Mercuric Acetate reaction

Mercuric acetate, reaction with cyclo-octatetraene, 50, 24 Mercuric oxide, use in oxidation of hydrazones, 50, 28 with 3-chlorocyclobutanecarboxylic acid and bromine to give 1-bromo-... 

Another method of preparing mercuric acetate is the oxidation of mercury metal using peracetic acid dissolved in acetic acid. Careful control of the temperature is extremely important because the reaction is quite exothermic. A preferred procedure is the addition of approximately half to two-thirds of the required total of peracetic acid solution to a dispersion of mercury metal in acetic acid to obtain the mercurous salt, followed by addition of the remainder of the peracetic acid to form the mercuric salt. The exothermic reaction is carried to completion by heating slowly and cautiously to reflux. This also serves to decompose excess peracid. It is possible and perhaps more economical to use 50% hydrogen peroxide instead of peracetic acid, but the reaction does not go quite as smoothly. 

Diuretics. Chlomieodrin [62-37-3] (methoxy(urea)propylmercuric chloride) (8), is prepared ia the same sort of reaction used for chloromethoxypropylmercuric acetate. Ahyl urea is used instead of aHyl chloride, together with methanol and mercuric acetate. The product, after dilution with water and neutralization, is precipitated with sodium chloride ... 

Unsaturation value can be determined by the reaction of the akyl or propenyl end group with mercuric acetate ia a methanolic solution to give acetoxymercuric methoxy compounds and acetic acid (ASTM D4671-87). The amount of acetic acid released ia this equimolar reaction is determined by titration with standard alcohoHc potassium hydroxide. Sodium bromide is normally added to convert the iasoluble mercuric oxide (a titration iaterference) to mercuric bromide. The value is usually expressed as meg KOH/g polyol which can be converted to OH No. units usiag multiplication by 56.1 or to percentage of vinyl usiag multiplication by 2.7. 

In a similar manner to the formation of pyridazines from AT-aminopyrroles, cinnolines or phthalazines are obtainable from the corresponding 1-aminooxindoles or 2-amino-phthalimides. If the relatively inaccessible 1-aminooxindoles are treated with lead tetraacetate, mercuric acetate, r-butyl hypochlorite (69JCS(C)772) or other agents, cinnolones are formed as shown in Scheme 105. The reaction was postulated to proceed via an intermediate... 

The olefin of the Voc group is very susceptible to electrophilic reagents and thus is readily cleaved by reaction with bromine or mercuric acetate. 

Alkynes react with mercuric acetate in acetic acid to give addition products. In the case of 3-hexyne, the product has -stereochemistry, but the Z-isomer is isolated from diphenylacetylene. The kinetics of the addition reaction are first-order in both alkyne and... 

This reagent can also be formed by reaction of bromine with mercuric acetate ... 

The oxidation of amines by mercuric acetate is an old reaction (54) which up until recent years was employed primarily to modify alkaloid structures (55). A systemic study of the oxidizing action of mercuric acetate by Leonard and co-workers led to the development of a general method for the synthesis of enamines from cyclic tertiary amines. An observation made after a large number of compounds were oxidized, but which is worth noting at the onset, is that a tertiary hydrogen alpha to the nitrogen atom is removed preferentially to a secondary a-hydrogen. 

The first compound studied (56) was quinolizidine (41), which can be readily converted to J >-dehydroquinolizidine (42) in 60% yield by the action of 4 moles of mercuric acetate in 5% aqueous acetic acid on 1 mole of the amine. Mercurous acetate precipitates as the reaction progresses at... 

The previous sections have dealt with stable C=N-I- functionality in aromatic rings as simple salts. Another class of iminium salt reactions can be found where the iminium salt is only an intermediate. The purpose of this section is to point out these reactions even though they do not show any striking differences in their reactivity from stable iminium salts. Such intermediates arise from a-chloroamines (133-135), isomerization of oxazolidines (136), reduction of a-aminoketones by the Clemmensen method (137-139), reductive alkylation by the Leuckart-Wallach (140-141) or Clarke-Eschweiler reaction (142), mercuric acetate oxidation of amines (46,93), and in reactions such as ketene with enamines (143). 

Another iminium intermediate that has been proposed is in the mercuric acetate oxidation of amines (46,9J). This reaction is discussed in the... 

Another convenient method for the preparation of tertiary enamines involves the dehydrogenation of saturated bases with mercuric acetate (111-116). A trans-1,2 elimination occurs, which requires an antiperi-planar position of the nitrogen-free electron pair and the eliminated atom. A preferential elimination of the hydrogen atom from the tertiary carbon atom is supposed. Overoxidation can be avoided by adding disodium ethyl-enediaminotetraacetate to the reaction mixture (117). 

Bohlmann (207) reported the reaction of /I -dehydroquinolizidine with methyl vinyl ketone and with propargyl aldehyde forming a partially saturated derivative of julolidine 135 and julolidine (136), respectively. Compound 135 can be prepared also by mercuric acetate dehydrogenation of ketone 137, which is formed by condensation of 1-bromoethylquinolizi-dine with ethyl acetoacetate (Scheme 11). 

The mercuric acetate dehydrogenation of carbomethoxydihydro-cleavacine (177) yields immonium salt 178, which undergoes transannular cyclization to give a mixture of coronaridine (180, R = Et, R, = H) and dihydrocantharanthine (180, R = H, Ri = Et). The reaction is accompanied... 

The dimer of 1-methyl- -pyrroline (39) was obtained by reduction of N-methylpyrrole with zinc and hydrochloric acid (132) and, together with the trimer, by mercuric acetate dehydrogenation of N-methylpyrrolidine (131). J -Pyrroline-N-oxides form dimers in a similar manner (302). Treatment of 1,2-dimethyl-zl -piperideine with formaldehyde, producing l-methyl-3-acetylpiperidine (603), serves as an example of a mixed aldol reaction (Scheme 18). 

The most general method for synthesis of cyclic enamines is the oxidation of tertiary amines with mercuric acetate, which has been investigated primarily by Leonard 111-116) and applied in numerous examples of structural investigation and in syntheses of alkaloids 102,117-121). The requirement of a tram-coplanar arrangement of an a proton and mercury complexed on nitrogen, in the optimum transition state, confers valuable selectivity to the reaction. It may thus be used as a kinetic probe for stereochemistry as well as for the formation of specific enamine isomers. 

The formation of an enamine from an a,a-disubstituted cyclopentanone and its reaction with methyl acrylate was used in a synthesis of clovene (JOS). In a synthetic route to aspidospermine, a cyclic enamine reacted with methyl acrylate to form an imonium salt, which regenerated a new cyclic enamine and allowed a subsequent internal enamine acylation reaction (309,310). The required cyclic enamine could not be obtained in this instance by base isomerization of the allylic amine precursor, but was obtained by mercuric acetate oxidation of its reduction product. Condensation of a dihydronaphthalene carboxylic ester with an enamine has also been reported (311). 

Recently, Kochetkov and Khomutova have reported on the mercuration of isoxazoles with mercuric acetate. The reaction occurs quite smoothly, more readily than for benzene derivatives and results in a 90-100% yield of 4-acetoxymercury derivatives (74) whose structure was proved by converting them to known 4-bromoisoxazoles (75). Under these reaction conditions isoxazole itself is oxidized by mercuric acetate, mercurous salts being thereby produced. 

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