1744
Vol. 60 TABLE V 2-METHYL-1-PENTENE
POLYMERIZATION O F
hfoles Heptane,‘J Sdlllple
fi.
Al(i-I!u)a, P.
n’(!-Bu)lb
’TiClr,
moles TiCh
g.
Monomer,
I 2 3
4 0.10 0.083 1.16 10 3.5 .10 .085 1.16 10 3.5 .10 . 085 1.16 10 X solvent ratio to mononier of 1.5 ( w t .ratio) failed to produce polymer. mer. (I
infrared analysis of carbon tetrachloride solutions of both 1,S-hexadiene and poly-l,5-hexadiene were made by comparing the absorption maxima of the C=C a t 1650 c m . 7 and the vinyl C-H at 920 cm.-’. The analysis showed t h a t the polymer contained from 5.6 t o 8.6’70 of the monomer units which still retained one of the two double bonds. KO attempt was made to dehydrogenate this polymer. A n a l . Calcd. for ( C S H ~ ~C), ~87.72; : H, 12.24. Foutid: C, 86.78; H , 12.16. Poly-2,5-dimethyl-l,5-hexadiene(XIV, XV).-Table I V shows the results of the polymerization of 2,5-dimethyl1,Shexadiene. These polymers had melting points of 8085” and a quantitative infrared analysis of carbon tetrachloride solutions of both 2,5-dimethyl-1,5-hexadiene and its polymer by comparison of the maxima for C=C and vinyl C H showed t h a t from 3.4 to 12.8% of the monomer units
[CONTRIBUTION FROM
THE
’J‘emp ,
Time, hr.
6.
I’olymer wt., g .
OC.
Conversion, %
30 30
*
54 1 10 54 1.3 13 50 54 1 10 A catalyst ratio of 3.0 failed to produce poly-
retained one double bond during polymerization. Yo attempt was made to dehydrogenate this polymer. Anal. Calcd. for (CsHla)n: C, 87.19; H, 12.81. Found: Sample 1 : C, 87.43; H , 12.57. Sample 2: C, 87.13; H, 13.21. Poly-2-methyl-l-pentene.-The results of polymerization of 2-methyl-1-pentene are shown in Table V. The oils obtained were combined and distilled under diminished pressure (150” (0.1 mm.)). The infrared spectrum of this hydrocarbon showed no unsaturation mas present in the molecule. A n a l . Calcd. for ( C B H ~ Z C, ) ~ :84.63; H , 14.37; mol. wt. ( n = 5), 425.8. Found: C, 85.45; H, 14.13; mol. wt., 424. URBANA, ILLISOIS
CHEMICAL LABORATORIES O F THE UKIVERSITY
OF
NOTRE DAME]
The Mechanism of Halide Reductions with Lithium Aluminum Hydride. VI. Reduction of Certain Bromohydrins and Epoxides192 BY ERNEST L. ELIELAND DAYIDw.DELhCONTE3 RECEIVED OCTOBER 24, 1937 Lithium alumiiiuni hydride rcduction of l,l-diphenyl-2-bromoetlianolyields 2,2-diplienylethanol, in addition tu the CXpected 1,l-diplienplethanol. Similarly, reduction of 1,1,2-triphenyl-2-bromoethanolyields 1,2,2-triphenylethannl, and reduction of 1,l-diphenyl-2-(~-chloroplienyl)-2-bromoethanol yields l-(p-chlorophenyl)-2,2-diphenylethanol.The “oxygen shift” observed in these reductions is explained on the basis of an epoxide intermediate. In accordance with this explana0
A
tion, it has been found t h a t lithium aluminum hydride reduction of unsymmetrically substituted epoxides, RR’C-CHR” in the presence of aluminum halides gives rise to the less highly substituted carbinols RR‘CHCHOHR”, although similar reduction in the absence of aluminum halides gives the more highly substituted carbinols RR’COHCH2R“. Tracer studies show t h a t the reduction of styrene oxide and isobutylene oxide in the presence of aluminum halides involves the corresponding aldehydes (phenylacetaldehyde and isobutyraldehyde) as intermediates, The implications of these results on the mechanism of reduction of halohydrins in general are discussed.
In a previous publication4 it has been shown through tracer studies that lithium aluminum hydride reduction of a halohydrin with tertiary halogen, such as 2-chloro-2-methyl-1-propanol(I), proceeds largely through a hydride shift
of this kind in lithium aluminum hydride reductions are already on record; thus reduction of the bicyclic bromoketone I1 gives rise to the alcohol 1115; in the treatment of trans-2-chlorocyclohcxanol Br
(CH3)zCHCHDOI-I
r
Br
i
(I)
It was the original aim of the present work i o CStablisli whether a corresponding alkyl shift would occur in the reduction of halohydrins of the type
I.
I RR’COHCX. Isolated instances of alkyl shifts
I
(1) Presented before t h e Organic Division of the American Chemical Society a t hliami, Fla., on April 11, 1957. For a preliminary communication of part of this work, see THISJ O U R N A L , 78, 3226 (1956); cf. also G. J. P a r k and R. Fuchs. J , O r g . Chem., 21, 1513 (1956). (2) Paper V , E. L. Elk1 and J. T. Traxler, THISJOURNAL, 78, 4049 (1956). (3) This paper is based on t h e Ph.D. dissertation of I). IY. Delmonte, Shell Research Fellow, 10,55-1856. (4) E. I,. Elk1 and Th. J. Prosser, THISJ O U R N A L , 78, 4045 (105(i).
Ill
(IV) with lithium aluminum hydride under drastic conditions some cyclopentaldehyde (V) is ob(5) A. C. Cope, E. S. Graham and D. J. Marshall, ibid., 76, 6159 (1954). These authors postulate rearrangement a t t h e bromoketone stage, hut, reasoning by analogy with t h e hydride shift i n eqn. (i),‘ w e prefer I n a s s l i m ? f h n t t h e rinx ronlrartion OTTIII’C a t the hrnmnl i g d r i n staxe.
