利用碘的挥发性提高ICP-AES测定碘的灵敏度

将碘化物稀溶液酸化,加H_2O_2氧化I-离子成I_2。溶液雾化时,I_2易挥发,单位时间进入ICP炬量增加,大大提高了测碘的灵敏度。检出限达0.8ppm。用粗食盐溶液及自来水为基体,测碘的回收率为93～99％。     

Reaction of allylic and benzylic alcohols and esters with PPh3/I2: one-pot synthesis of β,γ-unsaturated compounds

The treatment of tertiary and secondary allylic alcohols containing a terminal double bond, and their acetyl derivatives, with triphenylphosphine and iodine under mild conditions leads regiospecifically and in high stereoselectivity to the corresponding primary allylic iodides, which can react ‘in situ’ with diverse nucleophiles. Primary allylic alcohols and benzyl alcohols and acetates are also transformed into the corresponding iodides under these conditions.     

Kinetics of furfuryl alcohol polymerisation by iodine in methylene dichloride

The kinetic studies of furfuryl alcohol polymerisation by iodine in methylene dichloride showed a pseudo-first-order behaviour in monomer. The pseudo-first-order constant obtained varies linearly with the concentration of iodine. Our previous work on the system concluded for a pseudo-cationic polymerisation mechanism based on the admission of non-ionic propagating species. The good fitting among the experimental monomer concentration data and the one obtained from computer simulation justifies the mechanism proposed for the system. The set of estimated values of the rate parameters is also reported.     

Synthesis of highly functionalized indeno[1,2-b]furans

Some novel functionalized indeno[1,2-b]furans were synthesized from the reaction of indandione/indanone and aldehydes at room temperature followed by the reaction of the Knoevenagel condendensed intermediate with 4-hydroxycoumarins in the presence of iodine as catalyst in dimethyl sulfoxide (DMSO) under thermal conditions. The reaction involved in a condensation and Michael addition followed by lactone ring opening and intramolecular cyclization process to afford the product in high yield in easy work-up procedure.     

Iodine-catalyzed aerobic oxidation of o-alkylazoarenes to 2H-indazoles

An iodine-catalyzed aerobic-oxidative C-H functionalization of o-alkylazoarenes to afford 2H-indazoles has been developed. CuI was found to be an effective additive to accelerate the regeneration of iodine in the catalytic cycle. This catalytic system is suitable for both electron-rich and electron-deficient azoarenes and tolerates a variety of functional groups with high yields. A gram-scale reaction was successfully conducted, proving the scalability of this reaction.     

Solvent- and metal-free selective oxidation of thiols to disulfides using I2/DMSO catalytic system

We describe herein a simple, fast and inexpensive protocol for the oxidative coupling of thiols employing a stoichiometric amount of DMSO and iodine as the catalyst. Various aromatic disulfides were obtained in good to excellent yields in short reaction times at room temperature, while aliphatic disulfides were achieved in good yields when the reactions were conducted under microwave irradiation.     

室温下碘催化直接构建硫化吡唑啉酮

含硫化合物在有机合成、药物化学以及材料化学等领域具有重要的作用.到目前为止,科学家已经在C-S键的构建领域进行了很多工作.在构建C-S键的众多方法中,金属催化的C-S键合成反应是一类很重要的反应,但是此方法存在着催化剂对空气敏感、环境不友好等问题.因此,发展无金属催化的C-S键构建反应受到了人们越来越多的重视.基于我们在碘催化相关反应方面的研究,本文报道了一种碘催化的硫化吡唑啉酮类化合物的合成方法.我们选用3-甲基-1-苯基-2-吡唑啉-5-酮与二苯二硫醚为底物进行条件筛选实验,发现I2(10%)为催化剂,二氧六环为溶剂,H2O2为氧化剂为最优化的实验条件,目标产物硫化吡唑啉酮最高产率为88%.在最优化的反应条件下,我们尝试了带有不同官能团(NO2,Cl,OH等)的吡唑啉酮与二硫醚的反应,均能以较高产率得到目标产物.当含有杂环的二硫醚(2,2'-二硫二吡啶)作为反应底物时,也能以中等以上的产率得到相应的目标产物.另外还进行了对比试验,例如在反应体系中加入自由基捕获剂TEMPO,反应产率会大大降低,说明反应中应该有自由基中间体生成;如果反应体系中不加碘,则反应产率为零;如果反应体系中不加H2O2,则反应产率由88%降低至48%,说明碘和H2O2在反应中都起到了重要作用.通过以上对比试验,提出了可能的反应机理:首先,二硫醚发生均裂反应生成苯硫基自由基,然后苯硫基自由基与碘反应生成亲电的PhSI活性中间体,PhSI与异构化的吡唑啉酮发生亲电取代反应,生成目标产物硫化吡唑啉酮和HI,HI可以被H2O2氧化生成I2继续参与下一轮催化反应.以3-甲基-1-苯基-2-吡唑啉-5-酮与二苯二硫醚为底物,我们对此反应进行了放大试验,结果显示反应产率几乎没有降低,这为此反应的大规模应用奠定了基础.在此,我们发展了一种简单高效的合成硫化吡唑啉酮的反应,此方法无需金属催化剂,利用常见的碘为催化剂就可以以较高的产率得到目标产物.为合成含硫化合物提供了一种新的方法.     

乙酸中碘催化氧化苄醇为相应醛或酮(英文)

本文报道了用I2/NaNO2/4-OH-TEMPO为催化剂,空气为氧化剂,在冰乙酸中催化氧化苄醇的方法.文中考察了催化剂各组分和温度对催化氧化反应的影响,在催化过程中碘替代过渡金属作为4-OH-TEMPO的共催化剂,在选择条件下苄醇氧反应的产物产率达到90%,在反应过程中生成醛或酮.     

Iodine-promoted imino-Diels-Alder reaction of fluorinated imine with enol ether: synthesis of 2-perfluorophenyl tetrahydroquinoline derivatives

Iodine was used to catalyze the hetero-Diels-Alder reaction of pentafluorobenzylidineaniline (C₆F₅CHNAr 1) with enol ethers to afford the corresponding tetrahydroquinolines derivatives as a mixture of cis/trans stereoisomers in moderate yields. These products could also be prepared by one-pot, three-component reaction of pentafluorophenylaldehyde, anilines, and enol ethers under the same reaction condition. Mild and neutral reaction conditions, facile experimental procedure, and low price of iodine should make this method attractive for practical synthesis of many fluorinated tetrahydroquinoline derivatives.     

Selective iodination of vicinal cis-diols on ketopyranose templates

A regio- and stereoselective iodination has been performed on vicinal diols located on ketopyranose templates using the controlled- Garegg conditions. 3-O-Benzyl-1,2-O-isopropylidene-β-d-fructo- or psicopyranoses (1 or 4) were selectively iodinated, respectively, at C-5 or C-4 of the ketoses to afford the l-sorbo or d-sorbo iodohydrins.