Reactions of Thiol Compounds and Alkenes without any Added

34 Pages·2012·0.56 MB·English

FULL PAPER
DOI:10.1002/chem.201103252
Initiation of Radical Chain Reactions of Thiol Compounds and Alkenes
without any Added Initiator: Thiol-Catalyzed cis/trans Isomerization of
Methyl Oleate
Ursula Biermann,[a] Werner Butte,[a] Rainer Koch,[a] Patrice A. Fokou,[b] Ogˇuz T(cid:2)r(cid:2)nÅ,[c]
Michael A. R. Meier,[c] and J(cid:2)rgen O. Metzger*[a]
Abstract:Akineticstudyofthedodec- thiol1togiveastearylandasulfuranyl culated that the activation energy of
anethiol-catalyzed cis/trans isomeriza- radical through molecule-assisted ho- the isomerization was in good agree-
tion of methyl oleate (cis-2) without molysis (MAH) of the sulfur–hydrogen ment with the experimental result of
added initiator was performed by fo- bond. Fragmentation of the latter gives E =82kJm(cid:2)1. Overall, the results may
A
cusing on the initiation of the radical the thiyl radical, which catalyzes the explain that the thermal generation of
chain reaction. The reaction orders of cis/trans isomerization. A computation- thiylradicalswithoutanyinitiatorisre-
the rate of isomerization were 2 and al study of the EDA complex, MAH sponsible for many well-known ther-
0.5 for 1 and cis-2, respectively, and an reaction, and the sulfuranyl radical cal- mally initiated addition reactions of
overall kinetic isotope effect k /k of thiol compounds to alkenes and their
H D
2.8 was found. The initiation was respective polymerizations and for the
Keywords: isomerization · methyl
shown to be a complex reaction. The low shelf-life stability of cis-unsaturat-
oleate·molecule-assistedhomolysis
electron-donor/-acceptor (EDA) com- ed thiol compounds and of mixtures of
(MAH) · radicals · renewable re-
plex of dodecanethiol (1) and cis-2 alkenesandthiolcompounds.
sources
formedinapre-equilibriumreactswith
Introduction thiyl radicals.[4] These studies support the mechanism in
Scheme1; however,side reactions are also atwork and give
Thecis/transisomerizationofunsaturatedfattyacids,thatis, the same products but change the rate of reaction. Thus, for
oleic acid of lipids, in biological systems is of great impor-
tance.[1] Chatgilialoglu etal. showed that thiyl radicals are
among the most efficient isomerizing agents and studied in
detail the kinetics of the cis/trans isomerization of oleic acid
of phospholipids and methyl oleate with thiol compounds
occurringinaradicalchainreaction.[2–4]Thereactionwasin-
itiated by either the thermal decomposition of azo com-
pounds,[2] g-irradiation,[2,3] or photochemically generated
Scheme1.Thiyl radical-catalyzed isomerization of mono-unsaturated
fattyacidmethylesters.[2–4]
[a] Dr.U.Biermann,Prof.Dr.W.Butte,Dr.R.Koch,
theratherhighthiolconcentrationsof0.30and0.93m,blank
Prof.Dr.J.O.Metzger
InstituteofPureandAppliedChemistry experiments on nonirradiated samples showed some isomer-
UniversityofOldenburg,Carl-von-OssietzkyStr.9–11 ization. This outcome indicates “an unknown additional
26129Oldenburg(Germany)
thermal generation of thiyl radicals”, which could be of im-
Fax:[phone]
portanceinbiologicalsystems.[3]
E-mail:[email protected]
Theradicaladditionofthiolcompoundstoalkenesinitiat-
[b] Dr.P.A.Fokou
UniversityofAppliedSciencesEmden/Leer ed photochemically or thermally with radical initiators is a
FachbereichTechnik,NaWaRo well-known and intensively studied reaction.[5] It is well
Constantiaplatz4,26723Emden(Germany) known that certain thiol/ene mixtures are quite thermally
[c] O.T(cid:2)r(cid:2)nÅ,M.A.R.Meier unstable at room temperature, and many studies on the re-
KarlsruheInstituteofTechnology(KIT) lated shelf-life stability are available.[6] However, only very
InstituteofOrganicChemistry
few investigations on the initiation of this dark reaction
Fritz-HaberWeg6,76131Karlsruhe(Germany)
have been reported. In the 1980s, Nuyken etal. studied the
SupportinginformationforthisarticleisavailableontheWWW
underhttp://dx.doi.org/10.1002/chem.201103252. veryefficientthermallyinitiatedradicalpolymerizationof3-
