OCHEM I Final

Determining the best resonance structure

structure w more bonds, minimal charge (preferably neutral) or the negative charge is placed on the most e-neg atom or larger atom, more substituted to hold positive charges (tertiary), less substituted to hold negative charges (secondary)

acid strength increases when

pka decreases

base strength increases when

pka increases

equilibrium favors

less reactive, less acidic, larger pka, more stable

Four stabilizing effects of a conjugate base

resonance, inductive effective, hybridization, charge

Meso Compounds

even # of chiral centers, plan of symmetry, achiral

Zaiseff product

comes from a good leaving group and a small base

weak nucleophile/base

h2o, ch3oh, ch3sh

strong nucleophile/base

HO-, RO-, H2N-, Li, MgBr, R3N

Strong Nucleophile

CN-, N3-, RS-, R3P, R3P, R3N, PH3

Bulky Bases

t-BuO or LDA

When would a hydrohalogenation reaction have no racemic mixture products

no racemic mixture products come from when the carbon does not have a chiral center

Oxymercuration Demurcuration SRR

Stero: Anti

Regio: Mark

Rearr: None

Oxy-Demur Reagents

1. Hg(OAC)2, H2O

2. NaBH4

Oxymer-Demer

Hydroboration Oxidation SRR

Stero: Syn

Regio: Anti Mark

Rearr: none

Hydroboration Oxidation Reagents

BH3/ THF, OH-, H2O2, H2O

Hydroboration Oxidation

Halogenation SRR

Stero: Anti

Regio: none

Rearr: none

Halogenation

Halohydrin Formation SRR

Stero: Anti

Regio: Mark (OH on more substituted C)

Rearr: None

Halohydrin Formation

Acid Catalyzed Hydration SRR

Stero: Mix

Regio: Mark

Rearr: Yes

Acid Catalyzed Hydration

Syn Diol Addition no mechanism required SRR

Stero: Syn

Regio: none

Rearr: none

Syn Diol Addition

Oxidative Cleavage mechanism

cleaves a double bond to make aldehydes, ketones or carboxylic acid

Oxidative Clevage

Semi Hydrogenation (Syn) SRR

stero: syn

regio: none

rearr: none

Semi hydrogenation syn

Semi hydrogenation (anti) SRR

stero: anti addition

regio: none

rearr: none

Semi hydrogenation anti

Markovnikov’s Rule

addition of a protic acid to an unsymmetrical alkene, the halide will add to the carbon with less hydrogen atoms. the hydrogen will go on the carbon with more hydrogen atoms