Ammonia ammonolysis

An X-ray crystal structure of the Pr N-derivative shows the presence of a bent, 2-coordinate P atom, equal P- N distances, and accurately planar 3-coordinaie N atoms as in (c) above.In liquid ammonia ammonolysis also occurs ... 

The versatility of cyanide and bipyridyl ligands has been used to stabilize low oxidation states. By using potassium in liquid ammonia, K3Ti (CN)6 is reduced to K2Ti (CN)4 and TiBt3 - - KCN to K4Ti°(CN)4. With ZrBt3 and M CN (M = K, Rb) in liquid ammonia, ammonolysis occurs and zerovalent Zr is produced ... 

Extranuclear halogenoquinoxalines undergo aminolysis satisfactorily by primary, secondary, or tertiary amines direct aminolysis by ammonia (ammonolysis)... 

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. 

Amides are very easily prepared by the interaction of carboxylic esters with concentrated aqueous ammonia (ammonolysis). 

The replacement of a nuclear substituent such as hydroxyl (-OH), chloro, (-C1), or sulfonic acid (-S03H) with amino (-NH2) by the use of ammonia (ammonolysis) has been practiced for some time with feedstocks that have reaction-inducing groups present thereby making replacement easier. For example, l,4-dichloro-2-nitrobenzene can be changed readily to 4-chloro-2-nitroaniline by treatment with aqueous ammonia. Other molecules offer more processing difficulty, and pressure vessels are required for the production of aniline from chlorobenzene or from phenol (Fig. 3). 

Certain substances such as Zn(NH2)2 show amphoteric behaviour in liquid ammonia. Ammonolysis reactions take place in liquid ammonia forming amides and ammonium ions. 

Inorganic amides contain the ion NH2". They are formed by the action of ammonia on metals or by the ammonolysis of nitrides. The heavy metal amides are prepared by meta-thetical reactions in liquid ammonia, e.g. 

Aqueous ammonia and acryUc esters give tertiary amino esters, which form the corresponding amide upon ammonolysis (34). Modem methods of molecular quantum modelling have been appHed to the reaction pathway and energetics for several nucleophiles in these Michael additions (35,36). 

Hydrogenolysis is analogous to hydrolysis and ammonolysis, which involve the cleavage of a bond induced by the action of water and ammonia, respectively. Chemical bonds that are broken by hydrogenolysis reactions include carbon—carbon, carbon—oxygen, carbon—sulfur, and carbon—nitrogen bonds. An example of hydrogenolysis is the hydrodealkylation of toluene to form benzene and methane ... 

Ammonolysis. In a reaction closely related to aminolysis, ammonia [7664 1-7] reacts with polyamides, usually under pressure and at elevated temperatures (62). 

The ammonolysis of phenol (61—65) is a commercial process in Japan. Aristech Chemical Corporation (formerly USS Chemical Division of USX Corporation) currently operates a plant at Ha verb ill, Ohio to convert phenol to aniline. The plant s design is based on Halcon s process (66). In this process, phenol is vapori2ed, mixed with fresh and recycled ammonia, and fed to a reactor that contains a proprietary Lewis acid catalyst. The gas leaving the reactor is fed to a distillation column to recover ammonia overhead for recycle. Aniline, water, phenol, and a small quantity of by-product dipbenylamines are recovered from the bottom of the column and sent to the drying column, where water is removed. 

This is an example of an ammonolytic reaction ia which a chemical bond is broken by the addition of ammonia. It is analogous to the hydrolysis reactions of water. An impressive number of inorganic and organic compounds undergo ammonolysis. 

Amination. Amyl alcohols can react with ammonia or alkylamines to form primary, secondary, or tertiary-substituted amines. Eor example, 3-methyl-butylamine [107-85-7] is produced by reductive ammonolysis of 3-methyl-1-butanol over a Ni catalyst at 150°C (59). Some diisoamyl- and triisoamyl amines are also formed in this reaction. Good selectivities (88%) of neopentyl amine [5813-64-9] are similarly produced by reductive ammonolysis of neopentyl alcohol (60). 

Amination. Isopropyl alcohol can be aminated by either ammonolysis ia the presence of dehydration catalysts or reductive ammonolysis usiag hydrogeaatioa catalysts. Either method produces two amines isopropylamine [75-31-0] and diisopropylamine [108-18-9]. Virtually no trisubstituted amine, ie, triisopropyl amine [122-20-3], is produced. The ratio of mono- to diisopropylamine produced depends on the molar ratio of isopropyl alcohol and ammonia [7664-41-7] employed. Molar ratios of ammonia and hydrogen to alcohol range from 2 1—5 1 (35,36). 

Using hexamethylphosphoramide as the solvent, only the second reaction occurs. Disilane also reacts with potassium in 1,2-dimethoxyethane to form KS1H3, although S1H4 and nonvolatile polysHanes are also produced (28,31). Pure crystalline KSiH prepared from SiH and potassium in 1,2-dimethoxyethane has been obtained by slow evaporation of the solvent. WhenHquid ammonia is used as the solvent, only a small fraction of SiH is converted into metal salt most of the SiH undergoes ammonolysis (32). 

The analogous reaction with ammonia leads ultimately to sihcon nitride. In the past, hydrocarbon soluble fractions of the ammonolysis were iacorrecdy referred to as sihcon diimide. This improper designation occasionally persists as of the mid-1990s. 

