含Fe~(3+)的酸液对钢铁的腐蚀作用及其抑制

钢铁制品的酸浸去除轧制铁鳞以及换热设备酸洗除锈除垢时有Fe~(3+)产生.通过恒电位法和失重法研究了含Fe~(3+)的酸液对钢铁的腐蚀作用及其抑制,结果表明:Fe~(3+)的存在会促进钢铁的腐蚀,一定结构的硫脲衍生物和阴离子表面活性剂之间存在协同效应,能有效地抑制氢离子放电的阴极过程和Fe~(3+)还原的阴极过程,从而抑制金属的腐蚀.     

One‐Pot Thioetherification of Aryl Halides Using Thiourea and Alkyl Bromides Catalyzed by Copper(I) Iodide Free from Foul‐Smelling Thiols in Wet Polyethylene Glycol (PEG 200)

In this article, we have developed a new protocol for the thioarylation of structurally diverse alkyl bromides such as benzyl, cinnamyl, n‐octyl, cyclohexyl, cyclopentyl, and tert‐butyl bromides with aryl iodides, bromides and an activated chloride using thiourea catalyzed by copper(I) iodide in wet polyethylene glycol (PEG 200) as an eco‐friendly medium in the presence of potassium carbonate at 80 and 100 °C under an inert atmosphere. The process is free from foul‐smelling thiols which makes this method more practical for the thioetherification of aryl halides. Another important feature of this method is the variety of alkyl bromides which are commercially available for the in situ generation of thiolate ions with respect to the existing protocols in which the less commercially available thiols are directly used for the preparation of arylthio ethers.     

A convenient synthesis of alkyl-2-(2-imino-4-oxothiazolidin-5-ylidene)acetate derivatives involving an electrogenerated base of acetonitrile

We report a simple method for the synthesis of alkyl-2-(2-imino-4-oxothiazolidin-5-ylidene) acetate derivatives 3 in good yields under mild conditions. The electrogenerated cyanomethyl base (EGB), obtained from electroreduction of acetonitrile-0.1?M TBABF₄, assists the reaction between thiourea derivatives 1 and dialkyl acetylene dicarboxylate 2. The expected products, 3/4, and the structure obtained from X-ray diffraction confirm that the main products are the five-membered heterocycles 3. Furthermore, a mechanism, to explain the reaction pathways, is proposed based on the thermodynamic and kinetic data obtained from quantum calculations.     

New mechanism for the reaction of amines with zinc dithiocarbamates

This article reports a detailed reinvestigation of the reaction of bis(dialkyldithiocarbamato)zinc(II) (ZDAC) with amines. The reaction of primary amines with bis(dimethyldithiocarbamato)zinc(II) (ZDMC) results in the formation of a 1,1,3‐trisubstituted thiourea, a 1,3‐disubstituted thiourea, dimethylammonium dimethyldithiocarbamate (DMADC), ZnS, and H₂S. The ratio of formation between the two thiourea products strongly depends on the reaction conditions chosen. A new mechanism is proposed, which involves the formation of an amine–dithiocarbamic intermediate, from which the two most important products, a 1,1,3‐trisubstituted and a 1,3‐disubstituted thiourea, are formed. Also, direct transformation of the 1,1,3‐trisubstituted thiourea into the 1,3‐disubstituted thiourea via nucleophilic attack of the primary amine onto the thiocarboxy of the 1,1,3‐trisubstituted thiourea was found to occur, catalyzed by ZnCl₂. The reaction of primary amines with ZDACs is catalyzed by elemental sulfur, which has been attributed to sulfur insertion in the zinc–ligand ring of the ZDAC, resulting in a higher reactivity of the ZDAC complex. Finally, when ZDACs are reacted with a secondary amine, no thiourea products are formed and only a mixture of zinc dithiocarbamates is obtained. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1074–1083, 2001     

双官能团硫脲-胺催化剂催化不对称有机反应的研究进展

双官能团硫脲-胺催化剂因在不对称催化反应中表现出的高效、高对映选择性而受到广泛关注,已成功应用于催化各种不对称有机反应中,本文简述了双官能团硫脲-胺催化剂在Michael加成、1,2加成以及Michael-type串联反应中应用的研究进展。     

