 144.5 170.0 139.5 168.0 98.0 225.0 223.5 287.5 264.5
-11.7
Iodide -15.9 -33.7 -10.1 +49.9 $20.5 -10.5 -23.9 +10.1 -12.3
will be found among the compounds compiled in Table IV in which all of the compounds whose observed boiling points deviate from the calculated by more than & l O o have been listed. For example, the first of the chlorides in Table IV, 2-chloro-2-methylheptane, has been found to boil "with decomposition" at 145", 16.2" lower than the calculated. This seems quite unlikely in view of the boiling point of 132" given for the homolog, 2-chloro-2-methylhexane, which is only 13" less than the boiling point given for the heptane. It is possible, of course, that the low boiling point of the heptane derivative is due to extensive decomposition. If this is the case, the value of 145" should not be considered as the true boiling point. The second chloride in Table IV has a recorded boiling point about 15" higher than the calculated. This, also, seems unlikely since the similarly constituted 1-chloro-2-methylenebutanehas been found to boil at 102", only 0.8" less than the calculated. Many of the boiling points of the compounds appearing in Table IV may be compared with the boiling points of similar compounds and it appears that many of these boiling points have been determined &correctly. Consequently, we intend redetermining the boiling points of the compounds appearing in Table IV. It is quite probable that certain ones of these have been determined correctly and for them new b.p.n.'s will be required, but for the others new data should be obtained. SUMMARY
The observed boiling points of 437 organohalides obtained from the literature have been comp'ared with the calculated boiling points. The average deviation of the total, regardless of the accuracy of the experimental value, was 4.18'. Those halides deviating from the calculated by more than *lo' have been listed and will be reinvestigated. SALT LAKECITY,UTAH
REFERENCES (1) KINNEY, J. Am. Chem.Soc., 60,3032 (1938).
(2) KINNEY,Ind.Eng.Chem.,32,559 (1940);33,791 (1941);J . Org. Chem., 6,2u), 224 (1941). (3) KINNEY,Ind.Eng. Chem., 32, 561 (1940). (4) KINNEY,J. Org. Chem.,6,224 (1941).
