ALICYCLICO L E F I N S
Sept. 5 , 1957
into the chromatographic column in the manner described by Ray.3E The mixtures of olefins, with the exceptions of t h e isomeric butenes and cis- and trans-2-pentene, were separated by a 183 X 0.3-cm. column of 30% by weight carbethoxydimethylformamide impregnated on Celite 545 of 100-200 mesh size with helium as t h e eluent. The mixture of 1butene and cis- and trans-2-butene was analyzed by a similar column packed with 30y0 by weight dimethylformamide on Celite 545 and cooled t o -30", while the mixture of cis- and trans-2-pentene was separated by saturated silver nitrate in diethylene glycol, both with helium as eluent. In all cases, a thermal conductivity cell was used as a detector. The composition of each olefin mixture was computed from the chromatogram by determining the ratios of the individual peak areas. The individual peak areas were measured by t h e method of Cremer and Muller,37employing the product of peak height and half-band width, and were multiplied by a response factor which was obtained from the ratios of the areas produced by equal gaseous volumes of the standard olefins which comprised the mixture analyzed. The corrected area ratios gave directly the relative concentrations of the components in the mixture. Each ratio reported in Table V I and VI1 is the average of the ratios obtained from the analyses of two or more separate mixtures of olefins produced from decompositions of the same amine (36) X. H. R a y , J . A p p l . C h e m , 4, 82 (1954). (37) E. Cremer and R. Muller, 2. Elektrochem., 66, 217 (1951); M. Dimbat. P. E. Porter and F. H. Stross, Anal. Chem., 28, 290 (1956).
[CONTRIBUTION FROM THE
Amine Oxides.
4729
FROM A M I N E O X I D E S
oxide or quaternary base. By the above procedure, each ratio was determined with a n average deviation of 1-37, when the concentrations of the components in the mixture did not differ widely and of 6 7 , when the mixture consisted mainly of one olefin. On the basis of numerous calibration experiments carried out during t h e course of this work, it is estimated t h a t the absolute errors of the analyses are not significantly different from these deviations. T h e volatile components of the olefin mixtures t h a t were obtained from decomposition of the amine oxides and quaternary bases t h a t produce either styrene or 1-decene were obtained by the procedure described above, whereas the other olefins (styrene or 1-decene) were isolated as liquids by the methods which follow. The mixture of water, dialkylhydroxylamine (or tertiary amine) and styrene retained in the first tube of the decomposition apparatus (Fig. 1) was kept at 0" and stirred with a magnetic stirrer throughout the elution process. The mixture was diluted with ethrmol and the concentration of styrene was determined by conparison against standards with a Beckman DU spectrophotometer. T h e mixture of reaction products obtained from m ethyl-npropyl-n-decylamine oxide and dimethyl-n-propyl-n-decylammonium hydroxide, after removal of the propylme, was extracted with three 20-ml. portions of purified pentane. T h e combined pentane extracts were washed with 10 ml. and 5 ml. portions of 2.5 Nhydrochloric acid, then with 5 ml. of water and dried over anhydrous magnesium sulfate. The pentane was removed by distillation, and t h e residue, after weighing, was analyzed b y vapor-phase chromatography to determine the concentration of 1-decene. CAMBRIDGE, MASSACHUSETTS
DEPARTMENT OF CHEMISTRY, MASSACHUSETTS INSTITUTE O F
TECHNOLOGY]
IV. Alicyclic Olefins from Amine Oxides and Quaternary Ammonium Hydroxides','
B Y ARTHURc. C O P E ,
CARL
L.
BTJMGARDNER3 AND E D W A R D
E.