N-芳甲酰基-N’-(氟代吡啶-3-基)硫脲的微波合成及生物活性

在微波辐射下,以乙腈为介质,使芳甲酰氯、氟代3-氨基吡啶和硫氰酸铵发生一锅反应合成标题化合物,所得化合物经IR、1HNMR和元素分析确定。结果表明,在4.8 mmol芳甲酰氯、4.8 mmol硫氰酸铵、5.0 mmol氟代3-氨基吡啶、5 mL乙腈和80℃条件下,反应10 min完成,收率86.9%～93.2%,反应时间短、收率高、操作简便。初步生物活性测试结果表明,所合成的化合物具有一定的植物生长调节活性。     

Synthesis and Biological Evaluation of Novel Dehydroabietic Acid Derivatives Conjugated with Acyl-Thiourea Peptide Moiety as Antitumor Agents

A series of dehydroabietic acid (DHAA) acyl-thiourea derivatives were designed and synthesized as potent antitumor agents. The in vitro pharmacological screening results revealed that the target compounds exhibited potent cytotoxicity against HeLa, SK-OV-3 and MGC-803 tumor cell lines, while they showed lower cytotoxicity against HL-7702 normal human river cells. Compound 9n (IC₅₀ = 6.58 ± 1.11 μM) exhibited the best antitumor activity against the HeLa cell line and even displayed more potent inhibitory activity than commercial antitumor drug 5-FU (IC₅₀ = 36.58 ± 1.55 μM). The mechanism of representative compound 9n was then studied by acridine orange/ethidium bromide staining, Hoechst 33,258 staining, JC-1 mitochondrial membrane potential staining, TUNEL assay and flow cytometry, which illustrated that this compound could induce apoptosis in HeLa cells. Cell cycle analysis indicated that compound 9n mainly arrested HeLa cells in the S phase stage. Further investigation demonstrated that compound 9n induced apoptosis of HeLa cells through a mitochondrial pathway.     

Control of Six Contiguous Stereocenters in an Asymmetric Organocatalytic One‐Pot Michael/Michael/Aldol Addition Sequence

The asymmetric organocatalytic one‐pot synthesis of polyfunctionalized cyclohexanes is described. Starting from β‐keto esters, nitroalkenes and α,β‐unstaturated aldehydes and employing a bifunctional norephedrine‐based thiourea catalyst, six contiguous stereocenters including one quarternary center are generated. The one‐pot protocol follows a Michael/Michael/aldol addition sequence and affords the highly substituted cyclohexanes in moderate to very good yields (22–70%), diastereomeric ratios of dr>95:5 and excellent enantioselectivities of 91–99% ee.     

烯丙基异硫氰酸酯与胺反应的动力学及吸收光谱

烯丙基异硫氰酸酯（AITC）是辣根中最重要的生物活性成分，具有很高的抗肿瘤和抗癌活性，研究了AITC与哌啶、吗啉、二乙胺等胺类化合物的反应动力学和光谱性质。AITC与胺反应转化为硫脲舌，最大吸收峰强度有了极大的提高，摩尔吸光系数增加了十余倍;利用我们的发现，我们以光度法研究了该反应的动力学，证明该反应为二级反应，并求得了反应速率常数和反应活化能等参数；同时，讨论了反应机理。     

苯甲酰基硫脲及其衍生物的合成研究

以苯甲酰基异硫氰酸酯为原料,分别与2,4-二硝基苯肼和水合肼在相应条件下反应合成具生理活性的2,4-二硝基苯氨基苯甲酰基硫脲和氨基苯甲酰基硫脲。为了探索反应的最佳条件,分别对反应的溶剂、反应温度、反应时间以及展开剂的比例进行了探索。经大量的实验后,最终得到合成出产物的最优条件。产物经过净化处理,通过红外光谱和熔点的测定,表明产物即为目标产物2,4-二硝基苯氨基苯甲酰基硫脲和氨基苯甲酰基硫脲。