Aug. 20, 1958
REARRANGEMENT O F 3,3-DIMETHYL-2-BUTANONE-1-C'1 [CONTRIBUTION FROM THE
DEPARTMENT OF CHEMISTRY,
4349
UNIVERSITY O F ARKANSAS]
A Carbon-14 Tracer Study of the Acid-catalyzed Rearrangement of 3,3-Dimethyl-2b~tanone-1-C~~ BY THOMAS S. ROTHROCK AND ARTHURFRY^ RECEIVED JANUARY 11, 1958
3,3-Dimethyl-2-b~tanone-l-C'~ was treated with sulfuric acid under conditions which are known to produce rearrangements of similar aliphatic ketones. The carbon-14 was found to migrate away from the 1-position, presumably by a carbonium ion mechanism, and a t sufficiently long times to become equally distributed among the four methyl groups. The rate of this rearrangement was obtained and compared t o the reported rates for similar ketones. The recovered ketone was completely degraded, and no carbon-14 was found in the carbonyl carbon or the central carbon of the t-butyl group, No rearrangement of 2,2-dimethyl-3-pentanone took place upon treatment with Lucas reagent under conditions where alcohols, from which somewhat similar carbonium ions can be derived, rearranged extensively. The implications of these findings with respect to carbonium ion stabilities and the reversibility of the pinacol rearrangement are discussed.
Introduction Acid-catalyzed rearrangements of aromatic carbonyl compounds have been known for many years3 and considerable work has been done recently on similar rearrangements of aliphatic ketones. 4-s A11 of the mechanisms which have been proposed for these rearrangements of aliphatic ketones involve the conjugate acids of the ketones and, in most cases, other carbonium ion intermediates derived from them by alkyl group shifts. I n addition, one mechanisms involves the shift of the conjugate acid hydroxyl group to an adjacent carbon atom. A second mechanism7 involves the shift of the carbonyl oxygen to an adjacent carbon atom through the protonated oxide. A third mechanismg involves only alkyl group shifts. I n order to distinguish between mechanisms which involve migration of the carbonyl oxygen and those which do not, Barton and Porter6 treated 2,2,4,4-tetramethyl-3-pentanone-3-C14 with concentrated sulfuric acid and obtained 3,3,4,4-tetramethyl-2-pentanone-2-C14. Therefore, the main path for the rearrangement of this compound did not involve carbonyl oxygen migration.lO.ll However, on the basis of the reported data, it is not possible to exclude a small fraction of reaction by some other path. Application of the above mechanisms to 3,3dimethyl-2-butanone (methyl t-butyl ketone) leads (1) This work was abstracted from the Ph.D. thesis of Thomas S. Rothrock, University of Arkansas, 1958, a n d was supported by the Atomic Energy Commission. (2) T o whom correspondence concerning this paper should be sent. (3) For a recent review see S. N. Danilov, Reaktsii i Melody Issledowan, Org. Soedrneni, 4, 159 (1956). (4) M. Stiles a n d R. P. Mayer, Chemislry & Industry, 1357 (1957). ( 5 ) H. D. Zook, W. E. Smith and 1. L. Greene, THIS J O U R N A L , 79, 4436 (1957). (6) S. Barton and C. R. Porter, J . Chem. SOL, 2483 (1956). (7) H. Zook and S. C. Paviak, TKISJOURNAL, 1 7 , 2501 (1955). (8) S. Barton, F. Morton and C. R. Porter, Nature, 169, 373 (1952). (9) T. E. Zalesskaya, Zhur. obshchei Khim., 18, 1168 (1948). (10) Our work on ketone rearrangements was started before the publication of Barton and Porter's paper and our original intention was t o carry o u t a study similar t o their using 2,2-dimethyl-3pentanone-3-CI4. Upon publication of their work the emphasis of our work was shifted t o the present study. (11) Zook, Smith and Greenes point o u t t h a t formation of the protonated oxide from 2,2,4,4-tetramethyl-3-pentanone might be followed by rearrangement of the I-butyl group rather t h a n a methyl group. This would lead t o 3,3,4,4-tetramethyl-2-pentanonewithout migration of the carbonyl oxygen (the oxide ring would reopen in the same way in which i t originally formed). Thus the protonated oxide mechanism cannot be ruled o u t b y the work of Barton and Porter. nor can i t be excluded b y the results presented here.
