3814
ITOl. 82
OLIVERGRUMMITT AND ANDREW L. ENDRET [ COSTRIBUTIOS FROM
THE
DEPARTMENT O F CHEMISTRY, WESTERN RESERVEL-SIVERSITY, CLEVELAXD 6, OHIO]
Relative Reactivity of Maleic Anhydride and Sulfur Dioxide in 1,4-Addition Reactions to 2,3-Dimethyl-l,3-butadiene BY OLIVERGRUMMITT AND ANDREWL. ENDREY' RECEIVED DECEMBER 23, 1959 The relative reactivity of maleic anhydride and sulfur dioxide in their reactions with 2,3-dimethyl-1,3-butadieneto form the Diels-Alder adduct and cyclic sulfone was estimated by competitive relative rate measurements. Results were calculated for reactions in various solvents a t 0". 27', (approx.), and 50" as ratios of second-order rate constants, k l / k 2 , Diels-Alder reaction/sulfone reaction; these constants were not measured individually. Values for this ratio ranged from 39.3 t o 363 as reactant ratio, solvent and temperature were varied. Thus maleic anhydride is more reactive than sulfur dioxide in 1,i-addition under all conditions studied. The effect of solvent, particularly on the sulfone reaction, is interpreted in terms of dielectric constant and coordination of the solvent with sulfur dioxide. Increasing dielectric constant decreases the rate ratio as a straight line function for reactions in benzene, chloroform and liquid sulfur dioxide. I n mesitylene and the ether solvents, the ratios were higher than expected, according to dielectric constant, because of sulfur dioxidesolvent interaction. Increased temperature relatively favors the sulfone reaction. I n tetrahydrofuran solution this is partially attributed to the dissociation of solvated sulfur dioxide. Estimation of the differences in heats of activation for the two reactions indicated values 1.5-5 0 kcal. greater for the sulfone reaction.
1,3-Dienes may react with maleic anhydride to form Diels-Alder adducts and with sulfur dioxide to form cyclic sulfones. The literature on these reactions shows that maleic anhydride is probably more reactive than sulfur dioxide. It was the purpose of this work to measure the reactivity difference by means of competitive reactions. 2,3-Dimethyl-1,3-butadiene( I ) , maleic anhydride and/or sulfur dioxide were allowed to react in various solvents a t O o , approx. 27' and 50'
quantities of reactants a t room temperature for 36-48 hours vary from 4 to 82% (Table IT). The sulfone yield increases in the following series of solvents : tetrahydrofuran, mesitylene, benzene, bis-(2chloroethyl) ether and chloroform.
SCLFOSE
Expt.
TABLE 11" REACTIOSS AT A4PPROX.27" Solx.ent
Tetrahydrofuran 11 Mesitylene 16 Benzene 19 Chloroethyl ether 21 Chloroform 0- Also see Table 1-11.
7
-Molarity I
1.0 1.01 0.98 0.99
1.01
IT v A R I O U S S O L V E X T S
ofSO?
Time. hr.
0.94 .90 .89 .90 .92
48 48 48 48 48
Yield of 111,
5% 4.1 11.5 25 3 50 62
Preliminary experiments showed that the yield of the Diels-Alder adduct, 1,2-dimethyl-l-cyclohexene-4,5-dicarboxylic anhydride (11),2was almost With the behavior of the individual reactions independent of the nature of the solvent, but the established, competitive reactions were carried out sulfone reaction was strongly affected by the sol- in the same solvents a t room temperature for 48 vent. Therefore, five solvents of varying effects hours. Approximately 1 molar concentrations of I were selected : tetrahydrofuran, mesitylene, ben- and maleic anhydride were used, and the concentrazene, bis-(2-chloroethyl) ether and chloroform. tion of sulfur dioxide was varied from 1 to 10 molar. The yield of I1 from equimolar quantities of re- The reaction product was vacuum distilled, I11 was actants in all solvents a t room temperature for 38- estimated by measuring the sulfur dioxide formed 48 hours varied from 90 to 10070 (Table I). on heating,j and I1 was hydrolyzed to the dicarboxylic acid IV which was separated and measured TABLE Io acidimetrically . DIELS-ALDERREACTIOSSAT APPROX.27" I N V A R I O U S SOLDiel~-~4lderreactions are known to be second VENTS order,6 and the reasonable assumption was made that the sulfone reaction was also second order. From the quantities of reactants taken and products found, the ratio of the rate constants, k , / k z , was 1 Tetrahydrofuran 0.94 0.92 36 90 calculated' (Table 111) 2 Mesitylene .96 .92 48 97 4 5 6 a
Benzene Chloroethyl ether Chloroform Also see Table VI.
