Controlled oxidation of benzyl ethers on irradiated semiconductor powders

Irradiation of a suspension of powdered TiO₂, a photoactive semiconductor, in oxygen saturated acetonitrile leads to mild selective oxidation of substrates containing a benzylic methylene by conversion of that carbon to a carbonyl group. The method is shown to be synthetically useful for the preparation of esters from ethers and ketones from hydrocarbons. A critical analysis of the products and of the possible intermediates results in a plausible mechanistic pathway for these photooxidations.     

Radical polymerization of metal-coordinated monomers with ligands of pyrrole-containing schiff bases

The copper complexes and the cobalt complex with the ligand of 3-(2-pyrrolylmethyl-enimino)propene-1 (PIP) or p-(2-pyrrolylmethylenimino)styrene (PIS) were synthesized and homopolymerizations and the copolymerization with styrene, acrylonitrile, methyl methacrylate and acrylic acid studied. In the polymerization of chelate monomers, inhibition of radical polymerization by the central metal ion was observed, but the chelate polymer could be obtained only if the initiator was present in higher concentrations in the feed. It is considered that the strength of inhibition depends on the electronic configuration of d-orbitals of the central metal ion. The initiation mechanism of the cupric chelate monomer may be reduction of the metal ion by the redox reaction with a primary radical via the intramolecular electron transfer through the π-conjugated system of the ligand prior to the propagation step. This mechanism was verified by studying the redox reaction of various copper complexes with DPPH. In the system of the copper complex containing PIS and acylic acid the alternating copolymer could be obtained at any mole fraction of monomer mixture in feed.     

几种双冠醚Schiff碱与钾离子配位作用的量热滴定

用量热滴定法测定了四种双(苯并-15-冠-5)Schiff碱与钾离子在甲醇-水溶液中,25℃时配位作用的热力学性质,讨论了这些双冠醚与钾离子生成的蛤形夹心(clam sandwich)配位化合物中桥联长度和组成对配位稳定性的影响。     

Direct diacylation of schiff bases

A novel diacylation of Schiff bases occurs using catalytic quantities of cobalt carbonyl and phase transfer catalysis conditions.     

Ortho effects in schiff bases of diaminodicyanoethene

In the electron impact mass spectra of azomethines derived from various substituted aromatic aldehydes and diarninodicyanoethene the superposition of two ortho effects concurring with the azomethine group is apparent: one involving the amino group of the diaminodicyanoethene part accounts for the cyclization to [C₅H₃N₄]⁺ ions and the other involving ortho substituents of the benzylidene part which can interact with the azomethine moiety is responsible for specific fragment ions, suppressing the typical fragmentations of azomethines. The ortho effect was studied for the o-nitro derivative by labelling experiments, analysis of metastable transitions and collisional activation comparing model ions, demonstrating that the specific [M-H₂O]⁺˙ and [C₇H₅NO₂]⁺˙ ions are the result of cyclization processes.     

水溶性高分子担载二茂铁希夫碱的合成

合成了水溶性聚丙烯酸－N－乙烯基吡咯烷酮和聚甲基丙烯酸－N－乙 基吡咯 烷酮担载的二茂铁希夫碱，并用元素分析，FT－IR，UV－Vis，热分析，XPS，ICP ，小角激光散射（LALLS）等分析方法对其结构和组成进行了表征。     

某些西佛碱类化合物的质谱重排反应

研究了十四种西佛碱类化合物的电子轰击质谱，利用碰撞诱导解离(CID)和B/E联动扫描技术，证实了特殊重排产物的离子结构及生成机理，并利用亚稳离子测定方式对这类化合物的主要离子进行了归属。     

Reaction of schiff bases with α-halo ketones

1-Halomethyl-3-arylbenzo[f]quinoline derivatives were obtained by condensation of Schiff bases with α-halo ketones.     

Thermal stability of some ferrocene containing schiff bases

Taking into account the importance of thermal stability in the liquid crystals field, the study presents the thermal behavior of some ferrocene containing Schiff bases. Some other kinetic characteristics, such as reaction order (n), activation energy (E _a) and pre-exponential factor (lnA) have been also evaluated. The thermal stability series of Schiff bases was established analysis associated with three parameters (T _d, T _max, E _a) is: S₆<S₄<S₃<S₅<S₁<S₂.     

Determination of the rate of formation of the schiff bases of pyridoxal 5′-phosphate with polyallylamine

The formation constants of the Schiff bases of pyridoxal 5′-phosphate with polyallylamine were determined over the p^H range of the acetic-acetate buffer (3.9–5.5) at an ionic strength of 0.1 M and a temperature of 25°C. The results were consistent with the rapid formation of an ionized carbinolamine, T⁺, followed by deprotonation, in the rate-determining step, to a neutral carbinolamine, T°. Subsequent dehydration of T° in a rapid step yields the final Schiff base. The formation of T⁺ is a concerted process subject to specific acid catalysis. © 1995 John Wiley & Sons, Inc.     

