The Thermal Cis-Transisomerization of Cinnamic Acid Catalyzed by Iodine Citation Lotzkar, Harry (1937) The Thermal Cis-Transisomerization of Cinnamic Acid Catalyzed by Iodine. Master's thesis, California Institute of Technology. doi:10.7907/53cg-va67. https://resolver.caltech.edu/CaltechTHESIS:03182025-211218731 Abstract In this investigation, a study was made of the kinetics and mechanism suggested by the kinetics of the iodine-catalyzed thermal conversion of cis-cinnamic acid to trans-cinnamic acid. Berthoud and Urech studied the kinetics of the iodine-sensitized photo-chemical conversion of cis-cinnamic acid to trans-cinnamic acid and proposed a mechanism for it. They found that the reaction rate is given by [Equation. See abstract in scanned thesis for details] They suggested the following mechanism for the photochemical conversion: I 2 + h✓ → 2I C + I → CI CI → TI TI → T + I 2I → I 2 where C and T denote cis-cinnamic acid and trans-cinnamic acid, resp. Structurally, the conversion is represented as follows: [Formula. See abstract in scanned thesis for details] Item Type: Thesis (Master's thesis) Subject Keywords: (Chemistry) Degree Grantor: California Institute of Technology Division: Chemistry and Chemical Engineering Major Option: Chemistry Thesis Availability: Public (worldwide access) Research Advisor(s): Dickinson, Roscoe Gilkey Thesis Committee: Unknown, Unknown Defense Date: 1937 Record Number: CaltechTHESIS:03182025-211218731 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:03182025-211218731 DOI: 10.7907/53cg-va67 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 17071 Collection: CaltechTHESIS Deposited By: Ben Maggio Deposited On: 31 Mar 2025 18:48 Last Modified: 31 Mar 2025 18:53 Thesis Files PDF - Final Version See Usage Policy. 10MB Repository Staff Only: item control page

TEE TEER •' exs-T OF ClN ' lSO lZATlO ,IC AC·· CA'fALTZED :st IOD : . IA lTU? Of 4.fE }"ASAD~ • CAidFOB. OMIY. Th~· .l odtn.~atal7zed thermal c.o•...sion &f eta• e1nnam1e aeid ·tee tr •..· .. ·tnnamte. acid. tn this in1' •t .l g$t-:i on a.. $t,uey· -.v $ $9.de_. of tbe inet les .and the· •• ••• ;,~i1r-l ~m ~ .t.d\ by the kSnet\cs, of ' the· _ iQ~ ~ea.tal.,'s~d t h ~',;•·c on~~tou ~t o:1a,~1nt¼altlc acid. to t~a.ne. etnnamie acfd,. :Berihoud and ·. . _h(l) twUtd \he kJ»et.l a of l 1ij- !od.tne• een~lt·i ~ phot~heud.41 ~erst~ ot els- / c. · ic ac·ia. to- tran$.C:b ma•1~- act and , :; ·o,~sed a mecha:ntum · o r ll. !he,- found. t ·h at- ~h~ ~~-t-ia rale 1 gl..-n by ~he.f' ~sted \he f ollo-1'11ng mecbant • f:S the ;pb.:otru:heintcal on ~-erd,o .. + b..f-,.. !l + l ~ 01 ~ TI ft -?' f 21 ~ -1'.a + l ct -2- .:· t this p@lnt 1 wish t a ckn ewl dge and my app reci · ti~n far the su .=' g- . s ti@ns and xpr ssis tgnce ef Dr. R. G. Dickinson an er wh m this inv sti ~2 ti0n was c ndueted. 53$ Experimental The cie-cinn mic hydrtt gen - reducti @n .cid 'l;a s p repared by the f ph~:mylpr~p i a>l ic · a cid by a methe-d ess nti~lly du@ t The procedure·s fer malt ing phenylpr p i al ie acid . desori bed in V&lWl'le XII 0:f Organic S ynth sea {Wil ey and S ns) . w re u.s ed.. Br1 f- ly , ethyl cinnam t• wa s br0minated and the ethyl c<, , @ -di b r@me- {3 - phenylprepitmat 0btained was r f'l uxe with . lceh@lic pot · sh in which re cti@n -pot · astum phenylpr pi1 te was p r e duc e·d . r n li ber~t ing the a cid fr@m i ta ·s a lt with · dilu:te salphuric a c id, cru.d . p henylprepi lie acid w s btain ."' which was pure f ied by r ec y s tallizati ·n fr m c rb 0n tetr · chlerid . Th e yields f . r t hese prepar- atiens repo rted in Org n io ~yn theses were eb t a ined. The ccll@idal pa ll d iu.m( 3 ) u.sed in ·t he reduction ef the ph ·nylprep i olio a ~id w s prepared by adding 2.6 gr. of palladi1m chloride , di ss@lved in 160 ml. t inin~ jt1st rHhtgh pa ll~di um cb1e rid. @f wa ter c n- hydrt1>cbleric acid t · di sselv e the t@ a 150 ml . seluti s n Gf 1 . 