1024 JAPP AND MELDRUM: CVII1.--Homologues of Anhydracetonebenxil. By FRANCIS R. JAPP, F.R.S., and ANDREW N. MELDRUI, B.Sc. ANHYDRACETONEBENZIL, one of the products of the condensation of benzil with acetone under the influence of potassium hydroxide, was shown by Japp and Lander (Trans., 1897, 71, 123) to be a diphenyk cyclopentenolone of the formula By the condensation of benzil with homologues of acetone of the general formulte CH,R’*CO*CH, and CH,R*CO*CH2R’, Japp and Burton (Trans., 1887, 51,431) prepared various homologues of anhydr- acetonebenzil. The constitution of those members of this class which are formed from symmetrical homologues of acetone follows, as a matter of course, from that of anhydracetonebenzil itself; thus the condensation prodnct of benzil with diethyl ketone (loc.cit., p. 432) is C,H,*C=== CH . b(OH) mc,2>C0. 6 5HOMOLOGUES OF ANHYDRACETONEBENZIL. 1025 150'), if we distinguish the CH group in the pentacarhon ring of anhydracetonebenzil as the U-, and the CH, group as the /3-position (compare Trans,, 1899, 75, 1019). But in the case of the compounds obtained from unsymmetrical homologues of acetone, there are two possibilities; thus, from benzil and methyl ethyl ketone both the a- and the P-methyl derivative may be obtained : C,H *C===-CH 5 1 >CO C,H5*7 =C(CH,) C,H,* C( OH)*CH, and C,H,*C(OH)* CH( CH,) a-Methylanh ydracetonebenzil B-Met11 ylanhydracetonebenzil Japp and Lander (Zoc. cit., p. 129) found that a-derivatives are more stable towards permanganate in the cold than P-derivatives, and iu this way arrived at the conclusion that the monoalkyl derivatives of anhydracetonebenzil obtained by Japp and Burton belonged to the @class.* This conclusion was confirmed by Japp and Findlay, who found that these compounds did not interact with benzaldehyde to yield benzylidene derivatives, whereas anhydracetonebenzil compounds containing the methylene group readily do so.We have now repeated and largely extended Japp and Burton's work. Their method of preparing these compounds (loc. cit., p. 431) con- sisted in warmiqg a mixture of the ketone in question-thus methyl ethyl ketone-and benzil with aqueous potassium hydroxide for some days a t a temperature of 20-25'. This procedure left unchanged a considerable amount of benzil, which had to be removed by washing the product with ether.We find that in this way a soluble isomeride mas removed along with the benzil, and overlooked. By using a slight excess of the ketone and heating to a somewhat higher temperature, me ensure the total conversion of the benzil. The separation of the two isomerides then presents no difficulty. I n the foregoing mode of preparation, the sparingly soluble isomeride generally predominates; but we find that, by allowing the condensa- tion of the ketone with benzil to take place a t the ordinary tempera- ture in a 0.5 per cent. solution 'of potassium hydroxide in absolute alcohol, the more soluble isomeride is generally formed in greater quantity. (m. p. 118"). (m. p. 180'5"). * Although this conclusion happened to be correct, we have since convinced ourselves that, except in the case of acid deriv:itives of anhgdracetonebeuzil, which may be dissolved in a solution of sodium carbonate before applying the periiianganate test, the difference i n the ratc of oxidation is not suficicntly marked to serve as a means of distinguishing with certainty between the two classes. The open-chain condensation compounds of benzil with ketones may, however, be distinguished from anhydracetonebenzil derivatives by the inuch greater ease with which they are attackcd by permanganate.1026 JAYP AND MELDRUM: I n the case of the monoalkyl anhydracetonebenzils, the a-compounds are more soluble, and melt lower, than tho corresponding @corn- pounds.I n the condensation of b e n d with methyl ethyl ketone, there is formed, in addition to a-methylanhydracetonebenzil (m.p. 118') and P-methylanhydracetonebenzil (m. p. 1S0.5'), a third isomeride melting at 157'. Its formation was only once observed in the original conden- sation, but it can be prepared from the P-compound by leaving the latter for a month in contact with cold alcoholic 0.5 per cent. potassium hydroxide, or by boiling it with glacial acetic acid. I n both cases, the transformation is only partial, and, moreover, the resulting cornpound is partially retransformed into P-methylanhydracetonebenzil by allowing it to stand with alcoholic potassium hydroxide in the cold, bo that there is evidently an equilibrium. By heating alone a t 330°, it is totally converted into P-methylanhydracetonebenzil. We regard this compound as desylene-methyl ethyl ketorrze-probably the fumaroid Q6H, qO*CH2*CH3 form, C==Q .In its transformation into P-methyl- anhydracetonebenzil, it would first pass into the maleoid form, which would then undergo internal aldol condensation : I C6H5*C0 H 7sH5 7 >GO C H *C--CH C==C: I p --f C6H,*C(OH)*CH( CH,) 5 1 I C,H,*bO CH,- CH, Maleoid form. 8-Methylanhydracetonebenzil That this compound is not a stereoisomeride of P-methylanhydracet- onebenzil is, we consider, proved by the fact that it is so much more readily attacked by permanganate than the latter compound. The substance is, however, difficult to obtain in quantity, so that we have not been able t o make a detailed study of its reactions, and we there- fore put forward the above formula with reserve. A similar open-chain isomeride of up-dimethylanhydracetonebenzil is described later on.By boiling either a- or P-methylanhydracetonebenzil for a few minutes with fuming hydriodic acid, methyldiphenglcyclopentenone, (m. p. 180"). C,H,*fi*CH( CH3) phenylhydrazone. >CO (m. p. 77-78'), was obtained. It yields a The same migration of the double bonds occurs C,H,* C- CH2 during the reduction as in the formation of diphenylcyclopentenone, C,H,*S*CH, C,H,*C*CH, >CO, from anhydracetonebenzil. The symmetrical con-HOMOLOGUES OF ANHYDRACETONEBENZIL. 