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40.1.1.5.4.2.2 Method 2: The Hofmann Elimination Reaction

DOI: 10.1055/sos-SD-040-00344

Lawrence, S. A.Science of Synthesis, (200940515.

In contrast to ammonium halides, tetraalkylammonium hydroxides show two pathways of thermal degradation. If no alkyl substituent with a β-hydrogen is present, the hydroxide anion undergoes nucleophilic attack on the carbon of an alkyl residue to give an alkanol and a tertiary amine, e.g. formation of methanol and trimethylamine from tetramethylammonium hydroxide (see HoubenWeyl, Vol. 11/1, p 963). However, if a β-hydrogen is available, elimination of an alkene along with a tertiary amine is a competing process. Normally, mixtures of alkenes and alkanols are formed (Scheme 22).[‌62‌,‌63‌]

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Mee Meeeeee eeeeeeeeeee eeeeeeee (eeeee ee eeeeeeeee eeeeeeee ee ee eee Meeeeee eeeeeeeeee eeeeeeeeeee) eeeeeeeeeeee eeeeeeee eee eeeeeeee ee eeeeeeeee eeeeeeeeeeeeeee eee eeeeeeee eeee eeee eeeeeeeeeeeeeee, eeeeee eeeeeee eee eeeeeeeeeee eee eeee eeeeeeee.[‌88‌] Me ee eeeeeeeee eeeeeeee eee eeeeeeeee eeeeeee eeee eee ee eee eeeeeeeeeeee. Me eeeee ee eeeeeee eeee eeeeee eeeeeeeeeee, eeeeeeee ee eeeeeee eeee eeeeee(M) eeeee eee eeeee ee eeeeee e eeeeeeee eeeee eee ee eeeeee eee e eeeeeeeeee eeeeeeee eeeeeeeee [eee Meeeeee ee Meeeeeeee, Mee. 88 (Meeeeee), eee eeee MeeeeeMeee, Mee. 88/8, e 888]. Meee eeeeeeeeeeeeeeeeeeeeeee eeeeeeeeee eeee eee eeeeeeeee eeeee eeeeeeeeeeee eee eeeeee eeeee eeeeeeeeee ee eee eeeee eeeeeeeeeee eee eeeeeeeee eee eeeee eeeeee. Meee eeeeeeeeeeeeeeeeeeeeee eeeee eeeeee ee eeeee eeeeeee ee ee eeeee eeee eeeeee eeeee, eee eeeeee eeee eee eeeeeeee eeeeee eeee ee eeeeee; eeee eeeeeeeeeee ee eeeee ee eee Meeeeee eeee.[‌88‌] Meee eeeeeeeeeeeeeeee ee eee ee eeee ee eee eeee eeeeee eeeeeeee β-eeeeeeee eeeeee eee eeeeeee eeeeee eeee eee eeeeeeee eeeeee eeee. Meee ee ee eeeeee eeeeeeee ee eeeeee eeeeeeeeeee eeeeeeeee eeeee eee eeee eeeeeeeeeee eee eeee eeeeee eeeeeee ee eeeeeeee (Meeeeee'e eeee). Meeeeeeeeee ee eee-eeeeeeeeee eeee eeeeeeeeeee, eeeeeeee ee eeeeeeeee eeee eeeeee(M) eeeee eeeee eee-8-eee eeeee eeee eeeeeeeeeeeeee (Meeeee 88).[‌88‌]

Meeeee 88 Meeeeeeeeeeeee Meeeeeeee ee Mee-8-eee ee Meeeeee Meeeeeeeeee Meeeeeee[‌88‌]

Mee Meeeeee eeeeeeeeeee eeeeeeee ee eeee eeeeeeeee ee eeeeeeee eeeeeeeeee eee eeeeeeeeeeee eeeeee eee eeee, ee eeeee ee Meeeee 88.[‌88‌,‌88‌]

Meeeee 88 Meeeeeeeeeeeeeeeeee eeee eee Meeeeee Meeeeeeeeeeee ee Meeeeeeeeeeeeeeeeeeeee Meeeeeeeee[‌88‌,‌88‌]

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M8 Meeee (%) Mee
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(MM8)8Me 88 [‌88‌]
(MM8)8Me 88 [‌88‌]
(MM8)8Me 88 [‌88‌]

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Meeeee 88 Meeeeeeeeee-Meeeeeeee Meeeeeeeeeeee ee M,M,M,8,8-Meeeeeeeeeeeeeee-8-eeeeeeeeee Meeeeeeee[‌88‌]

Me eee Meeeeee eeeeeeeeeee eeeeeee eeeeeeeeeeee, eee eeeeeeee ee ee ee eeeeeeee eee eeeee eeeeeeeee. Meeeeee, eeee ee eeeeeeeee eee eee eeeeeeeeeee ee eeeeee eeeeeeeeee eeeee ω-(eeeeeeeeeeee)eee-8-eeee eee eeeeee (eee MeeeeeMeee, Mee. 88/8, e 888).[‌88‌] Me eeeeeeeeeeee eeeeeee ee eee eeeeeeeee ee M,M-eeeeeeeeeeeeeeeee-8,8-eeee-8-eeeee (88) eeee eee eeeeeeee eeeeee 88, eeeee ee eeee ee eeeeeeee eeee 8-eeeeee-8-eeeeeeeeee[8.8.8]eee-8-eee (M-eeeeeeeeeeeeeeeee) eee eeeeeeeeeee eeee eeeeeeeeeee (Meeeee 88).[‌88‌]

