Organic Chemistry (UBC Chem 233) Exam Questions and Answers Already Passed Latest Update

Organic Chemistry (UBC Chem 233) Exam Questions and Answers Already Passed Latest Update State the Huckel Rule - Answers continuous, planar rings of conjugated atoms display unusual stability if the number of pi electrons in the conjugated loops is 4n+2 where n is an integer. Reduction - Answers the gain of electrons, loss of double bonds Oxidation - Answers loss of electrons, gain of C-O bonds (or any other electronegative atom) and gain of double bonds (-ene) Bronsted-Lowry definition of acids/bases - Answers acid = proton donor base = proton acceptor Lewis definition of acid/bases - Answers acid = electron pair acceptor base = electron pair donor How do you decide acid is stronger? - Answers Hybridization: sp sp2 sp3 Electronegativity: F O N Cl Br Atom Size: larger = better Resonance pKA if pH pKa what happens - Answers you deprotonate! pKa of strong mineral acids (i.e. HCl, H2SO4, HBr) - Answers pKa= -5 pKa of the hydronium ion - Answers pKa= -3 pKa of Carboxylic Acids - Answers pKa= 5 pKa of phenols - Answers pKa= 9 pKa of ammonium (NH4) - Answers pKa= 10 pKa of water - Answers pKa= 15.74 pKa of methanol and primary alcohols - Answers pKa= 16 pKa of tert-butanol - Answers pKa= 18 pKa of aldehydes and ketones - Answers pKa= ~20 pKa of esters - Answers pKa= 25 pKa of terminal alkynes - Answers pKa= 25 pKa of primary and secondary amines (NH3) - Answers pKa= 40 pKa of alkanes - Answers pKa= 60 Sn2 - Answers Primary and secondary electrophile Need a good nucleophile (no bulk) Backside attack (inversion of stereochemistry) Bimolecular Polar Aprotic solvents E2 - Answers Anti-coplanar formation of H and LG -- formation of a double bond Good base, meh nucleophile Rip off an H... formation of the double bond shoves the LG out More substituted electrophile good, nucleophile bulk not important K-OtBu !!!! PBR3 - Answers Replaces OH group with Br through an SN2 (backside attack -- inversion of stereochemistry) SOCl2 - Answers Replaces OH group with Cl through an SN2 (backside attack -- inversion of stereochemistry) Tosylate - Answers Good leaving group, replaces an OH group by a pseudo-Sn2 reaction (no inversion of stereochemistry) Sn1 - Answers Formation of a carbocation by a good leaving group on a highly substituted electrophile leaving (RDS), nucleophile comes in. E1 - Answers Formation of a carbocation by a good leaving group on a highly substituted electrophile leaving (RDS), good base then rips off an adjacent H and forms a double bond. H2SO4 + H2O , or simply a strong acid such as HCl Electrophile has a C-C double bond - Answers Alkene Electrophilic Addition (with H2O = hydration of alkenes) State Markovnikov's rule - Answers Electrophilic addition to a C-C doulbe bond involves the formation of the more stable carbocation (H's attathed to C with more H's) Lindlars Catalyst AKA Poisoned Catalyst AKA Quinoline, Pd/BaSO4, CH3OH - Answers Reduces alkynes to "Syn" / Z-alkenes REDUCED TO ALKENES ONLY. NOT TO ALKANES NaNH3 or LiNH3 - Answers Reduces alkynes to "Anti" / E-alkenes