Piotr Milart

SYNTHESIS OF DI- AND TRIAMINO-1,1':3', 1 -TERPHENYLS FROM ARYLETHYLIDENE- AND ARYLIDENEMALONODINITRILES

Abstract A three-step synthesis of several di- ortriamino-m-terphenyls 19 – 23 from 3- or 4-nitrobenzylidene-malonodinitriles 1 and 1-[3- or 4-nitro(or amino)phenyl]ethylidenemalonodinitriles 2 is reported. Gewalds method was applied for a one-pot preparation from 1 and 2 of 5′-amino[1, 1′:3′, 1″-terphenyl]-4′, 6′-dicarbonitriles 5 – 15 which bear the nitro or amino/nitro groups on the side rings of the terphenyl system. An attempt to optimize yields of the terphenyls 5 – 15 by selective introduction of the nitro or amino functions on the phenyl groups of starting dinitriles 1 and 2 was carried out. Compounds 5 – 13 were smoothly reduced with tin and hydrochloric acid to afford 5′-amino[1, 1′:3′, 1″-terphenyl]-4′, 6′-dicarbonitriles 14 – 18 having only the amino groups on the side benzene rings. The terphenyls 14 – 18 were denitrilated to yield di- or triamino-1, 1′:3′, 1″-terphenyls 19 – 23 . The decyanation reaction was carried out by heating 14 – 18 for 4 h at 220°C in a pressure vessel (∼2.5 MPa) with ethanolic sodium hydroxide solution. Download full-size image

Proton transfer reactions from dimethyl (4-nitrophenyl)malonate to N-bases in acetonitrile

Abstract Deprotonations of dimethyl (4-nitrophenyl)malonate (C-acid) by 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 1,8-bis(dimethylamino)naphthalene (DMAN) in acetonitrile were studied by kinetic as well as FTIR and 1 H NMR spectroscopic methods. In the 1:1 mixture of C-acid with DMAN no proton transfer was found. The N-bases with guanidine-like character deprotonate C-acid in the acetonitrile solution quantitatively. The mechanisms of proton transfer reactions are discussed.

Crystal and molecular structures of pyrylium salts Part III. Crystal and molecular structure of 2,6-diphenyl- 4- (4-N,N-dimethylaminophenyl) pyrylium perchlorate: a case of a long distance substituent effect on geometry of the pyrylium ring

Abstract The crystal and molecular structure of 2,6-diphenyl-4- (4- N , N -dimethylaminophenyl)pyrylium perchlorate has been determined by X-ray diffraction methods given R=0.061 and mean esd for bond lengths 0.006 A and bond angles 0.3°. NMe 2 -substitution in the para position causes a strong through-resonance effect with the positively charged pyrylium ring. As a result, (i) a shortening of internal bond length with maintaining coplanarity, and (ii) a decrease of aromatic character of the pyrylium ring due to localization of two π-CC bonds, are observed.

Crystal and molecular sturcture of pyrylium salts: Part II. Crystal and molecular structure of 2,6-diphenyl-4-(4-nitrophenyl) pyrylium perchlorate nitromethane solvate, electronegativity effect on geometry of the action

Abstract The crystal and molecular structure of 2,6-diphenyl-4-(4-nitrophenyl)pyrylium perchlorate nitromethane solvate was solved with R =0.067 for 2827 reflections and mean esd for bond lengths 0.005A and bond angles 0.4°. Phenyl rings attached to positions 2,4 and 6 of the pyrylium ring exhibit a strong deformation of angular geometry indicating enhanced electronegativity of carbon atoms 2,4 and 6 due to the positive charge on them. Exocyclic valence angles at carbon atoms 2 and 6 of the pyrylium ring are strongly deformed from 120° due to the strongly electronegative oxygen atom with partial positive charge, STO-3G, 3-21G and 6-31G * ab initio calculations support this interpretation.