1027 stitution of the latter cyclopentenone was proved by Japp and Lander (Trans., 1897, 71, 132) by oxidising it to diphenylmaleic acid. By boiling a-methylanhydracetonebenzil for 5 hours with hydriodic acid and red phosphorus, it mas completely reduced to 1-methyl-2 : 3- C,H5*$2H*CH(CH,) C,H,*CH-CH, >CH2 (m.p. 6 2- 6 3"), already diphenylcyclopentane, obtained by Japp and 1Sluiaray (Trans., -1897, 71, 152), by the reduc- tion of a-anhydracetonebenzillavulic acid, the carboxyl group of the acid being eliminated in the latter case. a-Methylanhydrscetonebenzil, like anhydracetonebenzil itself, readily interacts with benzaldehyde under the influence of alcoholic potassium hydroxide in the cold, yielding a benzylidene derivative. Benxylidene- a-~r~eth~lc~~czzh~drucetonebenxil (m. p. 225") has the constitution C,H,* y: c (CH3 >> co C,H,* C(0H)-C=CH* U,H,' The other a-alkylanhydracetonebenzils yield similar benzylidene derivatives. When P-methylanhydracetonebenzil, on the other hand, is allowed to stand with benzaldehyde and alcoholic potassium hydroxide, there is, at first, apparently no action.After the mixture has stood for a month, however, it is found that a portion of the P-methylanhydr- acetonebenzil has been converted into the open-chain compound desylene-methyl ethyl ketone" (m. p. 157") already referred to, whilst a very small quantity of the benzylidene derivative of a-methylanhydr- acetonebenzil has been formed. This means that, in presence of the potassium hydroxide, a portion of the P-methylanhydracetonebenzil is hydrolysed to benzil and methyl ethyl ketone (the formation of the open-chain compound being an intermediate stage), and that these products of hydrolysis again interact, yielding, in part at least, a-methylanhydracetonebenzil, which then undergoes condensation with the benzaldehyde.a-Methylanhydracetonebenzil and benzil interact, in presence of alcoholic potassium hydroxide, to form a-metl~ylan~~~drucetoned~~enx~C32H2604 (dirnorphous ; silky needles, m. p. 1S5O ; and warty crystals, m. p. 194*), C18H1602 + C14H1002 = C32H26043 which is obtained in the form of the complex potassiun8 salt, C,2H,,04K,~,2H2604,4C~H5~OH. From this salt, the free substance is obtained by treating it with acetic acid. U- RiIetliylanhydracetouedi- * We a t first took this substance for an aldol condensation compound of benz- aldehyde with ~-metl~y~aiihgclmcetonebenzil (see Trans., 1899, 76, 1020, footnote). The difference in percentage composition is but small,1028 JAPP AND MELDRUM: b e n d may be more simply prepared by the action of an alcoholic solution of sodium ethoxide on a mixture of benzil (2 mols.) with methyl ethyl ketone (1 mol.) : C,H5*F0 2c6H5* Go + CH3*CO*C2H5 = C,,H,,O, + H20, the substance being thus obtained in the form of its sodium salt.When a-methplan hydracetonedibenzil is boiled with alcohol containing a few drops of sulphuric acid, it is esterified, yielding the compound C32H25(OC2H5)03 (m. p. 250O). I n yielding salts with caustic alkalis, and in being esterified under the foregoing conditions, a-methylanhydr- acetonedibenzil resembles ethyl anhydrodibenzilacetoacetate (Japp and Lander, Trans., 1896, 69, 736), and differs entirely from the corre- sponding compound from acetone and bend-anhydracetonedibenzil, C3,H2,04-of which it might otherwise appear to be the next higher homologue.By boiling a-metbylanhy dracetonebenzil with sulphuric acid some- what diluted with water, or with glacial acetic acid, a dehydration product, C,6H2s02 (m. p. 230°, with evolution of gas), is formed accord- ing to the equation The molecular weight of the resulting compoundis doubled in order to bring it into line with the corresponding compound, C24H2402, from anhydracetonebenzil (Japp and Lander, Trans., 1897, 71, 131). /3-Methylanhydracetonebenzil is converted into the same dehydration product, C36H2802, by heating it in a sealed tube with anhydrous formic acid ; whereas glacial acetic acid, as already mentioned, transforms it into desylene-methyl ethyl ketone. 2C,,H,,02 - 2H,O = C8sH2s02. EXPERIMENTAL. Condensation of Benail witTi Methyl Ethyl Ketone.>GO, C6H5*F=C(CH3) C,H,*C(OH) *CH2 Preparation of a-Ueth y lanh ydraceionebenxi I , C H *C---CH C,H,*C(OH) CH(CH,) and P-Met~ylanhydracetone6enxil, ' I >GO. -These compounds are formed by the condensation of benzil with methyl ethyl ketone under the influence of potassium hydroxide. With alcoholic potassium hydroxide, the a-compound is almost the sole product ; with aqueous potassium hydroxide, the P-compound slightly predominates. In the preparation of the a-compound, 10 grams of finely powdered benzil, 7 grams of methyl ethyl ketone, and 100 C.C. of alcoholic 0.5HOMOLOGUES O F ANHYDRACETONEBENZIL. 1029 per cent. potassium hydroxide (4 grams KOH to 1 litre of absolute alcohol *) were introduced into a flask which was then corked and, after dissolving the benzil by shaking, allowed to stand.The experiment was so arranged that the liquid nearly filled the flask and that the quantity of alcohol was just sufficient to dissolve the benzil. After standing a t the ordinary temperature for 17 days, the liquid, from which nothing had been deposited, was poured into alarge bulk of water ; this occasioned the separation of an oil, which speedily solidified to a mass of almost white crystals of the a-compound. After a single crystallisation from hot alcohol, the substance was pure. It formed large, flat, lozenge-shaped crystals melting a t 1 1 8 O . It is readily soluble both in alcohol and in ether. Analysis of a-met?