网络骨架组装工程：5-硝基间苯二甲酸形成的配位聚合物网络多样性

Two novel coordination polymers, [Cu(nip)(phen)]_n (1) and [Co₂(nip)₂(phen)₂]_n (2), have been synthesized by hydrothermal synthesis using 5-nitroisophthalic acid (H₂nip), 1,10-phenanthroline (phen) and metal salts and structurally characterized by X-ray single-crystal structure analysis. The results indicated that the nip ligand in compound 1 has a μ₃ mono-atomic bridging-monodentate coordination mode and the structure is a two-dimensional network, while the nip ligand in compound 2 has a chelating-bridging coordination mode and the structure is a one-dimensional network. CCDC: 222202, 1; 222203, 2.     

Trifluoropyruvic acid hydrate in heterocyclic synthesis: a facile synthesis of 5-hydroxy-5-trifluoromethylhydantoin derivatives

The reaction of trifluoropyruvic acid hydrate with urea derivatives affords 5-hydroxy-5-trifluoromethylhydantoin derivatives in good yield. The product orientation is consistent with the initial attack on the most active center, in trifluoropyruvic acid hydrate, towards nucleophiles     

两个由5-硝基间苯二甲酸和双咪唑基配体构筑的锰、钴配合物的合成及晶体结构

通过水热法合成了2个新的配合物[Mn(NIPH)(mbix)]_n (1)和[Co(NIPH)(mbix)(H₂O)₃]_2n·2nH₂O (2)(H₂NIPH=5-硝基间苯二甲酸,mbix=1,3-双(咪唑基-1-基)苯)。并对其进行了元素分析、红外光谱、紫外光谱、热重和X-射线单晶衍射测定。这两个配合物通过氢键和π-π相互作用形成了三维超分子网状结构。     

Structure of the reaction product of chloral hydrate and isocyanic acid

In a recent article describing the reactions of isocyanic acid with carbonyl compounds, Hoover, Stevenson, and Rothrock (1) observed that chloral reacted slowly with free isocyanic acid at 0° to give CCl₃CH(OH)NCO, m.p. 25°. On stirring with water, this was converted to a solid, m.p. 190-200°, assigned structure A. This latter substance was also produced by reaction of isocyanic acid directly with chloral hydrate.     

Reaction of esters of 2-substituted 5-pyrimidinecarboxylic acids with hydrazine hydrate

The reaction of methyl esters of 2-substituted 5-pyrimidinecarboxylic acids with hydrazine hydrate at 0–5°C results in the nucleophilic substitution of readily eliminating groups (Cl, CH₃O, CH₃S) at the position 2 of the pyrimidine ring, and, on the boiling with the 80% aqueous solution of hydrazine hydrate, the reaction is accompanied by the formation of hydrazides. The dimethylamino group at thepposition 2 of the pyrimidine ring is not substituted by hydrazine.Vilnius University, Vilnius 2006, Lithuania Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1528–1530, November, 1999.     

Synthesis of 5-substituted 1H-tetrazoles catalyzed by ytterbium triflate hydrate

Various 5-substituted 1H-tetrazoles were synthesized from aryl nitriles, alkyl nitriles, and vinyl nitriles reacting with sodium azide. The tetrazoles were recovered in high yield under mild conditions when the reaction was catalyzed by ytterbium triflate hydrate in dimethylformamide. Other rare-earth and post-transition metal catalysts were also investigated.     

Proton dynamics in the perchloric acid clathrate hydrate HClO4.5.5H2O

In the perchloric acid clathrate hydrate HClO4.5.5H2O, the perchlorate anions are contained inside an aqueous host crystalline matrix, positively charged because of the presence of delocalized acidic protons. Our experimental results demonstrate that the microscopic mechanisms of proton conductivity in this system are effective on a time scale ranging from nanosecond to picosecond. In the present paper, we discuss more specifically on the relaxation processes occurring on a nanosecond time scale by combining high-resolution quasielastic neutron scattering and 1H pulse-field-gradient nuclear magnetic resonance experiments. The combination of these two techniques allows us to probe proton dynamics in both space and time domains. The existence of two types of proton dynamical processes has been identified. The slowest one is associated to long-range translational diffusion of protons between crystallographic oxygen sites and has been precisely characterized with a self-diffusion coefficient of 3.5 x 10(-8) cm2/s at 220 K and an activation energy of 29.2+/-1.4 kJ/mol. The fastest dynamical process is due to water molecules' reorientations occurring every 0.7 ns at 220 K with an activation energy of 17.4+/-1.5 kJ/mol. This powerful multitechnique approach provides important information required to understand the microscopic origin of proton transport in an ionic clathrate hydrate.     

5-Aminoorotic acid derivatives

The 2,4,8-trioxo derivative of pyrimido[5,4-d][1,3]oxazine was synthesized, and esters and amides of 5-acetamidoorotic acid were obtained from it. The acetyl group in 5-acetamido-orotic acid esters is readily hydrolyzed in acidic media to give esters of 5-aminoorotic acid, while the acetyl group in amides of 5-acetamidoorotic acid do not undergo hydrolysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 270–272, February, 1973.Deceased.     

N‐Methyl‐dl‐aspartic acid mono­hydrate

The title compound, C₅H₉NO₄·H₂O, has been synthesized and crystallized. It crystallizes in Cc with one mol­ecule in the asymmetric unit. The compound is found in its zwitterionic form. d and l forms of the compound are linked in the crystal via O—H?O and N—H?O hydrogen bonds, both directly between the aspartic acid‐derivative entities and to the crystal water mol­ecule. A weak intramolecular N—H?O interaction is found. The carbon skeleton is slightly twisted with C—C—C—C = 166.83 (11)°. A comparison with other derivatives of aspartic acid shows only two rotamers – one with a near planar carbon skeleton and one with a significantly twisted carbon skeleton.     

Reduction of 2-amino-3- and -5-nitropyridine derivatives with hydrazine hydrate

The reactions of 2-amino-3-nitropyridine and 2-amino-5-nitropyridine with hydrazine hydrate resulted in elimination of the amino group and reduction of the nitro group with formation of 3-aminopyridine. A probable reaction mechanism involves addition of hydrazine hydrate at the N-C² bond, followed by elimination of ammonia and reduction of the nitro group to amino. 2-Amino-4-methyl-3-nitropyridine and 2-amino-5-methyl-3-nitropyridine reacted with hydrazine hydrate in a similar way.     

Kinetic studies of gas hydrate formation with low-dosage hydrate inhibitors

Pipeline blockage by gas hydrates is a serious problem in the petroleum industry. Low-dosage inhibitors have been developed for its cost-effective and environmentally acceptable characteristics. In a 1.072-L reactor with methane, ethane and propane gas mixture under the pressure of about 8.5 MPa at 4 °C, hydrate formation was investigated with low-dosage hydrate inhibitors PVP and GHI1, the change of the compressibility factor and gas composition in the gas phase was analyzed, the gas contents in hydrates were compared with PVP and GHI1 added, and the inhibition mechanism of GHI1 was discussed. The results show that PVP and GHI1 could effectively inhibit the growth of gas hydrates but not nucleation. Under the experimental condition with PVP added, methane and ethane occupied the small cavities of the hydrate crystal unit and the ability of ethane entering into hydrate cavities was weaker than that of methane. GHI1 could effectively inhibit molecules which could more readily form hydrates. The ether and hydroxy group of diethylene glycol monobutyl ether have the responsibility for stronger inhibition ability of GHI1 than PVP.