Acid amides, preparation reactions

The most frequent applications of these procedures he in the preparation of terminal alkynes Because the terminal alkyne product is acidic enough to transfer a proton to amide anion one equivalent of base m addition to the two equivalents required for dou ble dehydrohalogenation is needed Adding water or acid after the reaction is complete converts the sodium salt to the corresponding alkyne... 

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). 

Acetoiicetyliition Reactions. The best known and commercially most important reaction of diketene is the aceto acetylation of nucleophiles to give derivatives of acetoacetic acid (Fig. 2) (1,5,6). A wide variety of substances with acidic hydrogens can be acetoacetylated. This includes alcohols, amines, phenols, thiols, carboxyHc acids, amides, ureas, thioureas, urethanes, and sulfonamides. Where more than one functional group is present, ring closure often follows aceto acetylation, giving access to a variety of heterocycHc compounds. These reactions often require catalysts in the form of tertiary amines, acids, and mercury salts. Acetoacetate esters and acetoacetamides are the most important industrial intermediates prepared from diketene. 

Other Applications. Hydroxylamine-O-sulfonic acid [2950-43-8] h.2is many applications in the area of organic synthesis. The use of this material for organic transformations has been thoroughly reviewed (125,126). The preparation of the acid involves the reaction of hydroxjlamine [5470-11-1] with oleum in the presence of ammonium sulfate [7783-20-2] (127). The acid has found appHcation in the preparation of hydra2ines from amines, aUphatic amines from activated methylene compounds, aromatic amines from activated aromatic compounds, amides from esters, and oximes. It is also an important reagent in reductive deamination and specialty nitrile production. 

Chemical Properties. Like neopentanoic acid, neodecanoic acid, C2QH2QO2, undergoes reactions typical of carboxyHc acids. For example, neodecanoic acid is used to prepare acid chlorides, amides (76), and esters (7,11,77,78), and, like neopentanoic acid, is reduced to give alcohols and alkanes (21,24). One area of reaction chemistry that is different from the acids is the preparation of metal salts. Both neopentanoic acid and neodecanoic acid, like all carboxyHc acids, can form metal salts. However, in commercial appHcations, metal salt formation is much more important for neodecanoic acid than it is for neopentanoic acid. 

Polymerization of castor od, chemical or oxidative, results in higher viscosity or bodied ods that are more usehd in urethane coatings than the untreated castor od (87). Other castor derivatives used to prepare urethanes are amides prepared by reaction of castor od and alkanolamines, amides of ricinoleic acid with long-chain di- and triamines, and butanediol diricinoleate (88,89). 

These dyes aie prepared by the reaction of l-amino-4-nittoanthtaquinone-2-catboxylic acid amide (108) with cyanide in water (119). 

Shaw and McDowellhave prepared imidazolone derivatives by cyclization of a-acylamino amides. In a variation of this reaction the azlactone (30) was gradually converted to the hydroxamic acid (31) by methanolic hydroxylamine. Sodium methoxide and hydroxylamine readily gave the acyclic hydroxamic acid (32) which could be cyclized to 31 by dilute acid. Benzyloxyurea has been used in the sjrnthesis of pyrimidine hydroxamic acids (33) by reaction with /S-diketones followed by catalytic hydrogenation of the benzyl group. Protection... 

Amides, prepared by condensation of tryptamine or substituted tryptamines with a large number of aliphatic, homocyclic, aromatic,and heterocyclic acids, have been used in the reaction. In few cases only did ring closure fail. ... 

Many procedures for the formation of carboxylic acid amides are known in the literature. The most widely practiced method employs carboxylic acid chlorides as the electrophiles which react with the amine in the presence of an acid scavenger. Despite its wide scope, this protocol suffers from several drawbacks. Most notable are the limited stability of many acid chlorides and the need for hazardous reagents for their preparation (thionyl chloride, oxalyl chloride, phosgene etc.) which release corrosive and volatile by-products. Moreover, almost any other functional group in either reaction partner needs to be protected to ensure chemoselective amide formation.2 The procedure outlined above presents a convenient and catalytic alternative to this standard protocol. 