,87 1.02 0.98
.8i 1.02 0.93
36 48 48
95 98 99
Addition of sulfur dioxide to 2,3-dimethylbutadiene gives 3,4-dimethyl-2,5-dihydrothiophene I,1dioxide (III).4 The yields of I11 from equimolar (1) A Sherwin-Williams
fellowship granted to A. L . Endrey in 19.54-1955 is gratefully acknowledged. (2) E. H. Farmer and F. L. Warren, J. C k e m . SOL.,897 (1929). (3) The results given in Tables I-IX were satisfactorily verified by duplicate experiments. (1) H. J. Backer and J. A . Bottema, Rec. ! ? a s . chin%.,S1, 294 (1932).
k , / k ? = log _____ (1 - r / a ) log (1 - y ! b )
(1)
where kl kz
= =
x = y =
a = b =
rate constant of the Diels-Alder reaction rate constant of the sulfone reaction moles of I1 formed moles of I11 formed initial moles of maleic anhydride initial moles of sulfur dioxide
( 5 ) 0. Grummitt, A . E. Ardis and J. Fick, THISJ O U R N A L , 73, 5167 (1950). (6) L. J. Andrews and R . h f . Keefer, ibid., 77, 6284 (1955). (7) T . I,. Davis and J . M. Farnum, ibid., 66, 883 (1934).
July 20, 1960
RATIOSOF
1,&-ADDITION
TABLEI11 RATECOSSTANTSIN COMPETITIVE REACTIONS (APPROX.27”)“ Mole ratiosReactants I/inal. anhy./SOz/ solvent
-
7 -
Expl
a
Products
II/III
22 23 24 25
I n tetrahydrofuran l / l / O , 95/10.3 127.1 1/1/1,9/9,1 57.7 1/1/5.3/7.5 14.5 1/1/9.2/4.7 5.1
26 27 28 29
I n mesitylene 1/’1/0.86/5.7 53.1 1/1/2.0/5,1 29.6 1/1/4.8/4.4 9.8 1/1/9.5/2.9 3..4
30 31 32 33 34
I n benzene l/l/0.91/9.2 l/l/O. 94/9.1 1/1/1.9/8.2 1/1/4.6/7.1 1/1/10.0/4.3
45.1
11.8 18.5
YC
kdkz
363 300 173 89.6 154 135 96
75.5 117 114
88.6 73.0
3.4
51.0
35 36 37 38
I n chloroethyl ether 1/1/0.91/7.0 36.2 18.3 1/1/1, T/6.1 1/1/4.8/5.2 6.6 1/1/10.9/3.2 2.7
87.7 75.3 63.6 48.4
39 40 41 42
I n chloroform 1/1/1.2/10.3 26.8 1/1/2.1/9,1 13.7 1/1/4.9/7.5 5.3 1/1/8.6/4.9 3.1
67.2 55.0 46.1
1.5
molecular radius of reactant B dipole moment of the activated complex = molecular radius of the activated complex
rg = pc =
Application of equation 2 to the Diels-Alder and sulfone Competitive reactions gives
7.7
In liquid SO2 43 1/1/18.0/Also see Table VIII.
77.9
39.3
The ratios of rate constants, 363-39.3, shows that maleic anhydride is always more reactive than sulfur dioxide under these conditions. Maleic anhydride is relatively most reactive when equimolar quantities of diene, maleic anhydride and sulfur dioxide react in tetrahydrofuran (expt. 22). Maleic anhydride is least reactive when the organic solvent is replaced by a large excess of sulfur dioxide (expt. 43). In seeking an explanation for the strong effect of solvent on the sulfone formation and competitive reactions, differences in dielectric constant of the reaction media were considered. The general effect of dielectric constant on reaction rates is given by the Laidler-Eyring equations
where kl/kz = the apparent ratio of rate constants (ki/k2)o = the ratio of rate constant a t D = 1 r1 = molecular radius of maleic anhydride PI = dipole moment of maleic anhydride Tt = molecular radius of the activated complex in the Did-Alder reaction P2 = dipole moment of the activated complex in the Diels-Alder reaction r3 = molecular radius of sulfur dioxide M3 = dipole moment of sulfur dioxide r4 = molecular radius of the activated complex in the sulfone reaction 4’ = dipole moment of the activated coniplex in the sulfone reaction
For a constant temperature equation 3 can be simplified (C is a constant)
According to 4, a plot of log (kI/ka) against ( D - 1)/(2D 1) gives a straight line. This prediction cannot be tested exactly because the dielectric constant of the reaction mixture changes as the reaction progresses, and the dielectric constants of I1 and I11 are not known. As an approximation, the dielectric constants of the initial reaction mixtures were estimated from published dielectric constants of I, sulfur dioxide, maleic anhydride and the solvents on the assumption that the solutions were ideal. These data are summarized in Table IV and plotted in Fig. 1.