On the structural changes induced by hydrogenation in polyenic schiff bases

Ab initio theoretical investigations, at the STO-3G level, of the free and protonated 1-imino-deca-2,4,6,8-tetraenes and some of the dihydroderivatives are reported. It is shown that the saturation of the CC bonds leads to drastic modifications of the ground-state potential-energy hypersurface.     

Radical intermediates in the electrochemical reduction of alizarin

Conclusions In the electroreduction of alizarin in an aprotic medium the stepwise formation of the anion-radical and subsequently of the dianion has been observed; under conditions of the prolonged process the anion-radical disproportionates and through intermediate stages of deprotonation and reduction is converted into the stable dianion-radical.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 983–988, May, 1985.     

Triazolines VIII. Action of diazoalkanes on heterocyclic substituted schiff bases

Diazoalkanes have been found to add to heterocyclic substituted Schiff bases (imines), providing a very useful route to the synthesis of the hitherto unknown heterocyclic substituted Δ-1,2,3-triazolines. The orientation of the addition as well as the results of synthesis accord with previously reported mechanistic considerations. The direction of dipole orientation and the structure assigned to the adducts are elucidated by nmr spectroscopy.     

α一酮醛的Schiff碱类化合物的质谱断裂机理

本文通过低分辨、高分辨质谱及亚稳离子测定,对α-酮醛的Schiff碱类化合物的质谱断裂过程进行了研究。结果表明,这类化合物均不太稳定,分子离子峰的相对强度很小。分子的电子轰击质谱裂解有以下三种基本方式:(1)电离发生在碳氢不饱和双键的N原子上,得到m/z186的离子及其子离子m/z170,144,143;(2)电离发生在乙酰胺基的N原子上,经甲基上的H重排,丢失COCH2,得到m/z[M-COCH2][+]的离子及其骨架重排子离子; (3)电离发生在乙酰基的氧原子上,α断键产生m/z43的离子。取代基R的性质决定了断裂所采取的主要方式。α-酮醛的Schiff碱类化合物与喹啉环类化合物是同一原料和合成路线在不同溶剂中反应的不同产物,而在质谱离子源中,Schiff碱也存在转变为喹啉环的趋势。     

Template electrosynthesis of complexes of nickel with schiff bases

A suitable method is proposed for the electrosynthesis of complexes of nickel with Schiff bases containing a hydroxyl group (homogeneous catalysts of chemical and electrochemical reactions) in a single stage with a high material yield.A. E. Arbuzov Institute of Organic and Physical Chemistry, Russian Academy of Sciences, 420083 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1435–1437, June, 1992.     

Interaction of schiff bases with indandione-1, 3

A new method was examined for the synthesis of multinuclear systems based on dihydroquinoline and quinoline, consisting of the interaction of arylidene--naphthylamines with indandione-1, 3. The reaction of arylidene anilines with indandione-1,3 leads to the formation of arylidenindandiones-1, 3.     

Complexes of metals with paramagnetic 3-Imidazoline schiff bases

Methods for the synthesis of intracomplex bischelates CuL₂, NiL₂, CoL₂, and the mixed- ligand complex NiL₂y₂, where L is a deprotonated derivative of the stable nitroxide 4- (2′- hydroxyphenyl)- 2,2,5,5tetramethyl- 3- imidazoline- 1-oxyl, were developed. In the solid state, the compounds have a molecular structure. The most significant difference in the structure of ML₂ molecules lies in the values of the angle between the chelate rings (56.9‡ for CuL₂, 78.8‡ for CoL₂, and 0‡ for NiL₂. In complexes with paramagnetic metal ions, the intramolecular exchange interactions are ferromagnetic in character and are close in the order of magnitude (5.7 cm^{− 1} for CuL₂ and 6.8 cm⁻ for NiL₂Py₂) to the values for complexes with deprotonated enaminoketone derivatives of 3- imidazoline. The NiL₂ molecules, having a square coordination of the central atom, are biradicals with antiferromagnetic exchange interactions between the unpaired electrons of nitroxyl groups (− 3.6 cm⁻). The transformation of NiL₂ into NiL₂Py₂ leads to a transition of Ni(II) from the low- to high- spin state and to ferromagnetic exchange between the unpaired electrons of the paramagnetic centers. Translated fromZhumal Strukturnoi Khimii, Vol. 38, No. 4, pp. 750–761, July–August, 1997.     

Transient absorption spectra and photochromic mechanism of schiff bases

The transient absorption spectra of salicylideneaniline (SA) and salicylidenebenzylamine (SBA) have been investigated by means of the nanosecond laser flash photolysis. It has been found that the intermediates from the two compounds have different properties. According to the properties of the intermediates for compound SA, the primary photoproduct is a zwitterion produced by the excited singlet state, rather than a trans- keto isomer. The intermediate of compound SBA also was found to be a zwitterion, but produced not only by the excited singlet state but also by the excited triplet state. The photochromic mechanisms of the two compounds are proposed and discussed respectively.