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Metathesis of 1-Hexene and Cyclooctene J.Org. Chem. Vol.40 No. 6 , 1975 775Metathesis of 1-Hexene and Cyclooctenel

Joginder Lal* and Richard R. SmithGoodyear Tire an d Rubber Company, Research Division, Akron, Ohio 44316

Received August 28,1974Th e meta thesis reaction between 1-hexen e and cyclooctene was examined using several catalysts derived fromWCle and an organometallic compound. Using preferred catalysts, WC b EtOH/EtAlClZ or WCb ZEtzO/Bu4Sn,a high percentage of cyclooctene (>70 ) was consumed in a few hours. The reaction product consisted of linearnonconjugated polyenes belonging to three dif ferent homologous series. Th e principal com ponen t in the reactionprodu ct was Cl4Hzs (1,9-tetrad ecadiene ) resulting from th e cross-m etathesis of 1-hexe ne and cyclooctene. Ethy l-ene and 5-decene, formed by th e self-metath esis of 1-hexene, underw ent cro ss-metath esis with cyclooctene to pro-duce CloHlB (1,9-decadiene) an d ClsH34 (5,13-octadecadiene). Fur ther reaction of th ese prim ary cro ss-metath esisproduc ts with cyclooctene gave higher m embers of the homologous series. The influence of th e natu re of the cata-lyst, 1-hexene/cyclooctene molar ratio, and cyclooctene conversion on component distribution in the reactionproduct was determined.

Olefin metathesis is a transition metal catalyzed reactioninvolving the reorganization of bonds of olefins via transal-kylidenation?~~t has been investigated primarily for thepolymerization of cycloolefins into polyalkenamers. Bothheterogeneous4 and homogeneous5 catalysts have beenfound useful in promoting this reaction. Potential applica-tions of the olefin metathesis reaction have been recently

The cross-metathesis reaction between an a-olefin and acycloolefin or cyclodiene has been reported in the litera-ture.a ll HBrisson and Chauvin12 and Kelly13 independent-ly found tha t the product from the reaction of 1-penteneand cyclopentene consists primarily of linear nonconjugat-ed polyenes having one terminal double bond per molecule.Porr i and coworkers14 have studied t he reaction of norbor-nene with 1-pentene using catalysts derived from iridium.In all these studies, the reaction products were examinedafter low conversions of reactants (1-15%). In this paper,we have quantitatively characterized the reaction productresulting from the cross-metathesis of 1-hexene and cy-clooctene. Experimental conditions were chosen to give cy-clooctene conversions of 70 or greater. Several catalystsderived from WCl6 and an organometallic compound wereemployed for the study.

Resul ts and DiscussionWC16 EtOH/EtAlClZ Catalyst.2 A chromatogram ofthe reaction product from the cross-metathesis of 1-hexeneand cyclooctene using the WCb EtOH/EtAlC12 catalyst isshqwn in Figure 1.In order t o characterize the various com-

ponents in the mixture, seven fractions corresponding tothe glc peaks were isolated by the preparative glc unit andanalyzed by mass spectrum, nmr, and ir. The results aresummarized in Table I.Fractions 1 ,2 , and 3 comprising 7 ,8.5, and 40 w t of theproduct, respectively, were assigned (mass spectral data)the molecular formulas CloHls, C10H20, and C14H26, respec-tively, and correspond to the following structures:f r a c t i o n 1, 1 bd ec ad ie ne , CH,=CH(CH,) ,CH=CH,f r a c t i o n 2, 5-decene, C,H,CH=CHC,H,f r a c t i o n 3 , l ,%tetradecadiene, CH,=CH(CH,),CH=CHC4H,

Fraction 4 (12.5 wt 96 of product) was found t o containprimarily two compounds having the molecular formulasC18H32 and Cl~H34mass spectral data). These compoundswere present in molar proportions of 40 and 60 (glc).Based on the chemistry of the metathesis reaction, theywere assigned the structures CH2=1CH(CH2)sCH=]2CHzand C ~ H ~ C H = C H ( C H ~ ) C & H = C H C ~ H ~ ,espectively.

