Amides from acid salts

When we made acid anhydrides from acid chlorides plus car-boxylate salts, we used an anionic nucleophile RCO2 but, when we made amides from acid chlorides plus amines, we used a neutral nucleophile NH3, and not NH2. For proper comparisons, we should include in our table ROH (pXaH = -5 in other words, -5 is the pXa of ROH2) and NH3 (pXgH = 9 in other words, 9 is the pKaofNHj). 

The formation of amides from ammonium salts of oxygen acids is in fact only a part of the dissociation of the intermediate addition compound in amide formation from an amine and an acid. The formation of amide from ester and ammonia is similar to the formation of amide from... 

Carboxylic acid amides from amidinium salts s. 24,685... 

Amides (except urea and thiourea), imides and nitriles, after the above alkaline hydrolysis, give derivatives similarly to those from the alkaline solution obtained from ammonium salts (p. 360). (A) If the original compound is aromatic, acidification of the cold solution deposits the crystalline acid. (B) The cold solution, when carefully neutralised (p. 332) and treated with benzylthiuronium chloride, deposits the thiuromum salt. 

In general, the reactions of the perfluoro acids are similar to those of the hydrocarbon acids. Salts are formed with the ease expected of strong acids. The metal salts are all water soluble and much more soluble in organic solvents than the salts of the corresponding hydrocarbon acids. Esterification takes place readily with primary and secondary alcohols. Acid anhydrides can be prepared by distillation of the acids from phosphoms pentoxide. The amides are readily prepared by the ammonolysis of the acid haUdes, anhydrides, or esters and can be dehydrated to the corresponding nitriles (31). 

Most of the inhibitors in use are organic nitrogen compounds and these have been classified by Bregman as (a) aliphatic fatty acid derivatives, b) imidazolines, (c) quaternaries, (d) rosin derivatives (complex amine mixtures based on abietic acid) all of these will tend to have long-chain hydrocarbons, e.g. CigH, as part of the structure, (e) petroleum sulphonic acid salts of long-chain diamines (preferred to the diamines), (/) other salts of diamines and (g) fatty amides of aliphatic diamines. Actual compounds in use in classes (a) to d) include oleic and naphthenic acid salts of n-tallowpropylenediamine diamines RNH(CH2) NH2 in which R is a carbon chain of 8-22 atoms and x = 2-10 and reaction products of diamines with acids from the partial oxidation of liquid hydrocarbons. Attention has also been drawn to polyethoxylated compounds in which the water solubility can be controlled by the amount of ethylene oxide added to the molecule. 

This fully aromatic amide, based oil the amino acid p-aminobenzoic acid, can be spontaneously synthesized from p-aminobenzoic chloride.7 9 72 To prevent this occurring at an unwanted moment, the amine group is masked by forming the hydrochloric acid salt with hydrochloric acid. 

Our approach for chiral resolution is quite systematic. Instead of randomly screening different chiral acids with racemic 7, optically pure N-pMB 19 was prepared from 2, provided to us from Medicinal Chemistry. With 19, several salts with both enantiomers of chiral acids were prepared for evaluation of their crystallinity and solubility in various solvent systems. This is a more systematic way to discover an efficient classical resolution. First, a (+)-camphorsulfonic acid salt of 19 crystallized from EtOAc. One month later, a diastereomeric (-)-camphorsulfonic acid salt of 19 also crystallized. After several investigations on the two diastereomeric crystalline salts, it was determined that racemic 7 could be resolved nicely with (+)-camphorsulfonic acid from n-BuOAc kinetically. In practice, by heating racemic 7 with 1.3equiv (+)-camphorsulfonic acid in n-BuOAc under reflux for 30 min then slowly cooling to room temperature, a cmde diastereomeric mixture of the salt (59% ee) was obtained as a first crop. The first crop was recrystallized from n-BuOAc providing 95% ee salt 20 in 43% isolated yield. (The optical purity was further improved to -100% ee by additional recrystallization from n-BuOAc and the overall crystallization yield was 41%). This chiral resolution method was more efficient and economical than the original bis-camphanyl amide method. 

Like thallium(I) amide from which it is derived by treatment with potassium amide in liquid ammonia, the ammoniated salt (x = 2 or less) explodes violently on heating, friction, or contact with dilute acids or water. 

Scheme 3 outlines synthetic strategies for the introduction of a range of substituents on the amide, alkoxyl and acyloxyl side chains. Hydroxamic esters 23 are readily synthesised from potassium salts of hydroxamic acids 21 according to Cooley et al.7 8 9 or by condensation of the corresponding acid chloride 24 with an alkoxyamine. 

Since, as has been described above, amides can be obtained by removal of water from the ammonium salts of acids, nitriles can be prepared directly from ammonium salts in one operation by heating them with a powerful dehydrating agent, e.g. ammonium acetate with P205 ... 

A number of reagents derived from nitrate salts and acid anhydrides have been reported for the V-nitration of amides and related compounds. Crivello first reported the use of metal nitrates in trifluoroacetic anhydride (TFAA) for the nitration of aromatic systems. Chapman... 

Nylon 6 is also a polyamide, but is made from the monomer e-caprolactam, which is a cyclic amide of e-aminocaproic acid. Heat opens the lactam ring to give the amino acid salt, which forms amide bonds with other molecules by eliminating water. 

Write equations for the preparation of a given amide from an acyl halide, acid anhydride, or ammonium salt. 

An interesting synthesis of T-vinyl-l,2,3-dithiazolylimines 94 from Appel salt 20 and aziridines has been described <2005H(65)1601>. This procedure involves elimination of hydrogens from different nitrogen and carbon atoms. The reaction with aziridinecarboxylic acid ester or its amide 95 having the frarcr-configuration produces one of the possible... 

A vigorously stirred suspension of 0.2 to 1 mole of sodium amide in 200 ml of xylene, in which were dissolved 0.1 mole of a,a-diphenyl-7-hexamethyleneimino butyronitrile was boiled for 12 hours. Thereupon the excess of sodium amide was decomposed with water and the xylene layer was separated, washed with water and extracted with hydrochloric acid. This acidic extract was made strongly alkaline with concentrated lye and the separated base was extracted with ether. After drying, the ether was evaporated and the l,l-diphenyl-3-hexamethyleneimino propane distilled in vacuo. The boiling point was 170-174°C/1 mm, the refractive index nD20 = 1.56 36, and the density d420 = 1.009. From the oil obtained several acid additions and quaternary ammonium salts can be obtained by reaction with acids containing a non-toxic anion or esters thereof. The hydrochloric acid salt, for instance, melts at 189-192°C, the methiodide at 174-177°C under decomposition. 

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