FORMATION OF DERIVATIVES OF TETRAHYDRONAPHTHALENE. 87 IX.-The Formation of Derivatives of Tet Yahydro-naphthalene j+om y- Phenyl Fatty Acids. By GEORGE ARMAND ROBERT KON and ARNOLD STEVENSON. THE conditions governing the formation of dicyclic structures of the naphthalene type from benzene derivatives having a side-chain olf not less than four carbon atoms are a t present difficult to determine because we have as yet little knowledge of the effect on the valency directions of carbon atoms caused by their par-ticipation in an aromatic nucleus. That however the conditions are very similar to those which determine the formation of similar monocyclic structures from open-chain carbon derivatives has been clearly shown by experiments which have been carried out on the formation of ring structures through the catalytic action of sodium ethoxide on the relevant dinitrile.Thus it has been shown by Moore and Thorpe (T. 1908 93 176) that the transformation takes place with the greatest ease and by Thorpe (T. 1909 95, 1901) that the change > C X H YH2*CH2'CN $!H2-CH -+ CH,*CH(CN) c H,*C H2*CN can apparently be effected with equal readiness. That' six-membered rings of the two types also exhibit similar beha,viour is to be inferred from the results of a number of experi 88 KON AND STEVENSON THE FORMATION OF DERIVATIVES OF ments oif which the tlransformation represented below may be taken as an example (Atkinson and Thorpe T. 1906 89 1920): /\/\C:NH. CH2 CR, \/\/CH*C02Et Or 1 1 ' \/ /C€€*C02Et CN c NB NH2 Scheme (a).It is therefore remarkable that hitherto no examples appear to have been recorded illustrating the folrmatioin of a six-carbon saturated ring by the elimination of water from a y-phenyl fatty acid through the combination of the hydroxyl group of the carbolxylic complex with a hydrogen atom in the ortho-polsition of the benzene nucleus. The simplest compound which could exhibit this change would be y-phenylbutyric acid (I) but although this GI32 ( 3 3 2 //\/\GH2 + H,O co I I ' \/ P H 2 acid has been made t'he subjectl of exhaustive st'udy by several investigatolrs no record appears to ha,ve been ma.de of any such reaction. The rnat.t,er is an important olne because if a cha,nge of t,his kind cannot be effected it would indicate that there is an essent,ial difference bet<ween the colndit,iolns determining ring form-ation in open-chain compoands and; those of the type under dis-cussion and that the latter are not readily fosmed unless there is the possibility of the production of the true napht'halene nucleus, as illustrated by scheme (a).Tha'tt this is not the case is shown in the present paper wherein is described t,he formatioln of derivatives of fefrahydronaphfhalene frolm two typical derivativw eE y-phenylbutyric acid. It is also shown t,hat a. derivative of y-t.et.rahydroIphenylbutyric acid can be caused ta undergo the same change. It was evident that5 oin theoretical grolunds the derivativw of y-phenylbutyric acid folr use in these experiments should have been formed by hydrolysing the condensation products obtained by colndensing a suitable ketone with ethyl cyanoacetat,e and ammo,nia in accordance witb Guareschi's method but it has been CH,Ph CH,Ph\C,CH(CN) *CO CH,Ph \c/cH2'co2H \co \.N EI Et/ Et/ \CH(CN)*CO/ Et/ \CH,*CO,H (11.) (111.) w.TETRAHYDRONAPHTHALENE FROM T-PHENPL FATTY ACIDS. 89 shown already by Km and Thorpe (T. 1919 115 704) that the acid produced by hydrolysing the colndensation product (111) formed from benzyl ethyl ketone (11) by means of sulphuric acid does not possess the ekpected formula (IV) but has an abnormal structure. Attention was therefolre directed totwards determining the structure of this abnormal prolduct as well as that derived in a similar manner from benzyl methyl ketone and it was soon found that they were actually the tetrahydrojnaphthalene deriv-atives (V) and1 (VI) which had been formed by the elimination of water during the process of hydrolysis.The correctnem of this CH CH2 /\/\cR CH cc ~ I I f\l/\yMe*C H,*CO,H (V- 1 I I ' \/ P H 2 \ / \ P H 2 CO CO,H CHO (VI.) view of the constltution of these acids was shown by the formation of semicarbazones and by the proaduction of phthalic acid on oxidation wibh permanganate. In order to show that the condition of tlhe benzene nucleus did not have any appreciable effect on the formation of the second ring experiments were then carried out with the tetrahydro-ketone (cyclohexenylacetone VII) and in this case also the hydrated naphthalene derivative (IX) is the sole product formed on hydrolysing the imide (VIII) with sulphurio acid.It seems, CH2 /\ CH C CH CH \CH(C N -CO/ \/ \/ CH(CN).CO \NH f €1 R*CH,* CM e/ /"\"I FH E*CH,*COMe (VIII.) C'H CH2 (VII.) CH CH, /\/\ \/\/ $JH2 yMe*CH,*CO,H CK2 C CB, (=*) CH G 90 KON AND STEVENSON THE FORMATION OF DERIVATIVES O F therefore as i f the ease with which a ring closes is influenced by the character of the groups attached to the P-position oC the side-chain. It will be remembered that this point was raised in a recent paper (Day and Thorpe T. 1920 1\17 1465) but it is evident thatl much more experimental evidence will be necessary before any definite proinouncement can be made. An attempt was made to prepare the simplest member of the phenyl series (X) by hydrolysing the condensation produc'i.