~~Zanl~?ldrcccetoneb~n~~Z gave figures agreeing with the formula CI8Hl6O2 : 0,1585 gave 0.4734 CO, and 0-0866 H,O.C = 81.47 ; H = 6.07. 0.1402 ,, 0.4187 CO, ,, 0.0781 H20. C ~ 8 1 . 4 5 ; H=6.19. C,,H,,O, requires C = 81.82 ; H = 6.06 per cent. The yield from the above quantities was 8 grams, and the alcoholic mother liquor gave a small amount-considerably less than a gram- of the isomeric P-methglanhydracetonebenzil already obtained by Japp and Burton, I n order t o prepare p-methylanhydracetonebenzil in quantity, the method employed by Japp and Burton (loc. c k ) was, with slight modi- fications, adopted. Forty grams of benzil, 25 grams of methyl ethyl ketone, and 30 C.C. of aqueous potassium hydroxide of 33.3 per cent. strength were introduced into ti conical flask fitted with a condensing tube, the whole being placed on a metal plate over a water-bath and heated for 9 hours, shaking from time to time. The mixture, which had become brown, was poured into excess of hot water. The soljdi- fied substance was ground, washed with water, and well extracted with cold ether.The residue was dissolved in boiling alcohol; on cooling, prismatic crystals of P-met?~~Zanhydracetoneben~~Z mere deposited, which, after two or three recrystallisations, melted constantly a t is00 (179O, Japp and Burton). The alcoholic mother liquor gave n small quantity of octahedral crystals melting a t 157", of a substance rvhich is isomeric with the two foregoing, and which we regard as desylene- methyl ethyl ketone (u. infra). The ethereal extract gave a consider- able quantity of a-methylanhydracetonebenzil (m.p. 1 18O). I n the foregoing experiment, the quantity of a-compound obtained * Absolute alcohol should be used in these condecsations. I r Methylated spirit 1' (alcohol " denatured " with crude wood spirit ; compare Trans., 1897, 71, 297, footnote) must be avoided, as it contains acetone, which yields condensation cmn- pounds of its own with benzil. VOL. LXXIX. 4 A1030 JAPP AND MELDRUM: was 86 grams, and of j3-compound, 11 grams. Longer heating dimin- ished the proportion of the P-compound, and in addition, the resinous bye-products rendered the substances more difficult to purify. P-Methylanhydracetonebenzil has already been analysed by Japp and Burton. MoZecuZccr Weights of a- and P-MethyZanhydi*acetonebenzil.-The molecular weights of the two compounds were determined by Walker and Lumsden's modification of Landsberger's, ebullioscopic method, using alcohol (constant = 1560) as a solvent.a-Met?$anhydracetonebenzi!. SnBstance. Elevation. Volume. Mol. wt. 0.90s 0.32' 16% C.C. 267. 9 9 0-24 22-4 )) 263. C1,H,,O2 = 264. P- Methy ZanhydracetonebenxiZ. O*S96 0-292O 15.6 C.C. 308. 9 9 0.210 22.2 ,) 300. C1,H160, = 264. The two substances are therefore isomeric. -Five grams of a-methylanhydracetonebenzil, 2.5 grams of benzalde- hyde, and 65 C.C. of alcoholic potassium hydroxide (0.5 per cent.) were mixed, shaken until all had dissolved, and allowed to stand. Over- night, tufts of needle-shaped crystals had formed ; after 4 days they were separated and recrystallised from hot glacial acetic acid, from which the substance was deposited in colourless, slender, rectangular prisms melting a t 2 2 5 O .(Yield 3.6 grams.) 0.1608 gave 0.5018 CO, and 0.0839 H20. C,,H,,O, requires C = 85.23 ; H = 5.68 per cent. /I-Methylanhydracetonebenzil, when subjected to the above treatment Its behaviour on long standing Conversion of P-Methy ZanThydracet one benxi I into Desy Zene-methyl Ethy l C=85*11; H=5*80. for the same time, is quite unchanged. with the mixture is mentioned in the introduction. Ketone, '' ' *ciCH*c0*C2H5,-T~e I best mode of effecting this trans- C,H,* CO formation- is- by boiling P-methylanhydracetonebenzil with four times its weight of glacial acetic acid for 4 hours. The solution, on cooling, deposits needles or prisms of unchanged substance; and from theHOMOLOGUES OF ANHYDRACETONEBENZIL.1031 mother liquor, octahedral crystals of the open-chain compound, melt - ing a t 157', may be obtained. The same compound is also slowly formed when finely powdered P-methylanhydracetonebenzil is allowed to stand for a month or more with alcoholic potassium hydroxide (0.5 KOH per cent.) insufficient to dissolve it. The transformation is incomplete, as the reaction is reversible (see introduction). The formation of the same compound was also observed in the pre- paration of P-methylanhydracetonebenzil (v. supra). Analysis of the octahedral crystals (m. p. 157') showed that the substance, which we regard as desylene-methyl ethyZ ketone, is isomeric with a- and P-methylanhydracetonebenzil. 0.1485 gave 0.4431 CO, and 0,0798 H,O.C = 81.36 ; H = 5.97. 0.1629 ,, 0.4862 CO, ,, 0.0903 H,O. C=81*39 ; H=6*16. C18Hl,0, requires C = 81.82 ; H = 6.06 per cent. The reason for regarding this compound as structurally different from the methylanhydracetonebenzils is that it is much more readily attacked by permanganate. A small quantity of the compound was heated in an exhausted tube for a short time at 330'. There was no sign of decomposition, and the melted substance began to distil and collect in the cooler part of the tube. On crystallising the product from alcohol, it was found that i t had been re-converted into P-methylanhydracetonebenzil (m. p. 180'). a-Methylanhydracetonebenzil is quite unchanged by contact with alcoholic potassium hydroxide of the above strength. Boiling with glacial acetic acid dehydrates it, yielding the compound, C.1602802, melt- ing a t 230' (v.infrcc). Action of Dehydrating Agents on a- and P-Met~yl~nhydracetone- bend.