5 gt'". s dium prot albitu1te( 4 ) and s:f a quan tity of s~d ium hydrexid @ slio-htly m re th n that equiva lent te th . palladi um e.hl er ide. The palladiwn chleri de s l'.1ti on v• s ad.d.ed slo il l y with stir- ~ing s• th t the. pall a di um h7dr0xide ferm~d went int3 a c@ll oid al s t a te in th • pr ,sencj •1 the p reta lbinate ien wh ic h acts as a pr •tective c0lleid. This s~latien w~ s h e~ ted for two h0urs en~ wa ter b ~th at 60°0. during which -4- tim bydrotr.$n w s bubbled thr ugh it. Th 11 idal solution QS such w s used i n the s abseqaent reduction ef ph~nylprepiolic acid. Since the mcthed u~ed in th pr par tin af the s dium :pr talbinate w s • m@d1:fic td thm 0:f. the m th d by Paal( 4 ), ad tailed d -$C ri pt ien ef the preparation is iven. 60 gr. @f rti ns . e g-g- lbumen, • dded in sma ll w s shak n vdth a s Liti@n o:f 7.5 gr. ef s dL1m hydroxid in 250 ml. of w t r in a 500 ml. flask. hea t den ria ter b The mixture was tn f r ene h@ur u.n ti1 all but a sm- 1.1 residue was dissolved. The s@l · ti®n wan c osl d t red. Dilate , cetic acid was · dd<td t . th a larg evap r~t i n~ dish u.ntil pr~c i pit atien nd fil- s . lu.ti en in f the pr - t 1bin1c 1a.cid w acetic 9cid th n is r~q..1ired fer th ~dd~d beca . s th preci it tl n is pr~talbinic ~cid r.dis . elvcs. fter the mixture vas allowe d -to st. nd for 10 h ur~ se that the hydrsgen sulphid e was v. lved ,, the mixturo was centri- fug ed in 250 ml. bottles~ Th li quid W.iaS pt)'Ul"Od. the pr8talbinic acid packed en th b tt 0m of th ff and bottl s wa .s stirr .f u.p wi th 250 ml . por tiens 0:f w.ater ~nd oentri- :fu.ged a g · in. This pr@ C ilSB w s r pea ted antil th was fr ee fr m ~alts. The p rotalbinic ~cid was dri d by a11cking air thr0ugh 1 t @n a fi 1 t . r •,,sp r - yield w s r lized. cid ..\ bout ZO% In preparing the cell3id · 1 p lladium solution ~ described ab ov. 1.5 r. pret9lbinic a cid was -5add d t T 20 ml. f wat .r ·· nd d.is. e)lve-d by the addit ien 160 ml. eid.. eff ct .the redn.ctien ef ph~nylpr . p i lie f the c@ll idsl p ll~dium s l~ticn WQS , died te 20 ml. of s cli 1.m :ph ny·lp · •pi late 1:iti -n prep •' red by dies lving 6 gr. of ph nylpre i @lic ~aid in · n . quiv 1 nt 0m unt e:f s d i wn hydrexid·• salut i n . 'fh s l at i on cen- taine-d in a · 200 ml . . fl · s , , wa sh~lte:n as hydr gen., measured with ) hen the c l c u.1at~d am -u.nt gas bu.r tte. was..added. &f hydr Ren nee ss ry f r ths hs lf-r8ductien ef the phenylpr~pi @lic int rru.ptQ'!d,. t: cid b d b©on • dded th b . ut 50 minut -s was t"' re cti n . QS qair ~d f3r th~ pr c ss.. S· mewhst m0 e th n th ; eqll.i v 1 .nt , mo ·.m t e:f c., ld dilute sulphuric acid wa s dd9d sl ,wly with ~tiraing. Lh • cis- oinnamic ac i(l lib®ra t9d :fr~ro itg se.lt s perated ss ~n which we~ e xtr~cted with th~r. il T• s~para te the cl@- e@d i um c rb@n r te s0luti@n in .a se·p@ r ter.y funnel .. To the dded qaoeus 1 ve~ c eld dilut s ulphuric a ci d w· s aad the cis~cinnami e aci d li ber•ted frem it s lt aga in. sep • r a t A · $ an ail wh ich waa extr · cted . ith ether. Th namic f ir st pr~ r ~tl sn ef cryrt lline cid w s pr epa r d by by c @nvertin~ th v · p Qr - ting eff th ily. ci s -c innamic • cl d line 1miline salt ( 6 ). T-h t$ th i s-c inether nd cryst 1- ci s-cinn&mlc acid ws.as li b@r ted - 6- fr m it s s lt by addinq o ld dilute hydr chlari c ac id t the aniline s lt s~spend din littl~ wat r . ft mi xt:ire was filter d and the ci s - c inn"' m.ic The ci d w s re- hem lting-peint ~~ the ciscinnmic d id o~t c orrespend t any an® f the thre ci s -cinnsm ic acids