Chem.Eur.J.2012,18,8201–8207 (cid:3)2012Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim 8201
and 4-vinylbenzenethiol and dithiol compounds with dienes Becauseamoleculethathasanalkylchainwithacis-con-
anddiyneswithouttheadditionofanyspecialinitiator.[7]Ki- figured double bond and a thiol functionality should not be
netic evidence was found for the molecule-assisted homoly- stereochemically stable, we wondered about cis-octadec-9-
sis (MAH)[8] of the S(cid:2)H bond as an initiation reaction. The enethiol,whichiscommerciallyavailableandis“assignedto
activationenergyoftheaddition ofthiophenoltostyreneas prepare disordered self-assembled monolayers that may
a model reaction was E =65kJm(cid:2)1, which was in good have a significant influence on the fluidity of supported
A
agreement with the calculated activation energy of the bi- liquidmembranes.”[22]
molecular reaction of thiophenol and styrene to give a thiyl The question is open as to how the dark reaction of radi-
and a 1-phenylethyl radical as an initiation reaction caladditionreactionsofthiolcompoundstoalkenesandthe
(Scheme2).[9] Klemm and Sensfuß observed the formation thiol-catalyzed cis/trans isomerization of cis-alkenes ob-
served by Chatgilialoglu etal.[3] may be initiated without
any added initiator. To answer this question unambiguously,
we performed a kinetic and computational study of the
thiol-catalyzed thermal isomerization of methyl oleate be-
Scheme2.Radicalformationbyabimolecularreactionofathiolandan cause the isomerization reaction is much simpler than the
alkene,amoleculeassistedhomolysis(MAH).[9]
addition reaction and has been studied kinetically in
detail.[2–4]Mostimportantly,thereisnohydrogentransferin-
of an electron-donor/-acceptor (EDA) complex of a thiol volved in the isomerization reaction. Thus, we could have a
and alkene in solution by UV spectroscopic analysis and chance to verify or exclude unambiguously initiation
postulatedtheformationofathiylandanalkylradicalfrom through MAH[9] by performing an appropriate experiment
thisEDAcomplex(Scheme3).[10]Thisresultisequivalentto onthekineticisotopeeffectk /k .
H D
the MAH reaction postulatedby Nuyken etal.[9] EDAcom-
plexes of thiol compounds and alkenes have also been stud-
iedby1HNMRspectroscopicanalysis.[11] Results
In preliminary experiments, we treated dodecanethiol (1)
with methyl oleate (cis-2) in a ratio of 1.1:1 without a sol-
vent at 1188C (Scheme4). Analysis of the reaction solution
Scheme3.Radical formation via a EDA complex of a thiol and an
alkene.[10]
InitiationofradicalchainreactionsbyMAHormolecule-
induced homolysis[12] have been reported previously, for in-
stance, the thermal initiation of styrene polymerization
through the deMayo mechanism,[13] the thermally initiated Scheme4.Dodecanethiol-catalyzedisomerizationofmethyloleate(cis-2)
tomethylelaidate(trans-2).
additionofalkanestoalkenes[14]andalkynes[15](i.e.,theane
reaction), uncatalyzed transfer hydrogenation and transfer
hydrogenolysis,[16]andthethermallyinducedredoxreactions after 22hours showed a [trans-2]/ACHTUNGTRENNUNG[cis-2] ratio of 2.89:1. The
of carbonyl compounds and alcohols[17] fall into this catego- concentration of thiol 1 and the total concentration of cis-2
ry.Itmaybementionedthatthissimpleelementaryreaction and trans-2 was approximately constant over the reaction
of two closed-shell molecules to give two radicals, which is time. Only very small amounts (i.e., <5%) of the addition
the reverse reaction of the well-known disproportionation products methyl 9- and 10-dodecanethiylstearate were
reactionoftworadicals,hasnotfoundanentranceintotext- formed.Tracesofdidodecyldisulfide(7),theexpectedtermi-
booksandhasbeenremainedratherunknowndespitebeing nation product of the radical chain reaction, were also de-
suggestedabout50yearsago.[18]Recently,Mayerintroduced tected. The ratio of [trans-2]/ACHTUNGTRENNUNG[cis-2] at 898C was 0.83:1 after
a generalized concept for hydrogen-atom transfer (HAT) 24hours. The addition of AIBN as an initiator showed a
that included MAH reactions with a Marcus theory ap- [trans-2]/ACHTUNGTRENNUNG[cis-2]ratioof4.28:1after15minutes.
