Polymerization of bis(2-oxazoline) compounds with dicarboxylic acids

A side reaction was found in the reaction of a 2-oxazoline compound with a carboxylic acid. It is an oxazoline ring opening addition to an amide group formed by the main reaction. In addition, certain phosphites were found to act as catalyst for the side reaction. The rate constants of the main and side reactions in the system of 2-phenyl-2-oxazoline and n-octanoic acid were obtained through simulation of the reactions on an analog computer. The side reaction makes it impossible for a very high molecular weight polymer to form in the reaction of a bis-2-oxazoline with a dicarboxylic acid, but makes it possible for a new crosslinked polymer to form when excess bis-2-oxazoline and a dicarboxylic acid are heated in the presence of a certain phosphite.     

4,7‐Diiodo‐2,1,3‐benzothiadiazole and 7,7′‐diiodo‐4,4′‐bi(2,1,3‐benzothiadiazole)

In the crystal structures of the title compounds, C₆H₂I₂N₂S, (I), and C₁₂H₄I₂N₄S₂, (II), respectively, a large number of short inter‐heteroatom contacts, such as S?N, I?I and N?I, are observed. In (II), which is non‐centrosymmetric, two halves of the mol­ecule are related by a crystallographic twofold axis.     

Hydroxylation of ionized aromatics including carboxylic acid or amine using recombinant Streptomyces lividans cells expressing modified biphenyl dioxygenase genes

The bphA1(2072)A2A3A4 gene cluster codes for a shuffled biphenyl dioxygenase holoenzyme with broad substrate specificity. These bphA1(2072)A2A3A4 genes were expressed in the actinomycetes Streptomyces lividans using a thiostrepton-inducible promoter P_tipA. Biotransformation experiments of various aromatics including carboxylic acid or amine in their molecular structure, such as 1-naphthoic acid, 2-(1-naphthyl)acetic acid, diphenylamine, and 1-benzyl-4-piperidone, were performed using the recombinant S. lividans cells. These ionized aromatics were converted to the corresponding 1,2-dihydrodiol, mono- or tri-hydroxy forms in 48 h. The structure of the converted products was determined by their EI-MS, ¹H- and ¹³C NMR analysis, and several products were found to be novel compounds.     

Alternating copolymerization of isoprene and butadiene with acrylonitrile

Copolymerizations of acrylonitrile and isoprene or butadiene were carried out in the presence of a new catalytic system containing Cr(O-tert-Bu)₄ and AlEtCl₂. It was found that the copolymer compositions have a highly alternating structure, even with varying feed ratios of monomer. The nuclear magnetic resonance spectra of the copolymers obtained with this catalytic system were observed and are discussed in terms of the alternation.     

Synthesis of aromatic polythioamide-oxothioxoquinazolines from bis(1,3,4-thiadiazoline-5-thione) and aromatic bis-o-amino esters

Aromatic polythioamide-oxothioxoquinazolines were synthesized by the polycondensation of 2,2′-(m-phenylene)bis-1,3,4-thiadiazoline-5-thione with aromatic bis-o-amino esters. The polymerizations were carried out at 160°C in acidic media such as m-cresol, sulfolane, and polyphosphoric acid to produce polymers with reduced viscosities up to 0.5 dL/g. These polymers were soluble in polar aprotic solvents like N-methyl-2-pyrrolidone and some acidic media including m-cresol. The polythioamide-oxothioxoquinazolines showed relatively good thermal stability with 10% weight loss at 344–394°C in air.     

Effect of HF addition on the microwave-assisted acid-digestion for the determination of metals in coal by inductively coupled plasma-atomic emission spectrometry

The microwave-assisted acid-digestion for the determination of metals in coal by ICP-AES was investigated, especially focusing on the necessity of adding HF. By testing five certified reference materials, BCR-180, BCR-040, NIST-1632b, NIST-1632c, and SARM-20, it was found that the two-stage digestion without HF (HNO₃ + H₂O₂ was used) was very effective for the pretreatment of ICP-AES measurement. Both major metals (Al, Ca, Fe, and Mg) and minor or trace metals (Co, Cr, Cu, Mn, Ni, Pb, and Zn) in coal gave good recoveries for their certified or reference values. The possibility of ‘HF-memory effect’ was cancelled by the use of a set of vessels which had been never contacted with HF. Twenty-four Japanese standard coals (SS coals) were analyzed by the present method, and the concentrations of major metals measured by the present method provided very high accordance with those from the authentic JIS (Japanese Industrial Standard) method.     

3-Aroylmethyl derivatives of 2(1H)quinoxalinone and 2H-l,4-benzoxazin-2-ones existing in the enamine form

Seventeen derivatives of 2(1H)quinoxalinone and 2H-l,4-benzoxazin-2-one have been synthesized for structural study. All of the compounds having a substituted phenacyl, isonicotinoylmethyl, or 2-furoylmethyl side chain are shown to exist in the enamine form with an internal chelation both in the crystalline and solution states as evidenced by the ir and pmr spectra, respectively. In the gas phase, however, o-hydroxyphenacyl derivatives can exist in another type of intramolecularly hydrogen-bonded form which is supported by their mass spectra.     

The crystal structures of α- and β-CdUO4

The structural parameters of α- and β-CdUO₄ crystals are determined by X-ray powder diffraction technique. α-CdUO₄ is rhombohedral and cell parameters are a = 6.233(3) Å and α = 36.12(5)°. β-CdUO₄ crystallizes in a C-centered orthorhombic cell with a = 7.023(4), b = 6.849(3), c = 3.514 (2) Å. The space groups are $\text{R}\text{3}\text{m}$ for α-CdUO₄ and Cmmm for β-CdUO₄. α-CdUO₄: 1U in (000), 1Cd in ($\text{1}\text{2}\text{1}\text{2}\text{1}\text{2}$), 2O(1) in ±(uuu), 2O(2) in ±(vvv); u = 0.113, v = 0.350, Z = 1. β-CdUO₄: 2U in ($\text{000;}\text{1}\text{2}\text{1}\text{2}\text{0}$), 2Cd in ($\text{1}\text{2}\text{0}\text{1}\text{2}\text{; 0}\text{1}\text{2}\text{,}\text{1}\text{2}$), 4O(1) in ($\text{0, ±y, 0;}\text{1}\text{2}\text{,}\text{1}\text{2}\text{±y, 0}$), 4O(2) in ($\text{±x, 0,}\text{1}\text{2}\text{;}\text{1}\text{2}\text{±x,}\text{1}\text{2}\text{,}\text{1}\text{2}$); x = 0.159, y = 0.278, Z = 2. β-CdUO₄ contains collinear uranyl UO²⁺₂ groups with a UO(1) distance of 1.91 Å, located either along or parallel to the c axis whereas the UO(1) bond length in α-CdUO₄ is 1.98 Å which is longer than the usual uranyl bond length.