In alkaline medium

The general pattern of alkylation of 2-acylaininothiazoles parallels that of 2-aminothia2ole itself (see Section III.l). In neutral medium attack occurs on the ring nitrogen, and in alkaline medium a mixture of N-ring and N-amino alkylation takes place (40, 43, 161. 163). In acidic medium unusual behavior has been reported (477) 2-acetamido-4-substituted thiazoles react with acetic anhydride in the presence of sulfuric acid to yield 2-acetylimino-3-acetyl-4-phenyl-4-thiazolines (255) when R = Ph. but when R4 = Me or H no acetylation occurs (Scheme 151). The explanation rests perhaps in an acid-catalyzed heterocyclization with an acetylation on the open-chain compound (253), this compound being stabilized... 

Alkylation of 5-mercaptothiazole in alkaline medium takes place on sulfur (348, 362). 

TSPP is readily crystallised from water as the decahydrate between —0.4° and 79°C, and as the anhydrous salt above 79°C. The solubiUty of tetrasodium pyrophosphate is illustrated in Figure 8. The pH of a 1% solution is 10.2. TSPP is quite stable in alkaline medium but hydrolyses rapidly to orthophosphate under acid conditions. 

Trimethyl isocyanurate [827-16-7] can be synthesized in 60% yield by the reaction of CA with dimethyl sulfate in alkaline medium (13) or with diazomethane (63) and in essentially quantitative yield by thermal rearrangement of trimethyl cyanurate [877-89-4]. Isomerization of alkyl cyanurates to the corresponding isocyanurates is frequendy observed (11,64). 

Hydroxy-6-methyl-2-phenylpyridazin-3(2Fr)-one and 4-hydroxy-5-nitropyridazin-3(2FT)-one rearrange in acidic medium to 3-methyl-l-phenylpyrazole-5-carboxylic acid and 4-nitropyrazole-5-carboxylic acid. 4-Hydroxypyridazin-3(2FT)-ones with a hydroxy group or other group at positions 5 or 6, which is easily replaced in alkaline medium, are transformed into 5-(or 3-)pyrazolones with hot alkali. An interesting example is ring contraction of 5-chloro-4-(methylthio)-l-phenylpyridazin-6(lFT)-one which gives, besides pyrazole derivative (127), 4-hydroxy-5-methylthio-l-phenylpyridazin-6(lFf)-one (128 Scheme 41). 

HC(22)l). Other azopyrazoles (318) and (319) have been described in Section 4.04.2.1.4(viii). These compounds can be reduced to amines (zinc and acetic acid) or to arylhydrazines (zinc in alkaline medium) (67HC(22)l). 

The well-known reaction of Ni(II) with dimethylglyoxime (H Dm) in alkaline medium under the influence of such oxidants as persulphate and iodine is widely used for the photometric determination of nickel. The red product (RP) of this reaction is used for this purpose. However, the nature of this red compound has not been defined yet. Using of peroxyacids makes it possible to obtain additional data concerning the conditions and mechanism of generation of RP as well as to improve the metrological pai ameters of the method. 

Furoic acid has been made by oxidation of lactose followed by pyrolysis, by the oxidation of 2-acetylfuran, 2-methylfuran, or furfuryl alcohol using potassium ferricyanide in alkaline medium, and by other methods already listed. ... 

Fast blue salt B couples best with phenols in alkaline medium, e.g. with 11-nor-d -THC-9-carboxylic acid to yield the following red-colored product ... 

With dienones exchange of all potentially activated hydrogens is less certain. For example, in alkaline medium, androsta-3,5-dien-7-one (26) undergoes complete exchange, while only the 2,2,4-trideutero derivative... 

Similarly, 6-mercaptopurine in alkaline medium adds across the triple bond in 3,3,3-trifluoropropyne to form the carbon-sulfur bond to the carbon more remote from the trifluoromethyl group In trifluoromethyl-ferf-butyldiacetylene, the bond is formed to the carbon adjacent to the trifluoromethyl group [5] (equation 6)... 