proach.[19] Moreover, we studied the stereochemical stability of cis-
Theradicaladditionofthiolcompoundstoalkeneshasat- octadec-9-enethiol. A commercial sample[22] was used, and
tracted renewed interest as a “thiol/ene click reaction” be- the ratio of the trans and cis isomers, determined by GC
cause of quantitative yields, rapid reaction rates, mild reac- after arrival of the sample, was 0.98:1. At room tempera-
tion conditions, and compatibility with water and oxygen.[20] ture, the isomerization reaction continued (Scheme5). The
It has been demonstrated recently that mixing thiol and [trans]/ACHTUNGTRENNUNG[cis] ratio was 4:1 after 10days and the final ratio of
methyl 10-undecenoate, a renewable 1-alkene, gave the ad- 5.9:1 was obtained after about 38days (see FigureS1 in the
dition product quantitatively without the use of an initiator Supporting Information).[23] Chatgilialoglu etal. gave a
andundersolvent-freeconditions.[21] rather similar equilibrium ratio of 5.15:1 at room tempera-
tureformethyloleate.[4]
8202 www.chemeurj.org (cid:3)2012Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim Chem.Eur.J.2012,18,8201–8207
RadicalInitiationofaThermalThiol-CatalyzedIsomerizationReaction FULL PAPER
Scheme5.Isomerizationofcis-totrans-octadec-9-enethiol.
The kinetic investigation of the isomerization reaction
was performed by mixing the substrates thiol 1 and cis-2,
both freshly distilled under nitrogen, at room temperature
under nitrogen without any solvent. A homogeneous solu-
tionwasobtained.Theisomerizationreactionwasstudiedat
89,98,108,and1188Cbyusingamixtureof1andcis-2with
concentrations of 1.6 and 1.5m, respectively, at room tem-
perature in which the temperature dependence of the con-
Figure2.Rate of isomerization of cis-2 at 1188C: Dependence on the
centration of 1 and of cis-2 was taken into account (see Fig-
concentrationof1andcis-2.
ureS2 in the Supporting Information).[24] Two experiments
at each temperature were performed in two reactors in par-
allel. The ratio of [trans-2]/ACHTUNGTRENNUNG[cis-2] was determined by GC
analysis. The rate of isomerization r was constant over the
is
studied range of conversion (Figure1). Additionally, the de-
Figure3.Arrhenius presentation of the temperature dependence of the
rateconstantk givesE =82kJm(cid:2)1andA=2.0(cid:4)106m(cid:2)1.5s(cid:2)1.
exp. A
Figure1.Rate of isomerization of methyl oleate (cis-2) to trans-2 cata-
lyzedbydodecanethiol([cis-2]/[1]=1:1.1)at89,98,108,and1188C.
pendence of the rate of isomerization on the concentration
ofthereactantswasstudiedat1188Cbyusingmixturesof1
and cis-2 with concentrations of 3.1 and 0.49m and 0.4 and
2.28m, respectively (see Figure2 and Table S1 in the Sup-
portingInformationfortheresults).[23]
Evaluationofthedependenceoftherateofisomerization
on the concentration of 1 and 2 (Figure2) gives rate Equa-
tion(1) with rate constant k . The second reaction order
exp
for thiol 1 and 0.5 reaction order for cis-2 seems to be re- Figure4.Kinetic isotope effect: Rate of isomerization of cis-2 (0.96m)
markable. Furthermore, monodeuterated dodecanethiol catalyzed by thiol 1 (3.1m) and D-1 (3.1m), respectively (r =1.56(cid:4)
is,1
C12H25SD (D-1) was reacted at 1188C by using a mixture of 10(cid:2)4s(cid:2)1;ris,d-1=5.5(cid:4)10(cid:2)5s(cid:2)1).