but extende-: ov@r • range :frem 48° C .. .; 1 :Pbe yt ld f :er this pr@p.a r • ti 0n. was l w se in s@-cend quantity 0.:f c~-~- -0.inn -mic ~ cid th m@th d w s mad ifi e .d . In this c - sie th. o i l f c i s-cinn • - mic ac id we f r zen with selid c a rben disxid w· s allewed te- m~l t . On repe tin. ,· thi · pr c oss s v ora l tim s parti l ory~t · l1ization ~f th Th -e cis-cinn -.mic a ci d WiUJ pu:rofi ti ana fr -m hst wat r. and t h n oil w s ffected. by tae rs c rys talliz - From 10 rr. tf ph nylpr . p i lie a ci d 3.2 gr~ et ci s- c inn mic a ci d. which had been t~ic r crysta l lized from 100 ml . :p -rt io ns ~f w t ~r, was obtained . Tb~ m lting pe int e! this prep r a t ian W36 net sharp but ext@nded fr om 5880. t e 65 Ce c ryat:i lllz ati n 0f the ei l y ci s -ci nnamtc ei d. When the @il was diss0lved i n h t wa 'ter t0 pr•duc0 a satur~ted s oln.tien and th.e· s0l 1ti 0n c aa l ed, an eunlsi n in wa·ter was f r med.. o o·iua l.esoed tt a0w par t· -1c 1 es fte-r s0me t w•n ty minut""es &f stirr ing and s t- . tl.ed >t e th · bo tt om ef th • @f v@r . th emi nu t :f th, oil cit7,,s~ llin b: ak .r. \ hen a 1 rge quantity cis.-cinrr ic . cid was a'.dd .' ceurpl e te crystallizatien af th t@ the @muls i n, eil pr.rticles 1as effect d.. 1 -7- An alt&gether di fer nt ph n~m n n wes ®b A rve wh r the- ©il w s parti l ly cryst lized as a c ns quenoe of th • fre -e zing p r , c es d Rcri bed ( 46~C.) was in the c a s When w rm wa ter b@ve . dded t e the mixtu.re a :f c ryst ls and wh @le ms ss rev rt d to sa tura ted with th i 1 but· · n <.; 0ling th il, th selut i n., cis-cin n mic acid. an emnlsien was f&rmed frem which ce~ ·l te c rystallizatien f the acid f @llo~ed. Th tr · ns -ci nn mic acid used was E stman's which ha d b en rec ryst ll ized frem ht water. Th i~phene fre b ~nzene w s used. fr m 20 ml . ef b nzene, die selved in 100 ml. ch n~ed th specific o nductivi ty e f th 1 .0 x 10- 6 mhes ta 1.3 x 10- 6 mh s. Th w te r used v. Th . r s i due, f w·t r, w t r fr m s c mm@rci al di still d w• t .;r which ha d be@n r dis ti ll d f r m sp oi f ic c endua t ivity 0f th lka:lin pern • IJ.gan t . The · ter ~t 26eC. was 1.0 x 10- 6 mh -s. Iodine S8l1ti new re pr pared frem Merc~'s i din. A ALYTIC L MEJHOD Te determin the c mpgs i t i en taf a and tr ane -cinnamic :a ci ds dvanta g was t . ken ixt ure ef cisf the fact -Sth t ci s -:-c innanic cid L .. • bGnt fou.r ti rn •s a'S strimg an Gcid ~s tr~ns-cinnamic cid. A graph @f th © srec ific c nductivitigs ~t 25 C. f mixtur e. ©f th - tw@ cid s p rim~ntal d2t. v lues were ch e ked th Th Th s ~}ry1ng fr m 100% cis - cinnamio sp -cific ~and uctivity ef ~nd trans-cinnamic acids w retically. mixtur ~ e,f cis- c· loo.Lated as f ll@ws: L = the ep cific cenductance 0f a mixture tw '1. Cid s. f th 01= nermsl C nce-ntratien ef cis-cinnamic aoid. 02= nermal o@nc ntr - ti-n cl,= a .gr A,: f tr ns-cinnamic acid. e:f itmizatien 0:f cis-cinnam1c qui valent co~ductanc at infinite dilution. Cid. f ci s-ci na~mi c acid ')....-z= equ.ival nt e andu.ctance ef trans-cinnamio acid t infinit th + dilutien. mass actien 1 w. f r e ; cn - cid ~H)(A.1 )_ l lL\1) :: K1 (l) { 2) & 1 d sign t s ci -cinnami c seid m2 design t$3 tTans-cinn mic 8Cid K1 is th K2 is the ienizatien c@nstant f r trsns-einnamic acid i eniz ti©n c nst~nt f , ~ cis-cinnamic a cid ... g .. F r~m th m ss eti n law fer mixtur { 3) ( c 1tC, + Oz <£;:. )G 2 z ( ,0 2 - C2cl.,d ( 4) :: K2 On div iding (3) by (4) hence whence (~~ + C1 - K2)x2 -K1 = By ( 5) 0 similar substituti n -~ th• ab v v .lu . of ol, i n equati . n ( 4) . th·e •qu· t i n (K1 + K2)Y is obtoined wh re y has b · n sub s ti t uted f r ~~ ~ - K2 : 0 ( 6) -10- In s -· lvin _, equati@ns ( 5) and (6) the f ll wing = 1.41 X 10 -4• K1 K2: 3.68 x 10- 6 From the v·alu.e·s •f X and y obt~ i ned in se-.l ving eqtt tieas ( 6} and ( 6) values f ·e r cl., and J, z. are ebtained, vJhich, wh•n substituted in the equation /\., C~c£?,.)