Meeeee 88 Meeee Meeeeeee, eee Meeeeee Meeeeeeeeeeee ee eee Meeeeeeee ee M,M-Meeeeeeeeeeeeeeee-8,8-eeee-8-eeeee[‌88‌]

Meeeeeeeeeee Meeeeeeee

M,M,8,8-Meeeeeeeeeeeeeee-8-eeeee (88); Meeeeee Meeeeeeee:[‌88‌]

M,M,M,8,8-Meeeeeeeeeeeeeee-8-eeeeeeeeee eeeeee (88e, 8.88eee) eee eeeeeee eeee eeeeee Me8M ee M8M ee eeee eee eeeeeeeeee eeeeeeeee. Meeee eee eeeeeeee eee eeeeeeee, eee eeeeeeeeeeee MeM eee eeeeeee ee eeeeeeeeee eee eee eeeeeeee eeee eee eeeeeeeeeeee eeeee e M8 eeeeee ee eeeeeeeeeee eeeeeeee. Meeee eeee ee eee M8M eee eeee eeeeeee ee eeeeeeeeeeee, eee eeeeeeee eeeeeeeee eeeee ee eeeeeeeee eee eee eeeeeeeeeee eeee ee eeeeee 888°M. Mee eeeeeeee eeeeee eeee eeeeeeeee ee e eeee eeee eeeeee eeee 8M MMe ee ee eee eeee. Mee eeeeee eeeeeee (8e) eee eeeeeeeee ee e eeee ee 88°M. Meeee eee eeeeeeee eee eeeeeeee, eee MMe eeee eee eeeeee ee eeeeeee eeeee ee eeeeee eee eeeeeeee eeeeeee eeeeeeeeee (MeMM) eee eeee eeeeeeeeeee eeee MeMM eeee eee eeeeeeeeeeee eeeeeeeee. Me8M (8e) eee eeeeeeeee eeeee eeeeeeee ee eee eeee eeeeeeee M,M,8,8-eeeeeeeeeeeeeeee-8-eeeee, eeeee eee eeeeeeeee ee eee eeeeeee eeee; eeeee: 88 e (88%, ee eeeeeeee).

Meeeeeeeeeeeeeeee-8,8-eeee-8-eeeee (88):[‌88‌]

MMMMMMM: Meeeeeeeee, eeeeeeeee, ee eeee eeeeeeeeee ee eeeeeeeeeee eee ee eeeee.

8-Meeeee-8-eeeeeeeeee[8.8.8]eee-8-eee (88.8e, 888eeee), MeM (88e, 888eeee), eee eeeeeeeeeee (888eM) eeee eeeeee ee e 8-M eeeee eeeeeeee ee e eeeeee eeeeeeeee eee eeeeee ee 88°M eee 8e. Meeee eeeeeeee ee eeeeeee MeM (8e, 88eeee), eee eeeeeee eee eeeeee ee 88°M eee eeeeeee 8e. Meeeeeeeee eeeeeeeee e eeeee, eeeeeeeeeee eeee (88.8e). Mee eeeeeeee eee eeeeee eeee MeM (88e, 88eeee) ee 88°M eee 8e eee eeeeeeeeee eeeeeeee eeeeee (8e) eee eeeeeeee ee eeeeeeeeee; eeeee: 88.8e (88%).

Me8M eee eeeeeeee ee eeeeee e eeee ee MeMM (88.8e, 888eeee) ee M8M (888eM) ee MeMM8 (888e, 888eeee) ee M8M (888eM). Mee eeeeeeeeeee eee eeeeee eeeee eeee eeee eeeeee eee eeeee ee e eeeeeee ee eee eeeeeeee eeeeee 88 (88.8e, 8.888eee) eee M8M (888eM) ee e 8-M eeeee. Meeee eeeeeeeeee eeeeeeee eee eeeeeee ee 88°M eee 8e, eee eeeeeee eee eeeeeeee, eee eeeeeee ee MeM eee Me8M eeeeeee eee eeeeee eeee M8M eee eeee eeeeee eeee M8M (888eM) ee 8888°M eeee eeeeeeeeeeee eeeeeee eee 88eee. Meeee eeeeeeeee eeeee, eee eeeeeeee eeeeeeeee eeee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Meeeeee eeeee ee eeeeeeeeee ee eeeeee e eeee ee eeeeeeee eeeeeeee. Mee eeeeeeeeeee eee eeeeeeeeeee ee e 888-eM Meeeeee eeeee eeeeeeee ee e eeee-eeeeee eeeeeeee, eee eee eeeeeeeeee eeee eee eeeeeeeeee (eeee eeee eeeeeee) ee eeeeeee ee e eeee (888888°M/8888Meee). Mee eeeee eeeee ee eee eeeee eeee eeeeee eeee M8M (88eM) ee eeeeeeee eee eeeeeeeee eeeeeeeeee eeee, eee eee eeee eee eeeee eeeeeeeee ee eeeeeee ee eee eeee eeeeee. Mee eeeeeeeee eee eee eeeeeeeee eeee eee M8M ee eee eeeeeeeeee ee eeeeeeeeee eeee eeeeeeee ee Me8M (88eM eee 888eM). Mee Me8M eeeeeeee eeee eeeee (MeMM8) eee eeeeeeeee eeeeeee e eeeeee (88ee × 8.8ee) eeeeee eeee eeeee eeeeeee; eeeee: 88.8e (88%); ee 88°M/88Meee.

References