-One gram of a-methylanhydracetonebenzil was boiled for half- an-hour with 5 C.C. of sulphuric acid diluted with 10 C.C. of water, employing a reflux condenser. From the product, which was very dark coloured, crystals melting a t 230' were obtained. The following method yields the substance in a purer state. One gram of a-methylanhydracetonebenzil was boiled with 4 grams of glacial acetic acid for 4 hours. On cooling, the liquid deposited a crystalline compound which proved to be identical with that obtained by the action of hot dilute sulphuric acid. Recrystallised, first from glacial acetic acid and afterwards from amyl alcohol, it formed minute, very lustrous, oblique prisms or plates, melting, when rapidly heated, a t 230°, with evolution of gas-doubtless carbon monoxide, to judge from the analogy of the corresponding compound, C,,H,,O,, obtained from nnhydracetonebenzil (Japp and Burton, Trans., 1887, 51, 426).It is sparingly soluble in solvents of low boiling point, 4 A 21032 JAPP AND MELDRUM: Analysis gave figures agreeing with those required for the Formula 0.1321 gave 0.4240 CO, and 0.0734 H,O. P-Methylanhydracetonebenzil is not altered by boiling with sulphuric acid of the foregoing strength, whilst a stronger acid chars it. Boil- ing it with acetic acid, and even heating with the acid in a sealed tube at 130°, gave only desylene-methyl ethyl ketone, Heating with formic acid, however, converts it into the compound C3,H2,0,. Four grams of P-methglanhydracetonebenzil and 16 grams of concentrated formic acid were heated in a sealed tube a t 130' for 4 hours.The products were a pasty solid and a violet coloured liquid. The solid was dissolved in benzene, and light petroleum was added, which precipitated resinous matter. The filtrate yielded lustrous crystals of the compound C3,H,,02, which, after recrystallisation from acetic acid, melted at 230' with evolution of gas. a- and P-Methylanhydracetonebenzil thus yield the same compound, C36H2802, by elimination of the elements of water. The reason for doubling the formula of this substance is given in the introduction. Reduction of a- and ~-Me~hytanhyd~acetone6enxiZ with Hydriodic Acid : C36H2802D C = 87-54 ; H = 6.18.C36H2802 requires C = 87.82 ; H = 5.69 per cent. Formation of Methyldiphen y Zc yclopen tenone, C6H5*~*CH(GH3)>co, C6H,*-CH2 1-Methyl-2 : 3-diphenylcyclopentane, C6H5* 9H*cH(cH3)>CH2.-Ten grams of a-methylanhydracetonebenzil were boiled with excess of fuming C,H,*CH-CH, hydriodic acid (sp. gr. 1.9) for 5 minutes. Excess of water was added, and the solid substance, separated by filtration, was dissolved in ether. The ethereal solution was shake3 with dilute sulphurous acid, then with a solution of sodium carbonate, and dried with calcium chloride. On spontaneous evaporation, it gave crystals which, after repeated recrystal- lisation from light petroleum, were obtained in the form of faint yellow, oblique, flat prisms or plates melting constantIy at 77-78O.In another experiment, the residue which remained after expelling the ether was distilled under reduced pressure. The crude product passed over a t about 200' under a pressure of 12 mm. This procedure considerably facilitated the purification of the substance, but was attended with loss. The compound was finally crystallised from light petroleum. Analysis gave figures agreeing with those required for a rnethyldi- phenytc yclopentenone, C18H160. 0.1936 gave 0.6179 CO, and 0.1146 H,O. It melted, as above, at 77-78". C=87.04; H=6.58. 0.1730 ,, 0.5524 CO, ,, 0.1013 H,O. C = 87.08 ; H = 6-50. C,,H1,O requires C = S7*10 ; H = 6.45 per cent,HOMOLOGUES OF ANHYDRACETONEBEJSZIL. 1033 /3-Metbylanhydracetonebenzil was then reduced in precisely the same way with hydriodic acid.It yielded the same methyldiphenyl- cyclopentenone melting a t 77-78'. A supersaturated solution of the compound thus prepared inst,antly crystallised on adding a little of the crystalline compound obtained from a-methylanhydracetonebenzil. Met h yldipheny lcy clopen t enone forms a pheny Zhydraxone, I n preparing this compound) 1 gram of rnethyldiphenylcyclopentenone was heated with 1 gram of phenylhydrazine and about 6 C.C. of alcohol in a sealed tube for 5 hours at looo. Addition of dilute acetic acid and, subsequently, of water, caused the separation of an oil; this was dissolved in warm alcohol. The solution deposited clusters of minute, yellow prisms melting with decomposition a t from 145' to 152'accord- ing to the rate of heating.It decomposes on recrystallisation. Analysis gave figures agreeing with those required for the foregoing phert ylh ydraxone. 