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Topic: Hofmann Elimination

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	Amine Reactivity
		The tendency of Hofmann eliminations to give the less-substituted double bond isomer is commonly referred to as the Hofmann Rule, and contrasts strikingly with the Zaitsev Rule formulated for dehydrohalogenations and dehydrations.
		To understand why the base-induced elimination of 4º-ammonium salts behaves differently from that of alkyl halides it is necessary to reexamine the nature of the E2 transition state, first described for dehydrohalogenation.
		An elimination reaction, complementary to the Hofmann elimination, occurs when 3º-amine oxides, prepared by oxidizing 3º-amines with peroxides, are heated at temperatures of 150 to 200 ºC. This reaction is known as the Cope Elimination.
	www.cem.msu.edu /%7Ereusch/VirtualText/amine2.htm (2694 words)

	Matic, G., Hofmann, D. et al.; Elimination of immunoglobulin classes by a protein a versus an anti-human ... (Site not responding. Last check: 2007-10-14)
		Matic, G., Hofmann, D. et al.; Elimination of immunoglobulin classes by a protein a versus an anti-human immunoglobulin-antibody based system: evaluation of 602 sessions of extracorporeal immunoadsorption (IA).
		Elimination of immunoglobulin classes by a protein a versus an anti-human immunoglobulin-antibody based system: evaluation of 602 sessions of extracorporeal immunoadsorption (IA).
		Elimination of immunoglobulins by extracorporeal immunoadsorption based on specific binding to either staphylococcal protein A (Excorim) or sheep polyclonal antibodies directed against human IgG (Therasorb) is a meanwhile acknowledged therapy in certain pathological conditions.
	www.dialysis-north.de /papers/abs_matihof.htm (333 words)

	Curly arrows; elimination reactions
		This is elimination, or removal of HX from an alkyl halide.
		In the elimination of 2-bromo-2-methylbutane with a strong, unhindered base such as sodium ethoxide in ethanol, the two alkene products are formed in the ratio 7:3 respectively.
		Hofmann elimination is also favoured by substrates with bulky leaving groups such as Et Me As in substitution reactions, eliminations can occur by a variety of mechanisms, the most common being E2, E1 and E1
	www.abdn.ac.uk /~che545/org/e1.htm (594 words)

	Chapter 22: Hofmann elimination (Site not responding. Last check: 2007-10-14)
		Quaternary ammonium salts undergo an E2 elimination when heated with silver oxide, Ag O, in water.
		The initial steps are an example of the alkylation of an amine by methyl iodide.
		The mechanism of the elimination step is shown.
	www.chem.ucalgary.ca /courses/351/Carey/Ch22/ch22-3-4.html (154 words)

	Elimination Reactions (Site not responding. Last check: 2007-10-14)
		The E2 elimination is a bimolecular process (cf.
		As with SN substitution, E1 elimination processes are favoured by substrates that lead to relatively stable carbonium ions (usually tertiary) and involve very good leaving groups (e.g.
		Elimination reactions are a useful method for the preparation of alkenes from alkyl halides (or tosylates) and alcohols.
	www.nottingham.ac.uk /%7Epczpac1/Intro_BBC/Elim.html (483 words)

	Amines Chemistry Professor - Organic, Inorganic, High School, College, Chemistry Tutor - ChemistryProfessor.com (Site not responding. Last check: 2007-10-14)
		Reduction reactions, substitution reactions, the Gabriel Synthesis, the Hofmann rearrangement and reduction of azides are treated in the section on preparation of amines.
		It is strongly advised that the student have completed the unit on substitution vs. elimination reactions prior to undertaking the study of amines.
		The E2 mechanism for Hofmann elimination using quaternaries is discussed.
	chemistryprofessor.com /amines.htm (572 words)

	E2 Elimination Reaction (Site not responding. Last check: 2007-10-14)
		Base-induced elimination (dehydrohalogenation) of alkyl halides is a general reaction and is an excellent method for preparing alkenes.
		Elimination reactions almost always yield an isomeric mixture of alkenes, where this is possible.
		Under the reaction conditions, the elimination is regioselective and follows the Zaitsev rule when more than one route is available for the elimination of HX from an unsymmetrical alkyl halide.
	www.owlnet.rice.edu /~chem215/ER.html (1187 words)