...~ + L = C,J.., 1000 1000 permit L te be feund. A,=A~=37 8' In t ble I are shewn the observed and C lc-u.lat $d speei:fic cenduetivities o! mixtures ef c1s- and tranncinnamic aci ds at 25•0. &nd at a tota l c ncentr ,t ien of 0.003!1. and th PE ~ CEN T c 1S - CINNAMIC ACI D c _"resp ind ing value s f ~, and cl~ T.a.13LE I ~. <£2 l_x l03 (cALC-) L"-103 ( OBS-) 0.2206 0 . 2200 100. 0 o..1945 90.0 0.2006 0 . 05-874 0.2114 0 . 2108 80.0 0 . 2085 0.06418 0.2035 0.2025 70.0 0.2167 0.06568 0.1956 0.1 934 60.0 0.2248 0.07011 0.1848 0 . 1838 60.0 0.2343 0.07365 0.1746 0.1 743 40.0 o. 2453 0.07817 0.1,645 0 . 16·41 zo.o 0 . 2574 0.08299 0.1537 0.1637 20 . 0 0.2726 0.08900 0.1424 0.1421 10.0 0.2.893 0.09600 0.1508 0.130 7 0.1048 0.1188 - o._o ( I 0.1188 -11- lfe cer reeti0n wa i mad f e r the s p ci f ic c.· ndactivity v,ater b,e c use c • rb0nic cid which is th the f the c.hief impari ty in atsr is a w@. k •r acid -t han the oinnamic acids. fBE OOXDUOTIVIT'Y CELL · The cell censt nt was OF btain_e d by me su.ring the TO O·OO#N• ,ii, oG>nduct nc s •f selutiens"KOl extending f .r m O. OlW." at 25 0. valu s f .o-r th· ap ecific c0nducti vi ties •f the KCl s lu- Tb ti ens us6d were obtained fr- rn dat-a by Sh dlevsk:y( 6 ). Th• _specific conductivity 0:f th.• water us d was 0.8 x 10-6 mhes. C nc . ef KCl Sp cific c nduotivity af KCl plus that .a sist·a nce Cell ( ·hms) C•nstant f th~ solvent O.Oltf. 0 . 001414! 114.l 0.1608 o. 00511'. 0.0007190 223.5 0 . 1607 0.0021'. 0.000292.~ 648.l 0.1603 o.oour. 0.0001477 Sine 1085 0.1600 th.e r si stance tJ>f the solutions ef ·t h · cinn mic acids was :.r.aund 1000 hms, th c-e ll c@nstant u s d w e 0.1600. -12- C ndi i ons: (a kll c ductivit -~ s we re m su.r d at 25 C • .( b) T:he tet -1 c . ncentr tien .-f the c1nn mic acidll WhcHJ• c n~uctivi ty as t be m. asured vvas o. 003?1. {_c) The at· r 11 ed had specific condacti vi ty f •1. o x 1 o- 6 mhas.• Jd) ALL SOLUT\Ot-lS WERE PRE.PARED AT Z5°C. 1. -20 .m l. ef b nz e were placed. in a 250 ml. velu- metric flask · and the benzene was PllfllP•d off. 100 ml . ef. w t• wss add a t the tl sk and s shak n th r ughly . ?he speci:fic c 9ndu.cti vi ty f the w te.r ch n ed frem 1.0 X 10- 6 mhos. TO l.3X 10-"r-tHOS. 2 .. Th same was r peat d for 20 ml. if b nzen w S2!0.00UJ. in 1 2 . Likewis• th which sp cific c nduc - tiv1 ty ch,mged fr m 1 . 0 x 10-6 te 1.3 x 10-6 mh -s. f b .n zen • ~2,xQ.003lf. 3. In a third axperim·e nt 20 ml. in 1 2 • w re sea). d $:ff in · n ampule whi ch was then h -·atea. for :ffDt1r hours at 130· C. The c@ntents w re t~an.s f rred te the v lu.m tric fl ask a nd th and iodine w r pumped ah kn with 100 ml .. @f b n zen• '• ft r the r sid-u.e w - s ff . wa t r. th "C the w· t r ch ng. d fr$m 1.0 x 10·6 t nd uctivity f 1.3 x 10- 6 mh s . ~ 4. 0.4458 gr. - f cis-ci nnamic ac i d wer dissolved in AT~5°C . 50 ml . ef benz :n e ,. in a oali br t d. ve>·lum•tric fl&ii k t g 1v pipetted t a 0 . 06J. s luti n. ut A 6 ml. p rti n was nd tr ns fcrred t av lwnetric fl ask which 6 ml. ef be·n z ne.zico .005W. in 1 2 . w re add d. -13The benzene and 1 dine w re pumped ·e f:f and the -a cid was diss lved in 100 ml . ef wat r. c endu..ctiv'i ty f th :Ph• sp cific s lutien was 0 .0002191 wh ich c he cks :fairly well wi tb the speci f ie C-G}nductivi t y sf an aqueeus solution c noentr tin f cis-cinnamic ., oid •t a f 0.003N. 'fh r,f-re, the precedu.r i n handling the ci s -cinn mic acid frem the po i nt where it's s lu- tien in benzene is prep -red te the final an~lysis is aat1sfa ct s ry. 5. Bef re th therrr 1 exp ri • nts with c i s -cinn mic i semerizati , n w a c©nsi de r d . tr, ns-cinnamic ac i d 0.4438 gr. ef diss -lved in 50 ml. ef 0~ AT ,!