0-1181 gave 8.5 C.C. moist nitrogen at 13.5Oand 757 mm. N=8*46. C,,H,,N2 requires N = 8.28 per cent. In order to carry the reduction further than the formation of methyldiphenylcyclopentenone, and to obtain, if possible, the corre- sponding cyclopentane derivative, 10 grams of a-methylanhydracetone- benzil were boiled with 150 grams of hydriodic acid (sp. gr. 1.7) and 20 grams of red phosphorus for 5 hours. The product was worked up as described in the foregoing reduction experiments, removing iodine and then distilling under reduced pressure. A large fraction passed over between 160' and 200' under 20 mm.pressure ; on standing, it solidified. On dissolving it in ether and adding methyl alcohol, tufts of colourless, slender needles separated ; after recrystallising twice from the same solvents, they melted constantly at 62-63O. The sub- stance was identical with the 1 methyl-2 : 3-dip~enylcyclopenta~ ob- tained by Japp and Murray (Trans., 1897, 71, 153) by the reduction of a-anhyclrobenzill~vulic acid. A specimen prepared in the latter way a t once started the crystallisation of a supersaturated solution of the present compound. 0.1791 gave 05990 CO, and 0.1380 H,O. Condensation of u-Metl~ylanl~yd~cccetonebenxiZ with Bend ; Formation of a-MethyZan~~ydracetonedibenxiE, C,,HZ6O,.-The fact that anhydr- acetonebenzil interacts with b e n d in presence of dilute alcoholic potassium hydroxide to form an aldol condensation compound, anhydr- C=91*20 ; H=8.56, C1,H,, requires C = 91.52 ; H = 8.48 per cent.1034 JAPP AND MELDRUM : acetonedibenzil (Japp and Findlay, Trans., 1899, 75, l025), led us to try whether a-methylanhydracetonebenzil would exhibit an analogous behaviour.In our first experiment, we used the very dilute alcoholic potassium hydroxide which had proved efficacious in the previous condensations. The reaction took place ; but as the product proved to be a potassium salt, and as there was not sufficient potassium hydroxide present to form this salt with the whole of the other interacting substances, we repeated the experiment, using a stronger solution of the hydroxide, and obtained a much better result.3.3 grams of a-methylanhydracetonebenzil and 2.5 grams of b e n d were dissolved in 32 C.C. of alcoholic potassium hydroxide (2 grams of KOH to 100 C.C. of absolute alcohol). The solution was filtered into a small flask, which was corked up and the whole allowed to stand. (As the potassium salt cannot be recrystallised without decomposing it, it is necessary to obtain it pure at once.) After 4 days, there was a deposit of large, well-developed crystals ; these were separated, washed with cold alcohol, and air-dried by brief exposure on filter-paper. They effloresce on standing. The compound is a potassium salt of a-methyhnhydvacetonedibenzil, C3,H2,0,, and has the complex formula C3,H,50,K,C32H,,04,4C2H5* OH. Like the sodium salt of ethyl anhydrodibenzilacetoacetate (Japp and Lander, Trans., 1896, 69, 736), i t is readily soluble in benzene and is totally decomposed by boiling with alcohol. The potassium was determined in the ordinary way as sulphate ; the a-methylanhydracetonedibenzil by shaking a benzene solution of the salt with dilute hydrochloric acid, washing with water, and afterwards freeing from moisture and benzene, a process which could give only an approximate result ; and the alcohol of crystallisation by leaving the substance in a vacuum desiccator over sulphuric acid for 6 weeks, heating being inadmissible, The potassium determinations were made with different preparations.0-5784 gave 0.0414 K,SO,. K= 3.21. 0.7854 ,, 0.0566 K,SO,. K = 3.23. 2.0983 ,, 1.737 C32K2604. C3,H2,O,= 82-97. 1.3482 lost, on drying, 0.2070, C,H,* O H = 15.35.C3,H2,0,K,C,,~,,0,,4~2~G0 requires K = 3.33 ; C,,H,,O, = 81.02 ; C,H,O = 15.72 per cent. The sodium salt, which was not annlysed, was obtained direct from benzil and methyl ethyl ketone. Ten grams of benzil and 6.8 grams of methyl ethyl ketone were added to 200 C.C. of absolute alcohol in which 4.4 grams of sodium had previously been dissolved. There was a slight rise of temperature and the benzil went into solution. AfterHOMOLOGUES OF ANEYDRACETONEBENZIL. 1035 standing overnight in a corked flask, the liquid had deposited a large quantity of needle-shaped crystals. The substance was worked up for a-methylanhydracetonedibenzil after standing for 3 days. It mas identical with a sodium salt which we obtained by condensing a-methyl- anhydracetonebenzil with benzil by means of an alcoholic solution of sodium ethoxide.In order to obtain free a-methylanhydracetonedibenzil, either the potassium or the sodium salt, prepared as already described, is washed with cold alcohol and dissolved in benzene in the cold. By adding glacial acetic acid until the solution has an acid reaction and then shaking with water, the alkali metal is removed. The a-methyl- anhydracetonedibenzil soon begins to separate in a crystalline f orm from the benzene solution ; it is purified by recrystallisation from boil- ing alcohol. Two kinds of crystals are obtained : from the hot alcoholic solution, small? hard warty crystals melting a t 194O; from the cold solution, silky needles melting a t 185'. The two forms may be readily changed one into the other, and neither contains solvent of crystallisa- tion.The same two forms are deposited from a benzene solution. On analysis, the substance gave figures agreeing with those required for the formula of a-met?~~k~i.L?~ydi.aceto~aedibenzil, C,,H,,O,. Analysis I was made with the needles ; analysis I1 with the warty crystals. 0.1433 gave 0,4396 CO, and 0,0748 H,O. C = 80.57 ; H = 5.58. 0.1472 ), 0.4352 CO, ,? 0.0750 H,O. C=S0*63 ; H=5*66. C,2H,604 requires C = 81.01 ; H = 5.48 per cent. Like its analogue, ethyl anhydrodibenzilacetoacetate, it is difficult to burn. As the composition of the potassium salt of a-methylanhydracetone- dibenzil might be taken as pointing to a molecular weight twice as great as that represented by the formula C32H2604, an ebullioscopic determination of the molecular weight was made by the method already referred to, using alcohol (constant = 1560) as a solvent.a-Metl~ybnhydrc~ceto.lzedibenxil. Subs tinice. Elevation. Voliuiie. 