Cyclic anhydride, reaction with amine

In the first case, reaction with amines leads to amides amido acids formed when amines react with cyclic anhydrides can be recyclized to cyclic imides (p. 344). When mixed acyclic or asymmetrical cyclic anhydrides react, a mixture of products can be formed, although the stronger acid usually gives an ester (or amide) (56). Reaction of alcohols with anhydrides very often takes place even in the cold certain anhydrides, however, are resistent to heat and can be crystallized from ethanol (57) they can be cleaved by heating with sodium ethoxide in ethanol or benzene. If the acids formed by hydrolysis are solid and suitable for identification, this procedure can be considered as the simplest for identification purposes. When anhydrides of liquid acids are to be identified, the reaction with aromatic amines is generally employed mixed anhydrides are best identified by chromatography of acids formed on alkaline hydrolysis. 

The reactivity of hydrido(ethoxo) complex 4 was examined (Scheme 6-15) [8]. Metatheses similar to those postulated for alcohol exchange (Eq. 6.5) occurred between HCl, LiCl, phenyl acetate or primary amines and yielded complexes 94. The reaction of 4 with cyclic anhydrides proceeded similarly to give iridium-assisted ring opening products 95. Heterocumulenes afforded the inserhon products 96 into the Ir-O bond. 

This reaction, similar in scope and mechanism8S2 to 0-52, can be carried out with ammonia or primary or secondary amines.853 However, ammonia and primary amines can also give imides, in which two acyl groups are attached to the nitrogen. This is especially easy with cyclic anhydrides, which produce cyclic imides.854... 

For the copolymerization of epoxides with cyclic anhydrides and curing of epoxy resins, Lewis bases such as tertiary amines are most frequently used as initiators. In this case, terminal epoxides react with cyclic anhydrides at equimolar ratios. The time dependence of the consumption of epoxide and anhydride is almost the same for curing 35-36> and for model copolymerizations 39,40,45). The reaction is specific 39,40) to at least 99 %. In contrast, the copolymerization with non-terminal epoxides does not exhibit this high specificity, probably because of steric hindrances. The copolymerization of vinylcyclohexene oxide or cyclohexene oxide is specific only to 75-80 % and internal epoxides such as alkylepoxy stearates react with anhydrides only to 60-65 %. On the other hand, in the reaction of epoxy resins with maleic anhydride the consumption of anhydride is faster 65the products are discoloured and the gel is formed at a low anhydride conversion 39). Fischer 39) assumes that the other resonance form of maleic anhydride is involved in the reaction according to Eq. (33). 

However, the experimental data in the literature do not allow to determine the effect of the structure of the amines on the rate of copolymerization of epoxides with cyclic anhydrides, nor to verify the validity of Eq. (36) for this type of reaction. 

The reaction of cyclic anhydrides with amines can be different from that with alcohols, because in the case of amines, the amido acid formed during the first step (Eq. 2.9) can close a cycle to give an imide group (Eq. 2.10) ... 

After the amines, acid anhydrides constitute the next most commonly used reagents for curing epoxy monomers. The epoxy-acid reaction proceeds through a stepwise mechanism (Sec. 2.2.4) while the reaction of epoxides with cyclic anhydrides, initiated by Lewis bases, proceeds through a chain-wise polymerization, comprising initiation, propagation, and termination or chain transfer steps. Some of the postulated reactions are shown in Table 2.25 (Matejka et al., 1985b Mauri et al., 1997). 

In spite of a great number of studies devoted to curing with cyclic anhydrides, there existed a number of contraversial views concerning the reaction mechanism. Recent studies have revealedthat in the presence of tertiary amines the reaction can proceed also in the absence of proton donors. The tertiary amine reacts first with epoxide most probably via a zwitterion The simplified mechanism is as follows... 

Kluger, R., Hunt, J. C. Circumventive catalysis contrasting reaction patterns of tertiary and primary amines with cyclic anhydrides and the avoidance of intermediates. J. Am. Chem. Soc. 1989, 111,3325-3328. 

For the copolymerization of epoxides with cyclic anhydrides and curing of epoxy resins, Lewis bases such as tertiary amines are most frequently used as initiators. In this case, terminal epoxides react with cyclic anhydrides at equimolar ratios. The time dependence of the consumption of epoxide and anhydride is almost the same for curing copolymerizations jjjg reaction is specific... 

Furthermore, reaction of cyclic anhydride with aliphatic primary amine is more rapid than with aromatic amine [35, 72]. When the mutual reactivity of the Omctional groups is not high enough, their concentration can be increased or catalyst or small-size molecules can be added [124, 125]. 

Reaction of perthiophosphonic anhydrides (64) with amines leads first to (105) and then, by further attack, to (106). With ammonia itself the second addition proceeds at the same phosphorus atom as the initial attack, giving (107) and (108). The anhydride (64) is also reported to react with 1,3-dioIs to give cyclic phosphonyl disulphides (109). Thermal decomposition of phenylphosphinic anhydride (110) may lead to the formation of PhP since in the presence of benzil the formation of the phosphorane (111) was observed. ... 

Cyclic anhydrides of dibasic acids react with ammonia and certain amines to give cyclic imides, such as phthalimide (97%) and a-ethyl-glutarimide (85%). Aqueous ammonia, ammonium carbonate, and dry ammonia gas have been used. 2-Aminopyridine and phthalic anhydride react at 180° to yield N-(2 pyridyl)-phthalimide (76%). t-Butylphthali-mide is made by the action of phthalic anhydride on /-butylurea at 200-240°. The use of alkylureas in this reaction is general. ... 

Sn[N(TMS)2l2, A, A -carbonyldiimidazole (110, p. 1418), which behaves as in reaction 16-63, POCl3, °" TiCl4, ° molecular sieves,Lawesson s reagent (p. 1278), ° and (MeO)2POCl. ° Certain dicarboxylic acids form amides simply on treatment with primary aromatic amines. In these cases, the cyclic anhydride is an intermediate and is the species actually attacked by the amine. Carboxylic acids can also be converted to amides by heating with amides of carboxylic acids (exchange),sulfonic acids, or phosphoric acids, for example, ... 

Phosgenation of a-hydroxy acids affords cyclic mixed carboxylic-carbonic anhydrides which can be used as activated form of acid function in reaction with amines to afford amides as illustrated by the example given in scheme 182 (Ref. 235). 

Although in cyclic systems studied to date the N-oxide function has been for the most part incorporated into a six-membered ring system, there are several examples where pyrrolidine or dihydropyrrole A -oxides are the substrates. For instance, the reaction of amine oxide (55) with acetic anhydride at 0 C provides a convenient route to the 7V-alkylisoindole (56 equation 16). ... 

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