SCHWEIZER
RECEIVEDMARCH11, 1957 Thermal decompositions of the N-oxides of N,N-dimethyl-1-methylcycloalk-ylamines containing five-, six- and sevenmembered rings have been shown t o give olefins containing 97.5, 2.8 and 84.8'%, respectively, of the endocyclic isomers. T h e corresponding quaternary ammonium hydroxides follow the Hofmann rule when thermally decomposed t o yield mainly the methylenecycloalkanes. These results are interpreted in terms of the steric requirements of these various ring systems. Pyrolyses of the amine oxides and quaternary hydroxides derived from N,N-dimethylcycloalkylmethylamineshave been shown t o produce exclusively the expected methylenecycloalkanes in all cases b u t one. Trimethylcyclopentylmethylammonium hydroxide gave appreciable amounts of 1-methylcyclopentene. Possible mechanisms for the formation of this product are discussed.
Earlier work comparing the selective formation of olefins from unsymmetrical amine oxides and quaternary ammonium hydroxides has shown that these thermal decompositions give results that are quite similar except in cases where steric interactions influence the direction of elimination of quaternary ammonium ions but not amine oxides. Because of the steric interactions associated with alicyclic compounds, a study of the effect of ring size on the course of the two elimination reactions was undertaken. The olefins formed on thermal decomposition of amine oxides and quaternary ammonium hydroxides derived from homologous N,Kdimethyl-1-methylcycloalkylamines(I, n = 4, 5 , 6) were examined, in order to determine the relative amounts of methylenecycloalkane (Hofmann rule
(1) under (2) (3)
Sponsored by the Office of Ordnance Research, U. S . Army, Contract No. DA-19-020-ORD-3226, Project T B 2-0001 (1112). Paper 111, THISJ O U R N A L , 79, 4720 (1957). United States Rubber Co. Fellow, 1954-1956.
elimination) and 1-methylcycloalkene (Saytzeff rule elimination). In addition, the thermal decompositions of the amine oxides and quaternary ammonium hydroxides of the N,N-dimethylcycloalkylmethylamines, I1 ( n = 4, 5 , 6), were investigated. The compounds of type I were prepared by application of the Ritter reaction4 to the olefins obtained by dehydration of the corresponding 1-methylcycloalkanols. Properties of the S L X tertiary amines that were employed in this study, I and I1 ( n = 4, 5, 6), are summarized in Table I. The picrates, prepared as crystalline derivatives, are listed in Table 11. The corresponding amine oxides were prepared by allowing the amines to react with aqueous hydrogen peroxide. The rriethiodides of the tertiary amines (Table 111) were prepared and converted to the quaternary hydroxides. Two thermal decompositions of each amine oxide and quaternary base were conducted. The (olefins were analyzed by vapor-phase chromatographv, and the relative amounts of exo- and endo-cyclic ( 4 ) J J Ritter and J Kalish,
THIS J O U R N A L70, , 4048 (1948).
ARTHURc. COPE, CARLL. BUMGARDNER A N D EDWARD E.SCIIWEIZER
4730
VOl. 79
TABLE I ~Y,N-DIMETHYL TERTIARY AMIXES Yield,
%
Amine
B.P., O C .
~
1
~
5 d254 ~
Formula
i-( CHz)rC( d CH$)IY(CH3)2
92
152.5
1.4475 0.8508 CsHxiN
r(CHz)b-C(CH3)r\'( CHI)*
98
108.5 104.5 (35 mm.) 149.5"
c ( C H Z ) ~ ~ - C ( C H ~ ) N ( C H ~95 )Z ___A
E(piCHn)r-CHCHzN(
CH3)z
67
Carbon, % Calcd. Found
Hydrogen, % Calcd. Found
Nitrogen, % Found Calcd.
75.52
75.51
13.47 13.50 11.01 11.31
1.4590
,8695 C Q H I S S 76 53
i6.82
13.56 13.38
9 . 9 1 10.07
1.4686
,8834 CloHLIN
77.34 77.13
13.64 13.64
9.02
1.4385
,8158 CgHliK
9.20
78.5-79.5 1 4464 . . . . CgH19S (33 mm.). ~ ( C H Z ) ~ - C H C H Z . K ( C H 84b ~ ) ~ 102.0 (35 1.4581 ,8621 CKIH~LX77.34 77 12 13 G i 13.73 9 . 0 2 9 22 L A mm.) a Previously reported by M . Mousseron, R . Jaquier and R . Zagdoun, Bull. SOC. chinz. France, 197 (1952). After acidifying with hydrochloric acid and concentrating, the mixture was extracted continuously with ether for three days. T h e aqueous layer was made basic and the amine was isolated in the same manner as the other amines. z)rCHCH2N(CHa)i
74
TABLE I1 N,K-DIMETHYL TERTIARY AMINEPICRATES Carbon, So Found Calcd
Hydrogen, % Calcd. Found
Xitrogen, % Found Calcd.
