2. Provide formulas for the following cmpds: formic acid, acetone, methyl acetate, acetic anhydride O O O O O

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1 CEM263B2 Answers to Prctice Questions for Finl Exm T 1. Descrie the following terms: triglyceride; unsturted ftty cid, protein, peptide ond, Grignrd regent. ester mde from glycerol nd 3 long chin croxylic cids; long, unrnched croxylic cid contining C=C doule onds; high moleculr mss molecule mde y linkge of mino cids; mide ond etween cronyl group of one mino cid nd mino group of nother; compound contining the -MgX group 2. Provide formuls for the following cmpds: formic cid, cetone, methyl cette, cetic nhydride 3. Provide systemtic nmes for the following (no stereochemistry required). C 2 C C 3 3-ethyl pentnoic cid; propyl enzote;,- diethylcetmide; 2-methylcyclopentnecroxldehyde; 2-methylcyclopentnone; -methylcyclopentylmine ( -methylcyclopentnmine) 4. Determine the numer of nonequivlent hydrogens in the following compounds. Apply the letters A, B, C etc. to specify the identity of toms. c e d c 5 2 e 2 C C d 5 c 2 C 3 C 3 c C c Construct splitting tree for proton A in A ow is Pscl s Tringle used in MR? Wht does it predict? When cn it e pplied? used to determine the reltive res under the individul peks ( pek heights ) of n nmr multiplet; pplicle only if the δ vlues of the coupling prtners re resonly fr prt nd if ll coupling constnts involved hve identicl vlues.

2 7. Wht is more rective in cronyl ddition rxns, ketones or ldehydes? Explin. Generlly, ldehydes re more rective; in ketones, the lkyl group (tking the plce of the ldehydic ) is slightly electron donting. Therefore the cronyl C in ketones is less positive nd, consequently, is less ctive in nucleophilic rections. In ddition there is steric fctor: in ldehydes there is less crowding round the cronyl C nd nucleophilic regent hs esier ccess. 8. Wht does the Wolff- Kishner rection do? Wht re the rectnts involved? Wht re the products? it reduces keto to C 2 group; the regents required re 2 2 (hydrzine) nd K (strong se) 9. Consider cetldehyde. Show the structure of products formed y: hydrtion ; cynide ddition; ddition of C 3 Mg; hemicetl formtion in sic methnol; cetl formtion in cidic ethnol C C 3 C C 3 C C 3 C C 3 C C C 2 C 3 C C 3 C 3 C 2 C The Cnnizzro rection occurs only with wht kind of compounds? Give n exmple. Wht re the products in your exmple? rections involving ldehydes without α hydrogens C - C 2 C Cyclopentnecroxldehyde nd cyclohexnone re isomeric. Indicte two (2) MR fetures tht would clerly distinguish one from the other. the ldehyde hs 1 signl (d) t ~ 9 ppm nd 1 complex multiplet t ~ 2.5 ppm; while the ketone hs 4 triplet t ~2.5 ppm 12. Why re croxylic cids more cidic thn lcohols? i. the conjugte se (nion) of croxylic cids is stilized y resonnce ( or negtive chrge is deloclized over severl toms); this is not the cse for the conjugte se of lcohols; ii. the cronyl group, C=, polrizes the djcent - ond, therey fcilitting the relese of 13. Wht products would e otined from the rection of 1-pentnol with the following rectnts:. P 3,. S 2, c. Cr 3, 2, 2 S 4 ; d. PCC.. c. d. C 2 C e. Wht does PCC stnd for? pyridinium chlorochromte, mde from pyridine, & Cr Rnk the following compounds in order of incresing cidity. Explin your nswer. C 3 C 2 C 2 C 2 C 2 C 2 F C 2 C 2 F C 2 F F C F A B C D E A hs no e withdrwing groups, therefore is wekest. Acidity increses s electron withdrwing groups get closer to the cidic group nd s the numer of electron withdrwing groups increses.

3 A nturl product,c 5 10, provides the following spectroscopic dt. IR: 3400 cm -1, 1640 cm -1 MR: δ(ppm): 1.63 (3, s) or c 1.70 (3,s) or 3 C 3.83 (1, s, D 2 exchngele) e C C 4.15 (2,d, J=7z) d d e 3 C C (1,t,J=7z) c Identify the structurl feture responsile for ech ir nd nmr signl. Identify the sustnce, lso cm -1, group; 1640 cm -1, C=C ond 16. List three types of compounds tht hve D 2 exchngele protons. Specify the exchngele proton in ech cse. R R C R lcohols croxylic cids primry or secondry mines 17. Predict the products, if ny, of the rection of cetophenone with. B 4, then 3 ;. Tollens regent; c. C 3 Mg, then 3 ; d. 2 2, K e. C 3, c... d. e. C 3 no rxn C 3 C 3 C 3 C 3 C Wht product is formed if cetone is treted with pyrrolidine ( )?. Also provide the rection mechnism for this rection. B B 19. Wht product, if ny, is formed if C 3 is treted with. (q),. (q).. C C 3 ;. no rxn.