Fractions 5, 6, and 7 represented 14.5, 7 , and 5.5 wt ofthe product, respectively. The various compounds present-ed therein belonged to the following three different homol-ogous series of which CloHls in fraction 1, C14H26 in frac-tion 3, and C18H34 in fraction 4 were first members.Series A the main peaks are assigned to C14H26, C22H40,and C30H54 components of t he unsymmetric homologousseries CH2=[CH(CH2)6CH=].CHC4Hg representingabout 60w t of th e tota l product (primarily C14H26).Series B: composed of C18H34, C2~H48, nd C34H62 of thesymmetric homologous series C4HgCH=[CH(CH2)8-CH=],CHC~HS representing about 13 of the product.Series C: contained C10H18, ClsH32, C26H46, and C34H60of the symmetric homologous series CHz=[CH(CH2)6-CH=],CH2 representing about 14% of the product.In the above series, n is an integer and it s smallest valueis 1. All compounds belonging to the series A, B, and Cmust contain moieties derived from both the reactants.Consequently, 5-decene (fraction 2) is not included in se-ries B. Likewise, ethylene is not included in series C.The relative molar ratio of the first components of seriesA, B, and C, namely, C14H26, C18H34, and CloHls, respec-tively, containing one cyclooctene-derived octenamer unitand constituting a tr iad, was approximately 4:l: l. The com-ponents of the next triad containing two octenamer unitswere also present in a similar ratio. However, HBrisson, e ta1.,l2 reported triad ratios of 1 O : l : l to 20:l:l for the reac-tion of cyclooctene with propylene or 1-pentene in chloro-benzene with a WOCL/(CdH9)4Sn catalyst. The relativelyhigh proportion of series A components reported in the lat-ter stu dyjs presumably a consequence of the reaction cdndi-tions and low cyclooctene conversions (1-15%). IJnder ourexperimental conditions, cyclooctene conversion was 70%or greater. Apparently, the cross-metathesis reaction lead-ing to series A components prevails at low cycloolefin con-version but competing reactions leading to series B and Ccomponents become important as cyclooctene is depleted.A simplified reaction scheme is given in Scheme I. In addi-tion, series A components may get converted to series Band series C components by subsequent metathesis reac-tion.l5It should be noted t ha t peaks corresponding t o macrocy-clic oligomers C16H28 and C24H42, which are reported16 tobe formed during the ring opening polymerization of cy-clooctene, are not seen by mass spectrum in the meta thesisreaction product. However, C32H56 (tetramer) was ob-served in trace amounts in fraction 6. The absence ofC16H28 and C24H42 does not necessarily preclude their for-mation in small amounts and subsequent reaction with oneof the a-olefihs present. The formation of C32H56 in trace

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776 J.Org. Chern.,Vol.40 No. 6 1975 L a1 a n d S m i t hTable IC h a r a c t e r i z a t i o n of t h e Metathesis P r o d u c t a of 1-Hexeneand C y c l o o c t e n e ( W C l E . E t O H /E t A l C 1 2 C a t a l y s t )

G I Mass spectrumFraction Wt 96 of Parent mass Mol formula Xmrn0.b component I obsd ( m / e J c assigned A n a l Series

1 7 138.1393 ClOH18 2 te rm in al Cd o u b l e b o n d sdoub le bond1 i n t e r n a ldoub le bonds4 12.5f 250.2648* C18H34 C o n s i s t e n t w i t h6 0 m o l %C18H34 and 40m o l 5 CjEH3,2 i n t e r n a ldoub le bonds8 0 m o l %m o l % C2&6

2 8.5 140.1554* ClO 1 i n t e r n a l3 40e 194.2029* C 1 4 H 2 ~ 1 t e r m i n a l a n d A

B a nd C248 C18H32

5 14.5g 3 04.31 18* C22H40 1 t e r m i n a l a n d A

6 7 360.3749 * C26H48 C ons i s t e n t w i th B a nd C358 C26H46 C,,H4, and 207 5.5k 414.4244* C30H54 A, B, a nd440 C32H56 (t ra ce ) c (e xc e p t

468 i C34H60 C,,H,ti)470 C34H62a Reaction conditions were the same as shown for Figure 1. Fraction num bers refer to those in the chromatogram (Figure 1 .All fractionswere 98-99.5% pure, except fraction 1 (95% pure) and fraction 4 (81% pu re). Mass num bers with asterisks represent major peaks by highresolution mass spectrom etry, dHomologous series refer t o those in Scheme I. en30D1.4430; the internal double bond had 45% cis and 55%tran s (i r) . C18H34/C18H32 molar ratio = 1.50 (glc analysis using a 20-ft, 20% UC-W98 on 60-80 m esh C hromo sorb W column). g n30D 1.4622;60% cis and 40 trans double bonds (ir) . 93% of C30 an d 6% of C34. Fo r calc ula tions, 3% each of C34H60 and C34H62 was assume d to bepresent (glc analysis using column in footnote f . Mass peak was not observed (possibly due to side reactions?).