to the prediction that the methyl group in the 1position would exchange with the methyl groups of the t-butyl group. I n order to check this point, 3,3-dimethyI-2-b~tanone-l-C'~ was treated with sulfuric acid and the recovered ketone was degraded to determine the distribution of carbon-14 among the methyl groups. In view of the fact that extensive skeletal rearrangements are known to occur in carbonium ion reactions under certain condition~,~~ it . 'seemed ~ possible that some of the carbon-14 would be found in the carbonyl carbon or the central carbon of the t-butyl group. Accordingly, the recovered ketone was subjected to a complete stepwise degradation. The synthetic and degradative procedures used are outlined.
C14Br4 f C"HaC(CH3)nCOOH
1, excess CH31
+
f CI4H3C(CH3)2NH2
CO,
H NP
-+ 2, AgsO
heat C"HHIC(CHP)?N'(CH~)POH-+(CIl3)aN CH?C(CH3)CI4H.3
I
1
C H ~ = C ( C H P ) C ' ~ HHC03H ~ OH OH
+
CI4H2=C( CH3)2
-+
+
+
CI4HzC(CHa)2
I
OH
XnIO, +
/
OH
NaOT + C14H3COCH3-+ C14H13+ C14H3COOH
CL4HzO
The specific rate constants for the sulfuric acidcatalyzed rearrangements of the three ketones in which the hydrogens of the methyl group of tbutyl methyl ketone have been progressively replaced with methyl groups, have been measured by Zook, Smith and Greene.j When i t was found that carbon-14 rearrangement in 3,3-dimethyl-2-butan0ne-1-C'~ (t-butyl methyl ketone) did take place, the specific rate constant for the reaction was (12) J. D. Roberts, R. E. McMahon and J . S. Hine, THISJ O U R N A I . ,
l a , 4237 (1950). (13) R. L. Burwell, Jr., R. B. Scott, 1,. G. Maury and A. S. Hussey, ibid., 1 6 , 5822 (1954).
determined, since this ketone is another member of the above series. As a check of our work against that of Zook, Smith and Greene, the specific rate constant for the rearrangement of f-butyl ethyl ketone was measured, using vapor phase chromatography t o analyze the ketone niixtures produced. The action of Lucas reagent as a rearrangement catalyst for t-butyl ethyl ketone also was iiivestigatctl.
tinguishable from 1;ig. 1, sIi(iwing tlint at least most of the i n purity came from the unlabeled material. The results of t h e activity deterininations on the ketone anti its deri\.ativei are given in Tablc I. l'lie deviations givcn it] 'rahle I x i i l l the folloir iiig tables ai-c the average tl determinations. The molar activity \vas 3 to %?';, lower tliaii t h a t of its derivatives. This W:LS assumed t o be largely tliie to the impurity th:tt hu(l bwii slio.ivri to be preheiit iii t?ic inactive ketone used to clilute ~ I I C labeled kctone. 'i'his iinpurity presumably w:is wiii in tlic' 1)rqxir:~tioii:itirl liiirification of the rlcriv:itivc.;.
