HARDING AND WEIZMANN : LV-NONYLENIC ACID. 299xXXII.--hl-Nonylenic Acid.By VICTOR JOHN RARDING and CHARLES WEIZMANN.IN the present communication an account is given of the. pre-paration in large quantities and the means of identification ofAl-nonylenic acid, an acid of considerable technical importance.It was first obtained by Schneegans (Annden, 1885, 227, SO), whoprepared it by the condensation of heptaldehyde and sodiu300 HARDING AND WEIZMAKN : A~-NONYLEKIC ACID.acetate by means of acetic anhydride a t 160-170° for thirty hours.The yield was very poor, and its identification uncertain.Knevenagel (Friedlander : Fortschritte der Teerfarb enfabrikation,7 , 738) has also prepared this acid by the condensation of hept-aldehyde and malonic acid through the agency of piperidine.Theauthors, however, have not been able to obtain large yields by thismethod, the piperidine inducing condensation products of hept-aldehyde with itself similar in character to those obtained bymeans of alkalis. These high-boiling neutral products also occurredwhen other secondary or primary bases, such as diethylamine,ammonia, or aniline, were used as the condensing agent, and itwas only when tertiary bases were employed that good yields of thedesired acid were obtained. The heptylidenemalonic acid whichis first obtained,easily loses carbon dioxide to form Al-nonylenic acid,CH,*[CH2],*CHO+ CH,(CO2H),=H,O +CH,*[CH,],*CH:C(CO,H),,CH3*[CH2],*CH:CH*C0,H.This unsaturated acid, after purification by means of its bariumsalt, boils a t 144O/13 mm., and is obtained as a colourless oil witha characteristic odour.As a means of identification, the authorsrecommend the use of the amide or the p-toluidide, but moreespecially the former, as its preparation in a, pure state is botheasy and rapid. A'-Nonylenamide melts at 126-127O; thep-toluidide a't 73-74O. The dibromo-acid,CH3*[CH,],*CHBr*CHBr*C02H,although it has been obtained as a solid melting at 3 5 O , on accountof the difficulty with which it is prepared, is not suitable as ameans of identification. Al-Nonylenic acid, on reduction withsodium and alcohol, gives nonyl alcohol. I n order to control theconstitution of the unsaturated acid, an alternative method ofpreparation was adopted. This was the condensation of hept-aldehyde and ethyl bromoacetate by means of zinc:CH,*[CH2],*CH0 + Zn + CH,Br*CO,Et --+CH,*[CH2]5*CH(OZnBr)*CH2*C02Et -+CH,*[CH2],*CH(OH)*CH,*C02Et.Ethyl P-hydroxy-n-nonoate, on hydrolysis, gives the correspondingacid as a white, crystalline solid, melting at 57-59O.This acid haspreviously been prepared by Wagner (Ber., 1894, 27, 2736), whoobtained it by the oxidation of hexylallylcarbinol by means ofpermanganate. Wagner gives the melting point of this acid as48-51°, but we do not think there can be any doubt as to theidentity of the two substances. The removal of water from thehydroxy-acid waa accomplished by means of acetic anhydride, HARDING AND WEIZMANN : A1-NONYLENIC ACID. 301method which has been used with such conspicuous success byWallach to produce unsaturated acids containing the ethylenelinking in the aP-position.The identity of the two preparationsof A'-nonylenic acid was proved by means of their amides, a mixtureof the two preparations having the same melting point as theirseparate constituents.EXPERIMENT A L.Al-Nonylenic A cid, CH3*[CH,],*CH:CH*C02H.After many unsuccessful attempts, the following method ofpreparing Al-nonylenic acid was found to give the best results.One hundred grams of malonic acid were dissolved in 160 grams ofpyridine, and to the cold liquid was added 100 gra.ms of hept-aldehyde. The whole was kept at the ordinary temperature forthirty-six hours, and then gently heated on the water-bath for twohours. The product was poured into water, and acidified withhydrochloric acid.The oil was extracted by ether, and well washedwith water. The unsaturated acid was next removed from theethereal extract by means of sodium carbonate solution. Theethereal solution was dried and evaporated, when the very smallresidue which was obtained was found to consist almost entirely ofunchanged heptaldehyde, high