ilpril 5 , 1958
REDUCTION OF BROMOHYDRINS AND EPOXIDES
61:;
1745
No phenylbenzylcarbinol, the product to be expected from a phenyl shift in the bromohydrin VIII, was obtained; in fact comparison of the in-H+ ring-+ , -Ci\\'--CHO frared spectrum of the crude reduction mixture with that of authentic phenylbenzylcarbinol in11' v dicated the latter substance to be absent. The tosylate (VI) yields 2-isoi)ropyl-3-Iiiethylcyclopen- major product of the reduction was the expected tylcarbinol (VII) among other products.7 1,l-diphenylethanol (XI). In addition, however, CHI CH, substantial amounts of diphenylacetaldehy de and the corresponding alcohol (XII) 2,2-diphenylethanol \ ; /O€f (XII) were formed. Formation of these compounds " \ + involves a shift of the oxygen function (see Fig. 1). -CH20H A similar oxygen shift was observed in the reduc{kLTS tion of IX which yielded exclusively 1,2,2-triCH(CHa)s CI-I(CH,)z phenylethanol (XIII). This alcohol might alter171 VI natively have resulted from a phenyl shift, but this The compounds chosen for study in this work possibility mas excluded when it was found that were 1,l-diphenyl-2-broxnoethanol (VIII) and 1,- reduction of 1,l-diphenyl-2(p-chlorophenyl)-2-bro1,2-triphenyl-2-bromoethanol (IX). It would have moethanol (XIV) yielded only 1-(p-chloropheny1)been preferable to study 1,1,2,2-tetraphenyl-2- 2,2-diphenylethanol (XV), the product of the bromoethanol (X), since previous ~ o r khad ~ . in~ oxygen shift, completely free of 1,2--diphenyl-2(CtiHj)2COHCH2Br (CtiHb)3COHCHBrC611b (p-chloropheny1)-ethanol (XVI), the expected prodVI11 IX uct of a phenyl shift. Furthermore, it was shown ( C 6 H 6 ) L O H C B(C6H& r that the absence of a phenyl shift in XIIT is x not due to any inherent difference in behavior bedicated that a hydride shift would occur only in tween XIV and the corresponding chlorine-free halohydrins, such as I, in which the halogen is ter- compound IX, for in the presence of mercuric ion tiary. However, attempts to synthesize compound XIV does undergo a phenyl shift to give phenyl X were unsuccessfuL8 p-chlorobenzhydryl ketone (XI'II) . l o These reThe results of the reduction of compound VI11 sults are summarized in Fig. 1. are summarized in Table I. Very little reduction LAH occurred when a slight excess over the theoretically (C6H&COI-ICI12Br --+(CsHb)zCOHCH3-Irequired amount of hydride (0.5 mole, viz., 0.25 \'I11 XI mole for the acidic hydrogen and 0.25 mole for re(Cti'I15 j2C€ICH201 I duction of the halogen) was employed. Even SI1 with the use of 1.5 moles of hydride, substantial L.iIr amounts of bromohydrin remained unattacked and (CsIl6)zCOHCI IBrC6Hb -+ (CEI l;)?Cl I C l I O l I C ~ I f ~ somewhat better reduction (though still not comIS XI11 plete) was obtained with 2.4 moles of hydride which Hgf+ quantity was therefore used in all subsequent d c&IjCOCI-I(CS€I,)C6I-I,CI reductions of halohydrirsg SVII tainedfi; and reduction of cis-2-hydroxymenthyl
'(/
/
~
I _
(/
I
L.41 I TABLE I ( C ~ I ~ ~ ) ? C O H C H U ~ CE+ I~~CI 1, ~ - U I P H E ~ Y L - ~ - B K O M ~( E \ ~TI I I II) A N O L XIV 1,I-DiAIole ratio phenkl2,S-Diphcnyl(C6II~)~CIICI-IOIIC,II,CIt i 0 CljII,cIIolIcIl (C6H ,IC611.e1 L.4H/ Kraction Recovered, ethanol ethanol ( X I I ) , X \' XVI VI11 time, hr. V I I I , Yo ( X I ) , yo % Fig. 1. 0.6 10 70 1.5 10 24 The "oxygen shift" observed in the abovc reduc2.4 10 8 49 19b tions suggested almost compellingly that epoxides 2.4 2 12 42 4.2" were intermediates in the reduction of the halohy2.4 2d 1ee 33 51 drins VIII, IX and XIV to the rearranged alcohols a Kot analyzed. * Also obtained ca. 5y0 diphenylacetal- X I I , XI11 and XV. Yet such a suggestion apdehyde and benzophenone. e Also obtained ca. 147, carbonyl compound, largely diphenylacetaldehyde. d Tar- peared a t first sight unlikely, since it is well establishedll that reduction of an unsymmetrically trate work-up, all other runs were worked up with acid. e As 1,l-diphenylethylene oxide. f Also obtained CQ. 2.5% substituted epoxide with lithium aluminum hydride benzophenone. gives rise to the more highly substituted carbinol,
REDLTTIOX
OF
(6) hl. hlousseron, R. Jacquire, M. Jlousseron-Canet and R. Zagdoun, Bull. SOL. chim. France, 1013 (1952). (7) P. R. Jefferies and B . hlilligan, Chemistry&lndustry, 487 (1956). (8) D. Delmonte, unpublished results. (9) T h e stoichiometry of t h e reduction of halohydrins with lithium aluminum hydride remains uncertain. Whereas J. E. Johnson, R. H. Blizzard and H . 'A'. Carhart, THISJ O U R N A L , 7 0 , 3664 (1948), found t h a t i t requires one mole of t h e hydride t o reduce one mole of halide, R. E. Lutz, R. 1,. Wayland and I€. G. France, ;bid., 72, 5511 (1950), report ready removal of the aliphatic halogen in l-(p-bromophenyl)-2bromoethanol, p-BrCsHd2HOHCHrBr with a "molecular equivalent" of lithium aluminum hydride.
whereas compounds XII, XI11 and XV are the less highly substituted of the two possible isomeric carbinols. Thus the reduction of triphenylethylene (10) A corresponding phenyl shift which occurs when IX is treated with mercuric ion has been demonstrated by labeling: C. J. Collins 76, 5379 (1953). and W. A. Bonner, THISJOURNAL, (11) For examples see (a) PU'. G. Gaylord, "Reduction with Complex Metal Hydrides," Interscience Piiblishers, Inc., h-ew Y o r k , Pi. Y . , 1956, pp, 646-673; ( b ) V. h'l hlicovic and h1. I,. hlihailovic, "Lithium Aluminum Hydride in Organic Chemistry," Belgrade, Yugoslavia, 1955, pp. 68-74.
1746
ERNESTL. ELIELAND DAVIDW. DELMONTE
Vol. 80
TABLE I1
0 PRODUCTS O F
REDUCTIOS OF
R’
IZ
EPOXIDES
/\ RR’C-CHR”
WITH
LITHIUM XLUMISUMHYDRIDE
RR’COHCHsR’’ XX, 53
Yield,
%
12“
RR’CHCHOHR” XXI, yc
Alethod of anal.n
I3 CH3 H 60 100 0 11,3 CH3 Ii CH3 26 95--98h 2-5” M, I CH, CIil ca. 25c 100 CHa 0 I II CsH5 H 82 00-95”. 5- 10’‘ nr, I C6H5 I 92 100 CC“ 0 3, 15 CsH5 CsH5 12e 100 CsH5 0 C M, inass spectrometry; I, infrared spectroscopy; Is, actual isolation of pure m a t e r i d ; C, chroxnatugrapliic separatioii and isolation. T h e range given indicates the uncertainty of the analysis. Previous re;Ilso recovered epoxide.12 p o r t ~ mention ~ ~ only this product (plienylmetliylcarbinol). The presence of the isomeric 2-phenylethanol in the reaction product is likely but not absolutely certain. e Also 807, recovered epoxide.’* No reduction at all occurred with 0.35 mole of LiAlH4.