The oxazolone 43, prepared by reaction of 0-methylcaprolactim (42) with compound 1, undergoes a ring-opening reaction with methanolic HCl and cyclizes in alkaline medium to 1,5-pentamethyl-ene-2-phenylimidazole-4-carboxylic acid (44), which can be decar-boxylated easily. 

The same diamine, when treated with carbon disulfide in alkaline medium, yielded 2-mercapto- l//-imidazo[4,5-/]quinoline (88PS267,88SC973,86IJC264), which, on treatment with alkyl, aralkyl, and acid halides, gave the corresponding thioethers and thioesters 111, respectively (88PS267, 86IJC264). 

Benzotriazole (HL) with Me SAuCl in alkaline medium gives the polymeric [AuL] (79IC658). Another synthetic approach is based on interaction of benzotriazole with PhjPAuCl in the presence of potassium hydroxide, which yields first PhjPAuL and then the decomposition product [AuL]. ... 

Acylisoxazol-5-ones (129), which are -diketones, on being heated in alkaline medium undergo acyl-lactonic rearrangement to form stable isoxazole-4-carboxylic acids (130). ... 

A nitro group in the 4-position markedly increases the instability of the isoxazole ring in alkaline medium. This effect is clearly demonstrated by 3,5-dime thy 1-4-nitroisoxazole. Whereas 3,5-dimethyl-isoxazole is not affected by alkali, its 4-nitro-derivative (134) is cleaved by 2% sodium hydroxide. The structure of the product was proved by its conversion into a triazole (135) with phenyl diazonium chloride, according to the original authors. ... 

In the Webb and Levy test (60) for 2-deoxy pentoses, the same hydroxyaldehyde intermediate (4) (30), formed by treating the sugars with trichloracetic acid, reacts with p-nitrophenylhydrazine to yield the pyridazinium salt (5) from which a quinonoid dye (6) absorbing at 560 m/i, is formed in alkaline medium. 

Unless benzimidazoles can react as the anions, when 2-iodination is observed (90JHC673), iodine normally enters the 5-position initially, although N-iodination is also known in alkaline medium. 5-Hydroxybenzimi-... 

In acidic electrolytes only lead, because it forms passive layers on the active surfaces, has proven sufficiently chemically stable to produce durable storage batteries. In contrast, in alkaline medium there are several substances basically suitable as electrode materials nickel hydroxide, silver oxide, and manganese dioxide as positive active materials may be combined with zinc, cadmium, iron, or metal hydrides. In each case potassium hydroxide is the electrolyte, at a concentration — depending on battery systems and application — in the range of 1.15 - 1,45 gem"3. Several elec-... 

When performing the two-phase titration with benzethonium chloride in alkaline medium and in the presence of phenolphthalein as indicator, not only the monosulfonates but also the di- and polysulfonates are determined [19]. The content of di- and polysulfonates is the difference between two titration results giving the amounts of total sulfonates and monosulfonates. Identifying the endpoint requires some experience. 

The dissertation26 by de Bruijn, Monosaccharides in alkaline medium isomerization, degradation and oligomerization and other publications by... 

Fig. 5.—Simplified overall reaction scheme of monosaccharides in alkaline medium.

KINETICS AND MECHANISM OF DECOMPOSITION OF N-Br-AMINO ACIDS IN ALKALINE MEDIUM... 

We present here a kinetic study of the decomposition of the N-bromo derivatives of alanine, aminoisobutyric acid and proline in alkaline medium, where the mechanism of decomposition is not fiilly understood. A discussion of the different microscopic mechanisms that can be proposed is done in the light of the obtained experimental results. 

Influence of OH concentration on the reaction rate constant. From the dependence of the observed first order rate constant on the sodium hydroxide concentration, shown in Table 3, it can be established that equation (2) holds, where ko represents the contribution due to the unimolecular decomposition process and koH is the contribution due to the base-catalysed process in alkaline medium. 

The frequently used biuret reaction of proteins results in the formation of the following reddish-violet complex in alkaline medium [4, 2S, 26] ... 

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