Aromatic amidation

The copper-promoted arylation of amides is known as the Goldberg reaction. Similar to the traditional Ullmann reaction, this transformation suffered from high reaction temperatures and strictly Umited substrates. The introduction of suitable Ugands has changed this situation. 

---

Primary aromatic amides are crystaUine sohds with definite melting points. Upon boiling with 10-20 per cent, sodium or potassium hydroxide solution, they are hydrolysed with the evolution of ammonia (vapour turns red htmus paper blue and mercurous nitrate paper black) and the formation of the alkah metal salt of the acid ... 

The characterisation of a primary aromatic amide is based upon its own m.p. and the identification of the acid (see Section IV,175) produced on hydrolysis. A crystalline derivative may be prepared directly with xanthhydrol (for experimental details, see Section 111,110, 1). 

The melting points of a few selected primary aromatic amides (together with those of the xanthylamides, where known) are collected in Table IV,191. A more detailed list will be found in the column headed Amides in Table IV,175 (Armnalic Carboxylic Acids). 

OF SUBSTITUTED AROMATIC AMIDES (AROMATIC ACYLATED BASES)... 

The melting points of some typical substituted aromatic amides are collected in Table IV,192. Other examples will be found in the appropriate columns of Tables IV,100A and B Primary and Secondary Aromatic Amines) and of Table IV,175 (Aromatic Carboxylic Acids). 

By dehydration of aromatic amides with phosphorus pentoxide, for example ... 

It was found inadvisable to use more than four molecules of form-amide [ (47) when R = H] per molecule of anthranilic acid and the condensation produces best results when the mixture is heated at 120 -130°C for 2 hr followed by further heating at 170°-180 C for 2 hr. Other variants of this reaction involve the use of ammonium o-acylaminobenzoates, anthranilic acid in the presence of nitriles and acetic anhydride, o-acetamidonitrile with acetic anhydride or hydrogen peroxide, anthranilic esters and aliphatic or aromatic amides or amidines, isatoic anhydride with amides or amidines, and anthranilic esters with aryl iminochlorides in acetoned The mechanism proposed by Bogert and Gotthelf has had experimental supporR and is represented in Scheme 12. 

B. Aromatic Amides (ArC(O)NHR or RC(0)NHAr, where R can represent H, an alkyl group, or an aromatic group.)... 

Except for simple aromatic amides such as benzamide and acetanilide, derivatization is recommended. The most common derivatives used in this laboratory are TMS, acetate, and /V-dimeth-ylaminomethylene (for primary amides). 

In simple aromatic amides, fragmentation occurs on both sides of the carbonyl group. If a hydrogen is available in iV-substituted aromatic amides, it tends to migrate and form an aromatic amine... 

The polymerization of aromatic diamines with acid chlorides in solution works well.7 914 35 The basicity of the aromatic diamine is low and acid binding can be achieved with several compounds and even solvents such as TV-methylpyrrolidonc (NMP) and dimethylacetamide (DMAc). The all-para aromatic amide poly(p-phenyleneterephthalamide) can be synthesized in DM Ac.7,9,14 To prevent precipitation of the polymer, a salt such as calcium chloride or lithium chloride can be added. It is also possible to react the acid chloride with a silylated diamine ... 

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. 

An example will show the nature of electrical effects (resonance and field) on reactivity. In the alkaline hydrolysis of aromatic amides (10-11), the rate-determining step is the attack of hydroxide ion at the carbonyl carbon ... 

Mixed Phosphonate and Aromatic Amide Functionalized Primary... 

The nucleophile assisted ring-opening reactions of phosphonate bearing phthahmide 13 has been utihzed in the synthesis of mixed primary phosphine-phosphonate and aromatic amide functionahzed primary bisphosphines as out-hned in Scheme 6 [50],... 

White or colored gels are obtained with poly (vinyl alcohol) 26), by using the water-soluble salt of an aromatic amide where the hydroxy and carbonyl groups of the amide are attached to the same benzenoid ring. Several such compounds are illustrated in Figure 3. 

These compounds are not very stable and the first series members decompose at low temperatures. However, these decompositions do not represent any danger. They become dangerous in very specific operating conditions or with nitrated aromatic amides. 

---