	Amine - Wikipedia, the free encyclopedia
		Dissolving secondary and tertiary amines using strong acids like HI, HBr, or HCl does not lead to a lower grade amine and an alkylhalide, hence the nitrogen-group is not a preferred leaving group.
		The only kind of successful elimination is the elimination of an alkyl-group from quaternary ammonium salts, the so called Hofmann Elimination
		Because they are basic, amines can neutralize carboxylic acids to form the corresponding substituted ammonium carboxylate salts.
	en.wikipedia.org /wiki/Amine (729 words)

	elimination
		In all E2 cases, the base approaches the substrate and begins to bond with a proton on the carbon (the beta-carbon) next to the one which is attached to the leaving group (the alpha-carbon).
		It is important to remember that there are no reactive intermediates in the E2 reaction, and that important factors like stereochemistry (are the proton being removed and the leaving group antiperiplanar?) and regiochemistry (Zaitsev vs. Hofmann elimination) are to be considered.
		The third type of elimination pathway, the E1-CB is less common than either the E1 or the E2.
	iws.ohiolink.edu /chemistry/organic/elimination.html (564 words)

	Patent 4266087: Process for preparing a myrcenol, cis-ocimenol mixture substantially free of trans-ocimenol
		Q represents ##STR20## and R.sub.3 is an alkyl group of one to eight carbons or a benzyl group; (d) converting said salt to the corresponding E-3,7-dimethyl-7-hydroxy-2-octen-1-yl quaternary ammonium hydroxide of the formula ##STR21## and (e) subjecting said E-3,7-dimethyl-7-hydroxy-2-octen-1-yl quaternary ammonium hydroxide to Hofmann elimination conditions.
		It is the surprising and unexpected finding of this invention that the Hofmann elimination of an E-3,7-dimethyl-7-hydroxy-2-octen-1-yl trialkylammonium hydroxide (also referred to as the 7-hydroxygeranylamine quaternary hydroxide) proceeds to yield a mixture of myrcenol and cis-ocimenol which is substantially free of trans-ocimenol.
		There are a number of methods for running the Hofmann elimination described in the literature and such methods are adaptable to this invention.
	www.freepatentsonline.com /4266087.html (5059 words)

	Media Portfolio
		In the Hofmann elimination, the hydroxide ion abstracts a proton from the least substituted carbon.
		Unlike the Hofmann elimination, the Cope elimination requires the proton and the leaving group to be syn.
		This reaction, called the Hofmann rearrangement, is used to synthesize primary and aryl amines.
	wps.prenhall.com /wps/media/objects/340/348272/wade_ch19.html (2689 words)

	Characteristics of E2 Mechanism
		There is also a strong preference for the Hofmann elimination for certain leaving groups.
		Elimination reactions are often not strictly E1 or E2.
		The E1cB mechanism occurs when L is a poor leaving group and the structure of the substrate has an acidic H. It will be acidic because certain structural features are present that stabilize the conjugate base anion.
	www.ipfw.edu /chem/261/261Fall03/261nt02p.htm (685 words)

	Syllabus on Geriatric Anesthesiology
		Surprisingly, the newer long-acting relaxants, doxacurium and pipecuronium, which still depend on renal mechanisms for elimination from the body, seem to have pharmacodynamics that are unaffected by advanced age.
		Atracurium and cisatracurium, which depend on the kidney only as a secondary means of elimination from the body, do not have a prolonged duration of action in the elderly.
		They are eliminated primarily by Hofmann elimination, which is a temperature and base catalyzed process of spontaneous degradation.
	www.asahq.org /clinical/geriatrics/muscle.htm (632 words)

	Keywords (Site not responding. Last check: 2007-10-14)
		Atracurium is metabolized in blood by the process of Hofmann elimination and by ester hydrolysis.
		Hofmann elimination is a nonenzymatic, pH- and temperature-dependent phenomenon.
		Elimination of laudanosine is almost totally dependent on liver function.
	www.rashaduniversity.com /keywords.html (17861 words)

	1996-3 Q9-16
		onset of 2-4 min; duration of 30-40 min; elimination by ester hydrolysis
		The elimination of atracurium is via ester hydrolysis and ______, which are effected by temperature and _____.
		Two muscle relaxants that are eliminated via plasma cholinesterase (pseudocholinesterase) hydrolysis are _______ and _______; two muscle relaxants that are eliminated largely by hepatic metabolism are _______ and _______.
	www.courses.vcu.edu /ptxed/m2/1996/96-3_q9-16.htm (293 words)

