全卤制碱新工艺

叙述２０ｋｔ／ａ全卤隔膜法制烧碱工艺;探讨３０ｋｔ／ａ全卤离子膜法制烧碱工艺的两个方案。针对全卤隔膜法烧碱工艺存在４个关键问题提出新的工艺方案并已用于工业生产     

生物卤化反应的新领域

介绍了卤化物在生物系统的应用，综述了目前已探明的卤化反应及一些用于卤化反应中的生物催化酶。指出生物基因技术应用于卤化反应酶的生产中，能够产生一系列更有价值的卤化衍生物。生物卤化合成具有广阔的应用前景。     

Halogenation by Phase Transfer Catalysis

Several ketones have been halogenated with carbon tetrachloride employing basic phase transfer catalytic conditions. Acetophenone and phenylace-tone yield halogenated epoxides while several other aromatic compounds underwent α-oxidation.     

Enzymatic Late-Stage Halogenation of Peptides

The late-stage site-selective derivatisation of peptides has many potential applications in structure-activity relationship studies and postsynthetic modification or conjugation of bioactive compounds. The development of orthogonal methods for C−H functionalisation is crucial for such peptide derivatisation. Among them, biocatalytic methods are increasingly attracting attention. Tryptophan halogenases emerged as valuable catalysts to functionalise tryptophan (Trp), while direct enzyme-catalysed halogenation of synthetic peptides is yet unprecedented. Here, it is reported that the Trp 6-halogenase Thal accepts a wide range of amides and peptides containing a Trp moiety. Increasing the sequence length and reaction optimisation made bromination of pentapeptides feasible with good turnovers and a broad sequence scope, while regioselectivity turned out to be sequence dependent. Comparison of X-ray single crystal structures of Thal in complex with d -Trp and a dipeptide revealed a significantly altered binding mode for the peptide. The viability of this bioorthogonal approach was exemplified by halogenation of a cyclic RGD peptide.     

异香豆素类衍生物的卤化烷氧基化反应

以N-溴代丁二酰亚胺(NBS)、N-氯代丁二酰亚胺(NCS)分别为溴代、氯代试剂,醇类化合物作为反应原料及溶剂,实现了异香豆素类衍生物3,4-位的卤化烷氧基化反应.室温(25℃)下即可在3,4-位之间发生加成反应,合成具有潜在药理活性的异色满-1-酮类衍生物.对4-溴-3-甲氧基-3-苯基异色满-1-酮(Ⅳa)的合成反...     

酶催化卤化和去卤化反应

通过研究微生物降解卤素化合物发现了不同种类的去卤化酶,这些酶可以在好氧或厌氧条件下通过不同的作用机理脱去卤原子催化降解卤素化合物。到目前,通过生物法得到将近4000多种卤素化合物,早期仅分离并获得了催化卤化反应的卤过氧化物酶,近来,在研究细菌卤化代谢物的生物合成时发现了以FADH2为辅基的卤化酶。这种新型的卤化酶在卤化代谢物的生物合成中起催化作用。     

Halogenation of drugs enhances membrane binding and permeation

Halogenation of drugs is commonly used to enhance membrane binding and permeation. We quantify the effect of replacing a hydrogen residue by a chlorine or a trifluoromethyl residue in position C-2 of promazine, perazine, and perphenazine analogues. Moreover, we investigate the influence of the position (C-6 and C-7) of residue CF(3) in benzopyranols. The twelve drugs are characterized by surface activity measurements, which yield the cross-sectional area, the air-water partition coefficient, and the critical micelle concentration. By using the first two parameters (A(D) and K(aw)) and the appropriate membrane packing density, the lipid-water partition coefficients, are calculated in excellent agreement with the lipid-water partition coefficients measured by means of isothermal titration calorimetry for small unilamellar vesicles of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine. Replacement of a hydrogen residue by a chlorine and a trifluoromethyl residue enhances the free energy of partitioning into the lipid membrane, on average by deltaG(lw) approximately -1.3 or -4.5 kJ mol(-1), respectively, and the permeability coefficient by a factor of approximately 2 or approximately 9, respectively. Despite exhibiting practically identical hydrophobicities, the two benzopyranol analogues differ in their permeability coefficients by almost an order of magnitude; this is due to their different cross-sectional areas at the air-water and lipid-water interfaces.     