~°C . benzen•Aand 5 ml. por tions and transferr . d t v lume . fit w r pi p tt d &ut unpu.l s approxi mately 15 ml. in In era.rt I\ ch ck th pr ciai {in with hich the s lutien was prepared. the c ~ndactivity ef the acid conta i ned in 5 ml .. f the benzen was m•~·sured as d scri bed. abev . ampules. c nt~ining 5 ml . f)f th ff& s9lu.t1n • ch 0f f . ur sclut i en of th• " eid in b nzene . was add«td 5 ml . ef benz n - ,2..XO.OOBN. fo r differ nt 1 ngths f t i m a t 99 .4 C. in tight va por cbamh r. The c ntent d escrib@d pr vi usly. Thtv :res:ilts ar-e su.mm riz d in t abl e III. rnr light an lys.ed s -14- TABLE III Heating Sp ecific o nduct1vity f th• 0.00-3N. aqu.e us s~ln. cf cinnamic acid (% tr - n.s -einnamic acid) 0 0.0001196- S9.l 5 0.0001199· 98.9 10 0.0001203 98.5 47 0.0001192 99.4 91 0.000119-6 99.l Peried ef (H urs} C mpeaiti n -15- fBEHM+t,L rn~-~r 1. Startin :·'l:b 01' CI$-CJ..N . wi.th the a (• IC CID S@lu.tien t -e the a.di ti ta • :f 1 din cis-ein :uamic acid s lt1ti-· n all ried eat in the d rk e~ in red li~ht except in ae -ling @ff the ampul -s in 2. Th.e wa ter u.sed had a specific conductivity e:f 1.0 x 1-0- 6 mhes. 3. • 11 aqu @us selutiens ©f the cinnQmic acids· w re 0.003N. 4. and the o nduotivi ty me. surem ·n ts @r mad· at 25•c • fter th ~r tr nsf c0ntants f th the vGL.unetri-c flask and th pump d o:ff. th they wer .acids w r discol urod pum:ped •ff ag in. mpul s rd t nd benzene w r i@dine rediaaolve in b nz ne if ith iodine. • nd the benz n• This was repe- te·d until the acids were p rt ctly white. 6 ~ Th exp rim ntal pr@c@ciuro is ide-iatic ~1 with that des:c ri bed under nprel min ry e xp@r i m nts". 6. The hating ~pp~ratus was large t st tube c nt i ning the. censtant b0iling-p0int. liqu.id. larg Ins rted in a rub er st~pper which fitt din th m uth ef th raflu...x .c ondenser. and a br · · s tube in which the a mpule t/iT s /\ pl , c-ed ~ insure thermal e·quili bri't-Ui between the v ·p r ~f th bai1ing liquid and the c n tents a.m~ti.le. th e br·- se tub @f th w s :f.illed with miner l @11. VJ t r w -s u s e :1 f t~ the c ns t - nt t emJHH'tatu.re nbath 1 :ftH: tb@ .s e r · 2cti1»0.s t 99.4• C. and m i-t hyl oell0 s lve nd 122.s•c. n 122 . 2°c. fer those b t, in t emp er ture i s du.et !b0 vari ~t iQa two re -sens ; firstl y, twe di ff r ant fra cti ons .f the methyl cellos ©lve wer and sec @ndly . the b~.d 11:ng- temper& tur e v_ried fr m one c Gns t snt @f used the cell.es lve xper i m@nt te- the la xt. but remained v r the c ottrs • ef ny en -xp rimemt. 7. ifabl - IV i s a swnmary ef the results f er which ne c @rr cti @n wa.s ID''· de f r th benz en • residu.e. while ta ble V c ©r,it inS3 th se r®au.1 ts wi t h th zene resi due c orrection. eff ici~nt @! the Fr m th a ppl ied b n - t emp e~ ~t r o - v r .11 sp ei fi c rea c t ien rate o@nstant the 9v e r :a ll specific r @ncti n r ra te c 0nstan ts !. VII ef t ables IV amd v. specific re. c t i ·n rat th f_ ALL In e lc ulat ing the ev r all c onstQnt, i t • t;.S assumed th t eis-t-r · ns is@m r iza ti n ~-r ~oee s :tir,e t order with respect t tb SOLUTIONS eis-ci rm mio cid c m.centrati ·n. VVf=:Rf. PREPf\RE.D AT i!5°C. 9 -1 7- MOL·,9>i~ l't-1QuA R. CON~- colCCEfli~TIO#I OF CIS OF C l'11afli1"1 IC. i O PIN€ ACIO Tl=M1'- (•c) Ht=ATll'I(, PEit CEIVT" TIME TR/lNS - { liOl>R.S ) c,,.,,,,.,.,c Ac.1JJ 0 o.o 1, ~ ~ te.12.2-~•~ ~re/I]~ ~-30~ :Z-~03 -- 'lf•'l--·c 1 • 0 . 03 0.0016 9 .4 24 12. 4 0 ..00240 /"0.0620 2 0 .03 0.0016 9.4 50 25 ..l 0.00261 0 . 0649 3. 0 . 03 0 . 0015 ~9 .4 100 42 .8 0 . 002~3 0.0628 o.o~ 0.024 99 .4 24 40.l 0.00927 o. 0698 0.0016 122.2 10 31 . 