Experimental TABLE I ?vf01,.4R ~ k C T I V I T I G S ?OR 3,3-nIMsTHuI~-2-BlrT~~SOS~-l-~'4 Preparation of 3,3-Dimethyl-2-b~tanone-I-C~~.-3,3-Dimethyl-2-b~tanone-1-C~~ was prepared from trimethylacetpl A N D ITS D E R I V A T I V E S chloride and dimethyl-C14-cadmium by conventional proActivity in Compound ,uc./mmolc cedures." I n t h e final purification step, a benzene solution of the ketone was fractionated using a 90 cm. by 5 mm. 3,3-Di11ietli~l-2-butai1~iie-l-C~~ 0,1319 =k 0.0004 closed center monel spiral column at a 20/1 reflux ratio. The 2,4-Dinitrophen~~lhydr~zoiie of ketone fraction boiling a t 104" (730 mm.) was diluted t o the derecrystd. once from ethanol-water" 1 ::0s i 000'' sired activity level with unlabeled ketone which had been 3,~-Dinitrophcnylliydr3zoneof ketone purified in a similar manner. The reported's boiling point ( J f t-butyl methyl ketone is 104-105° (730 mm.). recrystd. twice from ethanol-water" , IXi6 .OO(E Radiochemical Purity of the 3,3-Dimethyl-2-butanone-l- 2,4-Dinitrophetiylhydrazoiie of ketone CI4.-The radiochemical purity of the labeled ketone was recrystd. once from petroleum ether" , i37(i rfr .0013 established by the determination of the activities of several derivatives. It was shown by analysis by vapor phase Oxime of ketone recrl-std. oiice from chromatography on a 25 f t . by ' / 4 in. Tide column t h a t ethanoI-xaterb ,1309 the labeled ketone contained about 1.5yo of a n impurity (see Semicarbazone of ketone recrystd. once Fig. 1). T h e labeled ketone as initially prepared was difrom ethanol' ,1352 i ,0009 luted with 20 t o 25 parts of unlabeled ketone. A vapor Carbon-1.2 tetrabromided*' . 1 3 5 7 & ,0016 phase chromatograph of the unlabeled ketone was indisTrimethylacetic acid'sf . 00 200 a 31.p. 126-127", reportedI6 m.p. 126-12i". * 1 I . p . 78-79", reportedI5 m.p. 78.5-79.5O. M.p. 156-157", reported'6 -m.p. 156-157'. M.p. 94-950, reported" 111.p. 94.3". a B.p. 160-162", reported's b.p. 163-164". f T h e carbon-14 tetrabromide and trimethylacetic acid were obtained from the sodium hypobromite cleavage of 3,3-diI80 ~iirtliyI-~-butanone-l-C~~.
+
ll
160
I40
u; 0
?
' .
B
2 120
G
60
L-
40
20
Attempted Detection of Isomeric Products Formed by the Treatment of 3,3-Dimethyl-Z-butanone with Concentrated Sulfuric Acid.-Ten grams of t-butyl methyl ketone was mixed, with cooling, with 20 ml. of concentrated sulfuric acid. T h e resulting mixture was stirred for 72 hours at 50 i 3' xhile protected from moisture with a drying tube flied with calcium chloride. The reaction mixture was poured on cracked ice and extracted with ether. The ether was washed with water until neutral, dried over anus sodium sulfate and distilled with a short Vigreux co umn. I : fraction boiling from 80-104" was collected. The contents of thc distillation flask distilled t o dryness a t tiiis point. ;Inalysis of the 80-104" fraction by vapor-phase chroniatography on a 20 ft. b y '/4 in. column containing polypropylene glycol supported on fire brick showed only the original ketone plus a small amount of a higher boiling impurity t o be present. This impurity was assumed t o be derived from the impurity present in the starting ketone since they were present in about the same amount. Isomerization of 3,3-Dimethyl-Z-b~tanone-l-C'~.-Twenty-one grams of 3,3-dimethyl-2-butanone-l-Ci4 was placed in a 250-1111. three-necked flask equipped with a Trubore stirrer, reflux condenser and a dropping funnel. T h e system \vas protected from moisture by a drying tube filled with calcium chloride. The ketone was cooled in an ice-bath and 40 1111.of 95.7% sulfuric acid was added slowly with stirring. After completion of the addition of the acid the reaction mixture was heated t o 40 =IC 2" aiid stirred at this temperature for 72 hours. The reaction mixture was then poured on cracked ice and extracted with ether. The ether was washed with water until neutral 1 dried over anhydrous sodium sulfate. Fourteen gr of 4,3-rli1nethyl-2-butanone-X-C~~ was recovered by (1 lation. Several similar experiments \ v u e carried out arid tlie reaction times, reaction tempera-
,,Impurity
'
Fig. I.--.\
Time
-
chromatogram of :~,.7-dimethyl-2-butanoiie-l(2'4.
(11) J. Cason, Ckein Revs, 40, 15 (1947). (13) 1. Heilbron, "Dictionary of Organic Compounds,'' 2nd e d . Oxlurd lJniver4ty Press, N e w l u r k , N. Y.,1953, Vol I V , p. 210.
(16) N. D. Cheronis a n d J . 13. Entrikin. "Semimicro Qualitative Organic Analysis," T h v m a s Y . Crowell Co., New York,N. Y.,3947, p. 396. (17) Reference 15, Vol. 1, p. 428. (131 Reference 16, Vol. l V , p. 224.