3101. wt. 0-613 0.13" 17.5 C.C. 420 ?) 0.10 22.5 425 C,,H2,04 = 474. This result decides in favour of the lower molecular weight. Ethylcction of a-Met~ykanh?/d.rwacetonediben;zil.--The fact that a hydro- gen atom in ethyl anhydrodibenzilacetoacetate may be replaced by ethyl by boiling the compound with alcohol containing a few drops of1036 JAPP AND MELDRUM: sulphuric acid (Japp and Lander, Trans., 1896, 69, '738) led us to try the same experiment with a-methylanhydracetonedibenzil. Five grams of a-methylan hydracetonedibenzil, 100 C.C.of absolute alcohol, and 5 drops of concentrated sulphuric acid mere boiled, using a reflux condenser, At first everything dissolved; but in a short time a separation of small crystals commenced, the amount of which gradu- ally increased, After 3 hours, the operation was interupted; the crystals were separated and washed with alcohol. They formed very sparingly soluble, colourless, short needles, melting a t 250'. Analysis showed that an ethyl derivative, C,2H,,(OC2HB)0,, had been formed. 0.1643 gave 0.4883 CO, and 0.0895 H,@. C = 81-09 ; H = 6.05. CsaH3,0, requires C = S1.27 ; N = 5.98 per cent, Condensation of Bend with othev Ketones. The condensations remaining to be described were all carried out by the methods already given for the preparation of a- and P-methyl- anhydracetonebenzil, the condensing agent being either alcoholic 0.5 per cent.potassium hydroxide (4 grams KOH to 1 litre of absolute alcohol) in the cold, or aqueous 33.3 per cent, potassium hydroxide a t a temperature somewhat under 100' (see preparation Gf P-methyl- anhydracetonebenzil). Where two isomeric condensation compounds are formed, the former method generally gives, as already mentioned, the better yield of the compound of lower melting point. The aepara- tion of the two isomerides was effected by fractional crystallisation from alcohol, occasionally preceded by extraction of the more soluble isomeride with ether. C,H,*y: C(CH,) CO- C,H, a-Besylene-ethyl Ethyl hTetone, .co , aitd aP-Di- 0 5 C(CH3)>C0.-In the ex- C,H,*Y- C,H,*C(OH)*CH( CH,) meth?/l~nhydracetone6en~~l, periment in which alcoholic potassium hydroxido was used, the pro- portions mere : benzil, 10 grams ; diethyl ketone, 7.5 grams j alcoholic potassium hydroxide (0.5 per cent.), 100 c.c., the whole being allowed to stand for a month. Crystals of up-dimethylanhydracetonebenzil separated, but a great part remained in the mother liquor along with the more soluble a-desylene-ethyl ethyl ketone. The product was pre- cipitated with water, and the crystalline precipitate resolved into its two constituents as already described in the precipitation of a-methyl- anh y dracetonebenzil.In the experiment with aqueous potassium hydroxide, the following proportions were used : benzil, 40 grams ; diethyl ketone, 30 grams ;HOMOLOGUES OF ANHYDRACETONEBENZIL.1037 aqueous potassium hydroxide (33.3 per cent,), 30 C.C. Time of heating 24 hours. (For mode of heating and of working up, see preparation of P-methylanhydracetonebenzil.) The products were the same as in the previous experiment, but the proportion of ap-dimethylanhydr- acetonebenzil was greater. The yield of this compound was 27 grams. aP-Dimetl~?/kLnh?/clrncetonebenziZ crystallises from alcohol in colour- less, rhomboidal plates or prisms, melting a t 150°, as described by Japp and Burton jloc. cit.), by whom it was prepared and analysed. a-Desylene-ethyl ethyl ketone is deposited from alcohol in large, oblique, four-sided prisms melting a t 128". Analysis showed that it was isomeric with the preceding compound. 0,1649 gave 0.4943 CO, and 0.0967 H,O.c! = 81.75 ; H = 6.52. 0,1670 ,, 0.5012 CO, ,, 0.0988 H,O. C=81.85 ; H=6*57. U,,H,,O, requires C = S2.01 ; H = 6-48 per cent. a-Desylene-ethyl ethyl ketone is much more readily attacked by per- manganate than a/?-dimethylanhydracetonebenzil, indicating that it is structurally different from, not merely stereoisomeric with, the latter compound. It is probably fumaroid u-desylene-ethyl ethyl ketone, as the maleoid form might be expected to undergo internal aldol conden- sation to up-dimethylanh ydracetonebenzil under the influence of potass- ium hydroxide. This change, however, takes place under the influence of heat. A small quantity of a-desylene-ethyl ethyl ketone was heated in an atmosphere of carbon dioxide at 300-320' for 10 minutes. The fused mass, which had turned light brown, was dissolved in alcohol; on seeding the solution with a trace of up-dimethylanhydracetonebenzil, it began to crystallise and deposited the characteristic rhomboidal plates of that substance, melting a t 149' (m.p. 150'). The trans- formation occurs as follows : C,H,.$X C(CH,)* CO* CH,*CH, - C6H5*Y= C(CH,)>CO C,H,*CO C,H,* C( OH)*CH(CH,) a-Desylene-ethyl ethyl ketone a~-Diniethylanhpdrace tonebenzil (m. p. 128"). (m. p. 150"). The former compound t,hus corresponds with desylene-methyl ethyl ketone, which under the influence of heat is converted into P-methyl- anhydracetonebenzil (u. supm). It may be noted that the transformation of a-desylene-ethyl ethyl ketone into up-dimethylanhydracetonebenzil does not take place when the substance is heated in a vacuum, as under these circumstances it distils without.change. the method with alcoholic potassium hydroxide mas employed. The1038 JAPP AND MELDRUM : proportions mere : b e n d , 10 grams ; methyl isopropyl ketone, 7.5 grams; alcoholic potassium hydroxide (0.5 per cent.), 125 C.C. The reaction was allowed to go on a t the ordinary temperature, Crystals of the new compound separated within a day. After standing for three days, the product was worked up in the usual may. I t crystallised from alcohol in clusters of prisms, with pyramidal ends, or in plates, melting at 181". Only this one substance was formed in the reaction. Analysis gave figures agreeing with the formula of PP-dinzetlqZ- ccnhydracetonebenxil. 