4 C 2 C 2 & C 2 cn oth e prepred from in multistep rections. Show ll steps for ech rection. C 2 C 2 C 2 C 1. B 3 P C / - 3 C 2 C 2 ether Mg C 2 Mg C 2 TF 21. Show -onding etween croxylic cid nd n lcohol molecule. nd mny more 22. Select two croxylic cids with the sme cron skeleton. Which one of your choices is more cidic. Explin. A = C 3 C 2, B = C 2 C 2. B is more cidic ecuse withdrws electrons y the inductive effect which stilizes the conjugte se of the cid. 23. Wht hppens if C 3 C 2 C 2 is treted with D 2. Wht effect does this tretment hve on the nmr spectrum. the cidic will e replced y D; the signl t ~11 ppm will dispper. 24. ow cn you prepre utnoic cid from 4-octene? Zn/Ac C Cr 3 2 S 4 C Show the two generl mechnistic steps involved in cyl sustitution rections. R X u R u 26.. Which re the 4 min cid derivtives we hve discussed in clss? cid hlides, cid nhydrides, esters nd mides X R u X. Which one of these is the most ctive in cyl sustitution rections. Why? cid hlides; they the hve tom ttched to the cronyl C which withdrws electron density from the prtilly positive cronyl C; ( electron dontion y conjugtion is poor ecuse the p oritls of chlorine re lrger thn those of C). Consequently the positive nture of the cronyl C is incresed nd nucleophilic rections re fcilitted.

5 c. Show concrete exmples of how ech of the other 3 cid derivtives cn e prepred from the most ctive one. C 3 C 2 3 C 3 C C C C 3 3 C C 3 3 C C C Wht products re formed when ethyl formte is treted with queous minerl cid? formic cid nd ethnol. Give detiled rection mechnism Why re esters more esily hydrolyzed thn mides? Be specific. The 2 group in mides nd the R group in esters oth donte electrons y the conjugtion effect nd withdrw electrons y the inductive effect. The conjugtive effect is pprox. similr while the inductive effect is greter in esters ecuse of the greter electronegtivity of. Therefore, the positive chrcter of the cronyl C is incresed thus mking nucleophilic rections such s hydrolysis esier. 29. Wht product is formed when X is treted with LiAl 4? 2 C 2 2 "X" 30. rgnize the following compounds in order of incresing cronyl sorption wvenumers 2 highest lowest 31. The Fischer esterifiction rection is n equilirium rection. Indicte two prcticl methods to shift the equilirium towrds formtion of product.. use excess lcohol (i.e., increse conc. of rectnt);. remove the product wter, perhps y distilltion.

6 ow mny protons in re singly ctivted 4, douly ctivted _1_?. Wht is the pproximte pk of this compound? β dicronyl compounds re nerly s cidic s phenols (see dtsheet), certinly more cidic thn lcohols; so let s sy out 10. c. Show the enol isomer which involves the douly ctivted proton. 33. Give n exmple of n ester tht cnnot form n enol ( no romtics, plese). C Wht product will e formed if X is treted with I 2 / -?. C 2 CI 3 "X" 35. Show the mechnism of cidic of romintion of cyclohexnone Show the conjugte se of propnl Wht re suitle rectnts to prepre y n α cronyl sustitution rection. I,. Show the rection steps involved. I C 2 3 C 2 2 C 2

7 c. Show the rection mechnism for the first two steps C 2 I 38. Descrie the rectnts needed to produce y direct lkyltion ; C 2 C 2 LDA - 78 o C C 2 C 3 C 2 I C 2 incl. comments on the specil precutions required. A full equivlent of lithium diisopropylmide ( strong nd ulky se)must e dded to the ester in the first step to convert ll of it to the enolte ( therey preventing isen rxn) t low temperture. Then dd iodoethne for the lkyltion rxn. 39. Give n exmple of simple ldol rection ( rectnts nd products). 2 3 C C 3 C C C C 40. If you tried to prepre C vi the ldol rection wht potentil prolems would you encounter. (Include listing 4 potentil side products) This mteril could potentilly e prepred y mixed ldol rxn, followed y dehydrtion. C C C The prolem is tht, in generl, such rections produce mixture of ldol products s well s multildols s shown in the following. C, C, C, C C...

8 41. Two different cyclic structures re the mjor products if is treted with se. Identify them , 42. Show the rection mechnism for the isen rection ( ester se),using ethyl propnote s n exmple Wht structurl fetures re present in the rectnts tht cn give Michel rection. ne rectnt should e n α,β unsturted keto cmpd, while the other should e the enolte of sturted cronyl compound, mono or douly ctivted.. Give concrete exmple incl. product Show the rection sequence of how cn e prepred y the Roinson nnultion rection. C 2

9 Compre the sicity of C 3 C Which is most sic _ethnmine_, which lest pyrrole_. Explin. Pyrrole is the lest sic ecuse the lone pir is tied up in the romtic system. In niline the lone pir is deloclized into the ring system. In ethnmine the lone pir occupies n sp 3 oritl ( well exposed) which mkes them more ville for interction with cids. 46. Complete the following rection equtions (C 3 ) 2 C 3 C 2 (C 3 ) 2 C 3 C C 3 C 2 LiAl ow mny different ses re present in DA? 4 Give generl description of these ses. heterocyclic mines with 1- or 2- ring systems 48. Wht re the three generl uilding locks present in nucleotide. phosphte ester, deoxyriose (5 C sugr) nd heterocyclic mines. 49. Show the cis nd trns configurtion of -methylpropnmide ( hint: mide ond). the resonnce structure with C, doule ond contriutes significntly to the structure of mides; therefore they cn hve cis nd trns configurtion trns: C 3 C 3 cis: C 3 C 3

10 50. Show the enoltes ( incl. resonnce structures ) for the following compounds. ow cn these enoltes e prepred? C C c. no enolte cn e formed since this cmpd hs no α hydrogen. d. is less stle For. nd. we need strong se such s 2 - to convert most of the cmpd to the enolte; while for d. - is strong enough, since it is douly ctivted. Consult pk tle. 51. Show the rection sequence for the preprtion of the following y Dieckmnn rection? C 2 C 2 C 2 C 2 C 2