D-1 (3.1m) and cis-2 (0.49m) to give r =5.5(cid:4)10(cid:2)5s(cid:2)1.
is,D-1
The experiment was performed in parallel with 1 to give
r =1.56(cid:4)10(cid:2)4s(cid:2)1 (Figure4), thus revealing an overall ki- The temperature dependence of k (Figure3) gives the
is,1 exp
neticisotopeeffectk /k of2.8. Arrhenius equation [Eq.(2)] (where E =82kJmol(cid:2)1 and
H D A
A=2.0(cid:4)106m(cid:2)1.5s(cid:2)1).
dð½t-2(cid:3)=½c-2(cid:3)Þ
ris ¼ dt ¼kexp½1(cid:3)2½2(cid:3)1=2 ð1Þ logkexp ¼6:3(cid:2)4285=T ð2Þ
Chem.Eur.J.2012,18,8201–8207 (cid:3)2012Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim www.chemeurj.org 8203
J.O.Metzgeretal.
Computational results: We performed DFT calculations
withthenew dispersion-corrected functional B97D.Thisap-
proach and several others have been developed with an im-
proved description of weak van der Waals interactions in
mind.[25] The suitability of B97D for the given problem has
beenevaluatedextensively.[26,27]
The structures for all the compounds shown in Scheme6
have been optimized and their relative enthalpies deter-
mined. Spin contamination does not play a significant role
in all the structures with unpaired electrons.[28] (The com-
plete results are compiled in Table S2 in the Supporting In-
formation).
Figure5.Energyprofileoftheinitiationreaction.
However,allthecalculatedenergiesof9-4and10-4differby
aslittleas3kJm(cid:2)1, sothatallthereportednumbersreferto
theradicalatthe10position.Thefragmentationofsulfuran-
yl radical 5 to thiyl radical 3 and thiol 1 is calculated to be
an endothermic but exergonic reaction (DH =19.4kJm(cid:2)1
R
andDG =(cid:2)31.1kJm(cid:2)1at1008C).
R
Scheme6.Radicalchainmechanismofthethermalisomerizationofcis-2
Discussion
catalyzedbythiol1.InitiationbyMAHofthiol1andtheEDAcomplex
of1andcis-2 formedinpre-equilibrium(reaction0)togivealkylradical
4andsulfuranylradical5inreaction1. Chatgilialoglu etal. showed that the thiol-catalyzed rate of
isomerization of cis-2 to trans-2 is directly proportional to
the steady-state concentration of thiyl radical 3 [Scheme1;
The enthalpic difference between cis-2 and trans-2 is cal- Eq.(3)].[2–4]
culated to be 3.8kJm(cid:2)1, which is about 1kJ lower than the
experimental results[3] and calculations by Chatgilialoglu dð½trans-2(cid:3)=½cis-2(cid:3)Þ kZkEþkEkZ
r ¼ ¼ a f a f ½3(cid:3)¼k ½3(cid:3) ð3Þ
etal.[4]TheEDAcomplexof1andcis-2isformedthrougha is dt kEkZ is
f f
hydrogen bond from thiol 1 to the electron-rich double
bond of cis-2 (see FigureS3 in the Supporting Information) The rate of the isomerization of the thermal reaction has
and possesses a reaction enthalpy of DH =(cid:2)39kJm(cid:2)1, but a reaction order of two and 0.5 for thiol 1 and cis-2, respec-
R
is endergonic because of entropic reasons. The reaction en- tively, thus giving the first evidence that both substrates are
thalpyoftheMAHreactionofthiol1andcis-2iscalculated involved in the initiation reaction of the radical chain and
tobe191kJm(cid:2)1.Incomparison,thereactionenthalpyofthe the formation of thiyl radical 3. Moreover, the kinetic iso-
MAH reaction of 1 and the EDA complex is determined to tope effect k /k gives ample evidence that a hydrogen-
H D
be 212kJm(cid:2)1. With respect to the substrates, this finding transfer reaction is involved in the rate-determining step of
gives a remarkably small enthalpy ofonly 173kJm(cid:2)1consid- theinitiationreaction.