Aug. 20, 1958
tures, ketone-acid ratios and percentages of the carbon-14 remaining in the I-position are given in Table 11. (Additional d a h of this t y p e were obtained in t h e kinetic experiments and are given in Table I\'.)
TABLE I1 REACTIONTIMES, REACTIONTEMPERATURES, KETONEACID RATIOSAND P E R C E N T A G E S O F THE CARBON-14 REh I A I N I S G I N THE XUMBEK OSE POSITION O F 3,3-DIMETHYL-2BUTAXONE-X-C'~ Renrrangementa
Reaction temp., OC.
4351
REARRANGEMENT OF ~ , ~ - D I ~ ' V I E T H Y L - ~ - B W T A N O N E - ~ - C ' ~
Reaction time
Keton?/acid ratio i n g./cc.
Carbon-14,
YO,,
I-positionb
1 40Zk2 72 hr. 0.525 41.3 24 hr. .50 78.0 2 40f2 3 4012 120 hr. .50 35.3 18 days .50 25.3 4 40 f 0 . 2 5 30 =!= 0.05 52 hr. .02 55.3 \I%h the exception of rearrangement 5 the concentration of the sulfuric acid used was 95.770. In rearrangement See Table I11 for the activities used to 5 it was 92.9%. determine these percentages.
sodium hydroxide and collected as barium carbonate according t o standard procedures. T h e residual solution was extracted with benzene t o remuve hydrazoic acid and other non-basic materials. T h e aqueous layer was cooled with an ice-bath, made basic with sodium hydroxide, saturated with potassium carbonate and extracted twice with ether. T h e ether extracts were combined a n d washed with a l0yo hydrochloric acid solution. T h e hydrochloric acid solution was evaporated t o dryness and the solid residue of l,l-dimethylethylamine-X-C14hydrochloride was recrystallized from ethanol-ethyl acetate t o give a product of m.p. 270-272', reportedzl m.p. 270-280". T h e phenylthiourea derivative, recrystallized from ethanol-water, ni:p. 119120°, reportedzz m.p. 119-120", was used for activity determinations. Hofmann Degradation of I,l-Dimethylethylamine-X-C14. -l,l-Dimethylethyl-X-C14-trimethylammoniumhydroxide was prepared by exhaustive methylation of 1,I-dimethylethylamine-X-C14 followed by treatment with silver oxide in the usual 1nanner.2~ The quaternary ammonium hydroxide was decomposed by heating in a distillation apparatus t h e output of which led through a n absorption train consisting of two gas wash bottles cooled in an ice-bath and containing a satuTated succinic acid solution, a cold trap
TABLE I11 MOLAR ACTIVITIESI N PC./MMOLEO F 3,3-DIMETHYL-2-BUTANONE-1-c14, 3,3-DIMETHYL-2-BUTANOXE-X-c'4AND POUNDS OBTAINED I N THE DEGRADATION OF 3,3-DIMETliYL-2-BUTANON3-x-c14 Compound
2
1
2,4-Dinitrophenylhydrazoneof starting ketone
0,1366 10.0002 2,4-Dinitrophenylhgdrazoneof recovd. ketone 0,1375 f0.0003 Carbon-14 tetrabromide 0.05636 10.00012 p-Phenylphenacyl ester of 2,2-dinieth~.l~~ropionic 0,08045" acid-X-C" f0.00006 Barium carbonate ......... l,l-Dimethylethylamine-X-C14 liydrochloride .........
0.1366 f0.0002 0.1368 fO.OOO1 0.1065 10.0008 0.03027 10.00006
......... ......... .........
Phenylthiourea of 1,l-dirnetlig.lethylaniine-X-C'4 Dimedon derivative of formaldehyde-C14 2,4-Dinitrophenylhydrazone of acetone-X-C14
.........
Iodoform-C1* a
.........
Rearrangement 3
0.1366 f0.0002 0.1383 fO.0008 0.04823 10.0000s 0.08771 10.00153 0.00 0,08906 10.00131 0.08933 * O . 00078 0.02992 f 0 . 00014 0.05981 1 0 .00059
..
