Ammonium acetate, hydrolysis

In the case of the salt of a weak acid and a weak base HAB, e.g. ammonium acetate, hydrolysis of both the ions occurs ... 

An excess of acetic acid is usually added before heating in order to repress the hydrolysis (and also the thermal dissociation) of the ammonium acetate, thus preventing the escape of ammonia. The excess of acetic acid, together with the water, is removed by slow fractional distillation. The method is rarely used except for the preparation of acetamide. 

Cyanoamidines such as (10) are converted into the more useful 2-formyl-A-norsteroids (11) by reduction with lithium in methylamine (buffered with ammonium acetate) followed by hydrolysis on hydrated alumina. This yields a mixture containing approximately 5 parts of the 2j5-aldehyde and 3 parts of the 2a-aldehyde (11). Both aldehydes are smoothly dehydrogenated by 2,3-dichloro-5,6-dicyanobenzoquinone in the presence of acid to the 2-formyl--A-iiorsteroids (12). ... 

Direct bromination readily yields the 6-bromo derivative (111), just as with uracil. Analogous chlorination and iodination requires the presence of alkalies and even then proceeds in low yield. The 6-chloro derivative (113) was also obtained by partial hydrolysis of the postulated 3,5,6-trichloro-l,2,4-triazine (e.g.. Section II,B,6). The 6-bromo derivative (5-bromo-6-azauracil) served as the starting substance for several other derivatives. It was converted to the amino derivative (114) by ammonium acetate which, by means of sodium nitrite in hydrochloric acid, yielded a mixture of 6-chloro and 6-hydroxy derivatives. A modified Schiemann reaction was not suitable for preparing the 6-fluoro derivative. The 6-hydroxy derivative (115) (an isomer of cyanuric acid and the most acidic substance of this group, pKa — 2.95) was more conveniently prepared by alkaline hydrolysis of the 6-amino derivative. Further the bromo derivative was reacted with ethanolamine to prepare the 6-(2-hydroxyethyl) derivative however, this could not be converted to the corresponding 2-chloroethyl derivative. Similarly, the dimethylamino, morpholino, and hydrazino derivatives were prepared from the 6-bromo com-pound. ... 

Substituents in the 6-position (cf. 267) show appreciable reactivity. 6-Bromo-as-triazine-3,5(2j, 4j )-dione (316) undergoes 6-substitution with secondary amines or hydrazine, with mercaptide anions or thiourea (78°, 16 hr), with molten ammonium acetate (170°, 24 hr, 53% yield), and with chloride ion during phosphorous oxychloride treatment to form 3,5,6-trichloro-as-triazine. The latter was characterized as the chloro analog of 316 by treatment with methanol (20°, heat evolution) and hydrolysis (neutral or acid) to the dioxo compound. The mercapto substituent in 6-mercapto-as-triazine-3,5(2iI,4if)-dione is displaced by secondary... 

Ammonia solutions are significantly more efficient than ammonium acetate as washing reagents. The process of fluorine content reduction is related to subsequent hydrolysis of fluoride and oxyfluoride contaminants by ammonia. 

RP-HPLC was also employed for the investigation of the hydrolysis behaviour of two fluorotriazine reactive dyes Cibacron blue F-R and Cibacron yellow F-4G. Chromatographic measurements were performed in an ODS column (50 X 4.6 mm i.d. particle size 5 /jm) at room temperature. The mobile phase was ACN-0.05 M ammonium acetate buffer containing 1 mM acetyhrimethylammonium bromide (47 53, v/v). Flow rates were 0.8 and 0.6 ml/min depending on the dyes to be separated. Dyes were detected at 275 nm. The hydrolysis of dyes was investigated both in the absence and presence of... 

