Containers hydrogen bromide

This tetrahydro-derivative, on demethylation by boiling in acetic acid containing hydrogen bromide, yields 6-acetyltetrahydro-a-morphimethine, m.p. 240-2° (vac.), which is hydrolysed by boiling normal soda solution to tetrahydro-a-morphimethine (II. MeO HO), m.p. 206-8° vac.) B. HCl, m.p. 243-9° vac ), — 29-6° (HjO) (Mosettig... 

When 35 was heated in acetic acid containing hydrogen bromide, the tribromide 46 was obtained as a single product in 74% yield. Debromina-tion of 46 with zinc dust in acetic acid furnished the cyclohexene derivative 47, which was converted into compound 48 by osmium tetraoxide hydroxyl-ation and acetylation. The substitution reaction of 48 with acetate ions provided carba-a-DL-glucopyranose pentaacetate (49), which gave the carba-sugar 50 on hydrolysis. ... 

More recently, a facile synthesis of 126 and pseudo-a-L-glucopyranose (137) has been described [32], When the bromolactone 38 was heated with glacial acetic containing hydrogen bromide and subsequently acetylated, DL-(l,3,5/2,4)-2,3-diacetoxy-4,5-dibromocyclohexane-l-carboxylic acid (130) was obtained [31], Resolution of 130 with optically active a-methylbenzylamines provided the enantiomer (131), m.p. 

Steroidal compounds with three potential sites of unsaturation in rings a and b are aromatized on heating at 85 °C with acetyl bromide containing hydrogen bromide, giving the 4-methyloestra-l,3,5(10)-triene (440). The detailed... 

Acetylaminophenylarsine (2-1 parts) is dissolved in 30 parts of methyl alcohol containing hydrogen bromide, and 4 5 parts of bismuth tri-bromide in methyl alcohol added. Addition of ether precipitates a heavy, black powder, decomposed by acids and alkalis. 

Zeehmeister found that commercial acetyl bromide (which contains hydrogen bromide and acetic acid) reacts very rapidly with cellulose, but that the reaction with pure acetyl bromide is very slow. The reactivity of the acetyl bromide increases with the addition of increasing proportions of water, because of resultant hydrolysis. 

Solanidine on hydrogenation in acetic acid in the presence of platinum oxide yields solanidan-3/3-ol (IX) in which the rings A and B are fused in the trans positions. Its epimer, solanidan-3a-ol (XI) is obtainable by reacting the p-toluenesulfonate of IX with potassium acetate. The ketone X, obtainable from IX by Oppenauer oxidation also yields XI when it is reduced catalytically in acetic acid containing hydrogen bromide in the presence of platinum oxide (6, 23, 40, 45). 

Hydrogen bromide may also be prepared by dropping bromine into benzene containing aluminium powder, which acts as a catalyst to the reaction ... 

The acid which comes over is a constant boiling mixture containing about 47 hydrogen bromide (density = 1.46 g cm... 

Treatment of dibromocarbene adduct (43) (Rji, = O) with aqueous methanol containing silver nitrate or perchlorate gives A-homo-estra-1 (10), 2,4a-triene-4,17-dione (45) in 21 % overall yield from the enol ether (42). The exact pathway is not known, but the first step may be formation of a bromo-homo-dienone facilitated by the methoxyl group, which then undergoes further loss of hydrogen bromide involving shift of a double bond by enolization. ... 

The formation of quaternary salts from benzyl halides and related compounds occurs readily and has been known for many years. More recently, Krohnke and co-workers, who have studied the reactions of many heterocyclic quaternary salts, reported the formation of 5 from pyridine and benzylidene dibromide on heating the reactants together for 1 hr at 100°. The salt is sufficiently stable to be recrystallized from methanol containing a trace of hydrogen bromide. Isoquinoline gives a similar salt. 

Robertson et al.261 measured rates of bromination of some aromatic hydrocarbons in acetic acid containing sodium acetate (to eliminate protonation of the aromatic by liberated hydrogen bromide) and lithium bromide (to reduce the rate to a measurable velocity ) at 25 °C, the second-order rate coefficients for 3-nitro-N,N-dimethylaniline and anisole being 14.2 and 0.016 respectively the former compound was thus stated to be about 1012 times as reactive as benzene (though no measurement of the latter rate coefficient, inferred to be 1.33 xlO-11, could be found in the literature) and this large rate spread gives one further indication of the unreactive nature of the electrophile. Other rates relative to benzene were ... 

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