=!=0.00027 T h e molar activity of 2,2-dimethylpropionic acid-X-C" from rearrangement 1 was 0.0779
Sodium Hypobromite Cleavage of 3,3-Dimethyl-2-bu-
tanone-X-C'4.--3,3-Dimethyl-2-b~tanone-X-C~~ was converted to carbon-14 tetrabromide arid 2,2-dimethylpropionic acid-X-C" following the procedure of Roberts and Yancey.19 A sample of the carbon-14 tetrabromide was purified for activity determinations by two sublimations, m.p. 94-95', reported" m.p. 94.3'. T h e ether solution of the 2,2-dimethylpropionic a ~ i d - X - C 'was ~ fractionated and the fraction boiling a t 160-162" was used for further degradative work. T h e reported18 b.p. for 2,2-dimethylpropionic acid is 163-164'. T h e p-phenylphenacyl ester of the acid was prepared a n d recrystalliied once from an ethanol-water mixture, m.p. 112.5-113.5', reported'* m.p. 113.1-114°. This purified ester was used for activity determinations. Degradation of 2,2-Dimethylpropionic Acid-X-Cl4 by the Schmidt Reaction.-2,2-Dimethylpropionic acid-X-C14 was converted to carbon-14 dioxide and 1,l-dimethylethylamineX-C" by treatment with hydrazoic acid in the usual man1ier.m T h e reaction was carried out in a sweep system. T h e carbon-I4 dioxide evolved was absorbed in a solution of ~
(19) J. D. Roberts and J. A. YanCey, THIS]OURNAL, 77, 5568 (1955). (20) H. Wolff, "Organic Reactions," Vol 111, John Wiley and Sons, Inc.. New York, N. Y., 1946, p. 307.
4
COM-
6
0.1366 =!=0.0002 0.1379 f0.0018 0.03459 +0. 00007 0.1043 10.0007 0.00 0.1021 10.0007
0.1017 zk0.0005 0.09966 2~0.00134 0.05625 ~0.00001 0.04546 Zk0.00107
.........
.........
.........
... .........
.........
......
.........
z!=
0.00019 pc./mmole.
cooled in a n ice-salt-bath, and a cold trap cooled with a Dry Ice-isopropyl alcohol mixture. A nitrogen source was connected to the distillation apparatus and, after the decomposition was complete, the whole system was swept with nitrogen for six hours. T h e 2-methylpropene-X-CI4 collected in the Dry Ice-isopropyl alcohol cooled trap. Degradation of 2-Methylpr0pene-X-C~~.-The degradation of 2-methylpropene-X-C14 followed t h e reaction sequence used by Roberts, McMahon and Hine.l* T h e 2methyl-l.,2-propanediol-X-C1* obtained boiled a t 96-97' (35 m m . ) , reported12 b.p. 96-97" (30 mni.). Because of the dificulty in working with the small amount of diol available, this material was degraded t o acetone and formaldehyde without further purification. T h e formaldehyde was isolated as the dimedon derivative, m.p. 190-191", reportedI2 m.p. 190-191 o , after recrystallization from ethanolwater. T h e acetone was isolated as the 2,4-dinitrophenylhydrazone, m.p. 125-126", reportedz4 m.p. 126" after recrystallization from ethanol-water. A portion of the ace(21) Reference 15, Vol. I, p. 289. (22) B. W.Howk,E. L. Little, S. L. Scott and G. M . Whitman, THIS JOURNAL. 76, 1899 (1954). (23) G. Norcross and H. T. Openshaw, J . Chrm. SOC., 1174 (1949). (24) Reference 15, Vol. I, p. 13.
4352
THOM;\S S.ROTHROCK .mri A
tone was degraded to iodoform, nt.p. 119--120', reportetl25 1n.p. 119O. Activity Determinations.--X11 compounds were converted to carbon dioxide by a \'an Slyke-Folch wet combustion method.26 The carbon dioxide obtained was transferred to a n ionization chamber by the method of Neville.2' The activity of the carbon dioxide was determined by the use of a vibrating reed electrometer connected to a Brown recorder. h uranium oxide standard was used as a control to eliminate errors due to instrumental variations and suitable background corrections were applied. -4lmost all of the reported activities are the averages of two determinations. Tlie average error in the activity determinations is from 0..i to 1.0'7,. Tlie molar activities of the ketone, both before and after rearrangement, and tlie various compounds obtained from the degradation of the rearranged ketone are given in Table 111.