Chemical/Physical. The estimated hydrolysis half-life of acetonitrile at 25 °C and pH 7 is >150,000 yr (Ellington et al., 1988). No measurable hydrolysis was observed at 85 °C at pH values 3.26 and 6.99. At 66.0 °C (pH 10.42) and 85.5 °C (pH 10.13), the hydrolysis half-lives based on first-order rate constants were 32.2 and 5.5 d, respectively (Ellington et al., 1987). The presence of hydroxide or hydronium ions facilitates hydrolysis transforming acetonitrile to the intermediate acetamide which undergoes hydrolysis forming acetic acid and ammonia (Kollig, 1993). Acetic acid and ammonia formed react quickly forming ammonium acetate. 

To complete the section on the synthesis of 4,4 -bipyridines, we summarize the methods reported for the preparation of some substituted 4,4 -bi-pyridines and 4,4 -bipyridinones. These methods are closely analogous to syntheses already discussed for some of the isomeric bipyridines. Thus the Hantzsch reaction using pyridine-4-aldehyde, ethyl acetoacetate, and ammonia gives 3,5-di(ethoxycarbonyl)-1,4-dihydro-2,6-dimethyl-4,4 -bipyridine, which after oxidation, followed by hydrolysis and decarboxylation, afforded 2,6-dimethyl-4,4 -bipyridine. Several related condensations have been reported. Similarly, pyridine-4-aldehyde and excess acetophenone gave l,5-diphenyl-3-(4-pyridyl)pentane-l,5-dione, which with ammonium acetate afforded 2,6-diphenyl-4,4 -bipyridine. Alternatively, 1-phenyl-3-(4-pyridyl)prop-2-enone, A-phenacylpyridinium bromide, and ammonium acetate gave the same diphenyl-4,4 -bipyridine, and extensions of this synthesis have been discribed. Condensation of pyridine-4-aldehyde with malononitrile in the presence of an alcohol and alkaline catalyst produced compounds such as whereas condensations of... 

The foregoing process is based on the method of W. A. Noyes and W. F. Goebel,9 in which equimolecular proportions of ammonium acetate and acetic acid are heated together, the acetic acid having been shown to accelerate both the dehydration of ammonium acetate and the hydrolysis of acetamide. 

DEAE cellulose chromatography was performed by application of a small volume of glycolipid in C M (1 1) to a 3 ml column of DEAE cellulose, acetate form, followed by elution with 5 column volumes of C M W (60 40 8). Bound glycolipids were eluted with 5 column columes of chloroform-methanol-ammonium acetate. The samples were dried and tested in the PFC assay as described below. Mild HC1 treatment was performed as previously described with 0.1 N HC1 at 80°C for 30 minutes (8). After hydrolysis the samples were neutralized with 0.1 N NaOH, dried and tested in the PFC assay. 

Soy-based milk formula D, G, FORM, BCA Reflux with 80% ethanol, centrifugation, partitioning Conjugates enzymatic hydrolysis, SPE with C18 C-18 MeOH- ammonium acetate HPLC/UV (260 nm), ECD or MS UV 5 ng, ED 10-15 pg 103... 

Human plasma D, DHD, G, ODMA Acidification, enzymatic hydrolysis, extraction with C18 SPE or diethyl ether, partitioning C-8 (Phenolphthalein glucuronide, 4-methylumbelliferone glucuronide, BCA) ACN-H20- ammonium acetate HPLC/MS/MS/ APCI(-) 24... 

Ammonium salts of strong acids, such as NH4C1 or NH4N03, however, can lower the pH and encourage the hydrolysis of clays. Salts of weak acids, such as acetates, can, conversely, increase the pH with possible precipitation of metal hydroxides - an effect countered, however, by the complexation of metals by acetate. This complexation also inhibits the reabsorption of released metals. Ammonium acetate (1 moll-1, pH 7) has, therefore, been widely adopted as a soil extractant and recommended by a consortium of European experts for extractable metal trials under the auspices of Bureau Communautaire de Reference (BCR) of the European commission (Castilho and Rix, 1993 Ure et al., 1993a, b). 

