ORGANIC CHEMISTRY 354

ELIMINATION REACTIONS

E1 and E2

KINETICS

STEREOCHEMISTRY

ISOTOPE EFFECT

ELIMINATION

**NUCLEOPHILES ARE ALSO BASES

CH₃CH₂Br + OH^-1 ---> CH₃CH₂OH + Br ^-1

CH₃CH₂Br + OH^-1 ---> CH₂=CH₂ + Br^-1 + H₂O

GENERALLY GET MIXTURES OF ALKENES.

ZAITSEV'S RULE: BASE INDUCED ELIMINATION REACTIONS GENERALLY GIVE MORE OF THE MORE HIGHLY SUBSTITUTED ALKENE. (MORE STABLE ALKENE)

E2 ELIMINATION

SECOND ORDER KINETICS

RATE = K [R-X] [BASE]

DOES NOT HAVE REARRANGEMENTS

STEREOCHEMISTRY

CONCERTED MECHANISM

MECHANISM ANIMATION FROM PROF. IVERSON, U of TEXAS

TRANSITION STATE

CHLOROCYCLOHEXANES!

continued

DEUTERIUM ISOTOPE EFFECT

E1 ELIMINATION

FIRST ORDER KINETICS

RATE = K [R-X]

NO DEUTERIUM ISOTOPE EFFECT

STEREOCHEMISTRY

MECHANISM (NOT CONCERTED!)

REARRANGEMENTS

SUMMARY

METHYL: S_N2.

PRIMARY: GENERALLY S_N2 EXCEPT WITH HINDERED STRONG BASES THEN E2.

SECONDARY: WEAK BASES S_N2 AND STRONG BASES E2.

TERTIARY: NO S_N2. IN SOLVOLYSIS (WEAK BASE), S_N1 AT LOWER TEMPERATURES AND S_N1/E1 MIXTURES AT HIGHER TEMPERATURES. STRONG BASE E2.

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