Preparation of 2,2-Dimethyl-3-pentanone.-2,2-Dixiieth!I-3-pentanone was prepared in 305% yield (based on t-butyl brornide) from t-butylmagnesium bromide and propionyl chloride folloxing the general procedure of Percival, Ji'agner and Cook.28 T h e ferric chloride catalyst appeared to have little if any effect. T h e final purification was carried out 1)y fr:ictionation using a 90 cm. by 5 mm. closed center monel slliral column at a 10/1 reflux ratio. The material used for further work had a boiling point of 121-125' (725 mni.), reported29 h.p. 123-124' (755 inin.). This material gave ;L .',~-tlinitroplien~lliy(~ra~one of I I I . ~ . 143-141°, reported30 lli
. I ) . 14,'3 ..%-144'.
Attempted Rearrangement of 2,2-Dimethyl-3-pentaone Using Lucas Reagent.-Following the Drocedure of Roberts :itid Vancey,l9 4 of t-butyl ethyl ketone, 10 ml. of methylenc chloride and 50 ml. of Lucas reagent (1.6 g. of zinc cliloride/rnl. of concentrated hydrochloric acid) were shaken at 30" for 3 hours. T h e layers were separated and t h e methylene chloride layer was washed with water and dried over anhydrous sodium sulfate. Most of the solvent was evaporated and analysis of t h e remaining material by vapor phase chromatography using a 25 f t . by 1/4 in. Tide column showed t h a t no detectable amount of t-amyl methyl ketone was present. Kinetic Experiments.-Specific rate constants for tlie rearrangement of 2,2-dimethyl-3-pentanone and of the carbott14 in 3,3-dirnethyl-2-butanone-l-C'*were determined following the procedure of Zook, Smith and Greene.5 For the :~,.7-dinietliyl-2-butano1ie-l-C'~,the amount of rearrangement \vas determined by measurement of the activity of the carbon-14 tetrabromide obtained from degradation of the ketone recovered after various reaction times. For the ",-"-ctimeth~.l-3-peritannne, the amount of rearrangement \vas determined by quantitative vapor phase chrornatography. T h e results of these experiments are given in Table It:. Since pure :3,3-dimethyl--"-pentanone, the product of the rearrangement of 2,2-dimethyl-3-pentanone, was not available, known mixtures of the two compounds could not I)e prepared t o use as a check on the method of anal therefore the accuracy of the chromatographic anal! be subject to some question. Plots of hi ( A , - A , ) / ( A -.4c)z'ersus time are slio~vnin Fig. 2 ; t h e terminology is that of Zook, Smith anti Greene.5 The values for the specific rate constants were obtained from least squares calculations and are presentetl i i i Table 1.1.
Discussion of Experimental Procedures The molar activity of the carbon-14 tetrabromide (see Table I) obtained from the cleavage of the unrearranged ketone was the same as t h a t of the starting ketone, and the trimethylacetic acid obtained was inactive. Therefore, no rearrangement occurred during the synthesis of the 3,3-dimethyl-2(2.5) Reference 1.5 Vol. 111. p. 29 ( 2 6 ) A . F r y , B. M . Tolbert and 51. Calvin, T r n n s . F n v o d n r Soc., 49, 1 1 4 4 (1953).
(2i! 0 . K Neville, THISJ O C R X A I . , 7 0 , 3499 (1948). ( 2 X ! \\', C. Percival, I FRY l
~ 'r.%Bi.IS
~ Yol. ~ 80
~ I \.
~lSf4lIc L)A'lA P'OK I i E A R R A N G E M E N I'S CJI? ~ ~ , ~ ~ - L ) I h l E L . H k ' I , - L '
HL-TAX0XE-l-C
'' .%SI)3,2-DIMETII~'L-3-PENTANOSE
?,?-I~inic~~liyl-:~-
iricme
~jciit
2,2ilimethyl-2pciit,one ,
::,.~-Dinietbyl-~--Li~itan~~~~~-l-C~~ Time, C l l R r i activity." 'I.C'C i n Time, ser. X 10-4 pc./"mole X I O ? l - l i o ~ i t i < set.. ~ i ~ X 10
:
I
rm"11nq
2.10 9 . 4 0 =t0.02 92.4 1.08 138 7 1.33 8.33i. . O ; S4.1 2,tti 7; s 9.fi-t 7 . 5 3 i. ,(i\) i4,1 ;3 34 1;s t i t7.B 3 70 i . O ( i .iC. t i t 32 ,57
