Efficient Synthesis of N,N′‐Disubstituted Ureas/Thioureas Catalyzed by Iodine

Iodine is an efficient catalyst for the synthesis of symmetrically N,N′‐disubstituted ureas/thioureas by heating respective amines or phenyl hydrazine and urea/thiourea on a preheated hot plate at 90–95°C, under solvent‐free conditions. The yields are excellent, and the reactions go to complete within 5–10 min.     

Synthesis and Antioxidant Activity of New Thiazole Analogues Possessing Urea,Thiourea, and Selenourea Functionality

A new series of urea, thiourea, and selenourea derivatives with thiazole moieties were synthesized by the nucleophilic addition reaction of (2-amino-4-(3-chlorophenyl)thiazol-5-yl)(2-chlorophenyl)methanone with various substituted isocyanates/ isothiocyanates/isoselenocynates in acetone having a catalytic amount of sodium hydroxide at room temperature with good yields. All the synthesized compounds were fully characterized by spectroscopic data and screened for their in vitro antioxidant activity using 1,1-diphenylpicrylhydrazyl (DPPH), nitric oxide (NO), and hydrogen peroxide (H₂O₂) radical scavenging methods. A preliminary study of the structure–activity relationship revealed that the compounds containing selenourea functionality along with halogen group have exhibited potent activity (IC₅₀ ≤ 0.0309 µmol/mL) compared to the standards (IC₅₀ ≤ 0.0814 µmol/mL). Thus the title compounds are a new class of potent antioxidant agents and worthy of further investigation.     

Diastereoselective Synthesis of Functionalized Tetrahydropyrimidin‐2‐thiones via ZnCl2 Promoted One‐pot Reactions

In the presence of zinc chloride, the in situ generated β‐enamino ester from the reaction of morpholine, piperidine and pyrrolidine with methyl propiolate reacted, with aromatic aldehydes and thiourea in ethanol resulting in the functionalized tetrahydropyrimidin‐2‐thiones in satisfactory yields and with good diastereoselectivity. When aromatic aldehydes bearing electron‐withdrawing group were used in the reaction, the 4‐hydroxytetrahydropyrimidin‐2‐thione derivatives were obtained as the main product.     

硫脲络合–火焰原子吸收光谱法测定低硅铝合金中的银含量

采用硫脲络合–火焰原子吸收光谱法测定低硅铝合金中的银元素含量。实验探讨了酸度及硫脲用量对银测定的影响及铝合金中基体元素与共存元素对银元素分析线的干扰情况。结果表明:选用9%的盐酸和3%的硝酸溶解试样最好,加入5 mL 50 g/L硫脲溶液可消除氯离子对试验结果的影响,基体铝元素和其它共存元素不干扰银的测定。根据低硅铝合金中银元素的含量范围,合成系列标准溶液,建立工作曲线,工作曲线的线性范围为0.05%~0.50%。银元素含量为0.30%的样品测定结果的相对标准偏差为0.15%(n=8),标准加入回收率为96.8%~98.5%。该方法操作简便、重现性好、测量结果准确可靠。     

功能化离子液体中两步高效合成N-取代硫脲

两步高效合成N-取代硫脲：（1）在[emim]SCN中以酰与伯胺为起始原料先合成得到N-烃基-N＇-酰基硫脲,反应速度快,产率高,功能化离子液体既作为第一步反应原料,又作为反应介质;（2）N-烃基-N′-酰基硫脲在NaOH/H2O/EtOH体系中以近100%的转化率水解得目标产物.提供了一种高效合成N-取代硫脲的绿色、...     

Synthesis and Herbicidal Activities of N''-(substituted pyrimidin-2-yl)-N-Substituted Phenoxyacetyl Thiourea Derivatives

Acylthiourea derivatives are well known for a wide range of biological activities likebactericidal, fungicidal, herbicidal, insecticidal action and regulating activity for plantgroWth"'. In recent years, substituted phenoxyacetic acid derivatives have beenreported as highly efficient herbicides4. In this paper. a series of substitutedphenoxyacetyl thiourea containing substituted pyrimidine ring sa~so were synthesizedand tested for their biological activities. All of them are new compounds and…     

Crown ether molecular complexes with urea and thiourea

Crystalline complexes of urea and thiourea with crown ethers, have been prepared, viz., 18-crown-6 (18C6), benzo-18-crown-6 (B18C6), dibenzo-18-crown-6 (DB18C6), dicyclohexano-18-crown-6 (DC 18C6) and dibenzo-24-crown-8 (DB24C8). While the complexes of the large ring size crown ether, DB24C8, have high ether to (thio)urea ratios, the stoichiometry of the others lies between one molecule of crown ether and from one to six molecules of (thio)urea. An IR spectral study of the urea and thiourea complexes showed that the behavior of thiourea in these complexes is clearly different from that of urea, indicating the role of sulphur in the interaction of thiourea with crown ethers. The urea and thiourea complexes were classified according to their stoichiometries and their IR spectral behavior into three classes for which credible structures were proposed.     

The electrochemical behavior of N-n-undecyl-N''-(sodium-p-amino-benzenesulfonate)thiourea and its interaction with bovine serum albumin

In pH 5.5 phosphate buffer solution,N-n-undecyl-N'-(sodium-p-amino-benzenesulfonate)thiourea(UPT)produced a pair of redox peaks on the bare glassy carbon electrode.At the multi-walled carbon nanotube(MWNT)modified electrode,the electrochemical behavior of UPT enhanced greatly.In the presence of bovine serum albumin (BSA),the peak currents of UPT decreased linearly due to the formation of a super-molecular complex.This method was successfully applied to the determination of BSA in a bovine serum sample.     

Thermodynamics of alcohols and monosaccharides in aqueous solutions of thiourea at 25°C

The excess enthalpies of twelve ternary aqueous solutions of alcohols or monosaccharides containing thiourea have been determined by flow microcalorimetry at 25°C. The coefficients of the virial expansion of the excess enthalpies are compared with those reported in the literature for the same ternary solutions containing urea in place of thiourea. The cross-interaction coefficients are positive for the thiourea-alcohol systems and depend on the length and branching of the alkyl chain of the alcohols. On the other hand, they are negative for the thiourea-monosaccharide systems. Thus, thiourea, as urea, can be used as a probe to reveal differences in the behavior of families of solutes characterized by the same functional groups. The results can be interpreted in terms of the relative stabilities of hydration cospheres of hydrophobic or hydrophilic solutes toward a chaotropic agent such as thiourea.Presented at the sixth Italian meeting on Calorimetry and Thermal Analysis (AICAT) held in Naples, December 4–7, 1984.