condensation products being pro-duced only in very small amount. The sodium carbonate washings,on acidification, extraction with ether, drying, and distillation,yielded 90 grams of Af-nonylenic acid, boiling a t 145-150°/ 12 mm.Analyses of this acid, even on redistillation, always showed adeficiency of carbon, and several methods of purification were tried,of which the following gave the best results. Eighty grams of thedistilled acid were boiled in 95 per cent.alcohol with 127 grams ofpure barium hydroxide. The barium salt which is formedgradually dissolves in much boiling alcohol, from which it separateson cooling as a white, crystalline powder. This, on acidifying withdilute hydrochloric acid and extraction with ether, gave about40 grams of pure Al-nonylenic acid, boiling constantly a t144O/13 mm.:0.1210 gave 0.3097 CO, and 0.1102 H,O.Al-Nonylenic acid is a colourless oil, with the faint odourcharacteristic of acids of this class. It is readily soluble in coldsodium carbonate solution, and instantly decolorises cold alkalinepermanganate. The preparation of Al-nonylenic acid in good yieldwas also attempted by condensing heptaldehyde and malonic acidby the use of piperidine (Kncevenagel, Zoc.cit.), but the yields wereC=69.7; H=10.1.C9H1602 requires C = 69-2 ; H = 10.2 per cent302 HARDING AND WEIZMANN : A~-NONYLENIC ACID,very poor, large amounts of high-boiling condensation products ofheptaldehyde with itself being formed. This is easily shown ifto heptaldehyde alone a few drops of piperidine are added. Theliquid rapidly becomes hot, loses the characteristic odour ofheptaldehyde, and decomposes on distillation. Similar results aregiven by other primary and secondary bases, such as ammonia,aniline, and diethylamine. The condensation of heptaldehyde andmalonic acid by means of dimethylaniline gave, from 100 grams ofheptaldehyde, 30 grams of hl-nonylenic acid and also some con-densation products of high boiling point.These we attribute to thepresence of methylaniline in the dimethylaniline employed.Af-Nonylenyl Chloride.-Nonylenic acid reacts vigorously withphosphorus pentachloride to form Al-nonylenyl chloride, boiling at144O/90 mm. :0.2861 gave 0.2335 AgC1. C1=19.9.The nzethyl and ethyl esters boil respectively at 110°/20 mm. and123O/25 mm.Af-Nonylenanzide, C8H,,*CO*NI12. - This most characteristicderivative of Al-nonylenic acid is very readily prepared by pouringthe acid chloride into concentrated aqueous ammonia,. The amideinstantly separates as a solid, and is collected and purified bycrystallisation from aqueous methyl alcohol or petroleum. Itcrystallises in beautiful pearly leaflets, melting at 126-127O :CgHl,OCl requires C = 29.1 per cent.0.1741 gave 13.9 C.C.N, (moist) at 20° and 752 mm.A*-Nonyleno-p-toluidide is prepared by adding the acid chlorideto a slight excess of p-toluidine and then gently warming. Theyellow, semi-solid mass which is produced is then treated severaltimes with dilute hydrochloric acid and with sodium carbonatesolution. The a'dhering oil is removed by contact with porousporcelain, and leaves the p-toluidide as it white solid, whichcrystallises from light petroleum in small, shining leaflets meltingat 73-74O:N=9.0.CgHIgON requires N=&9 per cent.0.1610 gave 7.6 C.C. N2 (moist) at 19O and 770 mm. N-5.5.C,,H2,0N requires N=5.7 per cent.&E'ydroxy-n-mono& Acid and i t s Ester,CH,.[CH,J,*CH(OH)*C~~*CO,E.This acid is easily and rapidly prepared by condensing hept-aldehyde and ethyl bromoacetate by means of zinc in benzenesolution.Eighty-eight grams of heptaldehyde and 128 grams ofethyl bromoacetate are mixed with twice their volume of benzeneHARDING AND WEIZMANN : A~-NONYLENIC ACID. 303and 52 grams of zinc added. The reaction is started by warmingon the water-bath, but when once commenced is extremely vigorous,and cooling must be resorted to. When the reaction has subsided,the condensation may be completed by heating on the water-bathfor a couple of hours. The viscous product is decomposed by iceand hydrochloric acid, extracted with ether, the ethereal extractwell washed with water, dried, and distilled, when ethyl P-hydroxy-n-nonoate passes over as a colourless, inodorous oil, boiling at145O/13 mm.:0.1381 gave 0.3302 CO, and 0.1287 H,O.C,,H,,03 requires C = 65.3 ; H = 10.8 per cent.When treated with an aqueous solution of hydrogen bromidesaturated at Oo, this hydrosy-ester only gives very small quantitiesof ethyl P-bromo-wnonoate, the hydroxy-group remaining un-affected. 