SOME STUDIES ' N FATTY ACID SER ES PART TWO CO-OLEFINIC FATTY ACIDS NATIONAL CHEMICAL LABORATORY, POONA- 8. - (1965 ) C 0 T E T S Page CHAPTER I limOiXJCTION 25-34 w-Olefinic fatty acids 25 Methods of synthesis 25 Methods utilising components 28 in which the co-olefinic group is already present. Methods in which the w-olefinic 30 group is produced by an elimiaation reaction. Other methods 31 References 33 CHAPTER II PYROLYSIS OF MAiiY-MEMBERED 36 - 130 LACTONESj A UEJJHIAL METHOD 1T(B THE SYNTHESIS OF «-0LEFiiac f a t t y a c i d s . Preliminary investigations 36 Pyrolysis of many-membered 43 lactones Preparation of ^J^-hydroxy 45 fatty acids Preparation of lactones 52 Pyrolysis of lactones 62 Discussion 67 Experimental 75 Summary 126 References 127 Page CHAPTER III SYSrmTIC 131 - 153 CHAM-SHOHTENIiia OF W-OLEb*INIC f a t t y a c id s Chain-shortening by 132 one carbon Chain-shortening 133 two carbons Chain-shortening by 136 three carbons Experimental 141 Summary 150 References 151 CHAPTER I INTRODUCTION 2 5 oj-OLH^’INIC FATTY AGIDS I.{TRQJUCTIQN The work described in this Part deals with the development of general method for the preparation of long chain co-olefinic fatty acids. cu-Olefinic acids offer an unique opportunity for degrading the molecule from one end in bits of one or more carbon atoms at a time. This work was of interest in comiection with the possible utilization of kamlolenic acid: H0CH2(CH2)3CH=CHCH=CH-CH=CH(CH2)7C00H the major component of the o il from the seeds of Mallotus phllippinensis. ’ It appears relevant, in connection with this work, to describe very briefly the state of our knowledge with regard to to-olefinic acids. Unlike the other saturated and unsaturated acids, terminally unsaturated fatty acids are not at all wide spread in nature,though 9-decenoic acid has either been detected, isolated or identified in 1 —8 human milk fat , in butter and milk fats of various animals , 9 * and in sperm head oil . METiiOJo Qi*' Table 1 summarises the properties of the known co-olefinic acids. 20 TABLE 1 : PHOPERTILS OF w-OLEt‘'Ii;aC FATTY ACIDS CH2=CH(CH2)nC00H Jo. n= ni.p. b .p . P r . H e f. mra °c 1 0 1 2 . 3 1 4 1 .9 1 .0 6 2 1 ^ ^ 1 0 ,1 2 i 65 30 - I 12 !i 3 .5 1 .0 4 5 ^ ^ 1 .4 8 5 ^ ^ ; 13 2 1 1[-39 163 1 .0 1 3 ^ ^ 1 .4 2 5 7 ^ ^ 1 0 ,1 4 ] [ 72-72 .5 14 - - ] 16 1 3 2 ,<-18 189 0.9843^® 1.434l'^’ ^ s 1 0 ,1 1 ,1 4 r 1 186-87 745 0 .9 9 8 7 ^ i 11 f w« 187-89 0 .9 8 4 1 6 ^ ^ - 1 15 4 3 !f 203 0 .J 6 1 0 ^ ° 1 .4 3 4 3 ^ ^ ] 1 0 ,1 1 [+1 107 16 0 .9 6 1 0 ^ ° 1.4385^'° ] 17 17 5 4 ;-6.5 225 0.952"^^ 1.4425^® 1 10 • 225-27 1 18 ;-6.5 125 15 0.3515^^-9 1.4404^^*^ J 19,11 ( Lthyl ester 210- 12) - 20,11 7 6 116-18 1 0.il46^^*® 1.4492^^ 19 20 8 7 143-48 15 0.9238^^ 1 .4 4 8 8 10,11 -0.5 155-60 14 1 .4 4 6 2 4 4 ] 2 8 124.5 275 0.3075^^ 1.4464^"^^^ 10 [24-25 165 15 11 2 4 ^2-23 131 1 0 .9 0 7 2 19 . .contd. ^ ( TABLE 1 (Gontd.) iN[o. n= m .p . b .p . P r. ^ R e f. mm °C 10 9 ( 143-44 3 0 .9 0 3 0 ^ ° 1 .4 5 1 0 ^ ^ ; 10,11,21 Cf .P .1 9 171-72 13 0.907^° - 22 11 10 192 2 5 a 10 « '38-39 192 20 9 21 162 S ;S8-38.2 18 5 15 1 22,11 12 11 Not reported r 13 12 1 198 8 I 10 [49.8- 195 8 - 3 22 [50 14 IS Ilot reported 1 5 14 Not reported 16 15 [55-55.5 ] 2 3 ,2 5 .55,5- ] 24 [56.1 Several methods have been used for the prepara- tion of these compounds , and these may be broadly divided into three groups. A. Methods utilising componeats in which the fl>-olefinic group is already present B. Methods in whicsh the w-olefinic group is produced by an elimination reaction. G. Other methods. o 8 A. Methods ut il l sing coigponents ia which the ui~oleflnlc group is already present. A number of compounds have been synthesized by chain extension of a suitable starting material by several of the available methods (Grrignard reaction, exchange with cyanide, malonic acid synthesis etc.)