ering the exothermic formation of the EDA complex To obtain more detailed information on the initiation re-
(Figure5). The activation energy of the MAH reaction is action,wecheckedthereactionorderforbothsubstratesex-
approximately equal to the reaction enthalpy because the pected for the initiation reactions suggested in previous re-
activation energy of the reverse disproportionation reaction ports.[9,10] The initiation by alkene-assisted homolysis of the
is approximately E =0kJm(cid:2)1.[14,16,18] The energy profile of S(cid:2)H bond in a bimolecular reaction of thiol 1 and cis-2 to
A
the initiation reaction is given in Figure5. In principle, two give thiyl radical 3 and alkyl radical 4, a MAH reaction as
regioisomeric alkyl radicals 4 with a single electron in the 9 suggested by Nuyken etal. (Scheme2),[9] would give a reac-
or 10 position (9-4 and 10-4, respectively) can be expected. tion order of 0.5 for 1 and cis-2, which is not in agreement
8204 www.chemeurj.org (cid:3)2012Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim Chem.Eur.J.2012,18,8201–8207
RadicalInitiationofaThermalThiol-CatalyzedIsomerizationReaction FULL PAPER
with the experimental results (see SchemeS1 in the Sup- rate-determining reaction step 1 (Scheme6). Interestingly
porting Information). Radical formation through a mono- andasfurther confirmationoftheproposedmechanism,the
molecular fission of the EDA complex of thiol 1 and alkene activationenergyoftheinitiationreactionthroughpre-equi-
cis-2 formed in a pre-equilibrium (Scheme3)[10] gives the librium 0 and reaction of EDA and 1 in reaction step 1
samereactionorderforbothsubstratesandcanbeexcluded (Scheme6) is calculated to be E =173kJm(cid:2)1, which is
A
aswell(seeSchemeS2intheSupportingInformation). about 19kJm(cid:2)1 lower than the activation energy of
The experimentally determined reaction order of two for 192kJm(cid:2)1 of the direct MAH reaction of 1 and cis-2
thiol 1 gives an indication that possibly more than one thiol (Figure5). The late transition state of the MAH reaction
moleculemaybeinvolvedintheinitiationreaction.Itcould gives evidence that no or only a very minor steric effect on
bepossible thattheEDAcomplex of thiol1 andalkenecis- therateofreaction1(Scheme6)canbeexpected.
2mayreactwithanotherequivalentofthiol1inaMAHre-
actiontogiveathiylandanalkylradicalandthiol1.There- (cid:2)k K (cid:3)1=2 1
r ¼k ½5(cid:3)¼k 1 EDA ½1(cid:3)2½2(cid:3)1=2
sulting steady-state concentration of radical 3 and the reac- is is is 2k K
t 3 ð4Þ
tion order of one for 1 was again not in agreement with the dð½t(cid:2)2(cid:3)=½c(cid:2)2(cid:3)Þ
experimentalresults(seeSchemeS3intheSupportingInfor- ris ¼ dt ¼kexp½1(cid:3)2½2(cid:3)1=2
mation).
However, a closer look at the steps in this initiation reac- (cid:2)k K (cid:3)1=2 1
k ¼k 1 EDA ð5Þ
tion showed that radical 3 is not obtained directly in the exp is 2kt K3
MAH step. In the first step, a sulfuranyl radical 5 may be
formed, as shown in reaction step 1, which is the rate-deter- EA;exp ¼EA;isþ0:5(cid:4)EA;1þDH0(cid:4) (cid:2)EA;t(cid:5)(cid:2)DH3(cid:4) ð6Þ
miningstepofScheme6.Therateofisomerizationobtained
for a radical chain reaction (as depicted in Scheme6) is To further confirm the validity of this mechanism, the
given in Equation(4) and is in perfect agreement with the overall activationenergy was determined by applying Equa-
experimental rate given in Equation(1) (see Scheme S4 in tion(6). By using the calculated data in Table S2 (see the
the Supporting Information).[29,30] The rate constant k is Supporting Information; E =212.5; DH(cid:4)=(cid:2)39.2; E =0;
giveninEquation(5). exp DH(cid:4)=19.4kJm(cid:2)1) and EA,1 (cid:5)10kJm(cid:2)1,[305] an actiAva,ttion
A,is
Intramolecular addition reactions of an alkylthiyl radical ener3gy E of about 77kJm(cid:2)1 is estimated, which is in
A,exp
with an additional SH group to give a cyclic sulfuranyl radi- good agreement with the experimentally derived activation
cal have been detected by laser flash photolysis.[31a,b] In con- energyofE =82kJm(cid:2)1[Figure3,Eq.(2)].