Aminoanthraquinone and Related Compounds. l-Amiuoanthraquiuone [82-45-1] (17) is the most important iatermediate for manufacturiag acid, reactive, disperse, and vat dyes. It has been manufactured from anthraquiaone-l-sulfonic acid [82-49-5] (16) by ammonolysis of the sulfo group with aqueous ammonia ia the presence of an oxidising agent such as nitroben2ene-3-sulfonic acid. 

Ammonolysis and Aminolysis. Esters and ammonia react to form amides and alcohols ... 

The progression from hydroxypyrazines/quinoxalines through the halo derivatives to the amines is a logical sequence in that, for practical purposes, this is the best method of synthesis of the amino compounds (see preceding Section). The ammonolysis proceeds most easily in the case of fluoro compounds. Fluoropyrazine reacts with aqueous ammonia at room temperature, whereas the reaction with chloropyrazine requires higher temperature and pressure. 

Initial C-perfluoroalkylation of p diketonesoccurs dunng thenUV irradiation in the presence of perfluoroalkyl iodides in liquid ammonia Pluorinated enami-noketones are obtained by subsequent ammonolysis of a difluoromethylene group and removal of the acetyl group [131] C-alkylation of dimethyl malonate takes... 

Solvates are perhaps less prevalent in compounds prepared from liquid ammonia solutions than are hydrates precipitated from aqueous systems, but large numbers of ammines are known, and their study formed the basis of Werner s theory of coordination compounds (1891-5). Frequently, however, solvolysis (ammonolysis) occurs (cf. hydrolysis). Examples are ... 

Sulfamide, (H2N)2S02, can be made by ammonolysis of SO3 or O2SCI2. It is a colourless crystalline material, mp 93°, which begins to decompose above this temperature. It is soluble in water to give a neutral non-electrolytic solution but in boiling water it decomposes to ammonia and sulfuric acid. The structure (Fig. 15.50c)... 

Ammonolysis of 2-chlorobenzothiazole in liquid ammonia was studied by Lemons et al. and found to be approximately first-order with respect to this substrate at the fairly high concentrations used. The actual nucleophilic reagent was, as expected, the neutral species NH3, and reaction via the amide ion NH2 arising from the autoprotolysis equilibrium [Eq. (5)] was excluded on the grounds that addition of ammonium chloride did not depress the reaction rate. In accordance with this interpretation and in connection with the existence of aromatic substitutions other than normal it is of interest that 2-chlorobenzothiazole was found to react difiFerently with sodamide, although the products were unidentified in this case. 

An alternative way to produce aniline is through ammonolysis of either chlorobenzene or phenol. The reaction of chlorobenzene with aqueous ammonia occurs over a copper salt catalyst at approximately 210°C and 65 atmospheres. The yield of aniline from this route is also about 96% ... 

Ammonolysis of phenol occurs in the vapor phase. In the Scientific Design Co. process (Figure 10-10), a mixed feed of ammonia and phenol is heated and passed over a heterogeneous catalyst in a fixed-bed sys-... 

Ammonolysis is the preferred route currently in use at the DuPont Company for the depolymerization of nylon-6,6 carpet waste. McKinney13 has described the reaction of nylon-6,6 and nylon-6 mixtures with ammonia at temperatures in the range of 300-350°C at a pressure of about 68 atm in the presence of an ammonium phosphate catalyst to form a mixture of nylon-6,6 and nylon-6 monomers (HMD A, A A, and s-caprolactam) and adiponitrile, 5-cyanovaleramide, 6-aminocapronitrile, and 6-aminocaproamide. 

In die case of nylon-6,6 waste recycled by ammonolysis, nylon is treated with ammonia in die presence of a phosphate catalyst. Reaction occurs at 330°C and 7 MPa. Distillation of die reaction mixture produces ammonia which is recycled and three fractions containing (a) caprolactam, (b) HMDA and aminocaproni-trile, and (c) adiponitrile. Aminocapronitrile and adiponitrile are hydrogenated to yield pure HMDA, and die caprolactam is eidier converted to aminocapronitrile by further ammonolysis or distilled to produce pure caprolactam. The HMDA produced by this process is extremely pure (>99.8).1 The main impurities are aminomediylcyclopentylaniiiie and tetrahydroazepine, which are expected to be removed more effectively in the larger distillation columns employed in the larger plants. 

Ammonolysis of PET involves the reaction of PET and ammonia with heating and usually in die presence of ethylene glycol to form terephdialdiamide. The reaction is catalyzed by zinc acetate. 

Ammonolysis of PET involves the reaction of PET with ammonia at temperatures of 70-180°C, usually under pressure in EG. The ammonolysis of PET postconsumer bottles has been canied out at temperatures in the range of 120-180°C and a pressure of ca. 2 MPa for 1-7 h. The TPA diamide formed may be converted to terephthalonitrile. Terephthalonitrile may be hydrogenated to form p-xylylenediamine and l,4-bis(aminomethyl)cyclohexane.12 A low-pressure PET ammonolysis process in EG has been developed. The process is catalyzed by 0.5 wt% zinc acetate at a temperature of 70°C and a PET-NH3 ratio of 1 6 (w/w). The yield of TPA diamide was 87%. 

---