Ammonolysis reactions

The second and third reactions are economical, but the first is not. The second reaction is used in a process where HCN is oxidized to (CN)2 and hydrolyzed in the presence of a strong acid catalyst to give oxamide. The third reaction is employed in a newly developed process where diaLkyl oxalates are converted to oxamide by the ammonolysis reaction. This reaction easily proceeds without catalysts and quantitatively gives oxamide as a powder. 

Lewis acids, such as the haUde salts of the alkaline-earth metals, Cu(I), Cu(II), 2inc, Fe(III), aluminum, etc, are effective catalysts for this reaction (63). The ammonolysis of polyamides obtained from post-consumer waste has been used to cleave the polymer chain as the first step in a recycle process in which mixtures of nylon-6,6 and nylon-6 can be reconverted to diamine (64). The advantage of this approach Hes in the fact that both the adipamide [628-94-4] and 6-aminohexanoamide can be converted to hexarnethylenediarnine via their respective nitriles in a conventional two-step process in the presence of the diamine formed in the original ammonolysis reaction, thus avoiding a difficult and cosdy separation process. In addition, the mixture of nylon-6,6 and nylon-6 appears to react faster than does either polyamide alone. 

The resultant Clear solution from the ammonolysis reaction was processed through "Amber-lite IR-120" ion exchange resin and converted into /3-S-mercaptoethanesulfonic acid in 93.7% yield (based on 3-S-thiuronium ethanesulfonate). 

Although the preparation of /3-mercaptoethanesulfonicacid through the ammonolysis reaction is the preferred method, it is also possible to prepare the sulfonic acid by the sodium hydroxide hydrolysis of /3-S-thiuronium ethanesulfonate followed by the ion exchange treatment. The resulting acid, however, is generally not as satisfactory as that prepared by the am-monolysis reaction. 

Here, we have selected a few representative examples of the enzymatic resolution of esters by aminolysis or ammonolysis reactions. On the other hand, the enzymatic acylation of racemic amines is also of great utility for the preparation of optically pure... 

Scheme 7.14 Resolution of a binaphthyl ester by an ammonolysis reaction.

The coammonolysis of CH3SiHCl2 and CH3(Un)SiCl2 in the indicated ratios was carried out by the procedure as described for the ammonolysis of CH3SiHCl2 [8]. A mixture of cyclic oligomeric silazanes is to be expected in these reactions, [(CH3(H)SiNH)x(CH3(Un)SiNH)y]n, with more than one ring size present. In each preparation, the soluble, liquid products were isolated and used in the base-catalyzed polymerizations. When a ratio CH3SiHCl2/CH3(Un)SiCl2 of x l (x>l) was used in the ammonolysis reaction, the CH3(H)Si/CH3(Un)Si ratio in the soluble ammonolysis product usually was somewhat less than x l. 

Ammonolysis. Reactions involving ammonia. Ammonolysis of esters, acyl chlorides, and anhydrides give amides aniline is produced by ammonolysis of chlorobenzene. The reaction is analogous to hydrolysis, with ammonia substituted for water. 

Polysilazanes can also be synthesized by catalytic dehydrocoupling (equation 4)28,29. The reaction works best with monosubstituted silanes (MeSiH3 is flammable) however, as with the ammonolysis reactions, molecular weights are normally less than 2000 Da. Hence, as-formed oligomers are not useful precursors. However, combinations of ammonolysis followed by catalytic dehydrocouphng provide access to useful precursors as discussed in the SiCN section. 

Since 1950, ammonolysis reactions of many dichlorosilanes have been studied. Usually cyclic trimers and tetramers were formed. But very little was known about the reaction mechanisms.14... 

The sequence of cations and anions is practically the same in the salt effect in deuterium exchange reactions and in the ammonolysis reactions... 

Ammonolysis reactions of oxo complexes with ammonia or alkali metal amides, for example, Eq. (63). 

The equivalent solvolysis product rearranges, as is exemplified by the ammonolysis reaction scheme ... 