+
\.
t
’
2.3 h
$4t 2.1-
-3
v
\ 1.9
1.7
t c
0.40
k = apparent rate constant ka = rate constant at D = 1 D = dielectric constant kg = Boltzmann constant T = absolute temperature PA = dipole moment of reactant A t‘A = molecular radius of reactant A pg = dipole moment of reactant B (8) S. Glasstone, K. 3. Laidler and H. Eyring, “The Theory of R a t e Processes.” McGraw-Hill Book Co.,Inc., S e w York. N. Y.,1941, p.
e l ]
\
0.42
0.44
(D - 1)/(2D
where
419.
3618
O F 2 , 3 - D I M E T H Y L - 1 ,%BUTADIENE
Fig. 1.-Change
+ 1).
0.46
in the ratio of rate constants with dielectric constant of the solvent.
The data obtained in benzene, chloroform and liquid sulfur dioxide solutions form a straight line. However, the reactions in tetrahydrofuran, mesitylene and chloroethyl ether do not conform to equation 4, and these data give three different curves. The straight line for the “normal” solvents, Le., benzene, chloroform and liauid sulfur
OLIVERGRUMMITT A N D AXGREW L. ENDREY
3616
p.ELATIoN
I. xpt.
TABLE I\' decrease its effective concmtration. Sulfur dioxide BETII-EENRATIOOF RATECONSTANTS A N D D ~ - addition compounds have been reported for various oxygenated organic compounds,loa benzene and alELECTRIC CONSTAXT kylated benzenes.lob The decreased effective conD - 1 D ki/kz
log (ki/kr)
(init. ream.)
-2
22 23 24 25
I n tetrahydrofuran (D = 7.39)" 363 2.560 10.55 300 2,477 11.1 12.1 173 2.238 89.6 1.962 13.32
26 27 28 29
154 135 96.0 75.5
8.99 10.01 11.41 13.10
0.4210 .4286 .4372 .4449
30 31 32 33 34
117 114 88.6 73.0 51.0
I n benzene ( D = 2.284 j" 2.0682 7.05 2,0569 7. 11 1.9474 8.00 1.8633 9.57 1.7076 12.15
0.4007 .4015 ,4118 ,4255 .4407
In mesitylene 2.188 2.130 1,982 1.878
0.4320 ,4355 .4405 .4460
(D = 2.333)"
35 36 37 38
I n chloroethyl ether (D = 21.2)" 87. 7 1.943 21.5 75.3 1.877 20.9 1.803 19.0 fi3.6 48.4 1.685 16.65
39 40 41 43
77.9 67.2 55.0 46.1
0.4659 .4649 .4615 .4563
In chloroform ( D = 4.806)"
43 0
VOl. 82
1.8915 1,8274 1.7404 1.6637
8.74 9.45 11.19 12.49
0.4188 .4246 .4358 .4423
I n liquid sulfur dioside (D = 13.6)" 0.4510 39.3 1.5944 14.82 Dielectric constants of the solvents are at approximately
25'.
dioxide, is expressed by equation 5 (found by the method of least squares) log ( k i / h ) = 5.806
- 9.34- 2D0 - +1 1
(5)
Thus sulfone formation is favored by increasing dielectric constant of the reaction medium. Since the rate of the Diets-Alder reaction also probably increases with increasing dielectric constant, as is true of cyclopentadiene-benzoquinonega and cyclohexadiene-maleic anhydride,gbit appears that the extent of change is much greater for the sulfone reaction under competitive conditions. The favorable effect of polar solvents or1 the sulfone reaction is in agreement with a polar mechanism of addition in which sulfur dioxide is an electrophilic reactant6
It is believed that the abnormal solvents-mesitylene, tetrahydrofuran and chloroethyl etherreact as Lewis bases with sulfur dioxide and thus (9) (a) R. A. Fairclough and C. N. Hinshelwood, J . Chem. SOL, 236 (1938); (b) Y.Yukawa and A. Isohisa, Mem. Znsl. Sci. Znd. Research Osaka U n i v . , 10 191 (1953); C . A , , 48, 7598 (1954).
centration of sulfur dioxide makes the ratio of reaction rates higher than predicted by the dielectric constant (equation 4). Maleic anhydride also reacts with certain of these solvents. Equilibrium constants for maleic anhydride-benzene reaction are 0.60-0.85 a t The extent of this reactior, is slightly greater than that of sulfur dioxide-benzene which has an equilibrium constant (25') of 0.47.1°b Mesitylene is more reactive with sulfur dioxide than with maleic anhydride; equilibrium constants (25') are 2.1 l l O b and 0.94-1 -3, respectively." Two consecutive reactions that would afiect the yields from the competitive reactions were considered: (1) dissociation of the sulfone and ( 2 ) displacement of sulfur dioxide from the sulfotle by maleic anhydride. Model experiments showed that neither of these complicating reactions occurred. Sulfone 111 is not dissociated whrn refluxed in water for 1 hour.I2 Maleic anhydride and I11 did not react in tetrahydrofuran, chloroethyl ether or benzene solution during 6 days a t room temperature. To determine the effect of temperature on the relative reactivity of maleic anhydride and sulfur dioxide, competitive reactions were run at Oo, 2 7 O (approx.), and 50' (Table V). Chloroform was TABLE V EFFECTOF TEMPERATURE ON THE RATIOOF RATE Cox-
--
Expt.