Preparation Of Thiol Acids, Thiol Esters And Amides By Reactions Of Carbonyl Sulfides With Grignard Reagents," Katritzky. A.R. Moutou, J.-L. Yang, Z. Org. Prep. Proceed. Int., 1995, 27, 361... 

Amides prepared from carboxylic acids and ammonia using CDI. Yields refer to reaction of the azolides with ammonia. 

Poly (2,4-d if luoro-1,5, pheny lene t r ime 11 i t ic amide-imide) was prepared by a two-step procedure 12 At the first step, the polyamic acid was prepared by reacting 2,4-difluoro-1,5-phenylene diamine with trimellitic anhydride acid chloride (with the mole ratio of one to one) in anhydrous N,N-dimethylacetaraide at room temperature under nitrogen. After reaction, the polymer was poured into water and precipitated. After filtration, the white solid was washed with distilled water and dried in a vacuum oven. The poly(amide-imide) was obtained from heating the polyamic acid at 220°C for 3 hours. The polyamic acid was dissolved in N,N-dimethyl acetamide or N,N-dimethyl forraamide, cast on glass plates, and the solvent evaporated in a vacuum oven to form a polyamic acid film before heating at 220°C. 

Fig. 56. Dependence of Mwof the microgels on the polymer yield in the anionic polymerization of EDMA in toluene by n-BuLi [254] (see Figure 53 caption for the reaction conditions). Reduced viscosity vs concentration of microgels a) Composition (mol %) N,N -methyl-enebisacrylamide (55%), methacrylamide (33%), methacrylic acid (2%), methacrylamido acetaldehyd-dimethylacetal (10%),measured at 20 °C in water, b) Composition (mol %) 1,4-DVB (35%), propenic acid amide-2-methyl-N-(4-methyl-2-butyl-l,3-dioxolane prepared by emulsion copolymerization and measured in dimethylformamide.

Dehydration (cf., 6, 648). A reagent (1), prepared in situ from (C6H5),PO and Tf20 in the molar ratio 2 1, effects dehydration, usually at 25°, of amides or oximes to nitriles in >90% yield. It also effects condensation of acids and amines to form amides. The reaction of an aryl carboxylic acid with an o-phenylenediamine promoted by 1 provides 2-arylbenzimidazoles in >80% yield (equation I). If the... 

In the cyclization of the (iodoaryl)diene, N-methyl-N-(l,5-hexadiene-3-yl)-2-iodobenzoic acid amide, the combined yield of the tricyclic products arising from a double intramolecular Heck reaction reached 52 % when the catalyst was prepared from [Pd(OAc)2] and 1,10-phenanthroline and the reaction was run in ethanol/water 1/1 (Scheme 6.4) [18,19]. Interestingly, in CH3CN the reaction did not proceed at all with this catalyst. It is also noteworthy, that Pd-phenanthroHne complexes are rarely used as catalysts in Heck-type reactions. 

Optically pure 2,3-dihydro-6//-l, 4-oxazin-2-ones were prepared in a two-step reaction from A-protected AAs and a-bromoketones (78JOC135). When heated in boiling toluene and HCl 2,2-dimethylamino acid amides were transformed into the corresponding 3,3-dimethyl-l,4-oxazine-2,5-diones (83TL1921 87HCA329). 

The instability of primary nitramines in acidic solution means that the nitration of the parent amine with nitric acid or its mixtures is not a feasible route to these compounds. The hydrolysis of secondary nitramides is probably the single most important route to primary nitramines. Accordingly, primary nitramines are often prepared by an indirect four step route (1) acylation of a primary amine to an amide, (2) A-nitration to a secondary nitramide, (3) hydrolysis or ammonolysis with aqueous base and (4) subsequent acidification to release the free nitramine (Equation 5.17). Substrates used in these reactions include sulfonamides, carbamates (urethanes), ureas and carboxylic acid amides like acetamides and formamides etc. The nitration of amides and related compounds has been discussed in Section 5.5. 

A / -disubstituted acid amides are often prepared by reaction of acyl halides with secondary amines. This method is attractive when the acyl halide is readily available. This is not the case with pentynoyl chloride, which has to be synthesised by a two-step procedure from butyne (see exp. 8). In analogy with the carboxyalkylarion with alkyl chloroformates (exp. 2), an... 

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