New synthesis of substituted biphenyls, biaryls, and terphenyls from arylidenemalonodinitriles, ethyl pyruvate, and malonodinitrile

The reaction of arylidenemalonodinitriles with ethyl pyruvate and malonodinitrile affords in one step ethyl 3-amino-2, 4-dicyano-5-arylbenzoates (2) which are then used in synthesis of 3-amino-5-arylbenzoic acids (4).

Quantitative treatment of surface potentials in Langmuir films from aromatic amphiphiles

It is shown that the surface potentials of Langmuir monolayers from aromatic compounds can be interpreted using the three-layer capacitor model of Demchak and Fort, with the same local dielectric constants employed for aliphatic compounds. Based on new data for monolayers from an acid, amine and ester compounds with an aromatic hydrophobic part, we show that the dielectric constant for the monolayer/water interface region is 6±1. Good agreement between experiment and theory was obtained by taking the dielectric constant of the monolayer/interface as 3.0±0.6, which are essentially the same as those obtained for long tail aliphatic compounds.

Conjugated schiff's bases—141: Cycloaddition of heterocumulenes to some 1-oxa-4-azabutadienes

Abstract 1-Oxa-4-azabutadienes proved to be prone to react with some heterocumulenes after 1,3-cycloaddition patterns yielding various 5,5-disubstituted derivatives of 1,3-diaryl-hydanotoins as it was shown by the chemical and spectroscopic analysis. Relatively high yields, mild reaction conditions and a very weak effect of solvent polarity on the reaction rate suggested a synchroneous mechanism involving 1,2-migration of a substituent.

Langmuir monolayers of polyphenylene carboxylic acids

Abstract A series of polyphenyl carboxylic acids with 3–6 uncondensed benzene rings and some of their analogues with a nitro and/or cyano group were synthesized and investigated at the air-water interface. They all can be treated as substituted m-terphenyls. It is determined that a system with at least four phenyl groups with the carboxyl group at a peripheral position are a prerequisite for the ability of monolayer formation. Their isotherms exhibit a large plateau attributed to the formation of bilayers.

Hydrogen bonds in the adduct of 1,8-bis(N,N-dimethylamino)naphthalene (DMAN) with 4-(p-nitrophenyl)disic acid (NPDA)

Abstract The structure and IR spectra of the 1:1 ionic adduct of 1,8-bis(dimethylamino)-naphthalene (DMAN) with 4-(p-nitrophenyl)disic acid (NPDA) were studied. The adduct crystallises in a triclinic system, space group Pl, a = 9.066(2), b = 10.156(2), c = 12.716(3) A , α = 99.02(2), β = 107.84(3), γ = 100,46(3)°, Z = 2. In the protonated DMAN the [NHN] + hydrogen bridge of 2.586(2) A length is close to symmetric with the v NHN stretching vibration band located in the region 300–700 cm −1 . The NPDA deprotonated molecules form centrosymmetric dimeric anions with the amide type NH·O hydrogen bonds of 2.827(2) A length. The negative charge of the anionic units is largely diffused over the nitrophenyl groups. The IR spectrum confirms medium strong NH·O hydrogen bonds formed in dimeric anions.

Crystal and molecular structure of the lithium p-nitrosophenolate dihydrate dimer: an example of a strong dependence of the π-electron cooperative substituent effect on the hydrogen-bonding network in the crystal lattice

Abstract The crystal and molecular structure of lithium p -nitrosophenolate dihydrate dimer (LNP) is solved by X-ray diffraction with relatively high precision (the mean esd for the bond lengths is 0.002–0.003 A; wR = 0.0433). NMR studies and ab initio (6-31G) calculations indicate that the free anions have primarily a quinoid structure, whose contribution to the crystal lattice strongly depends on hydrogen bonding. Comparison of the reported structure with sodium tri- and magnesium hexahydrate p -nitrosophenolate perchlorates indicates that LiO interactions somewhat resemble the hydrogen bond.