A
trast,anintermolecularadditionofsimplealkylthiylradicals The kinetic isotope effect k /k of the rate of isomeriza-
H D
to thiol or thioether compounds has not been directly ob- tion gives clear evidence that the cleavage of the S(cid:2)H bond
served in solution, which can be explained by the unfavora- is involved in the rate-determining reaction step. Equa-
ble equilibrium constantK (Scheme6). In contrast, thesta- tions(4) and (5) show that preferentially reaction 1
3
bilization of alkylthiyl radicals by the formation of sulfuran- (Scheme6), the MAH reaction of the EDA complex and
yl radicals RSS(H)R (R=CH, CH, i-CH, tert-CH) thiol 1, and, possibly to a small extent, equilibria 0 and 3
3 2 5 3 7 4 9
could be shown by photolysis of thiol compounds in glassy (Scheme6) can contribute to the isotope effect of the over-
matricesat77K.[31a,c]Moreover,thereactionofanoctadeca- all reaction (i.e., k /k =2.8). This result gives a kinetic iso-
H D
nethiyl radical with octadecanethiol via a sulfuranyl-type tope effect k /k of approximately 7.8 at 1188C. The ki-
1,H 1,D
radical to give the perthiyl radical was studied within the netic isotope effect of hydrogen abstraction by carbon radi-
channel of a thiol/thiourea clathrate.[32] Remarkably, in the cals from thiol compounds has been reported to be k /k =
H D
example discussed herein, the sulfuranyl radical is directly 1.9–6.6.[36]
formed in the initiation reaction 1 (Scheme6).[33] Thus, the
rateofisomerizationwillbeproportionaltothesteady-state
concentration of sulfuranyl radical 5 and the concentration Conclusion
of thiyl radical 3 will be steered by equilibrium 3
(Scheme6), which is strongly shifted to the right, as known The results of our study of the thermal thiol-catalyzed iso-
from a previous report[31] (see SchemesS4 and S5 in the merizationofcis-2areinagreementwithaninitiationofthe
Supporting Information) and shown by our DFT calcula- radical chain reaction by the formation of an EDA complex
tions(seeTableS2intheSupportingInformation). of a thiol and an alkene compound in a pre-equilibrium re-
The bond-dissociation energy of the S(cid:2)H bond of about action and a MAH reaction of an EDA complex and thiol
366kJm(cid:2)1[34] will be decreased by the MAH reaction of 1 compound to give an alkyl and a sulfuranyl radical. The
andcis-2toabout192kJm(cid:2)1(seeTableS2intheSupporting latterisinequilibriumwiththethiylradical,whichcatalyzes
Information)becauseofthesimultaneousformationofaC(cid:2) theisomerizationreaction.Itcanbeassumedthatthisinitia-
H bond in alkyl radical 4 with the homolytic dissociation of tion reaction can explain the “unknown additional thermal
the S(cid:2)H bond (Scheme2). Additionally, the activation generation of thiyl radicals” reported by Chatgilialoglu
energyoftheinitiationreactionwillbedecreasedbythepri- etal.[3] Moreover, it can be assumed that this reaction is the
mary formation of the stabilized sulfuranyl radical 5 in the initiationreactionofthemany well-known thermally initiat-
Chem.Eur.J.2012,18,8201–8207 (cid:3)2012Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim www.chemeurj.org 8205
J.O.Metzgeretal.
ed addition reactions of thiol compounds to alkenes and sions,andStefanieBaldauffortechnicalassistance.Generousallocation
their respective polymerizations without any initiator. Fur- ofcomputertimeattheCSC(UniversityofOldenburg)isgratefullyac-
knowledged.
thermore, this reaction is the reason for the low shelf-life
stability of cis-unsaturated thiol compounds and mixtures of
alkenes and thiol compounds, thus combining the sugges-
tionsofNuykenetal.[9]andKlemmandSensfuß.[10]
[1] C.Chatgilialoglu,C.Ferreri,Acc.Chem.Res.2005,38,441–448.
[2] C. Chatgilialoglu, C. Ferreri, M. Ballestri, Q.G. Mulazzani, L.
Landi,J.Am.Chem.Soc.2000,122,4593–4601.
