Black polyquinoxaline foams with strong chemisorption - produced by pyrolysis of aromatic nitrogen cpds., useful in air filters

摘要

Black absorbent thermally hardened foams with a specif. surface of =50 m2/g and a polyquinoxaline structure chains, are made by pyrolysis of a mixt. of =1 aromatic N-contg. cpd. X-Ar-Y (where Ar is an aromatic nucleus to which the substituents X and Y are directly bound; X is a subst. with a negative Hammett sigma-constant bound to the aromatic nucleus via a N, O or S atom and Y is a substit. with a positive Hammett sigma-constant bound to the aromatic nucleus via a N atom, and the substits X and/or Y may form part of a ring condensed to the aromatic nucleus). Typical starting materials are m- or p-nitroacetanilide, aminonitroluene, aminonitroxylenes, 2,6-dibromo-4-nitro-aniline, 5-nitro-1-naphthylamine, polymers -(CH2-CH(CONHC6H4NO2))-2-amino-5-nitropyridine, etc. The material is pref. liq. at pyrolysis temp. and the pyrolysis is carried out at 200-230 degrees C in the presence of a strong acid or base to promote condensation. Prods have excellent chemisorption props for polar molecules such as acids, halogens, heavy metal ions, HCN. etc. They are useful in gas mask and air filter elements to remove dangerous gases.