TABLE I11
0
P\
REDUCTIOS O F EPOXIDES RIZ’C-CHR” I
t a n c e q of hitidcred cjxi.\ides n h i c h rcqist reductiiin i i t c the revcrsal. T b v o obvious possibilitics COIIIC to listed in ref. l l l i , p. i-1. (13) R . I;. s y s t r o m G . urown, rrHIS RNA,,, 70, 3 i 3 * mind. Xccordillg to one (equation ii) aluminum halide coiirdinates with the qjoxide and favors an (1018>: I,. \V T r e \ c t y x n ~ lI V G . Brc,wn, L D L O . , 71, lti73 (194!l!. 117,
April 5, 1958
REDUCTION OF BROMOHYDRINS AND EPOXIDES
SNl-like opening of the epoxide ring with subsequent attack of hydride a t the more substituted carbon which bears the positive charge of the incipient carbonium According to the other (equation iii) the aluminum halide rearranges the epoxide to an aldehyde or ketone which is subsequently reduced to the product alcohol. -
0
A
IIR’C-CHK” -
-ilCId
XiCl~ I
0’
A
IIR’C-CI-IR”
----f
AlC!, 1
0-
0
A
RR’C-CHR”
--
AlCl3
Li.11H4
-+ RR’CHCOR”-+ _H_
RR’CHCHOHK”
(iii)
The former sequence (ii) resembles the reversal in direction of ring opening of epoxides observed with other nucleophiles (such as alcohols) upon addition of acid,14 whereas the latter (iii) is reminiscent of the course of the reaction of epoxides with Grignard reagents. l5 Reaction paths ii and iii may be differentiated by a tracer study employing lithium aluminum deuteride; if path ii is operative, the product should be RR’CDCHOHR” whereas path iii should yield RR’CHCDOHR”, species which may be distinguished readily by mass spectrometry. The experiment was carried out with styrene oxide as a representative primary-secondary epoxide and with isobutylene oxide as a representative primary-tertiary epoxide, since mass spectra of the four possible products to be expected in reduction of these oxides (2-phenylethanol-2-d, 2phenylethanol-1-d, isobutyl-2-d alcohol and isobutyl-1-d alcohol) were available from a previous i n ~ e s t i g a t i o n . ~Reduction of styrene oxide with lithium aluminum deuteride-aluminum chloride gave a 2-phenylethanol fraction which was 94y0 of the 1-d species with only 5% of the 2-d isomer (the remaining 1% was unlabeled). Similarly, the isobutyl alcohol fraction from an analogous reduction of isobutylene oxide was 90% 1-d isomer (CH3)zCHCHDOH and only 9% 2-d isomer, the remaining 1% being unlabelled. It follows therefore that path iii is by far the predominant course of the abnormal reduction of epoxides in the presence of aluminum halide and that therefore the reduction of epoxides with lithium aluminum hydride-aluminum halide resembles their reaction with Grignard reagents (whereas their reaction with lithium aluminum hydride alone resembles the reaction of epoxides with alkylmagnesiums).l6 It is known from the extensive work of E. Wiberg and co-workers17 that the addition of alu(14) Cf. E. L. Eliel in hl. Newman’s “Steric Effects in Organic Chemistry,” John Wiley and Sons, Inc., Kew York, N. Y . , 1956, chapter 2 , p. 112. (15) M. S . Kharasch and 0 . Reinmuth, “Grignard Reactions of Nonmetallic Substances,” Prentice-Hall, Iuc., New York, N . Y . , 1956, pp. 965-9137, (16) Reference 15, p. 995. (17) Summarized in ref. l l a , pp. 51-33; cf. alsu ref. l i b , p. 44.
1747
minum halides to lithium aluminum hydride leads to the formation of lithium halide (precipitated in the case of the chloride) and aluminum halohydrides of the type AlHzX and AlHX2. These halohydrides are, in general, weaker reducing agents than is lithium aluminum hydridels ; thus, for example, they do not reduce n-octyl bromidelg which is readily reduced by lithium aluminum hydride alone.g It is clear that in the above-described reductions, aluminum halohydrides are formed, and we believe that these are quite sluggish in attacking the epoxide as such, thus giving the excess aluminum halide, acting as a Lewis acid, an opportunity to rearrange the epoxide to a carbonyl compound first. This tendency for rearrangement prior to reduction is greatest in the case of triphenylethylene oxide (which suffers hardly any direct reduction even with lithium aluminum hydride alone, cf. Table 11) and least in the case of propylene oxide, probably because in the latter the migration terminus for the hydride shift is secondary and aliphatic and tfirefore the rearrangement to aldehyde is sluggish*5and not well able to compete even with the slowed-down direct reduction. However, the difference between propylene oxide on one hand and isobutylene and isoamylene oxide on the other may not be quite as large as implied in Table 111. According to this table, the tertiary epoxides yield no tertiary alcohol X X , but the secondary epoxide yields very predominantly secondary alcohol XX. Gnfortunately, in a control experiment in which a mixture of the two products XX [(CH3)2COHCHCH31 and X X I [(CH&CHCHOHCH31 to be expected from isoamylene oxide was treated with the lithium aluminum hydride-aluminum chloride, the tertiary alcohol X X was extensively destroyed by conversion to t-amyl chloridez0(found) and possibly olefin (not found). Therefore it is possible that reduction of isobutylene and isoamylene oxide by the mixed reagent yielded substantially more of the tertiary alcohol than was isolated ; nevertheless the total product yields are such that the conclusion that more X X is formed from propylene oxide than from isobutylene oxide remains valid, even though the contrast may not be as extreme as is implied in Table 111. In previous publications,*B4two paths have been indicated for the reduction of halohydrins to alcohols by lithium aluminum hydride, ziiz., an assisted bimolecular displacement (Fig. 3, C) for primary and secondary halohydrins and a hydride shift R’
RR’COHCHBrR” 0
+
A
A1 H2
C
Hz D
RR’C-CHR” ----f RR’CHCOR” -.--f RR’CHCIIOIIR” E
Fig. 3 (18) Cf.R. F. Npstrom, THIS JOr:Rlvat., 7 7 , 2544 (1955). (19) E. Wiberg and A. Jahn, Z. 1Valurforsciz., 7b, 580 (1952). ( 2 0 ) T h e reduction of conjugated unsaturated ketones t o hydrocarbons reported by J. Broome and B. R. Brown, Cheinisti,y b Iizduslrg, 1307 (195I3), also appears t o proceed t’in the chlorides: C==CC=O -+ C-CCOH + C=CCC1 -+ C-CCH, which, being allylic, may bc further reduced t o hydrocarbons by t h e mixed reagentlg; cf, J. Brootne, B. R . Brown a n d G. H. R. Summers, J. C h e w Soc., 2071 (1057).