Scheme IS c h e m a t i c D i a g r a m for Metathesis of C y c l o o c t e n e and 1-HexeneH e x e n e - c y c l o o c t e n e c r o s s - m e t a t h e s i s

H e x e n e s e l f - m e t a t h e s i sS e r i e s BC8H14)H + CH,=CH CdHgCH=CHCdH, 4H9CH=[CH(CH2)6CH=],CCHC4Hg

C4H9 C4H9 (C,OHZO) n z l+CHZ=CH2*

E t h y l e n e - c y c l o o c t e n e c r o s s - m e t a t h e s i sS e r i e s CV 1 4

(CIOHlJ n z 2(CH2)(fH + CH2=CH2 F CH2=CH(CH2)6CH=CH2 L CHz=[CH(CH2)GCH=],CH2

H

a Th e presence af ethylene was ascertained by glc on a 50-ft di-n-decyl phthal ate column.a m o u n t s m i g h t r e s u l t f r o m t h e i n t r a m o l ec u l a r c y cl i za t io nof the di te rm inal polye ne C34H60 (ser ies C; n = 4) y p i n c h -ing o ff e thy le n e .The e f f e c t o f r e ac t i o n t i m e o n t h e d i s t r i b u t i o n o f c o m p o -n e n t s i n s e r i e s A , B and C i s s h o w n i n F i g u r e 2 u s i n g t h eWC le C 2H50H/EtAlC 12 c a ta lys t . C yc looc te ne c ons um p-t i o n w a s i n c r e as e d t o 86wt f r o m 70%as the r e a c t io n t i m ew a s i n cr e a s e d t o 24 h r f r o m 0.25 hr. C o n c u r r e n t l y , t h e r ew a s a s l igh t de c re a s e in the we igh t pe rc e n ta ge o f s e r i e s Ac o m p o n e n t s as a c ons e que nc e o f an i n c r e a se i n t h e w e i g h t

p e r c e n t a g e s o f b o t h s e r i e s B a nd s e r i e s C c ompone n t s . I fthe m e t a t h e s i s p r o d u c t w e r e t o b e u t i l i z e d f o r c o p o ly m e r -i z a t io n w i t h an a - o l e f in t o p r o d u c e a n u n s a t u r a t e d c o p o l y -mer, i t i s d e s i ra b l e t o t e r m i n a t e the m e t a t h e s i s r e a c t i o na f t e r 30 m i n s i n c e i n c r e a se i n t h e r e l a ti v e a m o u n t o f s e r ie sC c o m p o n e n t s at l onge r re a c t ion t ime s w i l l i nc re a s e ge lc o n t e n t o f t h e c o p o ly m e r .C a ta ly s t s ys t e ms ba s e d on Et3A1 o r ( i -B u)3AI wi thWCl6. EtOH e x h i b i t e d l o w a c t i v i t y f o r t h e m e t a t h e s i sr e a c t i o n b e t w e e n 1 - h e x e n e and c yc looc te ne . T he y ga ve c y -

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Metathesis of I -Hexene and Cyclooctene

FR, 1W 1 8

-

J . Org. Chem. Vol. 40 No. 6 , 1975 777

FR.F R . 7R. 5 . __'l8"3? GHi FR. 6'1BH34 w 5 4

\

- I IFR 3I 'MH26

2 I4 8 12 16 20 24RETENTION TIME MIN.Figure 1. Chrom atogram of the reaction product in the metathe sisreaction of cyclooctene and 1-hexene. Conditions: catalyst, WCls.EtOH/EtAICI,; AI/W/O atom ic rati o = 4:l:l; 1-hexene/cyclooc-tene molar ratio = 2; cyclooctene/WCle molar ratio = 1300; reac-tion for 30 min at 25'.

v

T I M E , HOURSFigure 2. Effect of reaction time on product distribution in themetathesis reaction of cyclooctene and 1-hexene using WCla.EtOH/EtAlCIz catalys t. Conditions: same as in Figure 1.