Ammonolysis reactions. A broad classification of reactions is solvolysis. In hydrolysis reactions, water molecules are split or lysized as illustrated by the reaction... 

These physiologically active natural compounds 307 and 308 have been labelled with 13N in a simple and rapid one-step ammonolysis reaction (equations 124 and 125) in sealed glass vials. They were used for studies of biological function and in nuclear-medical studies. [13N]nicotinamide (NAM) has been found to be a useful tracer for studying the utilization of the vitamin, nicotinamide291. A comparison of the distribution of [13N]NAM with that of [nC]NAM has been carried out290,292. 

Since the only by-product is hydrogen, the purification of the precursors can be performed by evaporating all volatile components from the reaction mixture. The catalyst used remains in the precursor. An important advantage over ammonolysis reactions of chlorosilanes is the possibility of synthesizing highly cross-linked insoluble polymeric precursors, which are usually difficult to separate from solid by-products. 

Photoimmobilized catalysts have been recently shown to be active and of a steady state action in hydrogenation and ammonolysis reactions. 

Classical reactions involving nucleophiles such as saponification ("OH as the nucleophile), aminolysis (with amines also ammonia in ammonolysis reactions), transesterification (alkoxides, "OR) and others (hydrazinolysis, hydroxamic acid synthesis, etc.) have been adapted to solid phane and used to obtain, for instance, carboxylic acids, amides and esters. Internal or intramolecular nucleophilic attack has been employed to obtain cyclic products such as lactones, lactams (including cyclic peptides) and a great variety of heterocycles (hydantoins, diketopiperazines, benzodiazepinones, etc.). 

Two different polyurethanes were used as starting materials a solid elastomer based on a trifunctional polyethertriol, 1,4-butanediol and methylenebis(phenyl isocyanate) and a flexible foam where the diol was replaced by water. The ammonolysis reactions were carried out at 139 °C and 140 atm for 120 min, and with a polyurethane/ammonia weight ratio of 1. Under these conditions the polyurethane conversion was practically total. The ammonolysis reaction transforms the CO group into urea and the ester groups and derivatives of carboxylic acids into amides, whereas ether and hydroxy groups are inert towards ammonia. Scheme 2.7 illustrates the stoichiometry proposed by the authors for the ammonolysis of the polyether urethane. 

After the reaction, urea is separated by extraction with water whereas the polyol remains as a residue in the reactor. Therefore, under supercritical conditions the polyether polyols are separated from the mixture at the same time that the ammonolysis reaction progresses. The diamines and the diol can be separated by distillation or precipitation. The phosgenation of the amine leads to the corresponding diisocyanate, which together with the polyol and the diol may be used in the recovery of the raw polyurethane. 

The tertiary amines, trimethylamine and triethylamine, and the secondary amines, dimethyl, diethyl, and dipropyl, react with zirconium tetrachloride to form 1 2 addition compounds, whereas primary amines undergo ammonolysis reactions (151). 

It would be expected that in the ammonolysis reaction the oxygen bridge would disappear and, in its place, an NH bridge would be formed. From this point of view, imidodisulfamide (LXXVIII), which has already been described, is a diamide derived from disulfuric acid. The question then arises as to whether the corresponding monoamide (XCIII) can exist. 

Screening experiments utilized process stream ester feed, which consisted of about 22% w/v (0.91M) of the ester in toluene. Since toluene precluded the use of free ammonia due to its low solubility in toluene, solid ammonium carbamate was employed. Reactions were performed using a mixture of neat process feed, ammonium carbamate (71 g/L, 2 mol eq of ammonia), and biocatalyst (25 g/L), shaken at 400 rpm, 50°C. Under these conditions, CALB and its immobilized forms Novozym 435 and Chirazyme L2 provided racemization-free amide with yields of 69%, 43%, and 40%, together with 21%, 18%, and 22% of side products (by HPLC), respectively, while all other biocatalysts (lipases) furnished less than 5% of the desired product [42]. The ammonolysis reaction with free CALB was then optimized with regard to the temperature and the CALB and ammonium carbamate loads to increase yield from 56% to 71%, with side products varying from 7% to 19%. 

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