Pyridine 1:1 adducts of urea (Z′ = 1) and thiourea (Z′ = 8)

During our studies of urea and thiourea adducts, we noticed that no adducts with unsubstituted pyridine had been structurally investigated. The 1:1 adduct of pyridine and urea, C5H5N·CH4N2O, crystallizes in the P21/c space group with Z = 4. The structure is of a standard type for urea adducts, whereby the urea molecules form a ribbon, parallel to the a axis, consisting of linked R 2 2(8) rings, and the pyridine molecules are attached to the periphery of the ribbon by bifurcated (N—H...)2N hydrogen bonds. The 1:1 adduct of pyridine and thiourea, C5H5N·CH4N2S, crystallizes in the P21/n space group, with Z = 32 (Z′ = 8). The structure displays similar ribbons to those of the urea adduct. There are two independent ribbons parallel to the b axis at z ≃ 0 and 1 \over 2, and three at z ≃ 1 \over 4 and 3 \over 4; the latter are crosslinked to form a layer structure by additional long N—H...S interactions, which each formally replace one branch of a bifurcated hydrogen-bond system.

Selective Oxidation of Methane to Methanol with Organic Oxidants Catalyzed by Iodine in Non-Aqueous Acetic Acid Medium

Various organic oxidants including tert-butyl peroxybenzoate, tert-butyl hydroperioxide (TBHP), hydrogen peroxide-urea adduct, dicumyl peroxyide and peracetic acid solution were studied for the oxidation of methane to methanol via methyl acetate catalyzed by iodine in non-aqueous acetic acid medium. Among these organic oxidants investigated, tert-butyl hydroperioxide (TBHP) exhibited the highest methane conversion. The effects of various kinetic factors on the catalytic behavior of the TBHP-I2 system were investigated, and a quantitative yield of methyl acetate (18.9%) based on methane has been obtained under the optimized conditions. A possible mechanism involving electrophilic displacement has been suggested for this reaction.

Improved Preparation of 2,2-Dithiobis(Pyridine-N-Oxide)

2,2-Dithiobis(pyridine-N-oxide) (1) was prepared by reacting 2-pyridinethiol-N-oxide (2) and hydrogen peroxide-urea adduct (3) at the molar ratio of 1:1.25 and 45oC for 1.75h in high yield and purity of 91.6% and 99.6% respectively. The structures of product were characterized by IR, NMR.

Preparation methods of calcium sulphate and urea adduct

Preparation methods of calcium sulphate and urea adduct The paper presents the results of laboratory studies on the preparation of calcium sulphate and urea adduct by: grinding, compacting and mixing in the presence of physical water. A method for the measurement of urea conversion into the adduct form, which is based on the difference in solubility of free urea and the adduct bound urea CaSO4·4CO(NH2)2 in n-butanol, was developed. Mixing the reagents in the presence of physical water produced the best results. High urea conversion into the adduct form, over 85%, in the prepared samples indicates that this method can be successfully used to get CaSO4·4CO(NH2)2 adduct.