(Xl) produced from phenylacetaldehyde (XII) and cyanoiacetamide in accordance with the method of Day and Thorpe (Toc. c i t . ) but up to1 the present' WQ have only succeeded in obtaining a small quantity of the compound (XI) because under the usual conditions tho chief product is evidently derived irom the interaction of cyano-CHZ CH2 /'\A c ' q c N ) - co NH, 1 1 C H < ~ ~ ( ~ ~ ) - ~ ~ ()+ K- CH,. CO,H \/\/CHZ \/ C 0 acetamide and phenylacetaldehyde in equimollecular proportions. I t s structure has not as yet been completely elucidated and as it presents several points of interest i t is proposed to investigate it more fully. The behaviour of the acid (V) on regulated oxidation is interest-ing a number of intermediate compounds being formed before phthslic acid is finally produced.It is hoped to make these compounds the subject of a subsequent communication. E X P EK I M E N TAL. ac.-l-.Ueto-3-met hy It etraT~ya?ronnpT~thyl-3-ace t ic A cia? (V, p. 89). It was found that for the hydrolysis of the imide derived by Guareschi's process ( A t t i R. Accad. Sci. Torino 1900-1901 36, 443) from benzyl methyl ketoae Thole and Thorpe's method (T., 1911 99 445) did not give very satisfactory results the best yield being obtained with a large excess of 50 per cent. sulphuric acid (by volume). Twenty grams of iniide were heated under reflux with 400 C.C. s f acid with frequent shaking until solution took place and evolution of gas ceased when the liquid had become dar TETRAHYDRONAPHTHALENE PROM Y-PHENYL FATTY ACIDS.91 red. After diluting with 150 C.C. of water itl was extracted with ether yielding 12-14 grams of crude product (theory 16.3). The crude acid is yellow or brown but fin twice recrystallising from benzene i t is obtained in stellate clusters of colourless prisms melting at 155-156O (Fotund C= 71.35 ; H = 6.53. Ci3HI4O3 requires C=71*5; H=6*5 per c9nt. Silver salt. Found Ag= 32-97. CI3Ri,O,Ag requires Ag=33*2 per cent.). It is a weak acid not effervescing with sodium hydrogen carbonate and after boiling with 10 per cent. sodium hydroxide solution it4 is pre-cipitated by acid unchanged. The silver mercuric lead cupric, chromium aluminium ferric and ferrous salts form readily in the cold from the ammonium salt whilst the barium and calcium salts are solluble both in the1 cold and on boiling.The semicarbazone was prepared by warming an alcoholic sdu-tion of the acid with semicarbazide acetate. On keeping a dense, crystallinel mass formed which on recrystallising fratm alcohol, separated in fine needles melting at 2 2 1 O (Found N=15*44. C,,H,,O,N requires N = 15.3 per cent.). The oxidatioa to phthalic acid with potassium permanganate can be effected bath in acid and alkaline solution. I n the case of the former 4 grams olf tho acid (V) were dissolved in 150 C.C. of sulphuric acid (1 part of acid to 2 parts of water) and a warm, saturated solution olf potassium permanganate was added with heating un ti1 the supernatant' liquid above the precipitate which formed was pink. The excess of perinanganate was destroyed with oxalic acid and the liquid extracted with ether when 1 gram of crude phthalic acid was obtained.After recrystallisation from alcolhol and again from water it melted and decomposed a t 2 0 3 O , and on heating with resorcinol gave fluorescein (Found C= 57.65 ; H=3*83. Calc. C=57.8; IE=3*6 per cent.). The alkaline oxidation was carried out by dissolving the acid in sodium hydroxide sollution hsating on tho steam-bath and adding a warm saturated solution of potassium permanganate until the colour persisted. After destroying the excess of permanganate with sulphurous acid and filtering the liquid was1 extracted with ether the ethereal extract yielding crude phthalic acid which was identified as before. ac . -1 - X e i a- 3 - e t 7 b yl t e t rah ydrona ph thyl-3-ace tic A cid (VI , p.89). I n preparing this acid it is advisable tot use the pure imide as otherwise an oil is fornied which prevents the separation of the acid. Eight grams of imide were heated under reflux with 160 c. 92 RON AND STEVENSON THE FORMATION OF DERIVATIVES OF of sulphuric acid (1 part of acid to 1 part of water by vollume), with frequent shaking until solution took place and evolution of gas ceased. After diluting with water it was extracted with ether the ethereal extract giving on evaporation an oil which solidified in a vacuum yielding 1.4 grams of crude