8 0 . 0166 0.0170 . 0.439 o.o~ 0.0015 122.2 36 74.5 0.0169 0 . 0173 o..44'1 7 0 . 03 0.0016 1 22 . 8 19 53.7 0.0176 0 .01 72 0 . 444 8 0 .. 03 0.003 122 . 9 15 56.0 0.0238 0 . 0.2 31 0.422 9 0 .03 0 . 006 122 .. 2 11. 56.2 0 . 0326 0.0334 0.431 10 o.oi 0.012 122.9 5 43. 7 0.499 0 .0484 0.440 11 0.03 0 . .012 122.9 8 59. 5 b.0491 o. 0476 0.433 12 o.oz 0 . 024 122.6 ·6 .6 63.2 0.0668 0.0663 0.428 13 0 .09 0.0015 122.7 8 26.8 0 . 0166 0.0163 0.421 14 0.09 0.006 122 . 8 10 62.5 0 ,. 0321 0.0:313 0.404 1 6 0 . 09 0 .024 12 2 . 4 6.6 60.0 0.0612 0 .0617 0 . 398 I II .I I I IV V VI VII Vlll 4 5 0 . 03 6, ~ -y, --18T ' BLE V "Ol.. 11'-R c•M Co F Cl $ - c,,,,,.,,.,..,c; AC1a MOLA·R CONCINTRADo,t TEMP. ( 0 oF c) MeArlM Ej ·, -efl. CE'N T .rr eArJs,J M £ ( /-fo c/R3) I ~DINE' c,,,,.,,.,.,,,.,c A e1i, 0 o.o JL ~ - 303 1 0.03 0 . 0015 99 . 4 24 13 . 0 0 . 00251 2 0 . 03 0.0015 99 . 4 50 2 5.7 0 . 00258 lt,u.-s- •c. ? . •.• 0 :2 I 'I?.. ti Jl.'1.-S-~ r4 ~- - -""0 -'111 ~ 0.064 9 t0 . 0667 < 3 0 . 03 0 . 0015 99 . 4 100 43 . 3 0 . 00246 0.0636 4 0.09 0.024 99 . 4 24 40.4 0. 00937 0 . 0604 5 0 . 03 0.0015 122 . 2 10 32 . 3 0.0169 0 . 0173 0 . 447 6 0 . 03 0.0015 122 . 2 35 74 . 8 0 . 0171 0.0175 0.452 7 0 . 03 0.0015 122 . 8 19 54 . 1 0 . 0178 0 . 0174 0 . 4 50 8 0 . 03 0 . 003 122 . 9 15 56 . 5 0.0241 0 . 0234 0.427 9 o . 03 0 . 006 122 . 2 11 56 . 6 0 . 03 30 0 . 0338 0.436 10 0 . 03 0 . 012 122 . 9 5 44 . 0 0.0504 0.0488 0 . 444 11 0 . 03 0 . 012 122 . 9 8 59. 8 0.0495 0 . 0480 0.436 12 o . 03 0.024 1 22 . 6 6. 5 63 . 8 0 . 0679 0 . 0674 0.435 13 0 . 09 0 . 0015 122 . 7 8 26 . 7 0 . 0169 0.0166 0.429 14 0.09 0 . 006 122 . 8 10 52 . 5 0 . 0323 0.0315 0 . 406 15 0 . 09 0 . 024 122 . 4 6.5 60 . 1 0 . 0614 0 . 0619 0.399 I II III IV V VI VII VIII \p Cb Expct"im n t n bers l , 2 , 3 , 5, a m.d 6-, and th w re • btain d from th - i rs t p rep:;1r • t -i •n c nd activity curve f cis-cinnamic acid . nd the r - st Jr · obt ined fr m the $ . Coad prep -r tien. Tbs 3g.r ment etwe0-n th r ~11 ts -bt i n d fr0m the twe prep r tia·ns sh ws s me indic ti0n t .h • re i s no i m..t-urity in th - cis-cinn mic a ci d which might aifect the kinetics of th i s mer i z tien. _f tables IV a nd V pr v@s th t the as- C -l umn ? sumpti en , th t the rat f i . · m r i za ti n @f cis-cinn mic acid is fi rs t rd r with rs. c t t ci s -oinn"mic cid whQjn th @ c ncet · t~"ation 0:f the nly v r i bl . i s c &rr .. e; t . th - t the rat i s half-&rd r C lllmn 8 1 th · cenc ent r ~t i•n f th s 1th r@sp -·ct t f ci d is the t bl ssh 'WS th - iodine c nc - . trati n. wher C is th c ncen t r tin e:f t he cis - innamic &Cid cinn mic ae id and i din . mi gh t c~nceivably be 1ie ts th fermstien e fD6, ~ -dii ·d -fJ -ph nyl nr pi@n1c .cid. Th e t -emp~,r . ture c&eff i cie.n t ef th~ speci fie r~ . c·tion rate f r 10 -C. betw n 99.4 8 C. and 1 22 .6 C. i s c•lcula t d as fell@·rV s; wh ,r .e X i s the. t mpera t ure c~ e.f fici ·e nt :for 10 a .. 0.441 is k/ at 122.5 c .. and 0.06 61 i s k' o. 441 0.0651 whea-0 X = x2.31 =· 2. 29 t 99.4 C. - 20Tb · kin tics nth bas i8 f th f th f 11 ~ inJ mech~nism: 21 ( l) I2 ~ ( 2) C + I ~ CI { 3) CI---"> TI (4) TI~ T + I ( 5) 21 ~ wh re C ud T deneto , ois-cinn mica id and tr ns -cinnamic cid. r sp. 12 R • cti$nS 2,3, nd 4 c n b H- C-COOH H-C-COOl-f II +I~ \ H- C - c, H,.. H- c, -Cb HS" -'77' H-C-C OOH I C,Hs-c - H r ~ I When the st~ isnar., nd the i nt rm r .. nt&d etruct- H- C- coot-l II C"Hs- C- H + r I I qwti ns isom riz tin ca~ be explained c o p' und i~t f r tb :1tat i t omiu iodin s t up the f ll o ~ing v lid: (A) ( B} (O} On dding th s thr t (I 2 ) - k5(I) 2 : O 1 • . I : k1 . ;. ~I2l = [K lI2l . wh re IC is th q:1ili bri um constant f r the r c tiom. ( 21) Th• r t e at which th p cia-cinn · mie acid disap- rs is ~ivon by - d~; l. = k:2 ( C )( I) a.ad by r ·pl cing (I) by pr@ssi n ie btained, ~ ( +_2 ) ¼, th• reacti n r~ te ex.