44 45 39 46 47
1,
"C.
0 0 2Tb 50 50
STAN& M o l e ratio-
Reactaut I/mal. anhyd./SOr/ solvent
Products II/III
I n chloroform 1/1/0,94/10.5 1/1/0.97/10.3 1/1/1.2/10.3 1/1/0.90/10.2 1/1/0.93/10.2
In tetrahydrohran 0 1/1/4.9/7.7 0 1/1/5.1/7.6 2;6 1/1/5.3/7.5 50 50 1/1/4.8/7.6 50 1/1/5.0/7.5 51 0 Also see Table IX. b Approximately.
48 40 24
k;/k?
37.3 34.1 26.8 23.1 23.6
90.4 86.5 77.9 55.9 59.4
43.7 41.7 14.5 11.0 10.8
520 512 173 123.5 125
taken as a typical normal solvent and tetrahydrofuran as an abnormal type. In both solvents the lower temperature of 0' increased the ratio of rate constants and the higher temperature of 50' decreased the ratio. Thrrefore higher temperatures in the range of 0-50' relatively favor the addition of sulfur dioxide. J O U R N A L , 65, (10) (a) N . F. Albertson and W C. Pernelius, THIS 1687 (1943). (t) L. J. Andrews and R. AM.Reefer, ibid., 73, 4169 (1951). (11) L. J. Andrews and R. M. Reefer, ibid., 75, 3777 (1953). (12) The thermal stability of I11 is indicated by earlier work: equilibrium constants for the formation of butadiene sulfone are 176-180 (loo'), 304 (SOo); L. R. Drake, S. C. Stowe, and A. hl.
Partansky, ibid., 68, 2521 (1946). The decomposition temperature of 111 is higher than that of butadiene sulfone.5
July 20, 1960
3617
1,'LXDDITION OF 2,3-DIMETHYL-1,3-BUTADIEKE
TABLE VI
-
DIELS-ALDER&ACTIONS Maleic anhydride G. Mole
----I--
Expt.
G.
Solvent ( 6 . )
Mole
Tetrahydrofuran (39.5) 3.9 0.048 4.9 0.05 2 Mesitylene (31.7) ,043 4.1 3.55 ,042 3 Carbon tetrachloride (75.8) 4.1 ,050 4.7 .048 4 Benzene (52.8) 5.1 ,062 6.1 .062 5 Chloroethyl ether (44.5) ,043 4.25 3.55 ,043 ,041 6 Chloroform (54.3) 3.55 .043 4.0 Measured as the acid, then converted t o the anhydride, m.p. 76-77'.
1
Soln. Time, vol., ml. hr.
53.2 45.3 56.3 71.2 42.6 44.1
TABLE VI1 SELFONEREACTIONS Expt.
Solvent (g.)
Tetrahydrofuran (32.4) Mesitylene (30.9) Carbon tetrachloride (59.1) Benzene (32.6) Chloroethyl ether (45.0) Chloroform ( 5 5 . 2 ) bliued m.p. with 111, 115-130'.
7 11 13 16 19 21 a
-1G.
Mole
---SO-
G.
3.55 0.043 2.90 3.55 ,043 2.75 3.5.5 ,043 2.80 3.55 ,043 2.80 3.55 ,043 2.90 3.55 ,043 2.65
If the change in dielectric constant with temperature is assumed to be insignificant, the difference between the energies of activation for the DielsAlder and sulfone reactions can be calculated Ez) (l/T" - l/T') (6) In ( k l l k 2 ) ' = ratio of rate constants at T' absolute temp.
In (kl/k2)'
- In (kl/kg)"
= (E1 -
In (kllk,)" = ratio of rate constants a t T" absolute temp. El = energy of activation for the Diels-Alder reacn. = energy of activation for the sulfone reacn. E2
which was derived from the Arrhenius equation. l 3 In the range of 0 to SOo, El - E2 in chloroform is 1500 200 cal.; in tetrahydrofuran, 5000 f 40 cal.14 The larger difference in tetrahydrofuran reflects the greater decrease of kl/kp with increased temperature. This can be interpreted as the result of a higher effective concentration of sulfur dioxide because increased temperature has lowered the concentrat-ionof solvated sulfur dioxide.