0.1789 gave 0.5358 CO, and 0.1059 H,O.C = Sl.6S ; H = 6.58. 0.1326 ,, 0.3968 CO, ,, O*OSlO H,O. C=81*62; H=6*SO. C,,H,,O, requires C = 82.01 ; H = 6.48 per cent. That the compound is not an open-chain diketone follows from its That it is PP-dimethylanhydracetonebenzil is This will be high melting point." shown by the product which it yields on oxidation. described in a subsequent paper. C,Hb*Y=C(C H ) C,H,-C(0H) CH, a-EtjL?llunhyd.r.ucetonebenxiZ, >CO, and P-Ethyl- - ~~Ayd~acetone bend, CtiH,-~ C H > ~ ~ . - Forty grams of C,H5*C( OH)*CH( C,H,) b e n d , 30 grams of methyl n-propyl ketone, and 30 C.C. of aqueous 33.3 per cent. potassium hydroxide were heated for 16 hours in the way already described. The product, precipitated with water, mashed with ether, and recrystallised from alcohol, formed minute needles melting at 156", and was iden tical with the /3-etl.yEccnhydracetonebenxiZ pre- pared and analysed by Japp and Burton (Zoc. cit.).The ethereal extract gave a more soluble substance which crystallised from alcohol in large prisms, sometimes obliquely truncated, sometimes with pyramidal ends, melting at 114". This proved to be a-ethylanhydr- acetonebenxi 1. I n a second experiment, 10 grams of benzil, 7.5 grams of methyl m-propyl ketone, and 125 C.C. of alcoholic potassium hydroxide (0.5 per cent.) were mixed and allowed to stand at the ordinary temperature for a month, although a shorter time would doubtless have sufficed. The solution had turned brown. The same products were obtained as in the previous experiment, but the yield of the a-compound was better.Analysis of a-ethglanhydracetonebenzil (m. p. 114') gave figures agreeing with those required for the formula C,,H,,O,. C,H,*C:CH*CO*C(CH,), * Thus a-beuzoyl-P-trimethacetylstyrene, , from b e n d C,H;&O and niethyl tcrt. bntyl ketone (to be described in a later communication), melts as low as 115".HOMOLOGWES OB ANHYDRACETONEBENZIL. 1039 0.1756 gave 0.5276 CO, and 0.1036 H,O. C = 81.93 ; H = 6.55. 0.1644 ,, 0,4934 GO, ,, 0,0974 H,O. C=81°S5 ; H=6*58. C,,H,,O, requires C = 52.01 ; H = 6.48 per cent. -One gram of a-ethylanhydracetonebenzil (m. p. 1 la0), 0.5 gramof benz- aldehyde, and 12 C.C. of alcoholic potassium hydroxide (0.5 per cent.) were allowed to stand in a corked test-tube. As after 5 days nothing had separated, crystallisation was started by rubbing with a glass rod.The substance formed colourless needles, On heating, it showed signs of melting at 162-166', but did not entirely melt until 17s' was reached. 0.1748 gave 0.5437 CO, and 0-0961 H,O. C= S4.84 ; H= 6.10. CZ6H2,O2 requires C = 85.24 ; H = 6.01 per cent. P-Ethylanhydracetonebenzil, treated in the same manner, showed no sign of interacting with benzaldehyde. - C,H,* F=- -y(CH3)>C0.-The CcH, * C( OH) C (CHJ, a/3/3- Trimethylanhgdracetone benzil, condensation of benzil with ethyl isopropyl ketone did not take place readily. The best result, although far from a satisfactory one, was obtained by employing as a condensing agent a solution of sodium ethoxide in absolute alcohol. Ten grams of benzil, 6 grams of ethyl isopropyl ketone, and 100 c.c of absolute alcohol, in which 1.6 grams of sodium had previously been dissolved, were mixed and allowed to stand in a corked flask a t the ordinary temperature for 2 months.A shorter time would probably have sufficed. The liquid turned dark, and there was a slight separa- tion of crystals. Water was added, the precipitated substance was washed with ether to remove benzil, and the residue was recrystallised from alcohol. From hot solutions it was deposited in colourless, prismatic needles, by spontaneous evaporation in prisms, melting at 131'. The yield was less than a gram. Analysis gave figures agreeing with the formula C,,H,,02. 0.1566 gave 0.4721 CO, and 0-0993 H,O. C=82.21 ; H=7*04. 0.1721 ,, 0,5171 CO, ,, 0.1091 H,O. C=Sl.94 ; H=7*04. C,,H,,O, requires C = 82.19 ; H = 6.85 per cent.The relatively low melting point might suggest that this is an open- chain compound. We therefore heated the substance for 10 minutes at 300-320' in an atmosphere of carbon dioxide, but, beyond vola- tilising and condensing again in slender needles, it underwent no change. We must therefore assume that it is, as above formulated,1040 JAPP AND MELDRUM: aPP-frimet~yZani~yd1.cccetonebenx~1, since all the open-chain compounds formed in these condensations are converted on heating into the isomeric closed chain derivatives. The question could be finally settled only by a study of the reactions of the compound, but the dificulty of obtaining the necessary ethyl isopropyl ketone, and the smallness of the yield of the condensation product, make this for the present impossible.C6H5*FC(C H ) a-n-Propy~~niLydrucetone b e n d , ' >GO, and P-n-Pro- C,H,*C(OH)*CH, ~. PyZc~nrTLydr~ceto~~e~enziZ, C6H5*y CH>CO.