-~·<•-i-?\:. x ressly, D} B&wever. if Le cti n (2) is r versible. then .{ • ) WHER.I:: ft~ 1s THE S PECIFIC 1{EACTJON 'RATE COA.JST/:¼1'JT FO'R. TliF REVER,~E '/?.c-,:}c:r'JO>J. qua tien ( B) bee eno~ e and ' i i ! } : kz(C)(I) - ki{cI) - kz(CI) : O wh ne ( CI ) = k~ ( 0 )( I ) (k:2 + k:3) On substituting this v 1 e f ( Cl·) in -q tion '( • ) . F r the phet -cb @mic 1 r acti · n the mechanism is as :f 11 ws: {1) 12 + b-Y-'7" 21 {2} C + I ~ CI ( 3) CI~TI {4) TI-?T+ I ( 6) 2I~I2 I -22- =kz(C)(I ) - k3(CI) = 0 d(Cl) dt.• di~I) : k5(CI) - k4{TI) : 0 wh- en.c e . a.'.Id•1 ng ( ~" ' ', . (B ' }. 2 ktiioI 2 ~ k 0 ( I } : O n • r (I) : nd ( c' ) . [I; For th :phetoch -mic l rea cti ·n (2) _d{ C) = k {C}(I} dt 2 On r p 1 ac i• ng (I. '; by ~11IoI Q u_ 1 ~ k5 (D ) By c rrelating th rates of th v c ti n photechemical and th rmal cis -tr ns- i~om rizatien th f re3cti n (5) and th I2 ~ 2J c .ian be energy of ncti- hat oft action f r · cti· n btained. Fr the ph ot eh~mic l cis-tr ens- isom riz tioa (c!. eqa tien D) ass"'J.ming that tba reiacti&n I 2 +· h-Y ~ 2I ha n t t,mper ture ceeffici·e nt; and fer th-• t h .rmal ci a-trans- lsemeri-z ati B. -23;.. _ 0.441 - (cf,. 0.06bl q11.at ien D) Assume (I ) wh•r• Q 2 i s the energy f reaet i ~a of aetiv tiem ( 2} nd i s a,SJltUned t - be C$nst nt wi th r@speot t tem.p ~r ture. where 5 i s the• -r gy of aoti•atiea •f re ot ien -( 6) and. i s assumed te be c nstant with ~espect to t emperature . (I II) d( lnK) _ 6 H d'? - HT'2 where His the beat f re ction fer the r act i n 12 2I and i s assum d t b eons tsant with resp~ct t t mp0r t ur . On subtr .cti ng (II) fro m (I ) d ln ( k / (Y } 2 5 a:~ and 11 integra tien ln (k2/ {¥i, }ff 2 (k2/~)Tl 2 . 303 X l. 9--88 X 298 . 1 X 308. l ( l.eg l. 31 _ 10 308..l) i1 l eg 298--1 = 4 , 780 cal. On adding (II) and (III} -24dln(k 2 {K) d!r· aRd (l2 n inte~ration /KJ, 4 : 2 . 303 X 1.98://'72.5 X 395.6 (lg 6.'1"/ _ 1 396. 6 2l·o g 3'12 . 5} :: 23. 8·9 0 cal. Tb.er .f re. this Q5 2 - 2 = 4. 780 cal. If ~6 is as . umed to be zer .( the validity ssu.mptien is sh n."n t.h f 11 wing para.gr ph) then Q2 f = 4,780 cal. and AR = 38',. 220 cal. The spectroscepic vala If Q5 fer ~H at O A is 35,200 c 1. =o. with .very c llision f iedin at ms a mole-cu.le of iodine is produoed: 2I~ I2 According to the · inetic theory, the number o:f collisions of iodine stoma second is t o0 c. express ed in mols per litre per 2 73 • 1 wbereo i s the 126.92' ~ colli si on diameter of iodine atoms. The r fite at whicb iodine atoms. combine to :form iodi.ne- I molecu.les is - d( I) , , dt :: O (I) 2 • wher·e C is the speci.fie reaction t"a te con& tant when the concentr -tions are in mol s per litre and the time is in seconds. (7) According to van Vleck's potential curves of the iodine molecule <r can be assi gned the value 6 x 10-8 ems. 273 . .1 126.92 Rsb1nowitz and 10.5 x 1010 ( ood( 8 ) .f ound experimentally that o' = = 1. '73 x 10-lO when the concentrat.io-ns ar e in molecal.es p-e r cubic centimeter) for the re ct ion 1 2I~ 1 2 in hexane. It is assumed thgt the solvent molecules ha ve no. serio as influence on th e ra.te of co·l lisi on ·O f the iod.ine atoms. At le:a st. the reaction rate :to-~ 21--71 _2 is of the same order of magnit·ude in hexane and in carbon tetrachloride in wh1cb solution s th-tl experlmemt·s were p erformed by Rsb1nowi tz and Wood. The probably vale of Q& is zero and the poe. ible value l s nQt gre ter tha n several hundred c-alories . According to the kinetic theory. the number of collisions at temp era tu.re T, expr·asa·ed in mole per cubio cent.imeter pe-r