ERNEST L. ELIELAXD I ~ A V ILJ-. D DELMOIUTE
1748
Vol. 80
(Fig. 3, D) for halohydrins in which the halogen is of these epoxides only one gram-atom of halide tertiary. T o these should now be added the per mole of compound would be liberated and path via the epoxide (Fig. 3, E) as a third pos- the data in Table I11 show that this is not sibility.21 One must enquire, however, whether sufficient to suppress completely the formation of these three paths are really all separate. The pos- the tertiary alcohols, from the epoxides. Yet sibility exists, a priori, that the epoxide inter- no tertiary alcohols whatsoever were obtained mediate is converted, by means of aluminum in the reduction of X X I I and X X I I I . Finally, halide, to a halohydrin isomeric with that from if the reduction of 2-phenyl-2-chloropropionic acid which the epoxide was formed and that this halo- (XXIV) were to proceed via the epoxide, equation hydrin is then further reduced by path C or D. iv shows that the over-all reduction should entail Conversely, the halohydrins previously studied2 retention of optical configuration, since the reacmay have been first converted to epoxides which tion path involves two inversions. are then reduced by path E.22 C6H,(CH3)CClCOOH-+ C6Hj(CH3)CClCHzOH + Experimental evidence shows that the reduction XXIV of secondary halohydrins does not proceed via epoxides, or vice versa. Thus 2-chloro- 1-propanol upon reduction yields 1-propanol as the only CeHs(CH,)C-CH2 )CGHS(CH3)CHCH0 --+ chlorine-free p r o d ~ c t ~but , * ~propylene oxide yields C~HS(CHI)CHCHZOH(iv) largely 2-propanol, even in the presence of aluminum chloride. Again, 2-chloro-2-phenylethanol Actually, however, predominant inversion was obupon reduction with lithiuin aluminum deuteride served,22in agreeinelit with the reaction course yields largely 2-phenylethanol-2-d, whereas styrene postulated previously. Nevertheless, since invera reacoxide with the same teagent in the presence of sion of configuration was not aluminum chloride yields largely 2-phenylethanol- tion path entailing retention, such as iv, niay have 1-d. Therefore path C represents a discrete made a minor contribution. While thus it appears that not all halohydrin recourse of reduction. The evidence with respect to the tertiary halo- ductions proceed v& epoxides, i t is still a poshydrins, RR’CClCH20H, is not so clear-cut. The sibility that epoxide reductions proceed via halo(equation v), a t least in the case of terproducts obtained from these by r e d u ~ t i o n *ap, ~ > ~liydrins ~ pear t o be compatible with reaction via the epoxide. tiary epoxides. Such a possibility is suggested by Nevertheless, we believe that reduction of these 0 A AlXa A1& halohydrins does not involve the epoxide intermediate in a major way, but that, in the main, it RR’C-CHR” d R R ’ C X CI H R ” --+ H involves the discrete path D (Fig. 3). There are 0 several reasons for this assumption. Curtin and I AlXl hleislich have found that the two diastereoisoineric 1 - (i, - chlorophenyl) - 1,2 - diphenyl - 2 - bromoLi U I C I I I I ‘ C l r c l I ------+ IIII‘CIICIIOIIK” ( v ) ethanols upon treatment with ethylmagnesium I1 bromide give distinct rearrangenlent products, but 0 the corresponding diastereoisoineric a-(p-chlorophenyl)-stilbene oxides with ethylmagnesium bro- the work of House2j on the reaction epoxides with mide give the same rearrangement product and magnesium bromide. Further experiments are have concluded that the epoxides are not inter- required to clear up this point. Some time ago it was found that 3-acetoxy-9irietliates in the rearrangement of the bromohydrins.24 This observation shows that the rear- bromoergostanone-1 1 (XXlr) is reduced, by means rangement of halohydrins need izot proceed via of lithium aluminum hydride, to 3-hydroxyergosepoxides. There is experimental evidence that tanol-11 (XXVI) despite the fact that the brothe reduction of (CH,)&ClCH*OH (XXII) and mine in this conipound is tertiary.26 I t was sug(C~H5)2CC1COOH2~4~22 (XXIIT) does izot involve gested that reduction proceeds via the enolate of the corresponding epoxides for in the formation the ketone XXVII; but in view of the fact that enolates are usually resistant to further reduction,23
A
--
(21) Paths D and E are analogous t o those proposed by T. A. Geissman and K. I. Akawie, THISJ O U R N A L , 73, 1993 (19511, for the reaction of halohydrins with Grignard reagents. (22) It has been stated previously-E. L. Eliel and J . P. Freeman, i b i d . 74,9 23 (1952)-that epoxides are not intermediates in the reduction of a-chloroacids and chlorohydrins t o alcohols, since t h e alcohol, CsHs(CHa)COHCHs, obtained from a-methylstyrene oxide, CaHa(CHdC-CH2, was isomeric with t h a t , CeHs(CHdCHCHz-
\/
0 O H , obtained from a-chloro-a-phenylpropionic acid, CsHs(CHa)CClCOOH. This argument now turns o u t t o be invalid, since i t neglected t h e effect of t h e aluminum chloride-formed in t h e reduction of t h e chloroacid-on the course of reduction of t h e potential epoxide intermediate. ( 2 3 ) E. I,. Ellel, C. Herrmann and J. T. T r a x l r r , i h i d . , 78, 1103 ( 1R3fi), (2.1) U . Y . Curtin and E . K. hleislicii, ibid , 74, 590; (1952). See also ref. 25b for similar results with the positional isomers 2-bromo-3pentanol and 3-bromo-2-pentanol.
CsHi9
X
=
H or .\c RZ,,
/’.,A/-
I
I
xo/
____
XXV, XXYI, SXVII, XXVIII, XXIX,
R1 = =0, R z = Br R1 = OH, Rz = H Rt = S O , Rz H R3,Rz = >O R, = OH, R) = Br
V,,b’ ~
(25) (a) H . 0. House, ibid., 77, 3070 (1936); (b) 77, 5083 (1955); (c) see also h l . Tiffeneau and B. Tchoubar, Compl. veiid., 207, 918 (1938). (26) H . B. Henbest, E. R. H . Jones, A. A. Wagland and T . I. Wrigley, J. Ckem. S o r . , 2477 ( 1 0 5 5 ) . Rlnre recently, Dr. H ~ n h ~ \ t (private cnnimunication) has oLt;rinrrl independent evidence ( f r o m the reduction of 1,2-cycloherariedi,il monohrosylates) t h a t epoxides may he intermediates in such reductions. See also H. B. Henbest and T. I. Wrigley, i b i d . , 4,396 (1937).
April 5 , 19jS
REDUCTION OF BROXOHYDRINS AND EPOXIDES
the epoxide XXVIII (formed from the bromoketone XXV via the bromohydrin XXIX) appears a more likely intermediate, especially in view of the fact that XXVIII itself was a by-product of the reduction. The epoxide XXVIII is formed along with aluminum bromide which is assumed to rearrange it to ketone XXVII which is finally reduced to the product XXVI.