clooctene conversion of about 5% in 24 hr, with only onepeak (C14H26) detectable by glc.WCle CF&H20H/EtAlC12 Catalyst . The distributionof components in the three series is shown in Figure 3 forthe WCLj e CF&H20H/EtAlC12 catalyst. Cyclooctene con-version of 91 to 96% was obtained, with only slight changesin the product distribution, as the reaction time was in-creased from 0.25 to 24 hr. In calculating the product dis-tribution here, the relative proportions of components cor-responding to fractions 1and 2 as well as th e relative distri-bution of components in fractions 4, 6, and 7 were assumedto be the same as in Table i. This catalyst gave 44, 13, and18 wt of series A, B, and C components, respectively,compared to 60, 13, and 14% resulting from the C2HsOH-modified catalyst. Thus, the WCb C2H50H/EtAlC12 cata-lyst gives a higher proportion of the polymerizable compo-nents, together with a markedly improved ratio of seriesA/series C components. The data in Figures 2 and 3 indi-cate that the two catalyst systems appear to be essentiallydead after about 1hr.W Cb 2Et2O/Organ otin Catalysts . Several catalystsprepared from WCb 2Et20 and organotin compoundswere examined for the metathesis reaction between 1-hex-ene and cyclooctene. The reaction conditions were similarto those employed with WCb alcohol/EtAlCl2 catalysts(Figures 2 and 3). As shown in Table 11, only Bu&n and(C6&,)4Sn gave catalysts having fairly high activity. Thecatalysts based on organotin compounds having one or twochlorine atoms gave less than 5 cyclooctene conversionunder these conditions.Glc of the metathesis product from the tinhungsten-cat-alyzed reaction of 1-hexene and cyclooctene indicated t ha t

7

m 6

4 2 '40 0 5 i o I 5T I M E , H O U R S

Figure 3. Effect of reaction time on product distribution in themetathesis reaction of cyclooctene and I-hexene using WClfi.CF:$HZOH/EtAIC12 cata lyst . Cond itions: sam e as in Figure 1,

the various compounds present also belonged to the threehomologous series described earlier. The WCb 2Et20/Bu4Sn catalyst was examined at three different catalystlevels for the matathesis of 1-hexene and cyclooctene andthe results compared with those obtained by using WCk.EtOH/EtAlC12 (Figure 4). The rate of cyclooctene con-sumption with the tin catalyst is seen to be substantiallyslower (37% in 1 hr and 45% in 3 hr) than that obtainedwith the aluminum catalyst (-,80 in 1 hr) at R cyclooc-tene/WC& molar ratio of 1300. However, raising the cata-lyst level by 33 and 100 increased cyclooctene consump-tion t o about 76 and 85%, respectively, in 3 hr.The compositions of the metathesis products for the alu-minum- and tin-catalyzed reactions from Figure 4 are corn-pared in Figure 5 . For this purpose, the effect of reactiontime on the distribution of polymerizable (series A + C)and nonpolymerizable (series B) components is examined.The weight percentages of the t hree series were normalizedto 100 . Both the tin- and aluminum-based catalysts giveessentially identical d istribution of components when com-pared at cyclooctene/WCk, molar ratio of 1300. A t this cat-alyst level, the product consists of approximately 86-88%series A + C components and 14-12% series R componentsat the end of 3 hr. Upon increasing the WCk,-2Et20/

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778 J . Org. Chem., Vol.40 N G . , 1975 La1 and SmithS E R I E S A + C

Table TIMeta thesi s of 1-Hexene and Cyclooctene usingWCls-ZEtzO/Organotin Compound CatalystsaCyclooctene consumption, %sn p :

Tin compd (atom ic ratio) 2 r 24 hr

Bu$n 2 8ct-85 9 0Bu,SnCl 2 5 5DuzSnCl2 2 5 5(C,H,),Sn 2 5 37b4 43 47b(C, H, ),SnC 1 2 5 5@ 1-HexenejCyclooctene molar ratio 2 .0; cyclooctene/WClsmolar ratio 650; benzenejcyclooctene vol ratio 3; reaction at 25 ;n-octane used as the internal standard. a These reaction productshad essentially the same component distribution as that obtainedwith the BurS n catalyst a t equivalent conversion of cyclooctene.