sec-ond. between lllllike· molee ales is z = 1: 0 28.442'10 0 a-::~ • l 2 •~ TMl + ll2 M1M2 where the concentrations o1 an·d c.2 are expresse·d in mols per cnbic centimeter, ~ th e collision: di ameter , is ~nd e Mi and ~ are the masse-s ressed in ordinary molecular we i p-hta. I n applying this formula to re.e.ction ( 2 ·-, Cia + I Cis I, ~ the rate k "{ 1- 2 )½Cis, exp ressed in mol e pe-r ct1bic 0f.mt1mete-r . Q per second, la equ.:al to sZ e ~:tt¥ where S is an "orientation 1{ and st er ic f -a ctor i' . ff:+=· 2 Since K 2 When. the rate is expressed in mols per litre per nour, the -ape eific reaction rate constant k ' : 0.441 at 122.5°c. When the :1t te is e-xp.re sed in mols per cubic centi - eter pe r second, the specific reaction rate constant k II = 0.0038 7. {K is obta.in-e d from the value of .i1 F0 for the REAc-r,oAI I 2 ( g) ~ 2I( g.). or the purpose of this c,-lcu.lation at· 2,5°0 •. is u.s·e.d . It is !\Sau.med that the is the same in benzene . b. F 0 rea ener~y chang-e -27- K (at 122.5°C.) is obtained from the van't Hoff K2 e q t1a• t 1. on -- • ln.--::1 = 1 K. •• log K o 122.5C. K25°c. A u ~H T2 - T1 R( T T 1 2 ) 97.5 = 2.30335X,200 1. 98 8 (298.1 X 395 .6 ) - 6.356 5°c. = 6 .. . K122. _.;;;._;_;._______ 2.27 X 10 K25°c. or K . o . 122 5 0 = (2.98 x 10 - 1 5 }(2.27 x 10 6 ) ~ 6.77 x 10- 9 hen the concentrations a re expres ed in mols per cubic centimeter , the equilibrium constant, K. is equal to a 6.77 X 10-~ 1~ ~8~~.~0--x~- - -_- - - = 2.0~ x 10- v which is the 5 9 3 5 6 2 value to be subst it uted f or K in the equation f or sa;;_G • • • ~ : 4. 57 X 10- 7 . •. s ~ = _________ . ; . o. ; . o,;:; ._3s,;:; ._7.:. . .__ _ _ __ _ __ 148.06 4.57 X 10- 7 X 10 28 • 44 2 7 395 .6(1 26 .92 126.92 X 148.06 _:.o....;.. • 1 4,780 • t - 1.988 X 395 .6 = 5.53 X 10- 23 If the colli s ion di ameter is assc1IDe d to be 10 -7 ems., then the "steric and orientation fact ortt, S , is eq·,ial to 5 . 53 X 10- 9 . -28::. s 1. T-be kinetics of the eis-t.rans isomerization of oinnamic acid a-s studied snd the re:3 ction was :fo ind to be first order ith respect t -o the cie-cinna.Utic acid concentra-- ~ i tio.n snd half order with· reep-e ot to the iodine concen" de _ trat1.on: - dt 2. itJ-1 a 1a1"'ga in.ere se in the . rod11ot of the cis-cinna mic acid ·c-on-ce.nt ation and the iodine concentr tion 'the s.p ecific rea ction r ot e conat nt deo .: rease-d . AT 3. Th.e sJ)ecific rea o:tion rate const nt. is e q,1al to o.44·1A. where the concentrations are expressed in mols :pe.r li-tre and th-e time in hours { = 0.00.387, where the concentrations Qre exp-1... eused in mols per cu.bic c -e ntimeter snd the tLne in seconds . ) 4. The temreratnre coefficient o:f th.e tJp ec1:f1c re ction rate constant between 99.: 4°c~ and 122 .5°c .. i s 2.29 for 10°0. 5. F-rom the phot ochemi o,sl and thermal kinetic da ta of the cis-tr .,n is omeri zation of cinnami c a ci-d the heat of rea ction f ·o r the re _ction Cis + I ~ C1s l was found to be 4. 780 c lol'ies and - the he-a t of reaction for the reaction 1 2•?- 2I was fo.n.nd to be 38, 220 calories. ·.! 6. From the .k :inetio theory collision rate expression the i!.,. value- of sa,:l. ~ f a c-tortt and cT;_ 0 I ~~- ~- c . here S is the " steric a nd o r ientetion 1s the mean collision d.iameter of cds- cinnamic acid and iodine·,. wa s found ·t o be· 5. 63 x io- 2-3 cms. -29- - 1. '.Be-rthoud and Ureeh. J. Ch. Phy., 27. 291 (1930) 2. Paal ttd Hartmann. B . • ~- ~930 (19.09} 3. PBal · and Ambergar·. B ... 311. 1:33 (1904) 4. Paal , B .. 3'6.. 2197 ( 1902} ~ n~. ~. 2515 (.1890} 6~ Shedlovsky, J . . C .. s ., 54~ 1405 ( 1932) 6. Lieberm~nn . '1. v an Vleok. Physic . Rev ., 40_, 644 (1932) 8. Rabinowitz nd Wood. 'f rans. lhara-day Soc •. 32 .. 647 ( 1936)