*
Experimental Reparation of Materials.-2,3-Dimethyl-l,3-butadiene ( I ) was prepared by catalytic dehydration of pinacol over activated alumina a t 460-510' (20-100 mm.).u The typical yield was 5oyOb;%*OD 1.4387, reported1&1.4393. The main by-product, pinacolone, was recycled to give more diene. If pinacolone is the only impurity, the refractive index indicates that I is 99% pure. Malejc anhydride (Eastman Kodak Co.), after distilling a t 195 , melted 56-58'; sulfur dioxide (Ohio Chemical) was purified by bubbling through concentrated sulfuric acid, then passed through glass wool. Tetrahydrofuran (Matheson, Coleman and Bell) was refluxed over sodium for 12 hours, fresh sodium was added several times, and distilled t o collect the 66' fraction. Bis(2-chloroethyl) ether (Eastman Kodak Co.) was washed with 10% ferrous sulfate solution, water, dried over calcium sulfate and distilled a t 94" (33 mm.). (13) W. J. Moore, "Phy.;ical Chemistry," Prentice-Hall, Inc., N e w York, N . Y . , 1950,p. 528. (14) For the b::tadienc-maleic anhydride reaction in benzene the energy of activation is 1 1 7 lical.; B. Eisler and A. Wassermann, J . Chcm. Soc.. 1943 (1953). (15) L. F . Fieser, "Experiments in Organic Chemistry," 2nd ed., D. C. Heath and Co.,N e w York, N.Y . , 1941,p. 383. (16) P. N. Kogerman, Sifsher. nofurforsch.-Ge., Univ. Tariu, 41, No. 3-4, 62 pp. (1934);C.A , 29, 3297 (1935).
Vapor phase Son, mole
Mole
0.045 ,043 ,044 ,044 ,045 ,041
0.0045 .0063 .0049
Sol n
vol., ml.
.
43.5
Product M . p . , OC. G.
7 -
36 48 36 36 48 48
195" 76-77 77-78 200" 75-76 76-77
Time, hr.
--
48 42.7 48 44 48 ,0046 44.2 48 ,0060 43.8 48 ,0041 42.8 48
M.P., 'C.
115-125" 130-132 133-134 133-134 134-135 135-136
8.5 7.3 8.8 11.7 7.7 7.4
Product-
G.
%
90 97 100 95 98 98
%
0.26 4.1 0.72 11.6 1.12 17.4 1.62 25.3 3.18 50 3.91 62
Chloroform (Merck reagent) was purified.17 Benzene (Merck reagent) and anisole were dried by refluxing over sodium and distilled. Mesitylene (Eastman Kodak Co.) was washed with 75% sulfuric acid, water, dried over calcium sulfate, and distilled a t 162-163', reportedls 164.5164.8". 3,4-Dimethyl-2,5-dihydrothiophene 1,l-Dioxide (III).In 3 400-ml. pressure bottle 4.9 g. (0.06mole) of I and 43.2 g. (0.67mole) of sulfur dioxide were allowed t o stand for 12 hours a t room temperature. Unreacted material was evaporated a t room temperature under suction. The residue, 7.5 g. (88Gj,),was recrystallizad from 200 ml. of hot water and dried in a desiccator with calcium sulfate; m.p. 134.5135.5', reported6 135-186'. 2,3-Dimethyl-l,3-butadienePolysulfone.-In a 400-ml. pressure bottle 9 g. (0.11mole) of I, 12 g. (0.19 mole) of sulfur dioxide and 0.2 g. silver nitrate catalyst were allowed t o react for 2 hours a t room temperature. The non-volatile residue was ground, washed with ethanol, and dried in air t o give 15.2 g., 97%. The polysulfone is insoluble in organic solvents and in water. It darkens a t about 215' when heated in a melting point tube. In refluxing trimethylbenzene (160') the polymer slowly decomposes and sulfur dioxide is liberated.
cis-l,2-Dimethyl-l-cpclohexene-4,5-dicarboxylicAnhy-
dride (11) and Acid 1V.-Compound I1 was prepared by allowing maleic anhydride to react with a 10% excess of I in benzene or carbon tetrachloride (about two molar) a t room temperature for several days. Solvent and excess I were distilled in vacuo. Yields were quantitative, m.p. 77-78', reported'Q 78-79'. The anhydride I1 was converted to the sodium salt of I V by boiling-with an equivalent amount of 10% sodium hydroxide. After cooling, IV was precipitated with excess hydrochloric acid, filtered, washed with water, recrystallized from ethanol-water and dried in a desiccator with calcium sulfate; m.p. 199-200" dec., reportedlg 204' dec.; calcd. neut. equiv. 99.1,found 99.1. Compound I1 was regenerated by boiling IV with ten times the equivalent amount of acetic anhydride for 15 minutes. Acetic acid and excess anhydride were vacuum distilled t o leave I1 in quantitative yield; m.p. 75-80". Diels-Alder and Sulfone Reactions in Various Solvents.The Diels-Alder reactions (Tables I, VI) and sulfone reactions (Tables 11, VII) were carried out in 400-ml. pressure bottles a t room temperature. The volume of the reaction mixture was calculated from the weight of the components and densities. For the sulfone reaction, solvent, diene and (17) Reference 15, p . 365. (18) J. F . N o d s and D . Rubenstein. TEISJOURNAL, 61, 1169 (1939). (19) J. Boeseken and W. 3. F. de Rijck van der Gracht, Rcc. ;roo. chim., 66, 1203 (1937).