Experimental Section [3] C. Chatgilialoglu, A. Altieri, H. Fischer, J. Am. Chem. Soc. 2002,
124,12816–12823.
[4] C. Chatgilialoglu, A. Samadi, M. Guerra, H. Fischer, ChemPhy-
General: Dodecanethiol (1) and cis-octadec-9-enethiol were purchased
sChem2005,6,286–291.
from Aldrich (Steinheim, Germany). Methyl oleate (cis-2; 91.2% oleic
[5] K.Griesbaum,Angew.Chem.1970,82,276–290;Angew.Chem.Int.
acid,3.0%palmiticacid,2.8%linoleicacid,1.9%stearicacid)waspur-
Ed.Engl.1970,9,273–287.
chasedfromT+TOleochemieGmbH(Alzenau,Germany).Compounds
[6] C.E. Hoyle, T.Y. Lee, T. Roper, J. Polym. Sci. Part A 2004, 42,
1andcis-2weredistilledundernitrogenbymeansofaKugelrohroven
5301–5338.
and were stored under nitrogen. cis-Octadec-9-enethiol was used as re-
[7] a)O.Nuyken,M.Hofinger,R.Kerber,Polym.Bull.1980,2,21–24;
ceived.
b)O. Nuyken, M. Hofinger, Polym. Bull. 1981, 4, 75–82; c)O.
Analytical equipment: Analytical GC was performed on a Varian 3400 Nuyken,M.Hofinger,Polym.Bull.1981,4,335–341;d)O.Nuyken,
chromatograph with an flame ionization detector(FID) andfused-silica M.Hofinger,Polym.Bull.1981,4,343–350;e)O.Nuyken,F.Sieb-
capillarycolumnSP2380-FAME(60m;I.D.=0.25mm;dF=0.20mm;Su- zehnr(cid:2)bl, Polym. Bull. 1988, 19, 371–375; f)O. Nuyken, F. Sieb-
pelco).MassspectrawererecordedonaFinniganMAT95spectrometer. zehnr(cid:2)bl, Makromol. Chem. 1988, 189, 541–547; g)O. Nuyken, T.
1Hand13CNMRspectrawererecordedinCDCl3onaBrukerDRX500 Vçlkel,Makromol.Chem.RapidCommun.1990,11,365–373;h)O.
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8206 www.chemeurj.org (cid:3)2012Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim Chem.Eur.J.2012,18,8201–8207
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faster,thusgivingevidencethattheinitiationreaction1maybean Received:October14,2011
intra- and monomolecular MAH reaction; we thank a referee for Revised:February15,2012
thisvaluablesuggestion. Publishedonline:May16,2012
Chem.Eur.J.2012,18,8201–8207 (cid:3)2012Wiley-VCHVerlagGmbH&Co.KGaA,Weinheim www.chemeurj.org 8207
Supporting Information
(cid:2) Copyright Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, 2012
Initiation of Radical Chain Reactions of Thiol Compounds and Alkenes
without any Added Initiator: Thiol-Catalyzed cis/trans Isomerization of
Methyl Oleate
Ursula Biermann,[a] Werner Butte,[a] Rainer Koch,[a] Patrice A. Fokou,[b] Ogˇuz T(cid:2)r(cid:2)nÅ,[c]
Michael A. R. Meier,[c] and J(cid:2)rgen O. Metzger*[a]
chem_201103252_sm_miscellaneous_information.pdf
Supporting Information

Initiation of radical chain reactions of thiols and alkenes
without any added initiator: Thiol catalyzed cis-trans
isomerization of methyl oleate.

Ursula Biermann,[a]* Werner Butte,[a] Rainer Koch,[a] Patrice Fokou[b], Oguz Türünç,[c]
Michael. A. R. Meier,[c] Jürgen O. Metzger[a]

[a] Institute of Pure and Applied Chemistry, University of Oldenburg
Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg (Germany)

[b] University of Applied Sciences Emden/Leer, Fachbereich Technik, NaWaRo
Constantiaplatz 4, 26723 Emden, Germany

[c] Karlsruhe Institute of Technology (KIT), Institute of Organic Chemistry
Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany

1
Contents

Page
1. Tables S1-S3 3
2. Figures S1-S4 7
3. Schemes S1-S5 (Rate of isomerization depending on initiation 9
reaction)
4. Structural information of calculated molecules in Scheme 6 13

2