* Starting from vinyl ajagnesium and allyl aagnesiuia h alid es, acrylic and vinyl acetic acids have been prepared res­ pect ively^^*^^. From allyl bromide, vinyl acetic acid^^ and allyl acetic acid^^*^^ have been synthesized. Vinyl ethyl bromide has been used to prepare 5-hexenoic acid^"^*^^, vinyl propyl bromide was used to prepare 6-heptenoic acid^^, v/hich in turn, was elaborated to 8-nonenoic acid, which was, next, used as a starting material for 10-uudecenoic acid synthesis . The ready availability of 10-undecenoic 10 11 acid from castor oil cracking * * made possible its further elaboration into 11-dodecenoic acid^^, l2-tri- decenoic acid^^*^^, and 14-pentadeceiioic acid*^^. 17-octa- decenoic acid has been prepared from 10-undecenoic acid 23 24 by the following two routes * 2 9 •CH2= C H (C H 2;q c o o h !• EtOH, H2SO4 S0 ( 2:LiAIH4 ,et-tier CH2=CH(CH2/8C0CI CH2=CH(CH2)0CH2OH Anhyd- Et.OH PBrj S-CH^COCHgCOOEt, NaOEt, BrCH2( C COOEt 3 Na,ether CH2=CH(CH2 )gCH2Br 4 CH3C0CNa L(CH2)5 COOEt COOEt 1 Mg ,CdCl2 _ 2 EtOCO(CH2)5COCI, COCH. CeHg CH2=CH(CH2)qCC C (CH2,5CCOEt 3- Aq' NaOH + 4 H COCEt I-Aq- KOH CH= CH(CH2)gCH2C0(CH2)5C00H 2H^ 1 • Wolf -Kishner CH2=CH(CH2)gC0CH2(CH2)5C00Et reduction 2 K0H,Et0 H 1 Aq.NaOH 3 h" 2-H'^ 3 W olf-K1 shner reduction 3 0 B. ^Mettyids ia which the a)>oleriaic gruup j,a_ .MrodftftlA by aa ellmliiation reaction Several types of elimination reactions have been used. a) Jehydrohalo r enat 1 on Acrylic acid (2-propeaolc acid) has beea prepared by dehydrohalogenation of p-chloroproplonlc acid^^*^^. Similarly vinyl acetic acid has been synthesized from 1 ,2 -dlbromopropionitr il e^*^. b) Deamination 5-hexenoic acid and 6-heptenoic acid were prepared by deamination of 6-arainocaproic acid and 7-arainoheptanolc acid respectively, using nitrous acid for the pui’pose^^*^^. c) Electrolytic decarboxylation The Kolbe electrolysis of the half esters of several dicarboxylic acids has been shown to produce an co-olefinic acid ''ith one carbon less. Thus 5-hexenoic, 6-heptenoic, 7-octenoic and 8-nonenoic acids have been obtained by the electrolytic decar bo-K.yl at ion of the potassium salts of the half esters from pimelic^^, suberic^® azelaic^^’^^ and sebacic acids^^ respectively. d) Pyrolysis of polyesters Acrylic acid is being prepared commercially by the pyrolysis of polyesters obtainable from the poljnnerization 13 of B-propiolactone . 3i e) Psrrolysls of 8-hydroxy olefi.aic acid 10-Uadeceaoic acid is comiaerdally prepared by the pyrolysis of castor oil. The mechanism of this reaction has been investigated by Arnold and iraolins'tcy, who have profitably exploited this reaction for a variety 31-33 of purposes C. Jther methoas. Some specific methods are available for the synthesis of certain co-olefinic acids. Thus, for example, acrylic acid is being manufactured commercially by "carbonyl reaction" for which basic raw materials are acetylene, fiarboa monoxide (supplied as such or in the form of nickel IS carboiiyl) and water . This acid has also been prepared 13 by decarboxylation of maleic acid a*id catalytic "hydrolysis” of maleic anhydride^°»^^. Vinyl acetic acid has been synthesized from 3-butynoic acid by converting it to allenic acid followed by reduction 1 4 with lithium alumixiium hydride . Allyl acetic acid was prepared by the reduction of 27 methyl 4-pentynoate with sodium and alcohol 5-Hexenoic acid was obtained by decarboxylation of 28 A p-butenyl malonic acid . It has also been prepared from cyclohexanone through formation of 5-hexanal by ring-rupture 33 aad conversion of the aldehyde to hydroxamic acid followed by treatment with sulphuric acid^*^*^^. 33 REFERESiCES 1 A.W. Bosworth, J. Biol. Ghem, 106, 235 (1934), 2 I. Smedley, Bioehem. J. 6, 451 (1912). 3 A. Grriin and T. Wirth, Ber. 55, 2197 (1922). 4 I.P, Hilditch, Checiical Constitution of Natural Fats, Chapman and Hall Ltd. London (1956),125,319,513,514. 5 A.W. Bosworth and J.B. Brown, J. Biol. Chem. 103, 115 (1933). 6 R.W. Hisaouschneider and N.R. ELlis, ibid. 113, 219 (1936). 7 T.P. Hilditch and H.Jasperson, Bioehem. J. 38, 443 (1944). 8 X.T. Achaya and T.P. Hilditch, ?roc. Hoy. 3oc.(London) 137B. 187 (1950). 9 Y. Toyama and T. Tsuchiya, J. Chem. See. Japan, 56, 1313 (1935). 10 K .S , I4arld.ey, Fatty Acids, Part I , p p .1 1 2 , 110-136, Interscience Publishers Inc. New York (1J60), 11 A.W. Ralston, "Fatty Acids and their Derivatives" pp.81-95, John Wiley and i3ons, New York (1948). 12 R.E. Kirk and D.F, Othiaer, Encyclopedia of chemical Technology.