Table I11Effect of 1-Hexene/Cyclooctene Mola r Ratio on theCompositions of Metathesis P roduct(WCls.BEtzO/Bu. n Catalyst* )

\ I t %HcxeneICyclooctene molar ratio.__l__l

Component of ~metathesis product 0.5 1 o .O

C 1 0 H 1 8 9.7 10.2 14.2ClOH20 10 .5 14 .3 1 8 . 5C 1 + H 2 6 18.7 20 .2 29 .6C22H40 1 5 . 7 14 .6 10 .2C yclooctene 95 95 88

a Cyclooctene/WCle molar ratio = 1300; benzene/cvclooctenevol ratio = 3: reaction a t 26 for 3 hr; n-octane used as the internalstandard. Sn/W atomic ratio = 2.

c o n s u m e d , %

Bu4Sn level 33 to loo , the percentage of polymerizablecomponents decreased slightly to 79 with a correspondingincrease in nonpolymerizable components to 21%. Therewas essentially no change in the distribution when the reac-tion was allowed to continue for 24 hr and cyclooctene con-sumption increased by 10 .It should be noted that at thehigher levels of the tin catalyst, the amount of 5-decenebased on the total product increased from about 10 to 14compared to 7% with the aluminum system,Figures 4 and 5 show that the WCLj 2Et20/Eu4Sn sys-tem requires a somewhat higher catalyst level than the alu-minum system for obtaining in high conversion a polyeneproduct with a high percentage of polymerizable compo-nents. This catalyst system, in marked contrast to theWCl, EtOH/EtAlC12 system, gives easily reproducible re-sults. Scale-up of the metathesis reaction between 1-hexeneand cyclooctene in a I-gallon container gave a product hav-ing essentially the same component distribution as obtain-able in a 4-oz bottle.Effect of l-Hexene/6ydooctene Molar Ratio. In theprevious discussion, the molar ratio of 1-hexene/cyclooc-tene for the W/Al and W/Sn catalpst systems was kept a t 2in carrying out the metathesis reactions. This ratio was se-lected because our preliminary work with the W/A1 catalystsystem had shown that the relative amount of series Acomponents was highest at this ratio without any sacrificein the high conversion of cyclooctene to the polyene mix-ture. The effect of hexene/cyclooctene molar ratio on the

?PO

E7j l

; > . C ' i Z L 2 C L 4 s ; .,

I 2 - {I----%T I M E , H O U R S

Figure 5. Effect of reaction time on product distribution in themeta thesis reaction of cyclooctene and 1-hex ene. Conditions: sameas in Figure 4 ,

distribution of components in the WCL BEt2O/BudSn cat-alyzed metathesis product is shown in Table 111.To simpli-fy comparison, only the weight percentages of 614H26 andC22H4~of series A (peaks 3 and 5 ) , C ~ O H ~ Opeak 2) andC I O H I ~peak 1 of series C were determined from the chro-matograms since peaks for these components were well-defined. The overall conversion of cyclooctene to productsis reasonably similar for all three ratios. However, the ratio2 is preferred for the formation of 614H26, C10H20, andC10H18. The enhanced formation of CloHzo at this ratio isdue to the greater availability of 1-hexene for undergoingself-metathesis. The greater availability of cyclooctene atthe lower ratios contributes to enhancement in the forma-tion of C&40 at the expense of C14&fi by the cross-me-tathesis reaction between C14H26 and cyclooctene. Similar-ly, the areas of peaks 4 and 6 increased relative to th e com-bined area of peaks 1 and 2 at the lower ratios (data notshown), consistent with the increased cross-metathesis ofcyclooctene with CloHls and C~oHzo.

Experimental SectionMonomers and Solvent. High purity 1-hexene (Gulf) and ben-zene (Fischer) were dried by passing through an 1 8-in. activated-silica column and stored over molecular sieves (Linde 4.4-XW).Cyclooctene (Cities Service) was distilled over calcium hydride orpassed through a silica-alumina column prior to use.Catalysts. Solutions of EtAlC12 (1.55 M ) , organometallic tin

compounds (0.1-0.2 M ) , and WCl6 (0.05 M ere prepared in ben-zene under nitrogen. Solutions of WCh were modified by addingappropriate amounts of an alcohol or diethyl ether. In the case of(CsHj)&i, a 0.20 molar suspension in benzene was used.Monomers and solvents of high purity and freshly modifiedWC k solutions were found to be essential for obtaining reproduci-ble results.Metathesis Reaction. The experimental conditions were or-ganometallic/WCk molar ratio = 2-4; cyclooctenc/WClc molarratio = 650-1300; hexene/cyclooctene molar ratio = 0.5-2; ben-zene/cyclooctene volume ratio = 3. The order of addition was solu-tion of reactants, organometallic compound, WCh modified withe ther or an alcohol. In a typical experiment, the metathesis reac-tion mixture for characterization studies was prepared in a 1-qtbottle fitte d with a meta l cap having perforations and backed witha self-sealing gasket and Teflon linear. A solution of 0.50 mol of cy-clooctene, 1.0 mol of hexene, 200 ml of benzene, and 10 ml of n-

