No abstract

Acyl(quinoxalin-2-yl)ketenes generated by thermal decarbonylation of 3-acylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones react regioselectively with Schiff bases under solvent-free conditions to form pyrimido[1,6-a]quinoxaline derivatives in good yields.

Reactions of (Z)-3-(phenacylidene-2-oxo)-3,4-dihydroquinoxalin-2(1H)-ones and (Z)-3-(3,3-dimethyl-2-oxobutylidene)-3,4-dihydroquinoxalin-2(1H)-one with oxalyl chloride led to the formation of 3-acyl-1H-pyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones that at the thermal decarbonylation generated acyl(3-oxoquinoxalin-2-yl)ketenes which underwent the intramolecular stabilization giving 3-acylfuro[3,2-b]quinoxalin-2(4H)-ones.The thermal decarbonylation of 4-acyl-substituted 1H-pyrrole-2,3-diones fused with azaheterocycles at the [a] side (hetareno[a]-pyrrole-2,3-diones) is a convenient method for the generation of acyl(imidoyl)ketenes where the imidoyl fragment is included into the heterocyclic system [2][3][4][5].It was formerly established that the thermolysis of 3-aroyl-and 3-heteroyl-5-phenylpyrrolo[1,2-a] quinoxalin-1,2,4(5H)-triones resulted in the generation of aroyl-and heteroyl(3-oxo-4-phenylquinoxalin-2-yl)ketenes which underwent the stabilization through [4+2]-cyclodimerization followed by the [1,3]-acylotropic shift to provide 4-acyl-3-acyloxy-2-(3-oxo-4-phenyl-2-quinoxalinyl)-6-phenyl-1H-pyrido[1,2-a] quinoxalin-1,5-diones [4]. Yet even insignifi cant changes in the structure of the imidoylketene led to the alteration of its stabilization paths. For instance, the 4-unsubstituted 3-oxoquinoxalin-2-yl(ethoxycarbonyl)ketene originating from the thermolysis of 5-unsubstituted 3-ethoxycarbonylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-trione stabilized by the transformation of the quinoxalinone fragment from the amide into the hydroxyimine form with the subsequent intramolecular acylation of the hydroxyimine OH group by the ketene fragment [5].In order to examine the effect of the structure of _________ * For Communication LXXII, see [1]. the fuzed quinoxalone fragment of the pyrrolo[1,2-a] quinoxaline-1,2,4(5H)-triones on the stabilization routes of the quinoxalinylketenes obtained by the thermolysis of the former we investigated the methods of synthesis and thermolytic transformations of 3-acyl-1H-pyrrolo-[1,2-a]quinoxaline-1,2,4(5H)-triones, 5-unsubstituted analogs of 3-aroyl-and 3-heteroyl-5-phenylpyrrolo[1,2-a]-quinoxaline-1,2,4-triones [4]. (Z)-3-(2-Oxophenacylidene)-3,4-dihydroquinoxalin-2(1H)-ones Ia-Ig and (Z)-3-(3,3-dimethyl-2-oxobutylidene)-3,4-dihydroquinoxalin-2(1H)-one (Ih) were obtained reacting the esters of acylpyruvic acids with O-phenylenediamine by the known method [6, 7] (see the scheme).Compounds Ia-Ig are bright yellow crystalline substances of high melting points, readily soluble in DMF and DMSO, sparingly soluble in the common organic solvents, insoluble in water and alkanes.IR spectra of compounds Ia-Ig contain absorption bands of the stretching vibrations of the group N 1 H (3120-3170 cm -1 ), of N 4 H group involved into an intramolecular hydrogen bond of the H-chelate type (wide band at 3020-3060 cm -1 ), of amide carbonyl C 2 =O (1673-1688 cm -1 ), of the aroyl carbonyl group involved into the intramolecular hydrogen bond (wide band at 1603-1611 cm -1 ).

A facile de novo synthesis of meta-substituted arylamines based on three-component cyclo-condensation/aromatization of in situ generated imines with 1,3-diketones is described.

Hydrothermal liquefaction (HTL) of sewage sludge is considered in the article as an analogue of the natural processes of oil formation (catagenesis). A comparison of the physicochemical composition of primary and secondary sludge with type II kerogen (natural precursor of oil) showed their similarity. Both types of sludge have a slightly higher level of oxygen and nitrogen. The study tested the hypothesis that the elements included in the inorganic part of the oil source rocks can have a catalytic effect on the oil formation processes. For the conducted studies of sludge HTL, the catalysts containing cations and substances found in oil source rocks were chosen: as homogeneous catalysts (KOH, NaOH, NH4Fe(SO4)2, CoCl6, NiSO4, CuSO4, ZnSO4, MoO3) and as heterogeneous catalysts (MgO, Zeolite, Al2O3). The effectiveness of catalysts containing metal ions, zeolite and aluminum oxide has been proven. The highest biocrude yield was achieved in a process with NiSO4 as the catalyst in a dose 2 g per 10 g of sludge: oil yield increased by 34.9% and 63.4% in the processing of primary and secondary sludge, respectively. The use of catalysts provided an increase in fuel HHV by 10.8–12.5%, which is associated with a decrease in oxygen content (by 10.8–43.2%) with a simultaneous increase in carbon (by 7.9–10.9%) and hydrogen (by 6.5–18.7%) content.