LIALH~REDUCTION OF CYCLOHEXYLKETENE DIMERS
March 20, 1952
[CONTRIBUTION FROM DEPARTMENT OF CHEMISTRY, TENNESSEE A. AND I.
STATE
-1556
UNIVERSITY]
The Lithium Aluminum Hydride Reduction of Cyclohexylketene Dimer and (w-C yclohexylalkyl)-ke tene Dimers BY ALFREDS. SPRIGGS, CARLM. HILLAND GILBERT W. SENTER Five w-cyclohexyl substituted alkylketene dimers of the type [CsHu-(CHz).-CHCO]2, where n * 0 to 4, have been treated with lithium aluminum hydride. The reduction products isolated were 8-hydroxy ketones. Attempts to reduce the fourth member of this series were unsuccessful.
The versatility of lithium aluminum hydride as a reducing agent for various types of chemical systems has been demonstrated by several The reagent normally has no action on double bonds, but some examples are cited in which olefinic-bond reduction occurs. Studies have been I11 reported on ring opening of epoxy and lactone systems. Various mechanisms have been proposed was of special interest because it has been reported to account for the products resulting from the that a similar ketone obtained from ethylketene application of this reagent to the systems men- dimer was reduced by lithium aluminum hydride tioned. to the diol.? Also, it has been demonstrated in this Hill, et U Z . , ~ of this Laboratory have indicated3y Laboratory that catalytic hydrogenation of (I) ozonization and catalytic hydrogenation studies gave the corresponding diol compounds. Failure that certain ketene dimers exist chiefly in the @,r-of lithium aluminum hydride to reduce the ketene dimers to the diol compounds might be due to the unsaturated @-lactonestructure. incapacity of the reagent to reduce the exocyclic CeHii-( CH2)n-CH=C-CH-( CHz)n-CeHij carbon-carbon double bond. Hence, decomposition I I of the intermediate complex would be followed by 0-co isomerization to the keto form (11). I Lithium aluminum hydride reduction of monoIt was thought that the behavior of these dimers substituted ketene dimers of this type has not been toward lithium aluminum hydride would provide previously reported. further evidence of their structure. Acknowledgment.-The authors wish to express The ketene dimers used in this study were prepared by deliydrohalogenation of the corresponding appreciation to the Research Corporation for several Frederick Gardner C o t t r d grants which w-cyclohexyl substituted fatty acid chlorides.6 The reduction products isolated were @-hydroxy supported this study. Also, appreciation is exketones which indicated ring opening of the p- tended Dr. C. R. Dillard for assaying the lithium lactone structure a t the oxygen-carbonyl bond with aluminum hydride used in this investigation. Experimental8 subsequent reduction of the carbonyl group and isomerization of the enol form. Reduction of Ketene Dimers.-Essentially the same pro394
LiAlH,
1
cedure was followed in all reduction experiments.
The re-
C~H~~(CHZ)~CH=C-CH(CHZ)~CBH~~ duction of cyclohexylketene dimer was carried out as follows: OH I CH20H I
I+-[
3.
C ~ H I I ( C H Zl-C-CH-( )~+
II I
I1
CHz)nCeHn
0 CHiOH
The hydroxy ketones showed one hydroxyl group as determined by hydroxyl analysis and formed mono-3,5-dinitrobenzoates. These ketones gave negative tests for unsaturation, and were not affected by periodic acid. With 2,4-dinitrophenylhydrazine, three of the reduction products formed substituted pyrazolines. Hydroxy ketones of type (11)could not be further reduced with lithium aluminum hydride. This (1) R. F. Nystrom and W. G. Brown, THIS JOURNAL, 69, 1197 (1947); ibid., 69, 2548 (1947); ibid., 70,3738 (1948). (2) A. E. Finholt, A. C. Bond and H. I. Schlesinger, ibid., 69, 1198 (1947). (3) R.E. Lutz and D. F. Hinkley, ibid., 72, 4091 (1950). (4) L. W.Trevoy and W. G. Brown, ibid.. 71, 1675 (1949). (5) C. M.Hill, M . E. Hill, H. 1.Schofield and L. Haynes, ibid., 74, 166 (1952). (6) C. M .Hill and G . W. Senter. i b r d . , 71, 364 (1949).
A suspension containing 3 g. of lithium aluminum hydride (0.047 mole, 60% assay) in 75 ml. of dry diethyl ether was
placed in a three-necked flask equipped with a stirrer, condenser set for reflux, and a dropping funnel. Into the dropping funnel was placed 7 g. (0.027 mole) of cyclohexylketene dimer, b.p. 10&11lo (2 mm.). The flask was placed over a hot-plate and the dimer was added a t such a rate as to maintain a gentle reflux. After addition of the dimer, the reaction mixture was cooled in a water-bath and the excess lithium aluminum hydride cautiously decomposed with cold water. Hydrogen gas evolved and a white sludge formed. The entire mixture was transferred t o a large beaker, cooled in an ice-water-bath and 100 ml. of 20% sulfuric acid added slowly with stirring. The ether layer was separated and the aqueous layer extracted with several portions of ether. The ether layer and extracts were combined. washed with a saturated solution of sodium bicarbonate, then with water and dried over anhydrous magnesium sulfate. A semi-solid residue formed upon removal of the ether in vacuo. Distillation of the residue under reduced pressure gave 1.5 g. of a white waxy solid, m.p. 58.5-60°, b.p. 145-148"(4 mm.). Physical constants and analytical data of the reduction products are given in Table I. Preparation of Benzoates.-A sample of each reduction product was converted to its 3,5-dinitrobenzoate. Analytical data for these derivatives are shown in Table 11. (7) R. L. Wear, ibid., 79, 2390 (1951). ( 8 ) All melting points shown in this paper are corrected.