	Chem 266H (Site not responding. Last check: 2007-10-14)
		Be able to propose methods for synthesizing amines by reduction of nitro-cmpds, amides, nitriles, and azides, and methods for preparing the latter two by SN2 chemistry.
		Be able to write the reaction sequence for the Hofmann elimination of ammonium hydroxides (E2, anti) and the Cope elimination or amine oxides (concerted, syn), be able to draw the products.
		Realize that these both go with "Hofmann regiochem" (as opposed to "Saytzeff regiochem"), meaning that the less substituted alkene generally predominates.
	www.people.umass.edu /gjsnyder/Ch19H.html (358 words)

	Chapter 22 : Selectivity of Hofmann Elimination
		The staggered, antiperiplanar alignment is preferred because it aligns the two σbonds that become the π bond.
		Lets' look at the Hofmann elimination and the selectivity of the reaction:
		The CHIME image to the left shows the calculated energy minima of the sec-butyltrimethylammonium compound.
	www.chem.ucalgary.ca /courses/351/Carey5th/Ch22/ch22-3-4-1.html (224 words)

	ORGANIC CHEMISTRY II - CHAPTER 24 LECTURE OUTLINE (Site not responding. Last check: 2007-10-14)
		Hofmann Rearrangement: conversion of primary amides to amines with the loss of one carbon
		The only way seen so far to synthesize a fluorine into an aromatic compound is now introduced.
		The ortho-/para- directing power of the amine groups can be used during a synthesis, and the amine group can be eliminated or replaced in the last steps of the synthesis.
	www.sbuniv.edu /~ggray/CHE3314/cp24outl.html (1191 words)

	Nitrite Elimination and Hydrolytic Ring Cleavage in 2,4,6-Trinitrophenol (Picric Acid) Degradation -- Hofmann et al. 70 ...
		Nitrite Elimination and Hydrolytic Ring Cleavage in 2,4,6-Trinitrophenol (Picric Acid) Degradation -- Hofmann et al.
		Articles by Hofmann, K. Articles by Heiss, G. Applied and Environmental Microbiology, May 2004, p.
		Nitrite Elimination and Hydrolytic Ring Cleavage in 2,4,6-Trinitrophenol (Picric Acid) Degradation
	aem.asm.org /cgi/content/abstract/70/5/2854 (206 words)

	Chemistry Professor - Organic, Inorganic, High School, College, Chemistry Tutor - ChemistryProfessor.com (Site not responding. Last check: 2007-10-14)
		The factors which must be considered to prevent reduce competition between elimination and substitutions reactions, particularly in chain lengthening processes is noted.
		In the reverse of this process, the identification of a polypeptide by sequencing is discussed.
		The series of steps begins with elimination of disulfide linkages, followed by identification of the N-terminus using the Edman degradation with phenyl isothiiocyanate or the Sanger method with 2,4-dinitrofluorobenzene or some similar method.
	chemistryprofessor.com (11707 words)

	Atracurium Besylate detail at IndyaPharma (Site not responding. Last check: 2007-10-14)
		This is consistent with the results of in vitro studies which have shown that TRACRIUM is inactivated in plasma via two nonoxidative pathways: ester hydrolysis, catalyzed by nonspecific esterases; and Hofmann elimination, a nonenzymatic chemical process which occurs at physiological pH.
		The metabolites in bile and urine were similar, including products of Hofmann elimination and ester hydrolysis.
		Elderly patients may have slightly altered pharmacokinetic parameters compared to younger patients, with a slightly decreased total plasma clearance which is offset by a corresponding increase in volume of distribution.
	www.indyapharma.com /Atracurium-Besylate-detail.htm (4182 words)

	Hofmann Elimination
		Chapter 5: Structure and Preparation of Alkenes: Elimination Reactions
		The regioselectivity is opposite to that predicted by Zaitsevs rule
		The staggered, antiperiplanar alignment is preferred because it aligns the two s bonds that become the
	www.mhhe.com /physsci/chemistry/carey/student/olc/ch22hofmannelimination.html (437 words)