OLIVERGRUJIMITT AND ANDREWL. ENDREI’
3618
1.01. 82
TABLEVI11 COMPETITIVE REACTIOXS~
-92 23 24 25
---Sulfur G.
dioxideMole
---SolventG
Vapor phase SO2, mole
Mole
2.90 5.85 15.95 27,65
0,0453 ,0914 ,249 .432
32 28 23 14
0 3 3 6
In tetrahydrofuran 0,444 0.0043 ,393 ,0089 .3235 ,0209 ,2025 ,0334
.> 75 -.
29 26 22 14
9 i 9 9
0.249 ,222 ,1905 ,124
____
hlole
In mesitylene 0.0057 ,0120 ,0239 ,0366
7 7 6 5
25 01 35 64
0.0402 ,0388 ,0352 ,0312
0 0914 1928 522 1 03.5
0.00002A .0013% ,00358 0071
In benzene 0.0044 0047 0091 ,019; ,0352
i 7 7 6 5
30 33 04 40 40
0.0405 ,0407 ,0390 ,0355 ,0299
0 131 1425 ,309 .676 1 440
0.000898 ,000975 ,00211 ,00463 ,00985
7 6 6 5
17 94 38 32
0.0398 ,0385 ,0354 ,0295
0 163 308 7 89 1 61
0.001115 ,002107 ,00540 .01101
7 6 6 5
03 85 13 50
0.0390 ,0380 0340 ,0305
0 213 403 930 1 42
0.00146 ,00278 ,00636 ,00971
2 3;
0.0162
30 31 32 33 34
2.80 8.90 5.85 14.05 30 05
0.0437 ,0454 ,0914 ,2195 ,469
31 30 2T 24 14
2 7 7 0 5
0.400 ,3955 ,3548 ,3075 ,1858
35 36 37 38
2.85 5.35 14.65 32.65
0.0445 ,0836 ,229 ,5105
43 37 32 19
5 9 1 6
I n chloroethyl ether 0.3040 0.0052 ,265 ,0103 ,224 ,0232 ,1368 ,0388
39 40 41 42
3.55 6.35 14.85 25.90
0.0854 ,0992 ,2318 ,405
53 0
(1
G
0,0407 ,0398
6.30 14.75 28. 75
43
Mole
III---
34 19 71 00
0.0429 ,0973 ,2300 ,449
46 9 38 8 25 5
G
7 7 6 6
26 27 28 29
0.444 ,392 ,325 ,2135
-___ 11-
-.
Products
7
Expt
I n chloroform 0.0050 0091 ,0193 ,0311
.03i2 ,0332
I n liquid sulfur dioxide 53.15 0.830 .... 0.0500 4 40 0,0244 Taken: 3.55 g. (0,0433 mole) of I and 4.25 g. (0.0434 mole) of maleic anhydride.
hl-droquinone (0.01 g.) were added in order. Then the gas inlet ( a rubber stopper holding two pieces of glass tubing) was attached and the bottle cooled in ice-salt. T h e longer inlet tube reached almost t o the bottom of the bottle, the shorter outlet tube was attached t o a drying tube. The outside opening of the inlet tube was closed during cooling. When the bottle was cold, purified sulfur dioxide was passed in. The approximate amount was measured by a rotameter; the exact weight was found by weighing the pressure bottle. The volume of the solution was calculated from the weight of the components and densities. The quantity of sulfur dioxide in the liquid phase was found b y subtracting sulfur dioxide vapor from the sulfur dioxide total. The vapor quantity was calculated for ideal solutions
where
n, = moles of sulfur dioxide in the vapor phase Po = vapor pressure of sulfur dioxide a t TOabsolute temperature20 n t = total moles in the vessel R = gas constant K = compressibility factorzo volume of the vapor phase At the end of the reaction, solvent and volatile reactants were removed in V U C U O . Competitive Reactions.-These reactions (Tables 111, IV, V I I I ) were also run in 400-ml. pressure bottles. Maleic anhydride, solvent, hydroquinone (0.01 g.), sulfur dioxide and compound I were added in order. At the end of the
v=
(20) J. W. Mellor (ed.), “ A Comprehensive Treatise on Inorganic and Theoretical Chemistry,” Vol. X, Longmans, Green and Co., New T o r k . N. Y., 1930, pp. 191, 195.