合成橡胶卤化改性的研究进展

合成橡胶经卤化改性后,具有了许多新的优良特性,从而拓宽了它们的应用领域.当今人们已经对多种橡胶的卤化改性进行了研究,部分产品实现了工业化生产.卤化技术的发展方向是效率高、无污染、连续化、结构可控.本文介绍了国内外合成橡胶卤化改性的研究进展,提出了我国应加强合成橡胶的卤化改进研究.     

卤代法测定2,6-二异丙基苯酚的纯度

采用卤代法测定 2 ,6 二异丙基苯酚样品纯度。方法标准偏差 0 4 5,相对标准偏差 0 4 7     

Halogenation of styrene-butadiene rubber to improve its adhesion to polyurethanes

Halogenation of styrene-butadiene rubbers has been carried out using solutions containing different amounts (0.1-5 wt%) of trichloroisocyanuric acid in butan-2-one. The treated rubber surface showed increased peel strength in joints made with polyurethane adhesive. The effects of chlorination on the rubber surface were studied using scanning electron microscopy, contact angle measurements, and infrared spectroscopy. It was shown that cracks appear in the rubber surface after halogenation, a factor which favours adhesion; the larger the amount of trichloroisocyanuric acid used, the larger the number of cracks. On the other hand, chlorination of the carbon double bond (butadiene) and the formation of carboxylic acid groups seem to be the most important chemical changes in the chlorinated rubber surfaces. Chlorination increases the surface energy of the rubber, although this increase is a function of the rubber composition. In fact, for a simple rubber formulation, the polar component of the surface energy increases for the highest concentrations of chlorine on the rubber surface; but for rubber with a more complicated formulation, the same value of surface energy after chlorination was obtained, independently of the amount of trichloroisocyanuric acid added. A good correlation was found between the contact angle measurements, the infrared spectra, and the peel strength values.     

氯化苄法制备1,2-二苯乙烷机理初探

本文对氯化苄法制备1,2-二苯乙烷反应动力学进行了研究。根据文献和实验结果提出了一种新的反应机理,在合理假设和简化的基础上得到其动力学方程,该方程能较好地描述氯化苄缩合反应过程。     

Characterization of a Cyanobacterial Haloperoxidase and Evaluation of its Biocatalytic Halogenation Potential

Vanadium‐dependent haloperoxidases (VHPOs) are a class of halogenating enzymes found in fungi, lichen, algae, and bacteria. We report the cloning, purification, and characterization of a functional VHPO from the cyanobacterium Acaryochloris marina (AmVHPO), including its structure determination by X‐ray crystallography. Compared to other VHPOs, the AmVHPO features a unique set of disulfide bonds that stabilize the dodecameric assembly of the protein. Easy access by high‐yield recombinant expression, as well as resistance towards organic solvents and temperature, together with a distinct halogenation reactivity, make this enzyme a promising starting point for the development of biocatalytic transformations.     

Efficient Halogenation of Aromatic Systems Using N‐Halosuccinimides in Ionic Liquids

A simple, rapid and highly regioselective green protocol has been developed for the halogenation of aromatic systems with N‐halosuccinimides using room temperature ionic liquids (ILs) as novel and recyclable reaction media to produce the corresponding halogenated aromatic compounds in high to quantitative yields. N‐Halosuccinimides show enhanced reactivity in ionic liquids thereby reducing the reaction times dramatically and improving the yields substantially.     

