Ammonia compared with amines

Ammonolysis of Anthraquinonesulfonic Acids. The replacement of the —SO3H group by —NHj is limited to the anthraquinone series. The amination can be carried out readily at 165°C with concentrated aqueous ammonia. Compared with the similar ammonolysis of halogenoanthra-quinones, the reaction takes place at lower temperatures and purer amines can be obtained. 

Aminofurans substituted with electron-withdrawing groups e.g. NO2) are known and 3-amino-2-methylfuran is a relatively stable amine which can be acylated and diazotized. 2-Amino-3-acetylfurans are converted into 3-cyano-2-methylpyrroles on treatment with aqueous ammonia. This transformation is a further illustration of the relative instability of the amino derivatives of five-membered ring heterocycles compared with anilines (Scheme 67) (781003821). 

Two substituents on two N atoms increase the number of diaziridine structures as compared with oxaziridines, while some limitations as to the nature of substituents on N and C decrease it. Favored starting materials are formaldehyde, aliphatic aldehydes and ketones, together with ammonia and simple aliphatic amines. Aromatic amines do not react. Suitable aminating agents are chloramine, N-chloroalkylamines, hydroxylamine-O-sulfonic acid and their simple alkyl derivatives, but also oxaziridines unsubstituted at nitrogen. Combination of a carbonyl compound, an amine and an aminating agent leads to the standard procedures of diaziridine synthesis. 

NOTE Some recirculation of ammonia and amine takes place within the overall boiler plant system, although at higher pH much of the ammonia is lost at the deaerator vent. In practice, this recirculation coupled with low er-than-theoretical C02 liberation (as a result of the incomplete breakdown of sodium bicarbonate when present in the boiler) typically results in a reduced amine-demand for any particular boiler pressure. This reduced demand, compared with the apparent demand, results in real cost savings. 

LAB is sulfonated in the para position and the resulting sulfonic acid is then neutralised with caustic soda to produce the sodium salt, which is the most widely used form of LAS worldwide. Other salts such as ammonia and triethanol amine are also used, although in substantially lower amounts compared with NaLAS. 

Placing a proton on the X group presumably weakens the Cr-X bond. The enhanced lability is due to a reduced enthalpy of activation, compared with that associated with the step. Normally, the removal of unidentate ammonia or amine ligands from metal complexes is not accelerated by acid, since the nitrogen is coordinately saturated. This situation changes when we consider multidentates (Sec. 4.4.2). 

Amination of ketene has been studied by ab initio methods.Reactions of ammonia, its dimer, and its (mono)hydrate with ketene have been calculated and compared with earlier smdies of ammonia (at lower levels of theory), of water, and of water dimer. In general, the results favour initial addition of ammonia to the C=0 bond (giving the enol amide), as against addition to the C=C bond (which gives the amide directly). Amide formation is compared with the corresponding hydration reaction where enol acid and acid are the alternative immediate products. Most of the reactions, i.e. both additions and tautomerizations, are suggested to involve cyclic six-membered transition states. 

The comparatively simple method of preparation of tetrakis (trifluorophos-phine)nickel-(0) encouraged some scouting experiments on its still unexplored chemistry. Whereas the compound is hydrolytically remarkably stable, it was found to react readily with amines and ammonia with complete aminolysis of the phosphorus-fluorine bonds. Very typical of tetrakis(trifluorophosphine) nickel-(0) and similar fluorophosphine and chlorophosphine complexes of zerovalent nickel is the rapid decomposition with precipitation of elemental nickel by aqueous alkali hydroxide. 

The trend between increases in log A with E for reactions of amines (174) represented only approximate obedience to Eq. (2). The most notable feature of the exchange reactions of ammonia on eight metals (172) was the relatively small range of A (A log A - 0.8) compared with the variation in (21 < E < 58). 

Garrison (12, H, 51) and Maxwell (39, 40) consistently report much higher G values for carbonyl and ammonia production (G = 3 to 5) than those in Table II. Their values are based on extrapolations back to zero dose (39) or referred to the ammonia plus amine G value at zero dose obtained by Maxwell, Peterson, and Sharpless (39) and are intended to reflect initial radical yield values important in theoretical treatments (12, 51). Examining the data in these references shows that G values at higher doses approach those reported in Table II. For example, Maxwell (40) shows an observed G value at 1 megarad of about 0.4 for carbonyl production compared with the zero-dose extrapolation value of about 4.5. 

Inductive effects can also influence the basic strength of neutral molecules (e.g. amines). The pKb for ammonia is 4.74, which compares with pKb values for methylamine, ethylamine, and propylamine of 3.36, 3.25 and 3.33 respectively. 

Since amines are organic bases, water solutions show weakly basic properties. If the basicity of aliphatic amines and aromatic amines are compared to ammonia, aliphatic amines are stronger than ammonia, while aromatic amines are weaker. Amines characteristically react with acids to form ammonium salts the nonbonded electron pair on nitrogen bonds the hydrogen ion. 

The marked activation of the iV-oxide function on the chlorine atom of 2-chloropyrazine 4-oxide and 2-ehloro-3,6-dimethylpyrazine 4-oxide is also demonstrated by the milder conditions under which these compounds react with ammonia and amines compared with chloro-pyrazine and 2-chloro-3,6-dimethyl pyrazine, respectively. Although 2-chloropyrazine 4-oxide undergoes the expected displacement reaction with ammonia on heating at 115°-120° for 2.5 hours, reaction at 140° for 16 hours gives 2,3-diaminopyrazine, possibly as a result of an addition-elimination reaction on the initially formed 2-amino-pyrazine 4-oxide (Scheme 47).417... 

Although a variety of amines, particularly trimethylamine and n-butylamine have widely been used as poisons in catalytic reactions and for surface acidity determinations (20), comparably few spectroscopic data of adsorbed amines are available. As with ammonia, coordinatively adsorbed amines held by co-ordinatively unsaturated cations have preferentially been found on pure oxides (176, 193-196), whereas the protonated species were additionally observed on the surfaces of silica-aluminas and zeolites (196-199). However, protonated species have also been detected on n-butylamine adsorption on alumina (196) and trimethylamine adsorption on anatase (176) due to the high basicity of these aliphatic amines. In addition, there is some evidence for dissociative adsorption of n-butylamine (196) and trimethylamine (221) on silica-alumina. Some amines undergo chemical transformations at higher temperatures (195, 200) and aromatic amines, such as diphenylamine, have been shown to produce cation radicals on silica-alumina (201, 201a). 

The yields of primary amines over platinum oxide were improved in the presence of an excess molar equivalent of ammonium chloride in low pressure reductive alkylation of ammonia with ketones in methanol saturated with ammonia.10 With acetophenone and 4-methyl-2-pentanone, the yields of primary amine increased from 37 and 49% in the absence of ammonium chloride to 69 and 57-65%, respectively, in the presence of ammonium chloride. Moller obtained a much higher yield (>90%) of 1-phenethylamine from acetophenone by adding a small amount of acetic acid to methanol-ammonia with Raney Ni (eq. 6.6).15 The reductive amination of benzophenone in the presence of Raney Co and some ammonium acetate gave 70% yield ofbenzohy-drylamine, compared to only 19% under usual conditions with Raney Ni.3... 

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