1749
Anal. Calcd. for C!oHl?ClO: C, 77.79; H, 5 . 5 5 . Found: C, 77.87; H, 5.73. Lithium Aluminum Hydride Reductions. Reduction of 1,l-Diphenyl-2-bromoethanol (VIII) .-A solution of 20.8 g. (0.075 mole) of VI11 in 100 ml. of dry ether was added to a
slurry of 6.85 g. (0.181 mole) of lithium aluminum hydride in 150 nil. of ether (prepared in the usual way) over a period of 30 minutes, followed by a 2-hour reflux. Hydrolysis was effected by means of sodium potassium tartrate. The dried ether solution was concentrated t o give l j . 5 g. of a n oil which, according to Beilstein and silver nitrate Experimental tests, contained little if any halogen. Comparison of the infrared spectrum of the oil with reference spectra suggested i\ll melting and boiling points uncorrected. Infrared spectra by Mr. Rolland Ro; mass spectra by Mr. George the presence of 1,l-diphenylethylene oxide, of some alcohol component(s) and of a small amount of b e n z ~ p h e n o n e . ~ ~ Young; elementary analyses by Micro-Tech Laboratories, Diphenylacetaldehyde was absent. An entirely similar Skokie, Ill. product mixture was obtained when the reaction mixture 2,ZDiphenylethylene and its Epoxide.-Molten 2,2diwas worked up with 40y0 aqueous potassium hydroxide. phenylethanolZ3(17.5 g., 0.088 mole) was added slowly from An aliquot of the product was chromatographed on basic a pressure-equalized dropping funnel to a n excess of solid alumina. Four fractions were identified in the eluate. potassium hydroxide contained in a vacuum distillation apparatus maintained at ca. 150' and 10 mm. The crude The first one (15.5% recovery) was 1,l-diphenylethylene oxide, m.p. 50-56", undepressed by admikture of a n auolefin distilled as it was formed. Redistillation gave 7.63 g. (4870) of material boiling a t 135-139" (10 mm.), ~ Z O D thentic sample (m.p. 55.5-56OZg). The second one (2.2% recovery) was benzophenon? identified by its 2,4-dinitro1.6015 (lit.27 b.p. 134" (10 mm.), n z 01.6100). ~ Since the yield in this preparation was low, subsequent batches of 1,l- phenylhydrazone, m.p. 228 , mixture melting point with diphenylethylene were prepared by the method of reference authentic sample 228-230" (lit. 239'). The third fraction (16.5yo recovery) was 1,l-diphenylethanol, m . p . after re28. The olefin was converted t o the bromohydrin VIII, crystallization from petroleum ether (60-90') and mixture m.p. 71-72.5' (lit.2973-73.5') by means of N-bromoacetamide.29 1,l-Diphenylethylene oxide, m.p. 56-58' (lit.z9 melting point with authentic sample 80-81" (lit.3780-81'). The last fraction (20.1Y0 recovery) was a mixture. Frac55.5-56'), was obtained by treatment of either the bromotional crystallization from petroleum ether (b.p. 60-90'2 hydrin VIIIZ9or the monotosylate of 1,l-diphenplethylene gave 1,l-diphenylethanol, m.p. and mixture m.p. 80-81 glyco130 with base. (about 3 parts), and 2,2-;iphenylethanol, identified by its Derivatives of 1,1,2-Triphenylethane.-1,1,2-Triphenylphenylurethan, m.p. 127 , mixture m.p. with authentic ethanol, m.p. 87-88' (lit.29 86.5-87.5') was prepared from sample 128-131" (lit.3s 138-139') (about 1 part). benzophenone and benzylmagnesium chlorides1 and conBy multiplying the crude yield with the recovery figures verted t o 1,1,2-triphenyl-2-bromethanol( I X ) , m.p. 121122' (lit.32 124-126'), by means of N-bromo~uccinirnide.~~from the chromatogram, one obtains the yield, in grams, of each of the four products. Expressed as the usual mole Treatment of the bromohydrin with base32 gave triphenylpercentage, this is: 1,ldiphenylethylene oxide, 16.3%,; ethylene oxide, m.p. 74-76' (lit.3z (5-77'). 1,2,2-Triphenl,ldiphenylethanol, cu. 33Y0; 2,2-diphenylethanol, ca. ylethanol ( X I I I ) was prepared by lithium aluminum hy5%; and benzophenone, 2.5%. dride reduction of phenyl benzhydryl ketone.33 Since the When the reduction mixture was worked up with sulfuric ketone is not ether-soluble, i t was added to the standardized acid, the ratio of the yields of 1,l-diphenylethanol and 2,2hydride solution as ether slurry. The carbinol XI11 melted diphenylethanol was similar, but there was also obtained a at 86-88' (lit.3487'). substantial amount of diphenylacetaldehyde. It is be2-(p-Chlorophenyl)-l,l-diphenyl-Z-bromoethanol (XIV) .lieved t h a t this compound is a n artifact of the work-up proc2-(p-Chlorophenyl)-l,ldiphenylethanol, m.p. 115-119' ess. A longer reaction time with acidic work-up led t o (lit." 116'), was prepared from benzophenone and p more 2,2-diphenylethanol and less diphenylacetaldehyde. chlorobenzylmagnesium chloride. a It was brominated with The data are summarized in Table I. It should be noted PI;-bromosuccinimide in exactly the same way as the parent t h a t with acidic work-up, l,l-diphenyl-2-bromoethanol compound IX.32 The bromohydrin XIV, obtained in 91% (VIII) was recovered, b u t with basic or tartrate work-up yield, melted at 128-130' after recrystallization from petro1,l-diphenylethylene oxide was obtained instead, suggestleum ether Q.p. 60-90'). The analytical sample melted ing t h a t the epoxide results from unchanged bromohydrin at 129.5-130 during the work-up. It is also significant t h a t the 2,2-diAnal. Calcd. for CnoH16BrC10: C, 61.95; H, 4.16. phenylethanol : 1,l-diphenylethanol ratio increases with inFound: C, 61.69; H, 4.27. creasing conversion. This may be due to the accumulation l-(p-Chlorophenyl)-2,2-diphenylethanol (XV).-A solu- of halide ion in the reaction mixture as the reaction protion of 9.S1 g. (0.05 mole) of diphenylacetaldehyde inz2100 gresses, since this is known's t o impede the reduction of ml. of sodiumdried ether was added to p-chlorophenylhalogen in halohydrins (a process b y which 1,l-diphenylmagnesium bromide prepared from 1.22 (0.05 g.-atom) of ethanol may be formed from VIII) and to promote (vide magnesium and 9.57 g. (0.05 mole) of p-chlorobromobenzene infra) the formation of 2,2-diphenylethanol from 1,l-diin 100 ml. of ether and allowed to stand for 2.25 hr. a t room phenylethylene oxide which may be a fleeting intermediate temperature. The reaction mixture was cooled and hydroin the reduction. lyzed with a solution of 5.35 g. of ammonium chloride in 22 Reduction of 1,1,2-Tripheny1-2-bromoethanol(1x1 .-A ml. of water followed by 150 ml. of dilute hydrochloric acid. slurry of 14.12 g. (0.04 mole) of I X in 150 ml. of ether was Separation of the ether layer, drying over anhydrous potasadded slowly to 87 ml. (0.096 mole) of 1.1 Af ethereal lithium sium carbonate and concentration gave the product XV as a aluminum hydride. The mixture was heated a t reflux for crystalline solid melting at 153-155.5" after crystallization four hours and then worked up in the usual way to give 10.53 from petroleum ether (b.p. 90-120'), yiel! 3.88 g. (25%). g. (96y0 recovery) of white solid, m.p. 76-82". RecrystalliThe analytical sample melted at 154-155.5 . zation of this solid from petroleum ether (b.p. 60-90') gave 1,2,2-triphenylethanol ( X I I I ) , m.p. 87-88' (lit.3' 8 7 " ) , in (27) R. N. Jones, THIS J O U R N A L66, , 1823 (1943). 96% recovery. The mixture melting point with authentic (28) C. F. H. Allen and S. Converse, "Organic Syntheses," Coll. XI11 was 86-88' and the infrared spectra of the two samples Vol. I , John Wiley and Sons, Inc., h-ew York, N. Y., 1946, p. 220. (29) S. J. Cristol, J. R. D o u g l a s and J. S. Meek, THISJOURNAL, were identical. No additional bands appeared in the infrared spectrum of t h e crude product. The mixture melting 73, 816 (1951). point of the recrystallized product with 1,1,2-triphenpleth(30) E. L. Eliel and D. Delmonte. 1.Olg. Chem., 21, 596 (1956). anol was depressed t o 83-88' and the infrared spectra of the (31) C. Hell and F. Wiegandt, Ber., 37, 1429 (1904). (32) J. F. Lane and D. R. Walters, TEISJOURNAL, 73, 4234 (1951). two samples were distinct. (33) R. Anschiitz and P. Forster, Ann., 368, 93 (1909). (36) For the possible origin of this product see ref. 23, footnote 41. (34) M.St. Pierie, Bull. SOC. chim. France, [31 6, 292 (1891). (35) W. Tadros, K. Farahat and J. M. Robson, J . Chem. SOC.,430 (37) M. Tiffeneau, Ann. chim., [SI 10, 359 (1907). (1949). (38) P. R a m a r t and P.Amagat, ibid.. [lo]8, 290 (1927:).
