Download sn1 sn2 e1 e2 cheat sheet and more Cheat Sheet Organic Chemistry in PDF only on Docsity! Substitution and Elimination Reactions Comparative Chart Reaction Structure of RX Reactivity of Nu: Conc. Of Nu: Solvent Stereochemistry SN2 1>2>3 Only this reaction and E2 will most likely react with a primary RX Strong nucleophile favors reaction High concentration of nucleophile favors reaction Aprotic polar solvent favors a SN2 reaction if either of the reactants is charged ex: DMF DMSO Acetone inversion of configuration E2 3>2>1 Major product is more substituted alkene unless *the base is large *the alkyl halide is an alkyl flouride *the alkyl halide contains one or more double bonds Strong Base favors reaction High concentration of base favors reaction Aprotic polar solvent favors a E2 reaction if either of the reactants is charged ex: DMF DMSO Acetone If the reactant has 2 H bonded to the carbon from which a H is to be removed, both E and Z result. The conformers that has the bulkiest groups on opposite sides will be the major product. Anti and syn elimination– if it is cyclohexane, it has to be axial (anti) SN1 3>2>1 Forms a carbocation Not effected by strength of nucleophile but a weak nucleophile favors it by not favoring a SN2 reaction Not effected but low concentration disfavors a SN2 reaction Protic polar favors a SN1 reaction if the reactant is not charged. Ex: H2O, CH3OH, etc. Racemization (with some inversion because of ion pairing) E1 3>2>1 Forms a carbocation Weak base favors E1 reaction by disfavoring E2 reaction Not effected but a low concentration of base favors E1 by disfavoring a E2 reaction Protic polar favors a E1 reaction if the reactant is not charged. Ex: H2O, CH3OH, etc. Bulkiest groups on opposite sides SN Versus E Methyl halide Primary halide Secondary halide Tertiary halide SN2 reaction most favored No Elimination reactions! SN2 when the main reaction is with good nucleophiles/weak bases such as I- and CH3CO2- E2 if you use strong bulky bases such as t-butoxide steric effects SN2 if the main reaction is with weak base or Nu: where Pka of conjugate acid is 11 or less ex: I- or Ch3CO2- E2 if the main reaction is with a strong base or Nu: where Pka of conjugate acid is 11 or greater- , high temperatures and bulky bases increas elimination SN1/E1 are common in reactions with weak Nu: in polar protic solvents like water, high temps favor E1 E2 if Main reaction is with strong bases like OH- and RO- SN1/E1 if main reaction is with a poor Nu: High temperatures favor E1 out of the two.