The structures of these bisindole maleimides were confirmed by synthesis. The reaction of indolyl magnesium bromide (10) with 2,3-dibromo-A -methylmaleimide (11) in toluene led to bisindolylmaleimide (12), which was converted into arcyriarubin A (6) through alkaline hydrolysis followed by heating with ammonium acetate (Scheme 1). The reaction of 10 and 11 in THF yielded monosubstitution product (13) which after protection of the indole NH group with the Boc residue was used to prepare unsymmetrically substituted bisindolylmaleimide, arcyriarubin B (1) [8]. 

The first reported synthesis of MDMA was from safrole by converting it to its bromo derivative followed by reaction with meth-ylamine (Biniecki et al., 1960). Bailey et al. describe the synthesis of MDMA from 3,4-methylenedioxyphenylacetone using a Leuckart reaction with N-methylformamide and hydrolysis of the N-formyl derivative (Bailey et al., 1975). A third synthesis for MDMA described in the literature starts with peperonal which is reacted with nitroethane, ammonium acetate, and acetic acid to form a nitrostyrene derivative that is reduced to the ketone and then reacted with methylamine to form MDMA (Rabjohns, 1963). Using the method of Borch et al., MDMA can be synthesized by the reductive amination of the appropriate ketone in the presence of sodium cyanoborohydride (Borch et al., 1971). The MDMA syntheses used in clandestine laboratories are analogous. 

To make rosoxacin two heterocyclic systems must be constructed. Workers at the pharmaceutical company Sterling decided to build the pyridine in an ingenious version of the Hantzsch synthesis using acetylenic esters on 3-nitrobenzaldehyde. The ammonia was added as ammonium acetate. Oxidation with nitric acid made the pyridine, hydrolysis of the esters and decarboxylation removed the acid groups, and reduction with Fe(TT) and HC1 converted the nitro group into the amino group required for the quinolone synthesis. 

Such is the case of ammonium acetate, as the dissociation constants of acetic acid (Ka = 1-75 x 10 5) and of ammonium hydroxide (A"b = 171 x 10 5) are practically equal. In this case the hydrolysis can be described by the equation ... 

Figure 9.28 HPLC profile of papain-catalyzed B AEE hydrolysis product. Conditions column, juBondapak CN eluent, 0.05 M ammonium acetate-methanol (85 15) flow rate, 2.0 mL/min detector, 254 nm at ambient temperature (From Chen et al., 1982.)...

An amino acid, /6-amino-/0-phenylpropionic acid (70%), is made by adding ammonia to benzalmalonic ester (45%) followed by hydrolysis and decarboxylation by boiling hydrochloric acid. A single-step process to achieve the same result involves heating a mixture of malonic acid, benz-aldehyde, and ammonium acetate on the steam bath until evolution of carbor. dioxide ceases. ... 

Preparative Methods the most convenient preparation of (/ ,/ )-stilbenediamine is described in Organic Syntheses." Condensation of benzil and cyclohexanone in the presence of ammonium acetate and acetic acid (eq 1) produces a spirocyclic 2//-imidazole (mp 105-106 °C). Reduction with Lithium in THF/NH3 followed by an ethanol quench and hydrolysis with aqueous HCl (eq 2) affords the racemic diamine as a pale yellow solid (mp 81-82 °C). Resolution is achieved by multiple recrystallizations of the tartaric acid salts ifom water/ethanol. The sulfonamides are prepared by reaction of the enantiomeri-cally pure diamine with the appropriate anhydride or sulfonyl chloride in CH2CI2 in the presence of Triethylamine and a catalytic amount of 4-Dimethylaminopyridine (eq 3). 

Preparative Methods (i) preparation of racemic DPEN and its optical resolution Reaction of benzil and cyclohexanone in the presence of ammonium acetate and acetic acid at reflux temperature gives a cyclic bis-imine (1) (eq 1). Stereoselective reduction of the bis-imine with lithium in THF-liquid ammonia at —78 °C followed by addition of ethanol, then hydrolysis with hydrochloric acid and neutralization with sodium hydroxide produces the racemic diamine (2). Recrystallization of the l-tartaric acid salt from a 1 1 water-ethanol mixture followed by neutralization with sodium hydroxide, recrystallization from hexane results in (5,5)-DPEN (3) as colorless crystals. 

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