.
l7.iO
ERNEST L. ELIEI,AND DAVID Ti'. DELMONTE
VOl.
so
Reduction of Z-(p-Chlorophenyl)-ljl-dipheny1-2-brometh-indicated absence of niethylisopropylcarbinol (diagnostic anol [XIV),--I solution of 9.69 g. (0.026 mole) of X I V in bands a t 9.1, 9.8 and 10.23 p ) , but there was some un125 ml. of ether was added slowly to 55 ml. (0.06 mole) of changed epoxide as indicated by a band a t 11.6 p . The 1.1 111 ethereal lithium aluminum hydride and the mixture amount of recovered starting material was estimated at 10was heated a t reflux for four hours. Hydrolysis followed 2070 from the infrared spectrum and the yield of alcohol is by isolation of the product gave 6.6-l g. (7370) of crude mateaccordingly 25-30%. The p-nitrobenzoate of the reducrial melting a t 141-147'. The mixture melting point with tion product melted a t 83-84' undeprcssed by admixture of l-(p-chlorophenyl)-2,2-diphenylethanol (XXr) t-amyl p-nitrobenzoate (lit. 85'). authentic (m.p. 153-1555') was 145-162" and the two samples had Isobutylene Oxide.-Thc ether extract of the reaction identical infrared spectra. The spectrum of the product mixture after drying over potassium carbonate was coildiffered from t h a t of authentic 2-(p-chlorophenyl)-l,l-di- centraoted and distil!etl to give 26'3, of material boiling at phenylethanol. 80-84 (737 mm. 1, T L ~ O D 1.3872. Mass spectrometric Since recrystallization of the crude reaction product reanalysis of the product using the 59 peak for t-butyl alcohol turned only 78y6and raised the melting point to only 117and the 43 peak for isobutyl alcohol indicated a composi1 4 9 O , it mas suspected that perhaps the material might contion of 97.6y0 of t-butyl and 2.4yqisobutyl alcohol. The tain some of the isomeric 1,2-dipheny1-2-(p-chlorophenyl)- infrared spectrum of a synthetic mixture containing 97% tethanol (XXY), the product of a phenyl shift. Therefore butyl and ,370 isobutyl alcohol was in good agreement wlth the crude material ( 1 .OO g.) was oxidized with potsssium pert h a t of the reaction product. There was no doubt whatmanganate in pyridine and the acidic and neutral fractions of ever about the presence of the minor component (band a t the oxidation product were isolated. The acid melted at 9.58 M ) . 231-234' and had neut. eauiv. 151.4 (p-chlorobenzoic Propylene Oxide.-The crude material, isolated as above, acid melts a t 242' and has neut. equiv. 156.5). After subdistilled 79-82' (734 mm.), 12% 1.3778 (60% yield) (lit. limation the acid weighed 0.32 g. (63%) and melted at 233b.p. 83.3 , %*OD 1.3771 for isopropyl alcohol). The infrared 236", mixture melting point 238-239.5'. The neutral fracspectrum of the product was identical with t h a t of isopropyl tion weighed 0.64 g. and gave a negative Beilstein test for alcohol and showed no bands due to n-propyl alcohol. chlorine, indicating absence of p-chlorobenzophenone, which Mass spectral analysis confirmed a composition of 99% isowould have resulted by oxidation of XVI. Treatment of propyl alcohol. the neutral oil with dinitrophenylliydrazine reagent gave Reduction of Epoxides with Lithium Aluminurn Hydridebenzophenone 2,4-dinitrophenylhydrazone,m.p. 231-23j3 Aluminum Halide.-The reduction of styrene oxide is de(lit. 2 3 9 O ) , mixture melting point 238-2395", corresponding scribed in detail as being typical. Other reductions were in weight to 0.33 g. (56.5yG) of benzophenone. carried out similarly except as noted. Reductions of Epoxides with Lithium Aluminum Hydride Styrene Oxide.-Standardized 1.1 111ethereal lithium Alone.-These reductions were carried out by the standard aluminum hydride (36 ml., 0.04 mole) was added to a soluprocedure using 0.33-0.43 mole of 1.1 X standard lithium tion of 21.32 g. (0.16 mole) of anhydrous aluminum chloride aluminum hydride solution per mole of oxide. dl1 reaction in 50 ml. of cold sodium-dried ether. (The proportion of mixtures mere decomposed with water and sulfuric acid and the reagents is important. The use of lithium aluminum the reaction products, except those from 1,l-diphenyl- and hydride slurries did not give good results in this procedure.) triphenylethylene oxide were isolated by continuous ether ,4 solution of 19.22 g. (0.16 mole) of styrene oxide in 75 ml. estraction. of sodium-dried ether was added t o the mixed reagent over Triphenylethylene Oxide.-Vnder the above conditions, 48 minutes and the mixture boiled at reflux for two hours subsequently. Hydrolysis was effected by the addition of 97mc of the starting material, m.p. 70-73", mixture m.p. 7110 ml. of water followed by 125 ml. lOy0sulfuric acid. The 74', was recovered. Using two moles of hydride per mole of oxide gave a mixture (927, material recovery). Two ether layer was separated and the aqueous layer continuously extracted with ether for 18 hours. The combined ether grams of the mixture on crystallization from petroleum layers were dried over potassium carbonate, concentrated ether (b.p. 6G90") returned 0.90 g. of starting material, m.p. 73-74'. Chromatography of the mother liquor on and the residue distilled a t 0.9 mm. to give 13.96 g. (71%) of product, % ~ O D 1.5377. Mass sDectral analysis indicated basic alumina gave another 0.84 g. of starting material, 987, of 2-phenylethanol and 2ye 1-phenylethanol in the m.p. 73-74', and 0.26 g. of 1,1,2-triphenylethanol, m.p. product. The infrared spectrum was in good agreement 86-88', undepressed by admixture of a n authentic sample but depressed to 82-89' by admixture with 1,2,2-triphenyl- with t h a t of a mixture containing 95% of the 2-isomer and 5 % of the 1-isomer; however, i t is difficult to demonstrate ethanol. The infrared spectrum of the product was identical with t h a t of 1,1,2-triphenylethanol and distinct from the definite presence of the 1-isomer by infrared, as the prominent band a t 11.17 p in the spectrum of this compound that of the 1,2,2-isomer. is absent in all mixtures rich in the 2-isomer. The reactiou 1,l-Diphenylethylene Oxide.-The reduction product (94%) melted at 74.6-80°, mixture melting point with au- product was converted to the phenylurethan of 2-phenylethanol, m.p. 76-78", mixture melting point with an authentic 1,l-diphenylethanol 78-81 '. The two samples had thentic sample 77-79.5" (lit. 79'). identical infrared spectra, different from the spectrum of Other ratios of the reactant gave less complete reversal 2,2-diphenylethanol. Recrystallization of the reaction product (97.57, recovery) raised the melting point to 80- of the reduction, as indicated in Table 111. Trimethylethylene Oxide.-The reaction mixture WdS de81' (lit.3' 80-81'). The crude product was chromatocomposed with base and extracted continuously with ether graphically homogeneous. for 42 hours, dried, and concentrated to give 8.96 g. of Styrene Oxide.