product. On recrystallisation from benzene and light petrolenm itl separated in short' stout prisms which adhered firmly to glass and melted at 7 9 O (Found C = 72.18 ; H = 6.65.Cl4HIGO3 requires C = 72.4 ; H = 6.9 per cent'. Silver salt. Found Ag = 31.91. C,,H1,O3Ag requirw Ag=31-8 per cent.). The metallic salts re$emble those olf its homololgue the barium and calcium salts being solluble both in the cold and on heating whilst the salts of the heavy metals are readily precipitated1 in the cold. The semicarbazone prepared by treating an alcohojlic solution of the acid with semicarbazide acetate was twice recrystallised from alcohol when it separated in needles melting at 2100 (Found: W= 14.73. The oxidation to phthalic acid was carried out in acid solution in the manlier already described (p. 91) and was identified by the resorcinol test. CISH,,O,N requires N= 14.5 per cent.). Condensation of cycloHe x en y lac e t on e with E thy I Cy anoac e tat e : 3 5-Dicyano-2 6-dileeto-4-cyclo?iexenylmethyl-4-methyl~per-s i n e (VIII p.89). The ketone was prepared by Wallach's methold from cyclohexan-one and acetoae (Annalen 1912 394 362) 13-8 grams being con-densed with ethyl cyanoacetate and alcoholic ammosnia by Guareschi's method (Zoc. cit.) giving 12 grams of crude imide. When twice crystallised from alcohol it separated in colourless needles which shrank and darkeneld at 190° and melted and decom-posed a t 202O (Found N = 15.72. C&11,02N3 requires N = 15.5 per cent. ) . l-Reto-3-methyloctnhtydronaphthyl-3-acetic Acid (IX p. 89). It was again found thatl the use oh impure imide gave unsatis-factory results. Concentrated sulphuric acid viollently attacks the, imide in the cold but with an excess of 50 per cent.acid (by volume) the reaction proceeds smoothly. On heating under reflux until evolution of gas ceased and then diluting and extracting with ether an oil was obtained from the ethereal extract which solidified on lea,ving in a vacuum but the yield was rather poor, being only about 25 per cent. of the theoretical. On rscrystallisa TETRAHYDRONAPHTHALENE FROM 7-PHENYL PATTY ACIDS. 93 tim from ether the acid separated in collourless crystals which were however indefinite in form melting a t 90° (Found: C=70.05; H=8*17. Cl3Hl8O3 requires C=70*2; H=8.2 per cent. Titration with N / 10-sodium hydroxide. Found 8.25 C.C. Calc. (monobasic) 8.05 C.C. Silver salt. Found Ag = 32-81. C13H,,03Ag requires Ag = 32.8 per cent.).The metallic salts closely resemble those s f the two acids described above the barium and calcium salts being soluble botsh in the cold and on heating whilst those of the heavy metals form readily in the cold. The semicarbazone was prepared by treating an alcoholic solu-tion 09 the crude acid with semicarbazide acetate. It is very sparingly soluble in hot alcohol and after twice crystallising therefrom formed spherical aggregates of needles melting and decomposing a t 209-210° (Found N = 15-06. C,,H2,0,N, requires N = 15.1 per cent.). The oxidation to phthalic acid was carried obt with potassium permanganate and sulphuric acid in the manner described above, crude acid being employed. Phthalic acid was identified by the resorcind test. Condensatiolz of Pheny lace tald ehyd e with Cyan mce t amide .Cyanoacetamide (8-4 grams) and phenylacetaldehyde (6 grams) welre dissolved in 50 C.C. of water and sufficient alcohol to effect complete solution and 0.5 C.C. of a 50 per cent. aqueous solut4ion of p&assium hydroxide was added. The crystalline precipitate which had folrmed in the course of twenty-four hours was colllected and found to consist of two sub-stances which can be separated by extracting the mixture with boiling alcoshol. The insolluble residue which forms small needles melting a t 245O is the diamide of aaI-dicyano-P-benzylg~utaT~ acid CH,Ph*CH[CH(CN)*CO*NHz]z (Found * C = 62.00 ; H = 5-35; N=20*57. C,,H,,O,N requires C=62.2; H=5.2; N=20-7 per cent'.). The quantity of this substance obtained up to the present is t'oo small for the investigation of its behaviour on hydrolysis. The second substance which separates oa cololing the alcoholic extract crystallises in needles melting a t 2 0 4 O . We have not yet succeeded in obtaining colncordant figures oln analysis but the nitrogen content' (13.8-14.0 per cent.) clearly indicates that the substance is formed by the condensation of cyanoacetamide and phenylacetaldehyde in equimolecular proportions. * We are indebted t o Mr. J. N. E. Day for this analyeis 94 COFFEY THE ACTION OF THE CHLORIDES OE’ We are indebted to Professor J. F. Thorpe for much valuable advice and for the interest he has taken in our work; our thanks are also due to Mr. W. S. G . P. Norris of this College, for kindly preparing wnie of the materials require’d. TIXE IMPERIAL COLLEGE OF SCIENCE AND TEC~NOLOGY, SOUTH KENSINUTON. [Received Dccenzber 171h 192&