0 047 .lo1 3 T4 942
0.00032 ,00069 .0025ii 0064,i
reaction volatile components were vacuum distilled and the residue analyzed for I1 and 111. The Diels-Alder adduct I1 was measured as czs-1,2-dimethyl-l-cyclohexene-4,5-dicarboxylic acid (IV). This is insoluble in water while maleic acid (from excess maleic anhydride) is soluble. I n a typical model determination, the sample was dissolved in 10 ml. of 10% sodium hydroxide by boiling. Cooling in ice and adding 4 ml. of concentrated hydrochloric acid precipitated IV. This was filtered, washed three times with 5 ml. of ice cold water. The solid was dissolved in 100 ml. of 50% ethanal, then titrated with 0.25 N sodium hydroxide. This analysis was tested on four samples of 11; quantities taken and found were: (1) 1.0812 g., 1.075g.; (2)1.0284g., 1.025g.; (3)1.2314g., 1.230g.; (4) 0.9955 g., 0.990 g. The sulfone was determined by quantitative dissociation to I and sulfur dioxide and measurement of sulfur dioxide by reaction with excess standard sodiutn hydroxide, oxidation of sulfite to sulfate, and titration of excess alkali.6 I n a typical model determination, the sample plus 15 nil. of trimethylbenzene was refluxed (160’) for 1.5 hours. Liberated sulfur dioxide was absorbed in 50 ml. 0.25 V’. sodium hydroxide containing 1 ml. of 50% hydrogen peroxide. Excess base was titrated with 0.25 N hydrochloric acid. This analysis was tested on four samples of 111; quantities taken and found were: (1) 0.4495 g., 0.449 g.; (2)0.5280g.,0.529g.; (3)0.4855g.,0.184g.; (4)0.5521g., 0.551 g. In the competitive reactions approximately 1-g. samples of the product residue were used for the determination of 11 and 2-5-g. samples for 111. The procedure was tested on three known mixtures. (1) From a solution of 5.302 g. of 11, 0.4902 g. of 111, 0.5 g. of maleic anhydride and 48 g. chloroform, the solvent was removed in BUCUO and the residue analyzed; found: 5.25 g. of I1 and 0.484 g. of 111.
3619
1,2-DIPHENSLDIMETHYLENECSCLOBlJTA4NE
July 20, 1960
TABLE 1X COMPETITIVE REACTIONS AT 0" Expt.
t, 'C.
44 45
0 0
46 4i
50 50
-Sulfur G.
--Solvent-G.
dloxidehlole
Mole
Vapor phase S02, mole
AND
-
50""
71 -1-
G.
Mole
Products -111G.
7
Mole
In chloroform
2 70 2.80 2 70 2.80
54.05 52.95 52.60 52.75
0 0422
,0437 ,0422
.043i
0.453 ,444 ,4408
,442
0,0017 ,0017 ,0032 .0033
7.11 7.13 7.22 7.20
0.0395 ,0396 ,0400 .0399
0,155 ,170 ,254 ,247
0.00106 .00116 ,001735 ,00169
In tetrahydrofuran
0 14.15 0.221 14.60 ,228 0 50 14.35 .224 50 14.75 .230 Taken: 3.55 g. (0.0433mole) of I and
24.1 0.334 0.0072 6.87 0.0382 0.128 0.000875 ,328 ,0080 6.86 .133 ,000913 ,0381 23.65 .0152 6.82 .0378 .505 ,00345 23.7 .329 6.80 .510 ,00348 ,3245 .0156 ,0377 23.4 a 4.25 g . (0.0434mole) of maleic anhydride. Stability of 111.-An approximately one molar aqueous From a solution of 5.140 g. of 11, 0.517 g. of 111, ca. (2) 0.5e. of maleic anhvdride in 28 e. of benzene. the solvent solution of I11 was refluxed for one hour. No sulfur dioxide was detected in the solution or vapor by litmus paper or waskmoved, etc.; found: 5.10gyof I1 and 0.511g. of 111. (3) From a mixture of 4.473 g. of 11, 1.004 g. of 111, odor. Compound 111, 1.1 g., and maleic anhydride, 0.8 g., dis0.111 g. of polysulfone ( a possible by-product), 0.7785 g. of solved in 14.7 g. of tetrahydrofuran, were allowed to stand maleic anhydride, and 32 g. of chloroethyl ether, the polyfor 6 weeks a t room temperature. The solution was evapsulfone was removed by filtration. The solvent was removed, orated and the residue dissolved in 15 ml. of 10% sodium etc.; found: 4.37 g. of I1 and 0.966g. of 111. 48
49 50 51