-The extracted reaction product was crude product from 10.0 g. of epoxide. Distillation of the distilled to give 14.0 g. (82%) of material boiling at 62-69" (1.8 nim.), %*OD 1.5280. Mass spectral analysis using the Droduct yielded 3.29 g. (32Y0) of material boiling a t 110107 peak for CsH6CHOHCH3and the 91 peak for CsHsCH?- 116', n% 1.4097 and 3.24 g. of high-boiling product. The CH?OH indicated a composition of 93 yo of 1-phenylethanol infrared spectrum of the first fraction was identical with that and 770 2-phenylethanol. However, this analysis was of authentic methylisopropylcarbinol and the diagnostic bands of t-amyl alcohol a t 7.8, 8.4 (broad), 10.65 and 13,73 somewhat untrustworthy, as synthetic mixtures of the two p were absent, The a-naphthylurethan of this fractlon components, for reasons unknown, did not give accurate mass spectrometric analyses. The analysis was therefore melted a t 111-112° and did not depress the melting point of an authentic sample (alcohol purchased from Columbia checked by comparing the infrared spectrum of the mixture Organic Chemicals Co.) (lit. m.p. 109'). with synthetic mixtures containing 85, 90 and 95% of the In a control experiment, a mixture of equal parts of t-amyl I-isomer and 15, 10 and 5y0of the 2-isomer, respectively. alcohol and rnethylisopropylcarhinol was added to the This again suggested t h a t the mixture contained 90-9570 lithium aluminum hydride-aluminum chloride reagent. of 1-phenylethanol, the remainder being the 2-isomer. The infrared spectrum of the recovered product indicated However, the presence of the latter could not be established with certainty, as the only characteristic band of the 2- that the i-amyl alcohol had been destroyed. In another experiment in which t-amvl alcohol alone was subjected to isomer ( a t 9.6 p ) is masked in all mistures rich in 1-isomer. the mixed reagent, some t-amyl chloride was obtained. Trimethylethylene Oxide.-The reaction mixture was Isobutylene Oxide.-The reduction was carried out as decomposed with base, as acid decomposition converted unchanged epoxide into glycol. Continuous extraction (36 described for styrene oxide. The product (55%) was collected at 80-135' (746 mm.), ~ 2 1,4032. 0 ~ Mass spectral hr.) followed by drying, concentration and distillation yielded 3.47 g. of t-amyl alcohol. The infrared spectrum analysis indicated a composition of 93.1y0isobutyl alcohol
tt
April 5, 1958
REDUCTION OF BROMOHYDRINS AND EPOXIDES
and 6.67c t-butyl alcohol. The infrared spectrum was in agreement with a composition of 9570 isobutyl and 5 % tbutyl alcohol. The presence of t-butyl alcohol appears to be real, as suggested by a shoulder at 10.97 p which is absent in the spectrum of pure isobutyl alcohol (t-butyl alcohol has a prominent band at 10.99 p ) . A reduction with 0.5 mole lithium aluminum hydride in the presence of 0.25 mole of aluminum chloride gave a product containing 7Oyct-butyl alcohol and only 30% isobutyl alcohol. Propylene Oxide.-The reaction was carried out as described for styrene oxide and the extracted product was distilled and collected in two fractions: (1) b.p. 80-96" (741 mm.), n Z o1.3808 ~ and ( 2 ) b.p. 128-129" (739 mm.), %*OD 1.4335. Fraction 1 by infrared spectrum appeared to be a mixture of n-propyl and isopropyl alcohol. Mass spectral analysis, using the 31 peak for n-propyl alcohol and the 45 peak for isopropyl alcohol, indicated 84% isopropyl and 167, n-propyl alcohol. The infrared spectrum of the product was very similar to t h a t of a mixture of 81% isopropyl and 197, n-propyl alcohol. Fraction 2 was identical in infrared spectrum with an authentic specimen of l-chloro2-propanol (spectrum kindly provided by Professor C. A. VanderWerf), lit.38 b.p. 64.5" (75 mm.), %*OD 1.4387. The spectrum differed from t h a t of 2-chloro-l-propanol.23 Very little reversal was obtained using 0.3 mole of lithium aluminum hydride and 0.25 mole of aluminum chloride per mole of propylene oxide (6. Table 111). 1,l-Diphenylethylene Oxide. (a) .-The reduction was carried out as described for styrene oxide, except t h a t a 2070 excess of the Li.41H4-A1C13 reagent mas employed, the reaction mixture was worked up with 207, sodium hydroxide solution, and the product was not extracted continuously. T h e crude product (89% yield) was an oil whose infrared spectrum was nearly identical with that of 2,2-diphenylethanol. Chromatography of this material on basic alumina gave, in over 85% recovery, a fraction whose infrared spectrum was identical with that of 2,2-diphen>-lethanol and which, after crystallization from mixed petroleum ether (b.p. 30-90°), melted at 60-62", undepressed by admixture of authentic 2,2-diphenylethanol (lit.3Sm.p. 62'). No 1,ldiphenylethanol was evident in any of the fractions of t h e chromatogram. (b) Using Lithium Aluminum Hydride and Allyl Bromide. --A solution of 3.02 g. (0.025 mole) of allyl bromide in 30 ml. of sodium-dried ether was added rapidly to 60.0 ml. (0.066 mole) of 1.1 Jf ethereal lithium aluminum hydride and the solution boiled a t reflux for 40 minutes. X solution of 4.91 g. (0.025 mole) of 1,I-diphenylethylene oxide in 7 5 ml. of ether was then added over ten minutes and the mixture boiled for ten hours more. The mixture was worked u p with dilute sulfuric acid in the usual way and the crude product analyzed as under (a) with the results entered in Table 111. The diphenylacetaldehyde probably originated in the work-up by action of sulfuric acid on unchanged epoxide. Triphenylethylene Oxide.-The reduction was carried out as described for 1,l-diphenylethylene oxide under ( b ) . The crude product was obtained in 987, yield and melted a t 83-85', mixture melting point with authentic 1,2,%-triphenplethanol 83-86'. Recrystallization (93 % recovery) raised the melting point to 84-87". The infrared spectrum of the crude and the recrystallized product and authentic 1,2,2-triphenylethanol were identical and different from the spectrum of 1,1,2-triphenylethanol. However, the complete absence of the latter isomer was not established with certainty. Reductions with Lithium Aluminum Deuteride-Aluminum Chloride. (a) Isobutylene Oxide.-The reduction was carried out with the same proportions of reagents as t h e corresponding reduction with the hydride; hut since i t is uneconomical to prepare clear solutions of lithium aluminum deuteride, the powdered deuteride (2.01 g., 0.048 mole, 20% excess) was added to a solution of 21.33 g. (0.16 mole) of anhy-drous aluminum chloride in 100 ml. of dry ether. Another 50 ml. of ether was added and the mixture heated at reflux with stirring for 90 minutes. A solution of 11.54 g. (0.16 mole) of isobutylene oxide in 75 ml. of ether was added over 45 minutes to the deuteride mixture cooled previously to room temperature and t h e mixture was then (39) W. Fickett, H. K. Garner a n d H. J. Lucas. THIS JOURNAL, 73, 50G4 (1951).