octane (glc internal standard) was sparged with nitrogen for threeminutes. The catalyst components, 0.75 ml of EtAlClz and 8.0 mlof WCl6 EtO H solutions, were added by syringe into the reactantssolution and th e bottle was capped under nitrogen. After agitationon a mechanical shaker for 30 min (a mbien t temperature, 25O), glcanalysis of th e homogeneous reaction m ixture indicated a 94% con-

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Synthesis of Fatt y Acids Using Organocopper(1) Ate Complexes J . Org. Chem., VoE.40 No. 6 1975 779sumption of cyclooctene. Th e reaction was termin ated a t this pointwith 1ml of met,hanol. T he resulting mixture was concentrated ona roto-evaporator u nder aspirator v acuum to remove benzene, hex-ene, and cyclooctene prior to fractionation by preparative glc.Analytical Frocedures. Analysis by glc was routinely per-formed on a Hewlett-Packard 7620A Model gas chromatographusing a 6 f t X in. 10 UC-W 98 on 80-100 mesh Diatop ort S col-umn, pro grammed from 80 to 270 in 20 min.As stated earlier, a typical metathesis product was concentratedby th e removal of benzene, hexene, and cyclooctene. T he concen-trat e was fractionated by means of a Hewle tt-Pa ckar d preparativegas chromatograph unit and seven fractions were isolated. Theywere analyzed by nmr, ir, and mass spectrum.Nmr analyses were carried out on a Varian A60 spectrometerand ir spectra recorded on a Perkin-Elmer Model 21 spectropho-tometer. High resolution mass spectrum measurements were madeon a Du P on t Model 21 -1lOC mass spectrometer using perfluoro-kerosene as the i~ fe ren ce ompound.

Acknowledgment . The authors are grateful to R. A.Hively and R. E. Hinton for glc fractionation, Dr. T. L.Folk for mass spectroscopy, Dr. H. Y. Chen and B. A. Sib-bio for nmr, J. K. Clark and R. A. Scott for ir. and D. K.Romain for technical assistance.

Registry No.-1-Hexene, 592-41-6; cyclooctene, 931-88-4;WCls, 132 83-01-7; EtO H/Et AlCI z, 53777-80-3; CF3CHZOH/Et-A1C12, 53777-81-4; 2EtzO /B~& 3n, 53777-82-5; 2EtzOIBu3SnC1,53777-83-6; 2E tzO /Bu zSn Cl~ , 53777-84-7; 2EtzO/(CcHa)4Sn,53777-8 5-8; 2EtaO/(CsH&SnC1, 53777-86-9.

R e f e r e n c e s a n d N o t e s(1) Presented in part at a meeting of the Division of Polymer Chemistry,164th National Meeting of the American Chemical Society, New York,N.Y., August 27-September 1, 1972.2) N. Calderon, H. Y. Chen. and K. W. Scott, Tetrahedron Lett., 33271967).3) N. Calderon, E. A. Ofstead, J. P. Ward, W. A. Judy, and K . W. Scott, JAmer. Chem. SOC.,90,4133 1968).4) G. C. Bailey, Catal. Rev., 3, 37 1969).5) W. B. Hughes, Organomefal. Chem. Syn. 1, 341 1972).6) K . W. Scott, Polym. P r e p Amer. Chem. SOC.,Div. Polym. Chem., 13,7) N. Calderon, Accounts Chem. Res., 5, 127 1972).8) N. Caideron and K. W. Scott, Belgian Patent No. 759,774, Feb. 15,9) G.C. Ray and D. L. Crain, Belgian Patent No.694,420 to Phillips Petro-