hydroxide. Cooling, filtering and washing gave 0.8 g. of 111, m.p. 129-131". When the alkaline filtrate was acidified with hydrochloric acid, no precipitate of IV formed. I n a second experiment, 1.0 g. of 111, 4.0 g. of maleic anhydride and 37 ml. of chloroethyl ether were allowed to stand for 6 days a t room temperature. The solution was D = ZXi.Di (8) distilled in DUCUO,the residue was treated with 15 ml. of hot, 10% sodium hydroxide. .4fter cooling and extraction with where Xi is the mole fraction of the i'th component and D , 50 ml. of benzene, distillation of the benzene gave 1.0 g. is its dielectric constant. The following dielectric constant of I11 as the residue, m.p. 131.5-133.5'. The alkaline data were used: I , 2.102a t 25OZ1;maleic anhydride, 50.0 a t filtrate gave no precipitate on acidifying. 60°22;sulfur dioxide, 14.3 a t 14.5", 13.3 a t 32°,23and 13.6 In a third experiment, 1.0 g. of 111, 4.0 g. of maleic ana t 27' by interpolation; chloroform, 4.806a t 20'24; benzene, hydride and 37 ml. of benzene were allowed to stand for 6 2.284 a t 2OoZ5;bis-(P-chloroethyl) ether, 21.2 a t 2Ooz6; days a t room temperature. Separating this mixture as betetrahydrofuran, 7.39 a t 25'2'; mesitylene, 2.356 a t 20°.28 fore gave 0.93 g. of 111, m.p. 125-128", while the alkaline filtrate gave no precipitate on acidifying. (21) E. H . Farmer and F. L. Warren, J . Chein. Soc., 1300 (1933). Competitive Reactions at 0 ' and SOo.-Calculations and (22) P. Walden, 2 physik. Chem., 46, 174 (1903). experimental procedure were the same as for the room (23) P. Eversheim, A n i t . P h y s . , 141 8, 539 (1902). temperature reactions, except that 200-ml. pressure bottles (24) A. Weissberger, ed., "Technique of Organic Chemistry," Vol. were used a t 50 =!r 0.5' (Tables V and I X ) . Before calculating the ratio of rate constants and dielectric constants, sulfur dioxide in the vapor phase was estimated by equation 7, and the amount subtracted from total sulfur dioxide. The dielectric constant D was calculated for ideal solutions
V I I , "Organic Solvents," 2nd ed. rev., Interscience Publishers, Inc., S e w York, N. Y., 1955, p. 193. (25) Reference 24, p , 72. (26) Reference 24, p . 256.
[CONTRIBUTION FROM
THE
(27) F. E. Critchfield, J. A. Gibson and J. L. Hall. THISJ O U R N A L , 76, 6044 (1953). (28) T. W. Richards and J. W. Hipley, ibid., 41, 2010 (1919).
BAKERLABORATORY OF CHEMISTRY, CORNELLUSIVERSITY ]
Cyclobutane Diolefins.
1,2-Diphenyldi1nethylenecyclobutane'~~
BY A. T. BLOM~UIST AND YVONNE C. MEINWALD RECEIVEDDECEMBER 3, 1959 Thermal decomposition of 1,2-bis-(dimethylaminomethyl)-3,4-diphenylcyclobutanedioxide affords a 1 : 1 mixture of isomeric dienes, 1,2-diphenyldimethylenecyclobutane(111) and 3-methylene-l,4-diphenyl-2-methylcyclobutene (I). The completely exocyclic conjugated diene I11 undergoes normal 1,4-Diels-Alder addition reactions with both maleic anhydride and tetracyanoethylene.
The unusual formation of spiro compounds v i a 1,2-cycloaddition of tetracyanoethylene (TCNE) to certain conjugated cyclobutane polyolefins, such as I and 11, was described in earlier papers.2a-c Subsequently, J. K. Williams also observed similar addition reactions for other derivatives of methyl-
enecyclob~tane.~On the basis of pertinent studies reported to date, the facile l,&cycloaddition of T C N E to 193-conjugated dienes appears to be limited to dienes which possess a rigid transoid
(1) This study was supported b y the National Science Foundation, Grants NSF-G2922 and NSF-G5923. (2) For preceding related papers see A. T. Blomquist and Y. C. hleinwald: (a) THISJOCRNAL, 79, 5316 (1957); (b) 79, 5317 (1957); (c) 81, 667 (1959).
C6H6CH-c=CH2
C~H~C=C-CH~
I
I I
C~H~C-C=CH~ C~H~CH-C=CH~
I1
!
Cd36C-c=CH9 I1
1
1
C6H5CH-c=CHz I11
arrangement of the double bonds and hence are (3) J. K. Williams, ibid., 81, 4013 (1959).