17.51
heated a t reflux for two more hours. Decomposition with 10 ml. of water and 150 ml. of 1070 sulfuric acid was followed by continuous extraction for 72 hours of the aqueous layer. The combined ether layers were dried over potassium carbonate and fractionated and the fraction boiling a t 106-108" (747 mm.), %*OD 1.3980, weighing 3.86 g. was retained as deuterated isobbtyl alcohol (isobutyl alcohol has b.p. 107.5' (752 mm.), %%OD 1.3955). The fraction was analyzed mass spectrometrically using the reference spectra previously r e ~ o r d e d . ~ , The ~ " 32 peak (for isobutyl-ld alcohol), 44 peak (for isobutyl 2-d alcohol) and 31 peak (for light isobutyl alcohol) were used in the analysis which indicated a composition of 90.070 (CH3)~CHCHDOIIarckRerick performed the reductions of trimethylethylenc oxide and h r . hlark Mersereau coijperated in the reductions of 1,1-diphenylethylene and 1,1.diphenyl-2-bromoethanol.
(44) AI. Kollarits and
[COSTRIBUTIOX FROM THE CHEMISTRY
A-OTRE
DAME,INDIANA
DEPARTMENT, VXIVERSITY
O F NOTRE DAME]
A New Method for Preparing Arylsuccinonitriles BY R. B D A V I S ~ RECEIVED OCTOXER 11, 1837 An aldehyde, a n arylmethylene cyanide and a n alkali metal cyauide react t o form ;in arylsuccitioriitrile. Sonic rieiv arylsuccinonitriles have been prepared by this method.
Previously, the preferred method for preparing 2,3-diphenylsuccinonitrile was the method described by Lapworth and I\lcRae2 in which benzaldehyde benzyl cyanide were condensed to CYphenylcinnamonitrile using a base as a catalyst. Then hydrogen cvanide was added to the CYphenylcinnamonitrile to produce 2,3-diphenylsuccinonitrile. I t has now been found that benzaldehyde, benzyl cyanide and sodium cyanide react to give this product in excellent yield. 0
( y H
+
@cH2cs
+ S a C N --+ h-c /'
CN
' ' (J+
-CHC€I-/
SJOII
Furthermore, it has been found that the reaction is general to the extent that other aldehydes and other arylmethylene cyanides may be used, and certain arylmethylene halides may be used in place of benzyl cyanide. Table I will serve to illustrate the versatility of the reaction. The aldehyde, a slight excess of arylmethylene compound and the alkali metal cyanide are allowed to react in the presence of methanol or mixtures of methanol and water. Best results are obtained when about 2.5 to 3 moles of alkali metal cyanide per mole of the aldehyde are used. When the arylmethylene cyanide is produced in situ from an arylmethylene halide, a larger excess of the arylmethylene halide is employed as well as a corresponding larger excess of the alkali metal cyanide. As the reaction proceeds alkali metal hydroxide is produced. During the early stages of the reaction, the base produced may actually be beneficial, but :I$ its concentration increases, i t may become (1) R e \ erend Ralph B Davls, C S C ( 2 1 4 I a p n u r t h a n d 3 h XIcRae, J. Chem Soc., 121, 1700 (1922).
detrimental. I n one preparation of 2,3-diphenylsuccinonitrile, when a few grams of potassium hydroxide was added to the reaction mixture a t the start and equivalent amounts of benzaldehyde and acetic acid gradually added, the product was obtained in improved yield. Experimental3 Preparation of 2,3-Diphenylsuccinonitrile. A.--X mixture of 100 i d . of distilled water and 61.2 g. (1.25 moles) of sodium cyanide was warmed until nearly all the cyanide dissolved. Absolute, acetone-free methanol (400 ml.) was added, the mixture was heated to reflux, and 50 g. (0.425 mole) of benzyl cyanide was added all at once. A solution of 53 g. (0.5 mole) of benzaldehyde and 30 g. (0.256 mole) of benzyl ?!-anide was then added drop\\-ise over 30 minutes with stirring at reflux. After the addition was completed, the reaction mixture was stirred at reflux for a n additional 30 minutes. During the course of the reaction, a colorless solid precipitated and the liquid gradually took on a dark blue-green cnlor. The reaction mixture was allowed to cool (2.5 hr.), was filtered with suctiorl, and the solid was washed well with ii5(,'; ~nctlinni~l-~~vater, with water, agait~ with i57, meth:tnol-'ivnter and then with ether. The colorless solid material weighed 59.5 g.;(;;( yield), m.p. 204205". A sample recr nllized from glacial acetic acid with practically quantitati recovery, as described by McRae and Bannard,4 nielted a t 235-239" (lit.4 240-241' cor.). B.-Following the same method as described in A , with the exception t h a t 81 g. ( I .25 moles) of potassium cranide was used in place of the sodium cyanide, there was obtained 85.5 g. (74% yield) of product, m.p. 204-205'. C.--A mixture of 100 1111.of distilled water, 61.2 g. (1.25 moles) of N a C S and 5 g. (0.089mole) of potassium hydroxide was warmed until all solid had dissolved. ilbsolute, acetone-free methanol was added (400 ml.), the mixture heated to boiling and 50 g. (0.425 mole) of benzyl cyanlde introduced all at once. This was followed by a mixture of 53 g. (0.5 mole) of benzaldehyde, 30 g. (0.256 mole) of benzyl cyanide and 30 g. (0.5 mole) of glacinl acetic acid; the first 10 ml. was added over 20 minutes, precipitation then began and addition of the rerrlnining aldehyde mixture was completed in 90 minutes. The mixture was refluxed for 15 minutes after addition a n d then cooled in an ice-bath with stirring. Filtration, washing of the osolid with 250 ml. of 80% methanol, 300 nil. of H20at G O , and another 250 ml. (3) Melting points are uncorrected. (4) J. A. McRae a n d R A . R . nnnnnrd, Org. S y n t h e s e s , 33, 63 il!)52),
