3-Nitrophthalic anhydride derivatives with

Derivatives with 3-nitrophthalic anhydride. 3-Nitrophthalic anhydride reacts with primary and secondary amines to yield nitro-phthalamic acids it does not react with tertiary amines. The phthalamic acid derived from a primary amine undergoes dehydration when heated to 145° to give a neutral A -substituted 3-nitrophthalimide. The phthalamic acid from a secondary amine is stable to heat and is, of course, soluble in alkali. The reagent therefore provides a method for distinguishing and separating a mixture of primary and secondary amines. 

Nitrophthalic anhydride reacts with primary and secondary amines according to equations (21) and (22) on mild heating. On further heating at about 145° dehydration (equation 23) takes place in the case of primary amines, while the phthalamic acids (40) derived from secondary amines are stable. Compounds 40 and 41 can be easily distinguished by their chemical properties. 

Experimental details for the preparation of derivatives with benzoyl chloride and with 3-nitrophthalic anhydride are given in Section IV,100,2 and 7. 

Other derivatives can be prepared by reaction of the alcohol with an acid anhydride. For example, phthalic or 3-nitrophthalic anhydride (I mol) and the alcohol (Imol) are refluxed for half to one hour in a non-hydroxylic solvent, e.g. toluene or alcohol-free chloroform, and then cooled. The phthalate ester crystallises out, is precipitated by the addition of low boiling petroleum ether or is isolated by ev toration of the solvent. It is recrystallised from water, 50% aqueous ethanol, toluene or low boiling petroleum ether. Such an ester has a characteristic melting point and the alcohol can be recovered by acid or alkaline hydrolysis. 

Phthalic anhydrides readily form hydrogen phthalate esters on reaction with alcohols the derivatives from 3-nitrophthalic anhydride are usually nicely crystalline compounds and are hence suitable for purposes of characterisation. Hydrogen phthalate esters are also useful in appropriate instances for the resolution of racemic alcohols (Section 5.19). 

An imide monomer was synthesised from 4-nitrophthalic anhydride N-(4 -carboxyphenyl)>4-(4 -carboxyphenoxy)phthaHmide. (14). This was reacted (via its dimethyl ester) with chloro- or phenylhydroquinone to form wholly aromatic co-poly(esterimide)s which were found to exhibit a nematic phase in the melt. Similar PEIs derived from aliphatic diols produced only isotropic polymers. Thus, PEI derived from 4-(4 -carboxyphenoxy)phthalimide and n-do-decane diol melted at 162 °C, Tg=66 °C, and was isotropic [28]. The above imide monomer based on phthalic anhydride was therefore shown to be a poor mes-ogen compared with its trimellitic anhydride analogue (4). 

Kricheldorf has reported the synthesis of lyotropic poly(amide-imide)s and poly(benzoxazole-amide)s. These were prepared by the polycondensation of N,N-bis(trimethylsilyl)-p-phenylenediamine or N,AT -bis(trimethylsilyl)-3,3 -dim-ethylbenzidine with the diacyl chloride of trimellitimide of p-aminobenzoic acid, or the imide formed from p-amino benzoic acid and terephthalic acid. Lyotropic behaviour was observed in cone, sulphuric acid solution [38]. A series of thermotropic poly(imide-amide)s was prepared based on trimellitimides formed from trimellitic anhydride and an a, -bis(4-aminophenoxy) alkane with carbon chain lengths 9-12. Melting points were in the range 250-300 °C. They formed smectic A phases and tended to degrade around the isotropisation temperatures (around 350 °C). Pendant methyl groups or occupied meta- groups tended to prevent mesophase formation [39]. Novel LC poly(imide-amides) have also been synthesised from new diamine spacers derived from linear diaminoalkanes and 4-nitrophthalic anhydride. A smectic and nematic phase were observed when 4,4 -biphenyl dicarboxylic acid was used as co-monomer [40]. 

Among chemical methods for the separation of amines, those of Hinsberg (reaction with / -toluenesulfonyl chloride) and of Alexander (94) (reaction with 3-nitrophthalic anhydride) are most commonly used. Tertiary amines do not react with the reagents mentioned and they can be separated after the reaction — for example, by extraction. Derivatives of primary amines with p-toluenesulfonyl chloride are soluble in alkali hydroxide solutions, in contrast to sulfonamides of secondary amines this is utilized for their separation. When primary and secondary amines are separated by reacting them with 3-nitrophthalic anhydride, use is made of the fact that only phthal-imine acids derived from primary amines can be cyclized. Practical utilization of both procedures is demonstrated by the separated of a mixture of aniline, ethylaniline, and diethylaniline. However, it should be mentioned that in a number of cases the procedures fail or do not lead to a sufficiently sharp separation. Negatively substituted amines which do not react with / -toluenesulfonyl chloride can be separated with 3-nitrophthalic anhydride. Some p-toluenesulfonamides of primary amines are poorly soluble in alkali. The derivative of primary amine with 3-nitrophthalic anhydride is cyclized merely by boiling in benzene, and the phthalimide formed is soluble in benzene and can be isolated together with the tertiary amine. 

Several thioureas have been synthesized by ring-opening reactions of heterocyclic compounds such as l,3-dithiolan-2-thiones, 5-arylimino-l,2,4-dithiazolidine-3-thiones, benzoxazole-2-thiones, and 3,1-benzo-thiazine-4-thione derivatives. Similarly, the action of triphenylphosphine on 5-amino-l,2,4-dithiazolo-3-thiones gave thiocarbamoyl isothiocyanates (304). Other thioureas have been obtained by thermolytic decarbonylation of 2-amino-5(4H)-thiazolones and by treatment of 4,5,6,7-tetrahydro-cyclopenta-l,3-dioxin-4-one" and 3-nitrophthalic anhydride with thiourea. ... 

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