Acetonitrile, hydrolysis reactions

Solvent Effects. The conversion of dihydroanthracene could be increased by adding water to the pyridine solvent (Table III). An 86% conversion to anthraquinone was obtained when 95% aqueous pyridine was used as the solvent. Furthermore, methanol could be substituted for the water with equivalent results. Other solvents were tried in place of pyridine (Table IV). The data indicate that 95% aqueous pyridine gave the best yields, although aniline gave nearly similar results. When acetonitrile and dimethylformamide were used, the large amounts of unreacted starting material indicate that these solvents may have deactivated the base by undergoing a hydrolysis reaction. 

The authors assumed that the precipitation of these metal sulfides was controlled by the hydrolysis reaction of TAA promoted by proton in the acidic conditions. However, the hydrolysis of TAA observed in acidic and alkaline ranges is a much slower process than observed in the precipitation of these metal sulfides (7-12), and it may not be accelerated by consumption of S2 ions because of its irreversible nature. In addition, the reaction virtually finished with a great part of the starting metal ions and TAA left unreacted. Also, it has already been verified that the probability of direct reaction of TAA with metal ions is zero or at least negligible from its strong dependence of pH in reactivity (7). Thus, it seems reasonable to consider that the main path is the release of S2 ions from TAA according to the following reaction scheme with the production of acetonitrile (7,13) as found in the reaction of TAA with Cd2+ ions in an alkaline media ... 

Table 2. (i-Acetylamino Mercury(n) Chlorides by Reaction of Alkenes with Hg(NOs)2 and Acetonitrile, Hydrolysis and Treatment with Sodium Chloride32... 

Cellulase was found to be effective in the synthesis of artificial cellulose in a single-step reaction by polycondensation of /J-D-cellobiosyl fluoride (Scheme 13).123 The polymerization is a repetition of the transglycosylation reaction, which became predominant over the hydrolysis reaction when the enzymatic polycondensation was carried out in a mixed solvent of acetonitrile/acetate buffer (5 1, pH 5). This synthesis is therefore kinetically controlled as well as equilibrium controlled. The fi configuration of the Cl fluorine atom is necessary to form a reactive intermediate leading to a / (1—4) product via a double displacement mechanism .124 Thus, this method provided the first successful in vitro synthesis of cellulose, the most abundant biomacromolecules on the earth, the synthesis of which had been unsolved for one-half a century.123... 

Laboratory studies have provided evidence that photochemical and photocatalytic (Section 6.8) steps might play an important role in the formation of amino acids or various heterocyclic compounds from very simple molecules. For example, UVC irradiation of acetonitrile ammonia water mixture produces hexamethylenetetramine, a potential precursor of amino acids, via two-step photoinitiated fragmentation of acetamide (formed by acetonitrile hydrolysis) to give carbon oxide, which undergoes further photochemical and dark reactions (Scheme 6.184).1183... 

Fluorescamine has also been employed for postcolumn derivatization with fluorescence detection. As discussed previously, a fluorescent product is generated in the presence of primary amines within a few seconds. Fluorescamine undergoes hydrolysis, but the hydrolysis reaction is much slower than the reaction with primary amines and the product of that reaction does not fluoresce. For postcolumn addition, the reagent is added as a solution in acetone, acetonitrile, or methanol. As with OPA, proline can be detected through conversion to aminobutyraldehyde by oxidation with N-chlorosuccinimide. Unlike OPA, fluorescamine reacts poorly with ammonia. Therefore, problems with baseline drift are not as prominent. Since the reaction of fluorescamine with primary amines produces an equilibrated mixture of two products, it is used most frequently as a postcolumn reagent. 

Hydrolysis reactions were followed by monitoring the appearance of nitrophenol spectrophotometrically using a HITACHI 220A spectrophotometer. The reaction was conducted in a quartz cell in the water-jacketed cell holder of the 220A. Temperature was maintained at 25°C by a HAAKE F3 circulating water bath. The reaction was initiated by adding a stock solution of ester in acetonitrile to a buffer solution in the quartz cell. 

Allylalion of the alkoxymalonitrile 231 followed by hydrolysis affords acyl cyanide, which is converted into the amide 232. Hence the reagent 231 can be used as an acyl anion equivalent[144]. Methoxy(phenylthio)acetonitrile is allylated with allylic carbonates or vinyloxiranes. After allylation. they are converted into esters or lactones. The intramolecular version using 233 has been applied to the synthesis of the macrolide 234[37]. The /i,7-unsaturated nitrile 235 is prepared by the reaction of allylic carbonate with trimethylsilyl cyanide[145]. 

Hydrolysis of TEOS in various solvents is such that for a particular system increases directiy with the concentration of H" or H O" in acidic media and with the concentration of OH in basic media. The dominant factor in controlling the hydrolysis rate is pH (21). However, the nature of the acid plays an important role, so that a small addition of HCl induces a 1500-fold increase in whereas acetic acid has Httie effect. Hydrolysis is also temperature-dependent. The reaction rate increases 10-fold when the temperature is varied from 20 to 45°C. Nmr experiments show that varies in different solvents as foUows acetonitrile > methanol > dimethylformamide > dioxane > formamide, where the k in acetonitrile is about 20 times larger than the k in formamide. The nature of the alkoxy groups on the siHcon atom also influences the rate constant. The longer and the bulkier the alkoxide group, the lower the (3). 

The formation of ethyl cyano(pentafluorophenyl)acetate illustrates the intermolecular nucleophilic displacement of fluoride ion from an aromatic ring by a stabilized carbanion. The reaction proceeds readily as a result of the activation imparted by the electron-withdrawing fluorine atoms. The selective hydrolysis of a cyano ester to a nitrile has been described. (Pentafluorophenyl)acetonitrile has also been prepared by cyanide displacement on (pentafluorophenyl)methyl halides. However, this direct displacement is always aecompanied by an undesirable side reaetion to yield 15-20% of 2,3-bis(pentafluoro-phenyl)propionitrile. 

The kinetics of alkaline hydrolysis of phenyl cinnamate were studied at 25°C, in solutions containing 0.8% acetonitrile ionic strength, 0.3 M initial ester, 8.19 X 10- M reaction followed spectrophotometrically in 5-cm cells at 295 nm. For studies at three pH values, these absorbance data were obtained. The pH was established with sodium hydroxide of the normality specified in the heading of the table (as titrimetrically determined). 

Thus, simple ketones or aliphatic aldehydes may be successfully used as starting materials in the CSIC (Carbanion mediated Sulfonate Intramolecular Cyclization) reaction. Ai-alkylsulfonamides could be also cyclized under CSIC conditions (99T(55)7625) affording the spiroisothiazoline 79. By treatment with TMSCl, Nal in acetonitrile at r.t., hydrolysis of the enamine and formation of the corresponding keto derivative 80 was obtained. 

The method is very useful for the synthesis of physiologically interesting a-mcthylamino acids, e.g., methyl dopa from the 3,4-dimethoxybenzyl derivative. The excellent stereoselection achieved in the process, however, is caused by the preferential crystallization of one pure diastereomerfrom the equilibrium mixture formed in the reversible Strecker reaction. Thus, the pure diastcrcomers with benzyl substituents, dissolved in chloroform or acetonitrile, give equilibrium mixtures of both diastereomers in a ratio of about 7 347. This effect has also been found for other s-methylamino nitriles of quite different structure49. If the amino nitrile (R1 = Bn) is synthesized in acetonitrile solution, the diastereomers do not crystallize while immediate hydrolysis indicates a ratio of the diastereomeric amino nitriles (S)I(R) of 86 1447. 

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