CiaHpoKaOj
47.19
46.93
5 66
5 80
15.72
15 73
232.6-233.8 d.a
CljH22SdO:
48 64
48.52
5 99
5.90
15.13
15 2 3
217.4-218.4a
Ci~Hz4P.rT4Oi
49.99
50.13
6.29
6.36
14.58
14.63
~ ( C H ~ ) ~ - C H C H ~ K ( C H B90 )~
142.8-143.8,'
C141-120S407
47.19
47.08
5.66
5.71
15.78
15.78
r(CHz)g-CHCHzN( CH3)2
124.6-125.3
C ~ G H ~ ~ S ~49.99 O;
50.29
6.29
6.45
14.58
13.63
Yield,
%
Amine
M.p., OC.
Formula
~ ( C H ~ ) ~ - C ( C H ~ ) N ( C H ~ )94 Z
250.8-252.0 d.'
r(CH2)5-C(CH~)N(CH3)2
92
c--(CHZ)G-Y(CH~)N(CHB)Z
94
L-J
100
L _ -J
a
Recrystallized from dry ethyl acetate.
Recrystallized from absolute ethanol
TABLE 111 'rRIhlETHY1,AMMONITM IODIDES Carbon, ' j , M.p., O C . Found Formula Calcd.
Yield,
%
Methiodides
Hydrogen, '% Calcd. Found
Iodine, % Calcd. Found
r(CHz)&( CHa)K( CH3)J
79
255.4-258, 4 d.a
CgHzoXI
40.16
39.88
7.49
7.21
47.15
47.35
r(CH2)$-C(CHa)N( CH3)31
98
257.6-260.4 d.b
CloHzzNI
12,11
4%.48
7.83
7,71
44.82
44.79
~ ( C H ~ ) ~ - C ( C H ~ ) ~ ( C H82~ ) B I263 6-264 6 d.b
CIIHNSI
43 45
44 35
8 14
7 82
42 70
42 63
c-( C H ~ ) ~ - C H C H ~ S ( C H J ) J I94
205 8-206 Sh
C9H2"Sl
40 16
40 36
7 49
7 39
47 15
-17 23
~ ( C H ~ ) ~ - C H C H Z S ( C H ~99 )~I
226.5-227 5 d.b,c
Cio€IuSI
I - ( C H ~ ) ~ - C H C H ~ S ( C H ~ )95 BI
240.2-240.6hsd
C I I H ~ ~ X I 44.43
44.52
8.14
8.05
42.70
42.71
a
Recrystallized from absolute ethanol Recrystallized from methanol-acetone mixtures Previously reported by 0 Wallach, ilnn , 353, 302 (1907).
Previou-ly
reported b y
0 . Wallach, A n n , 353, 284 (1907)
isomers were determined. A summary of the results obtained from the amine oxides and quaternary ammonium hydroxides derived from the N,K-dimethyl-1-methylcycloalkylaminesis shown in Table IV. Table V contains the results of the TABLE 0 1 EFIXS
*
AMMONIUM I1
Amine oxides
4 5 6
4 3
0
Iv
AMINE O X I D E S A S D TRIMETHYLr-i HYDROXIDES OF ( CHZ), C( CHB)K(CH,),
OBTAINED PROM
4 v e . yield, 7F Olefin Amine
77
2
84
3 2
84
71 85 84
1 0 9
1
Composition of olefin mixture in weight % Exocyclic Endocyclic
2.5 97.2 15.2
91 0 98 n 78 2
97.5 2 8 84.8