-In the first experiment, 40 grams of benzil, 34 grams of methyl n-butyl ketone, c6H5* C(OH) *CH(C,H7) and 30 C.C. of 33.3 per cent. aqueous potassium hydroxide were heated for 34 hours. The process was carried out as in the preparation of P-methylanhydracetonebenzil. I n working up the product, the ethereal extract gave a substance which was deposited from ether in large, flat, obliquely truncated prisms, and from alcohol in six-sided plates, melt- ing a t 89'. This proved to be a-n-~opylanrTLydl.acetonebenzil. The sparingly soluble residue, recrystallised from alcohol, was deposited in clusters of slender prisms melting at 152O.This was P-n-propyZanhydr- acetonebenxil. It formed the chieF product. The yield of purified P-compound was 12.5 grams, In a second experiment, a mixture of 10 grams of benzil, 8.5 grams of methyl n-butyl ketone, and 125 C.C. of alcoholic potassium hydr- oxide (0.5 per cent.) was allowed to stand in a corked flask a t the ordinary temperature for a month. The products were the same as in the former case, but the yield of a-n-propylanhydracetonebenzil was better. Analysis of a-n-propylanhydracetonebenzil (m. p. 89') : 0.1783 gave 0.5372 CO, and 0.1077 H,O. C = 82-19 ; H= 6.73. 0.1813 ,, 0.5440 CO, ,, 0.1162 H,O. C = 81-83 ; H = 7.12. C,,H,,O, requires C = 82.19 ; H = 6-85 per cent. Analysis of P-n-propylanhydracetonebenzil (m.p. 152') : 0.1836 gave 0.5530 CO, and 0.1121 H,O. C = S2.13 ; H= 6.78. 0.1850 ,, 0.5570 CO, ,, 0.1151 H,O. C=S2.12; H=6.90. C,,H,,O, requires C = 88.19 ; H = 6.85 per cent. Benx y Zidene- a-n-pop ylarh ydracet onehenxi I, C6H50~:C(C3H?)>C0 C,H5* c( OH) -c=c13[*C6H5 -The condensation of u-n-propylanhydracetonebenzil with benzaldehyde was carried out as in the case of the other a-compounds, the reaction taking place in this case also in the cold. The benzylidene derivative was deposited from its hot alcoholic solution in clusters of small laminae melting at 166O.HOMOLOGUES OF ANHYDRACETONEBENZIL. 1041 0.1591 gave 0.4970 CO, and 0.0930 H,O. C,7H,,0, requires C = 85.26 j H = 6-32 per cent. P-n-Propylanhydracetonebenzil did not interact with benzaldehyde.C= 85.19 ; H= 6.49. C,H,*C=-C(C H ) a~-DiethyZccnh~/clrcccetonebenziZ, C,H,. &OH). CH(C ) >CO.-When 2 5 benzil and dipropyl ketone were heated with aqueous potassium hydr- oxide, no condensation took place. The action of alcoholic potassium hydroxide in the cold, however, gave the desired result. A mixture of 10 grams of benzil, 10 grams of dipropyl ketone, and 125 C.C. of alcoholic potassium hydroxide (0.5 per cent.) was allowed to stand in a corked flask a t the ordinary temperature for a month. On pouring the product into water, an oil separated which speedily became crystalline. By recrystallisation from alcohol, only one pro- duct could be obtained : plates of rhombic outline, striated parallel to the shorter diagonal, melting at 113-114'.It was not changed by heating for 10 minutes at 300--320' in an atmosphere of carbon dioxide, thus showing that it is not an open-chain compound. Analysis gave figures agreeing with those required for the formula of diethylanhyd~acetonebenzil. 0.1453 gave 0,4379 CO, and 0.0943 H,O. C = 82.19 ; H = 7.21. 0.2047 ,, 0,6180 CO, ,, 0.1328 H,O, C=82.33 ; H=7*20. C21H2202 requires C = 82.35 ; H = 7.19 per cent. C H *C-C(C5H11) a-n-ArnytccnhydrucetonebensiZ, C6H6*C(OH)* I- CH, >CO, and P-n-anzyl- . C,H,*Y--- -- anhydracetonebenxi~, C,H,*C(OH)*CH(C,H,,) CH>CO.-Forty grams of benzil, 44 grams of methyl n-hexyl ketone, and 30 C.C. of 33.3 per cent. aqueous potassium hydroxide were heated for 15 hours as described under the preparation of P-methylanhydracetonebenzil, the Product being afterwards worked up in the usual way. Only P-umylanhydracetone- benxiZ-slender, silky needles melting a t 150*5O, described and analysed by Japp and Burton-was obtained. In a second experiment, a mixture of 10 grams of benzil, 11 grams of methyl n-hexyl ketone, and 125 C.C. of alcoholic potassium hydr- oxide (0.5 per cent.) was allowed to stand in a corked flask for a month. On pouring into water, the product which separated was partly crvstalline, partly oily. The solid portion, after crystallisation from alcohol, yielded needles of P-amylanhydracetonebenzil melting at 150.5'. The oil, on long standing, also gave crystals-large, six-sided plates-which after recrystallising twice from light petroleum melted constantly at 57O, and proved to be the isomeric a-amykanhydvacetone- benzil. The yield of the latter compound is fairly good.1042 BONE AND JERDAN: THE DIRECT UNION OF Analysis of a-amylanhydracetonebenzil (m. p. 57O) : 0.1763 gave 0,5338 CO, and 0.1210 H,O. C = 82.56 ; H = 7.63. 0.1678 ,, 0.5067 CO, ,, 0.1142 H,O. C = S2.35 ; H = 7.56. C,,H,,O, requires C = 82.50 ; H = 7.50 per cent. Benxyliclene-a-amy Zan~?ldracetonebenz~l, %H,* ~:C(C5HlJ>CO C,H,* C(0H)-C=CH*C,H,' -This compound was prepared like the other benzylidene derivatives of a-compounds. It is deposited from its solution in boiling alcohol in colourless needles melting at 1 5 6 O . 0.1595 gave 0.4985 CO, and 0*1011 H,O. C,9H2s0, requires C = 85.29 ; H = 6.86 per cent. P-Amylanhydracetonebenzil does not interact with benzaldehyde. One of us is a t present engaged, conjointly with Mr. Arthur C. Michie, in studying the products of the oxidation of the various methyl homologues of anhydracetonebenzil. C=85*21 ; H=7*04. The foregoing two papers form a continuation of a general investi- gation of the reactions of ketonic compounds (compare Trans., 1897, 71, 123), and the expenses incident,al to the work have for some years past been in part defrayed by various allotments from the Government Grant Fund of the Royal Society. CHEMICAL DEPARTMENT, UNIVERSITY OF ABERDEEN.