Amines reaction with amide bases

Reactions with Amines and Amides. Hydroxybenzaldehydes undergo the normal reactions with aUphatic and aromatic primary amines to form imines and Schiff bases reaction with hydroxylamine gives an oxime, reaction with hydrazines gives hydrazones, and reactions with semicarbazide give semicarbazones. The reaction of 4-hydroxybenzaldehyde with hydroxylamine hydrochloride is a convenient method for the preparation of 4-cyanophenol (52,53). 

Carboxyhc acids react with aryl isocyanates, at elevated temperatures to yield anhydrides. The anhydrides subsequently evolve carbon dioxide to yield amines at elevated temperatures (70—72). The aromatic amines are further converted into amides by reaction with excess anhydride. Ortho diacids, such as phthahc acid [88-99-3J, react with aryl isocyanates to yield the corresponding A/-aryl phthalimides (73). Reactions with carboxyhc acids are irreversible and commercially used to prepare polyamides and polyimides, two classes of high performance polymers for high temperature appHcations where chemical resistance is important. Base catalysis is recommended to reduce the formation of substituted urea by-products (74). 

Both aliphatic and aromatic amines have been investigated in this reaction with similar results. This confirms that the reaction is a general reaction with amines in aqueous medium. The conversions of aromatic amines to secondary amides are lower than that of the aliphatic amines. This is because aromatic amines are generally weaker bases and poorer nucleophiles. 

The N atom of an amide, however, is much less basic than the N atom of an amine, so it does not undergo a similar Lewis acid-base reaction with AICI3. A three-step reaction sequence involving an intermediate amide can thus be used to form the products of the Friedel-Crafts reaction. 

Figure 10 Schematic representation of the most common reactions for labeling an amine (a) reaction with isothiocyanate to give a thiourea (b) reaction with a Succinimidil ester to give an amide (c) reaction with a sulfonyl chloride to give a sulfonamide (d) reaction with an aldehyde to give an imine (Schiff s base) and (e) reaction with a carbodiimide-activated carboxylic acid to give an amide.

Some of these transformations were accompanied by additional reactions, e.g. formylation of the aromatic or heteroaromatic - nucleus or CH-acidic methyl groups further dehydration of amides to nitriles was observed. Adducts from amides and PCI3, sulfonyl halides or SO2CI2/SCXZI2 from which amidines can be obtained by reaction with amine derivatives (compare Section 2.7.2.5 and refs. 5 and 14) have not found wide application for this purpose. An interesting reaction is the preparation of the amidine (294 equation 158) from 7V-pentafluorophenylformamide. By thermal decomposition of the adducts from secondary amides and 7V,iV-dialkylcarbamoyl chlorides amidinium salts were synthesized from which the amidines (295 equation 159) were set free by treatment with bases. " ... 

P(NB/MA) proved to be surprisingly resistant to hydrolysis, both in solution and as a thin film(2. Moreover, the diacid prepared by hydrolysis in concentrated TMAH reverts to the anhydride upon heating(2ri). Similarly, alcoholysis with methanol is difficult and the methyl half-ester reverts to the anhydride on heating(2ri). Reactions with amines to yield poly(amic acids) and poly(imides) proceed more readily. However polyimides are too strongly absoibing at 193 nm to make suitable resist matrices. Also, because primaiy amines are potent imidization catalysts for amic adds(P), amidization of P(1 /MA) with these also causes strong absoibance at 193 nm. Selective amidization can be achieved with buU secondary amines which yield stable poly(amic add) with aqueous base solubility and acceptable transparency (absorbance = ca 0.5 AU/pm at 193 nm). These materials... 

Alcohols are hydrocarbon derivatives containing one or more OH groups. Ethers are formed by a condensation reaction of two molecules of alcohol. Several functional groups contain the carbonyl (C=0) group, including aldehydes, ketones, carboxylic acids, esters, and amides. Aldehydes and ketones can be produced by the oxidation of certain alcohols. Further oxidation of the aldehydes produces carboxylic acids. Carboxylic acids can form esters by a condensation reaction with alcohols, or they can form amides by a condensation reaction with amines. Esters imdergo hydrolysis (saponification) in the presence of strong bases. 

Careful mechanistic studies on the carbonylation process have been reported by Yamamoto, including studies with isolated model compounds. - These studies have revealed several reaction pathways, and the particular pathway depends on whether the electrophile is an aryl or benzyl halide and whether the nucleophile is an amine or an alkoxide. The existing experimental data suggest that the latter pathway b in Scheme 17.29 involving insertion of CO into the palladium-aryl bond to form a benzoylpalladium halide intermediate occurs. These complexes have been isolated with PMe and PPhj as ligand and have been shown to form the ester product upon reaction with an alcohol and amine base and to form the amide products upon reaction with amine alone. 

Tertiary amides (and thioamides) with an a-proton react instead to give chloro enamines. These can undergo nucleophilic substitution (eq 15). CSiloro enamines are also intermediates in synthetically useful dehydrogenation reactions, using Pyridine N-Oxide or DMSO as oxidant (eq 16). Tertiary ureas and thioureas form related adducts which have been utilized in the synthesis of hindered guanidine bases by further reaction with amines (eq 17).33... 

Reaction with ammonia and amines (Sec tion 20 14) Acyl chlorides react with am monia and amines to form amides A base such as sodium hydroxide is normally added to react with the hydrogen chio ride produced... 

Another drawback to the use of amino-substituted benzenes in electrophilic aromatic substitution reactions is that Friedel-Crafts reactions are not successful (Section 16.3). The amino group forms an acid-base complex with the AICI3 catalyst, which prevents further reaction from occurring. Both drawbacks can be overcome, however, b3 carrying out electrophilic aromatic substitution reactions on the corresponding amide rather than on the free amine. 

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