MPOC Ch8. Forthe aboveelimination 1 7. Dissociation. than C D. If C HID bond is breaking in the RDS Kitshouldbe than KD

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1 MPOC Ch8 KineicisoopeEffec soopeshave he same chemical properies Labeling will no changehemechanism H o Ph Br v ph H D D O D Ph rbr ph u soopes can minimally perurb he rim leadingo a change in An rae KE KD ligh isoope heavyisoope Forhe aboveeliminaion 1 7 Origin Vibraional saes are quanized The lowes energy vibraional sae Zero poin energy 2PE H X D V forceconsan Mr mx.m.noew1e g reduced mass Mx Mmolecule UH Loser1Hisher E vibraion VD Smaller Lower E vibraion Lower 2 PE MorsePoenial Dissociaion µzpe Breaking C H requires less C D 2PE energy han C D f C HD bond is breaking in he RDS Kishouldbe han KD is issues sa EEance

2 Experimens o Sudy Rin Mechanisms Z Z Z Z T N0z N Oz KD pka 8 S 2 H or D pka 5.6 This is a primary LGOy Oxidaion i TO iz Cg lo kbrag Ki 7.2 kineic isoope effec C H C D bond breaks in he RDS Maximum of 8 Lower for early or lae ransiion saes o o H o c i P.T S Hol 1 Ho Cr H o Cri f orange Wih C D he colorchase b bo is much slower M Primark k E Horas l o CT KHA 5.9 green R NMR GL HPLC can all be Used o deermine produc raios o measure KE Secondary Kineicsoope Effec C HC D bonds are close o he reacive sie bu do no break in he RDS Sp's Sp2 in RDS dissociaive Ph i fpn ifiii.us PhfEjf H D H has CP smaller Normal Secondary KE 1 1,4 L KE barrier

3 Sp Sp's in RDS associaive 0 H RDS 11 HCN 11 Ar HD Ar HD ART HD CN CN 0.73 nverse Secondary KE commonly D Fi The ou of plane bending dominaes he secondary ki Hy Hb Dhassmaller us 5 barrier 800cm 1350cm weaker forceconsan Smaller C HC D Gap Bc 8 FCTETS Fbc Oas 8Ts k 0.96 W w Grea LG more Sp3 like X inverse S of OTS Secondary KE BC w more sp2 like T.i Ef c io B normal secondary KE

4 Experimens o Sudy Rin Mechanisms LinearFreeaionships LEER Goal Sudy how subsiuens influence he rae or equilibrium of a rim HammePlos Scale o measure he abiliy of subsiuens o influence he acidiy of benzoic acid x 7 0 ho 7 he X mea or para f 7 0 o o pka 4.21 g HE y me EDG o N 4 TW6 pka 4.48 Y pka Subsiuen parameer o for eachsubsiuen For Ph CO of O ox log K PKa H pka KH when 0 0 X EDG Lessacidichan PhCO when 0 X EWG More acidichan PhCO For PhCO opera ome.la induciveeffec inducive e resonance effec y Ho 0 7 K Rho P Nin KO Using Ph as a reference rxn ha creaes a 0 Chase Compare oher rxn o see if i involves a or 0

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6 O Ar fele Ph Y Ar q B RDS Near Ar p 3 Builds up in RDS o_o puff Ar NK Ph o g A Hl H s pu Nk Ar Ar go Ph O_O Near Ar Ar 101 p 1 S Builds up in RDS NL Ph Ex 6 Esimae K when X NO me o im log 1k Po 1 popo Kx 1000 KH M s MS A non linear plo can indicae change in mechanism or RDS lien Bo Bo 7710

7 i OheroosformechorismDeerminaif Wih EWG he eliminaion becomes he RDS 1 denify all producs 2 nermediaetrapping SEE f 7 rapwih furan Nk 3 Crossover Experimen Use o see if a reacan breaksapar before recombining o give a produc Claisen Rearrangemen Pan.n

8 5 Pah B F oo Experimen a is OT 7 e Xx 6 Mus operae via a CrossoverProducs Concered Mechanism No Formed 4 Sereochemical Analysis Cl be a c Oc by Odb s 0 13 Experimen yes go f en Consisen wih mechanism C Cl Oas S soope Tracing p o Ph p which subsiuen migraed

9 Benzyne n me 6 Radical Clocks e Traps Used o rap a suspecedradical inermediae j j y K 108 s l Newcomb Terahedron l K 109 S i in Ph Ph Ph K 10 s Example Tk z Eo r Ta r r EQyR Naure L Na EOzC R Eoze ri carbene coffee P R 74 R f RMR R

10 Experimens o Sudy Rin Mechanisms 100 Used cyclopropane as a radical rap.o.e T T T T r ou Ph CozE Ph RadicalCaion Trap Newcomb JACS XJR g R g R r 9 Phl home phl home phl me H R H Phl Once p me R