	Second Year
		Preparation of carboxylic acids (review: by oxidation of alkenes, aldehydes, primary alcohols, alkylbenzenes, methyl ketones (haloform reaction), by hydrolysis of cyanohydrins and other nitriles, by carbonation of Grignard reagents).
		Preparation of amines : by reductive amination, by acylation-reduction, by reduction of nitro compounds, by nucleophilic aromatic substitution, by direct alkylation of ammonia and amines, by reduction of azides and nitriles, by Gabriel synthesis and through Hofmann rearrangement.
		The synthesis and reactions of b-dicarbonyl Compounds : Acidity of b-dicarbonyl compounds, Claisen condensation (synthesis of b-keto esters), Dieckmann condensation, crossed Claisen condensations : with benzoate, formate, carbonate and oxalate esters.
	www.cmb.ac.lk /temp/new_science/Chemistry/html/second_year.htm (1740 words)

	New Page
		III ; The hofmann degradation of rhoeagenine methiodide M. RozwadowskaJ.
		Ureas from N-Chloroamidines; An Aza-Analogous Hofmann Degradation Sonnenschein, Helmut; Schmitz, Ernst
		Optically Active trans-Cyclooctene from an Asymmetric Hofmann Elimination.
	people.bu.edu /jaylowe/Named%20reactions/H/Hofmann%20degradation/Hofmann%20ref/Hoffman%20ref.htm (462 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		Chemical breakdown by Hofmann elimination is rapid at physiological pH and temperature, whereas
		In addition to the non-enzymic decomposition by "Hofmann Elimination", atracurium may also undergo an enzymic
		Atracurium spontaneously decomposes at physiologic pH via the Hofmann elimination reaction and may also undergo
	www.vrac.iastate.edu /~berleant/MedRep/AE/Acetylchol~Ester.htm (2487 words)

	Hoffmann degradation
		Primary, secondary and tertiary amines are subject to elimination.
		Reaction often takes place at elevated temperatures (100-200 C) and reduced pressures.
		Elimination also follows the Hofmann rule: least substituted alkenes will form preferentially.
	people.bu.edu /jaylowe/Named%20reactions/H/Hofmann%20degradation/hoffmann.htm (174 words)

	[No title] (Site not responding. Last check: 2007-10-14)
		The results are compatible with the working hypothesis that spontaneous degradation of atracurium via Hofmann elimination results in generation of two equivalents of reactive electrophilic
		In vitro and in vivo evaluation of mucoadhesive microspheres prepared for the gastrointestinal tract using polyglycerol
		formed during the first step in Hofmann elimination.
	www.vrac.iastate.edu /~berleant/MedRep/EP/Ester~Propenoate.htm (1863 words)

	Importance of the organ-independent elimination of cisatracurium -- Kisor et al. 83 (5): 1065 -- Anesthesia & Analgesia
		Importance of the organ-independent elimination of cisatracurium -- Kisor et al.
		clearance of cisatracurium due to Hofmann elimination and organ elimination
		The elimination rate constant from the peripheral compartment could not be
	www.anesthesia-analgesia.org /cgi/content/abstract/83/5/1065 (415 words)

	Ege Chapter 22
		Know the mechanism for the Hofmann Rearrangement (16.
		Is a quaternary ammonium salt a good leaving group?
		Which hydrogen is removed in the elimination (E2) step?
	virtual.parkland.edu /kozaneck/chemistry202/objectives/ege_chapter_22.htm (270 words)

	W. H. Freeman Publishers - Organic Chemistry
		Further Reactions of Haloalkanes: Unimolecular Substitution and Pathways of Elimination
		7-6 Unimolecular Elimination: E1 7-7 Bimolecular Elimination: E2 7-8 Competition between Substitution and Elimination: Structure Determines Function
		9-2 Reactions of Alcohols with Strong Acids: Alkyloxonium Ions in Substitution and Elimination Reactions of Alcohols
	www.whfreeman.com /college/book.asp?disc=&id_product=2001003132&compType=TOC (3265 words)

	ACS Organic Division, Organic Reactions--Publication (Site not responding. Last check: 2007-10-14)
		The Hofmann Reaction: Everett L. Wallis and John F. Lane
		Olefins from Amines: The Hofmann Elimination Reaction and Amine Oxide Pyrolysis: Arthur C. Cope and Elmer R. Trumbull
		Preparation of α,β-Unsaturated Carbonyl Compounds and Nitriles by Selenoxide Elimination: Hans J. Reich and Susan Wollowitz
	www.organicdivision.org /orgreact.html (2323 words)

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