MILTONU. SOFFER, ROUERTA A. STEWAKT AND GKACE L. SMIITIJ
1556
IFol. 74
TABLEI LITHIUM
ALUMINUM HYDRIDE REDUCTION PRODUCTS OF W-CYCLOHEXYLALKYLKETENE DIMERS OF TYPE: [C&ll(CH2)n-CHCO]l
Moles reagent
Yield,
n per mole dimer
%
Formula
0 1.8 CiJItsOn 1 1.7 ClbH& 2 1.8 GoHMOZ" 4 2.0 (&H& Refractive inclcx% 1.4771.
21 62 45 71
No. OH
0.82 .77 .90
OC. B p .
M.P., OC.
hfm.
145-148 168-172 94-96
4 3 10
.XI
58.5-60 52.5-53.5
39.5-40
-
Analyses, % Carbon Hydrogen Calcd. Found Calcd. Found
76.2 77.1 77.9 79.1
76.6 76.9 78.3 78.8
11.1 11.4 11.8 12.1
11.4 11.8 12.2 12.0
TABLE I1 DERIVATIVES OF REDUCTION PRODUCTS OF TYPE(11) ,---
n
Formula
3,5-Dinitrobenzoate M.P., Nitrogen, % ' OC. Calcd. Found
0 GsHmOrNz 104-104.4 6.28 1 SSHI~O~NZ 58-58.5 5.91 2 Cz;HsaOrNz 55-56 5.58 4 CuHts07Nza 59 5.02 Attempts to isolate the pyrazoline were unsuccessful.
Pyrazoline
Formula
M.P., OC.
6.42 GIHJoN~O~ 64-65 6.01 C24HJ4NtOl 109 D 5.70 5.20 CaoHaNiOt 112-1 13 b Anal. Calcd.: C, 66.7; H,8.24. Found:
Preparation of Substituted Pyrazo1ines.-Treatment of samples of the reduction products with 2,44initrophenylhydrazine, in the usual manner, gave deep orange colored pyrazolines. Several modifications of this procedure failed to produce a suitable derivative of the reduction product
Nitrogen, % Calcd. Found
13.5 12.7
13.7 12.3
10.6 10.9 C, 67.2; H, 8.40.
where n = 2. Analytical data of thcsc derivativcs are describcd Table 11.
iii
KASHVILLE 8, TENNESSEE RECEIVED SEPTEMBER 25, 1951
[CONTRIBUTION FROM THE CHEMICAL LABORATORIES OF SMITH COLLEGE AND WELLESLEY COLLEGE, AND THE DYSON PERRINS LABORATORY OF OXFORD UNIVERSITY;
Some Unusual Reactions of 2-Tetralone BY MILTON D. SOFFER, ROBERTA A. STEWART AND GRACE L. SMITH Methoxide catalyzed condensation of dimethyl oxalate with 2-tetralone in non-polar media, results in substitution in the 3-position accompanied by dehydrogenation of the tetralone nucleus a t the expense of the side chain. The structure of the is shown by dcgradation. 2-Tetralone is smoothly converted to 8-naphthol product, methyl 3-hydroxy-2-naphthylglycolatt, by the action of bromine.
Although the alkylation of 2-tetralone and its a unique course. -.The crystalline product had the monocyclic analog, phenylacetone, proceeds ex- expected enolic properties, but failed to undergo clusively1*2in the highly reactive position, CI, elimination of carbon monoxide when heated with ester condensation may take a different course. powdered soft g l a s s The isolation of methanol It has been shown recently that while formylation of phenyl acetone with ethyl formate occurs a t Ca in the presence of sodium alkoxide or sodamide in non-polar '~'OOXIC media (ether), the reaction in alcoliolic sodium methoxide or ethoxide proceeds exclusively a t C1.s On the other hand, the only product reported from the condensation of phenylacetone with ethyl oxalate in the presence of ethanolic sodium \Coon \CH?OH ethoxide is the C3-glyoxalate.4 I I u , R = CHz 111 IV In the present work it was shown III), 11 = 1 I tliat the glyoxalation of %tetralone, with methyl oxalate and dry sodium methox- from the latter treatment5 precluded an initial lacide in benzene, occurs in the 3-position and takes tone structure. for the '-glyoxalate Inspection Of the (1) M. D. Soffer, R. A . Stewart, J. C. Cavagnol, H. E. Gellerson (I) shows that i t may be regarded as the fully and E. A. Bowler, T H I SJOCKNAL. 72, 3704 (1950). (2) C. hl. Suter and A. \T, Weston, ibid., 64, 533 (1942). ketonoid form of the phenolic hydroxy ester, IIa, (3) M . Montagne, Bol. i m t . win. Univ. Aufon. M c x . , 2 , N O . 2, 57 which could from the glyoxalate by a series (19.16); C. A , , 44, 130 (1990). (4) 11. Keskin, RLO.fnculld .rei. u t l i u . I l f n n b u l , Scr. A, 11, KO.'4. 143 (1046).
( 5 ) I\'. E. Ihchnianii, \V. Cole and A. I.. \\'ilds,
824 (1040).
TiIIS JorrRNaL,
62,