6-Hydroxy-naonoic acid is easily obtained by thehydrolysis of its ester by means of alcoholic potash. The potassiumsalt, which separates in large plates from the alcoholic solutionon cooling, is collected, dissolved in a little water, cooled with ice,and acidified, when 8-hydroxy-n-nonoic acid separates as an oilwhich rapidly solidifies. This is collected, any adhering oil beingremoved by contact with porous porcelain, and purified bycrystallisation from hot water, or from light petroleum, when itmelts a t 57-59O:C=65*2 ; H = 10.4.0.1193 gave 0.2707 CO, and 0.1102 H,O.P-Kydroxy-mnonoic acid crystallises in short needles as a white,inodorous compound.It is readily soluble in cold benzene, alcohol,chloroform, acetic acid, o r ethyl acetate, and is stable towardscold alkaline permanganate. It is instantly soluble in cold sodiumcarbonate solution. When treated with an acetic acid solution ofhydrogen bromide and gently warmed, it yields P-bromo-n-nonoicacid as a heavy oil.C=61*9; H=10.2.C9HI8O3 requires C = 62.1 ; H = 10.3 per cent.Preparation of Al-Nonylenic Acid from P-Hydroxy-n-nonoic A c i d .In order to confirm the constitution of Al-nonylenic acid preparedfrom heptaldehyde a d malonic acid, it was deemed advisable toprepare it from P-hydroxy-n-nonoic acid, using acetic anhydride asa dehydrating agent. Ten grams of crude P-hydroxy-n-nonoic acidwere boiled with 50 C.C.of acetic anhydride for four hours. Theproduct was poured into water, and distilled in a current of steam,when the unsaturated acid passed over slowly. The distillate wassaturated with ammonium sulphate, extracted with ether, and frac304 HARDIKG AND WEIZMAX” : A~-NONYLENIC ACID.tionated under diminished pressure, when the acid (5 grams) wasfound to boil at 181°/60 mm.:0.1315 gave 0.3293 CO, and 0.1237 H,O.C,H,,O, requires C = 69.2 ; H = 10.2 per cent.The acid prepared in this way possessed a sharper odour than thatprepared by the first method, but its identity was proved beyondall doubt by its conversion into the acid chloride and then intothe amide.The amide, when crystallised from petroleum, meltedat 126O, and when mixed with a specimen of Al-nonylenamideprepared from malonic acid, no alteration in the melting point wasobserved.C=65.3; H=10*4.Reduction of Ethjl Al-Non$enate to Nonyl Alcohol.Fifty grams of ethyl nonylenate, prepared from the crude acid,are dissolved in 150 grams of absolute alcohol, and gradually addedto 50 grams of sodium contained in a large flask provided with itreflux condenser, the temperature being kept at 150O. The reduc-tion is very vigorous, and alcohol must be added from time to timeto complete the solution of the sodium. When all the sodium hasdissolved, the product is distilled in a current of steam, the nonylalcohol being extracted by ether and fractionated. The yield is35 per cent. The nonyl alcohol was identified by means of itsphenylurethane.aP-Dibromo-n-nonoic A cid, CH,*[CH,],*CHBr*CHBr*CO,H.This acid is prepared by the addition of bromine to a solutionof Al-nonylenic acid in carbon disulphide until the bromine ceasesto be decolorised. The carbon disulphide is distilled off, the aciddissolved in ether, washed with dilute sulphurous acid, dried, andthe ether evaporated. After a long time in an evacuated desiccator,the yellow oil gradually solidifies to a white, crystalline solid.This is pressed on porous porcelain to remove adhering oil, but theacid is too soluble in all organic solvents to permit of a convenientcrystallisation. It melts a t 3 5 O :0’2125 gave 0.2450 AgBr. Br=49*1.C9H160,Br2 requires Br = 50.6 per cent.It is soluble in dilute sodium carbonate solution, but the solutioxrapidly becomes cloudy, owing to the separation of a-bromo-Al-nonylenic acid.THE UNIVERSITY,MANCHESTER