10) E. A. Zuech, W. B. Hughes, D. H.Kubicek, and E. T. Kittleman, J Amer.(I) C. Pinazzi and D. Reyx, C. R. Acad. Sci. Ser. C 76, 1077 1973).12) J. L. Herisson and Y. Chauvin, Makromol. Chem., 141, 161 1970).13) W . J. Kelly, Paper presented at the 163rd National Meeting of the Amer-ican Chemical Society, Division of Petroleum Chemistry, April 9-14,1972.14) L. Porri, R. Rossi, P. Diversi, and A. Lucherini, Polym. Prepr., Amer.Chem. Soc.,Div. Polym.Chem., 13, 897 1972).(15) The formation of series B and series C components from series A com-ponents was demonstrated by carrying out the metathesis reaction be-

tween l-hexene and C14H26 fraction 3 from preparative glc). The prin-cipal products were CiOH20 and C18H34 of series B and C10Hla of seriesC. in addition, appreciable amounts of C22H40 of series A and C2d-48 ofseries B were also obtained. Likewise, components of series C can beconverted into series B components and vice versa.16) K. W. Scott, N. Calderon, E. A. Ofstead, W. A. Judy, and J. P. Ward,Advan. Chem. Ser., No. 91, 399 1969).17) G. Pampus, G. Lehnert, and D. Maertens, Polym Prepr., Amer. Chem.SOC. Div. Polym. Chem., 13, 880 1972).

874 1972).

1971, to Goodyear Tire and Rubber Co.leum Co.Chem. Soc., 92, 528 1970).

Synthesis of Fatty Acids Using Organocopper(1) Ate Complexes Derivedfrom Grignard Reagents1

David E. Bergbreiter2 and George M. WhitesidesDepar tment of Chemis try , Massachuse t ts Ins t i tu t e o f Technology , Cambr idge , Massachuse t ts 02139

Received August 13 1974Fa tty a rid este rs have been synthesized in good yield by reaction between co pper(1) ate complexes formed fromrnethylcopper(1) and primary or secondary Grignard reagents and esters of primary iodoalkylcarboxylic acids.Th e synthetic method is illustrated with pro cedures for CHz=CH(CHz)1gCOzCzHs, CsHsCHzO(CHz)16COzCzHs,C H d C H z ) 2 5 C O z C z H 5 , C I ~ ~ O Z C ( C H Z ) Z ~ C O Z C H ~ ,~ H ~ O Z C ( C H Z ) ~ ~ C O ~ C Z H ~ ,nd CH~(CHZ)~CH(CH~)(CHZ)~O-C02CH3. The reaction sequence uses starting Grignard reagent with high efficiency, provides product mixturesthat are conveniently worked up, and tolerates a variety of functional groups. It provides the most direct routepresently available to a variety of representative classes of simple fatty acids.

A number of procedures for the synthesis of fatty acidsare availab1e.J Those most commonly used for fatty acidsnot containing extensive unsaturation include the reactionof carbonyl compounds with alkylidene ph os ph or an e~ ,~heKolbe anodic coupling of half esters of dicarboxylic acids,5and the acylation of enamines with acid chlorides followedby hydrolysis of the resulting P-diketones and Wolff-Kish-ner reduction of the product keto acid.6The reaction of carbonyl compounds with alkylidenephosphoranes is particularly useful for the preparation ofdiastereomerically pure unsaturated fatty acids, and hasalso been used in the preparation of branched-chain fattyacids. Its deficiencies are that it often involves multiplesteps of only moderate yields and requires a difficult sepa-ration of products from triphenylphosphine oxide. Kolbeelectrolysis of half esters of dicarboxylic acids is a usefulroute to symmetrical long-chain dicarboxylic acid esters,but is not applicable to the preparation of unsymmetricalcompounds. The procedure developed by Hunig and co-workers is applicable to the synthesis of asymmetrically di-

substituted fatty acids, symmetrically disubstituted fattyacids, and both straight- and branched-chain fatty acids.Although versatile, it is lengthy.We have developed an efficient alternative t o these pro-cedures based on carbon-carbon bond formation by selec-tive coupling between one alkyl group of a mixed cop-per(1) ate complex and primary iodoalkyl carboxylic es-terse7This procedure is compatible with a number of func-tional groups, yields products cleanly and in high yield, andis applicable to a number of representative classes of fattyacids.Results

Both primary and secondary Grignard reagents reactwith methyIcopper(1) and form copper(1) ate complexesthat selectively transfer the alkyl group originally bondedto magnesium in high yield in alkylation reactions. Byusing the readily available methyl or ethyl ll-iodoundeca-noate in this reaction, i t is possible to synthesize a varietyof fatty acids. A typical procedure-that for ethyl 21-do-