Extended Biocatalytic Halogenation Cascades Involving a Single-Polypeptide Regeneration System for Diffusible FADH2

Flavin-dependent halogenases have attracted increasing interest for aryl halogenation at unactivated C−H positions because they are characterised by high regioselectivity, while requiring only FADH₂, halide salts, and O₂. Their use in combined crosslinked enzyme aggregates (combiCLEAs) together with an NADH-dependent flavin reductase and an NADH-regeneration system for the preparative halogenation of tryptophan and indole derivatives has been previously described. However, multiple cultivations and protein purification steps are necessary for their production. We present a bifunctional regeneration enzyme for two-step catalytic flavin regeneration using phosphite as an inexpensive sacrificial substrate. This fusion protein proved amenable to co-expression with various flavin-dependent Trp-halogenases and enables carrier-free immobilisation as combiCLEAs from a single cultivation for protein production and the preparative synthesis of halotryptophan. The scalability of this system was demonstrated by fed-batch fermentation in bench-top bioreactors on a 2.5 L scale. Furthermore, the inclusion of a 6-halotryptophan-specific dioxygenase into the co-expression strain further converts the halogenation product to the kynurenine derivative. This reaction cascade enables the one-pot synthesis of l -4-Cl-kynurenine and its brominated analogue on a preparative scale.     

含"C=C"化合物不饱和度卤化法测定条件的研究

1 前言 有机化合物的官能团是指有机物中具有一定的结构特征,并能反映该化合物的物理特性和化学特性的原子或原子团。有机物官能团分析就是根据这些物理特性或化学特性所进行的官能团含量测定。该分析主要解决两个问题,一是通过对试样中某组分的特征官能团的定量测定,从而确定组分在试样中的百分含量,这主要是应用于有机化工生产中原料、中间体的控制分析和成品的规格分析;二是通过对有机物特征官能团的定量测定,     

Halogenation effect promoted low bandgap polymers based on asymmetric isoindigo unit with low energy loss

To optimize the energy levels of the structural framework of isoindigo polymers, a series of asymmetric isoindigo based low bandgap polymers with chlorine, fluorine and thiazole substituents was constructed and their optical, electrochemical and photovoltaic properties were comparatively evaluated for the impact of different substitutions. In comparison with the polymer based on 2,2'‐bithiophene and isoindigo unit (PTi) with non‐substituted bithiophene as the donor moiety, the highest occupied molecular orbital energy level for the newly synthesized polymers is significantly decreased, and in turn an improvement of the open‐circuit voltage (V_OC) is noted in the corresponding photovoltaic devices. More importantly, combined with a low bandgap of 1.32 eV, the energy losses (E_loss) could be reduced to 0.61 eV for polymer based on chlorinated 2,2'‐bithiophene and isoindigo unit (PCl). In addition, the halogen moieties are observed to be superior in device fabrication and give better values than the thiazole substituent. Both fluorinated and chlorinated polymer donors exhibited improved performance compared with the original polymer PTi. Consequently, this work not only presents the influence of different electron withdrawing substituents on the physicochemical and photovoltaic performance, but also backs the concept of how to reduce the energy loss via the heteroatom effect. © 2020 Society of Chemical Industry     

Halogenation par voie electrochimique de composes ethyleniques—II. Chloration du cyclohexene dans differents solvants nucleophiles

The electrochemical chlorination of cyclohexene has been studied in the same solvents (acetonitrile, N,N-dimethylformamide, dimethylsulfoxide and methanol) as those previously used for the bromination of this alkene.The oxidation peaks of the chloride ion are modified by addition of cyclohexene in a different way according to the solvent used. The simultaneous formation of mixed compounds with dichlorocyclohexane shows the solvents participation to the nucleophilic attack of the chloronium ion.     

A New Catalytic Route for the Oxidative Halogenation of Cyclic Enol Ethers using Tungstate Exchanged on Takovite

An efficient and benign method for the regio‐ and stereoselective synthesis of halohydrins and β‐halo ethers from dihydropyrans, dihydrofurans and anhydro sugars in the presence of a halide salt and hydrogen peroxide is presented with tungstate‐exchanged takovite as oxidation catalyst.