我国硫脲生产现状及市场分析

介绍了我国硫脲的生产现状,工业上大多数厂家采用硫化氢和石灰氮法生产, 2003年全国硫脲产量为 6万t;硫脲在医药、造纸、纺织、橡胶及印染等行业具有广泛的应用。综述了国内外硫脲的生产和市场现状,目前世界硫脲的总产能为 8万t/a,并预测今后几年硫脲的消费将保持增长的趋势。建议我国应发挥原料和价格优势,大力发展硫脲及其下游产品的开发工作。     

硫脲在酪氨酸酶催化中的抑制动力学

研究了硫脲对蘑菇酪氨酸酶活力的抑制效应。实验结果表明,硫脲与酪氨酸酶催化氧化产物醌反应,形成了无色的L-DOPA衍生物,从而阻断了多巴色素的形成。硫脲导致酪氨酸酶活力下降50%时的浓度(IC50)为1.37 mmol·L-1,在降低酶活的同时,硫脲能明显延长该酶的延滞时间,表现为不可逆反竞争性抑制。     

以炼厂硫化氢为原料生产硫脲的试验及可能性研究

试验采用国内硫脲的主流生产工艺,即以硫化氢气体为原料石灰氮一步法生产硫脲,制定了试验方法和步骤。试验共做了5次,在前4次试验的基础上逐步改进和完善,终于在第5次试验产出合格的工业硫脲产品,同时证明了以炼厂硫化氢气体为原料可以生产出合格的硫脲产品。     

Influence of organic additives on the initial stages of copper electrodeposition on polycrystalline platinum

Effects of two additives, thiourea and saccharin, on copper electrodeposition from acid sulphate solutions were investigated by different electrochemical methods (cyclic voltammetry, chronoamperometry, and electrochemical quartz crystal microbalance) as well as by different observation techniques (scanning electron microscopy and atomic force microscopy). The morphology of copper coating obtained with thiourea leads to a smooth and bright deposit whereas it is only slightly modified by saccharin. The electrochemical reactions of copper electrodeposition were modified by the formation of complexes between thiourea and copper. However, in presence of saccharin, the kinetics and morphology of copper coating remain unchanged. From X-ray photoelectron spectroscopy analysis, thiourea was found to react with copper or copper ions by strong bond formation between the sulphur atoms of thiourea molecule and copper. This is the evidence of the adsorption of thiourea on the coating. Moreover, the thiourea action starts in the initial stages, allowing a homogeneous nuclei size and a large nuclei density. Finally, the nucleation mechanism of electrodeposition appears to be modified according to the additives used.     

论氧气法制胍衍生物的化学反应

通过对硫脲衍生物分子化学键的研究，发现了氧气法不仅适用于生产二苯胍，还适用于生产其他胍衍生物。就是说，硫脲衍生物可以通过氧气法制成相应的胍衍生物。氧气法生产胍衍生物的化学反应过程中，铜离子的催化作用发生在硫脲衍生物与氧气进行反应生成二氧化硫脲衍生物的反应阶段。铜离子的催化作用表现为消除硫脲衍生物分子母体的共轭π键，使硫基π键孤离出来，并使硫基极化。本文讨论硫脲衍生物分子母体的化学键及其变化，叙述氧气法制胍衍生物的化学反应。     

硫脲改性D301树脂的制备及其对AuCl_4~–的吸附性能

使用硫脲对一种苯乙烯系阴离子交换树脂——D301树脂进行改性,先在D301树脂大分子链上接枝聚甲基丙烯酸缩水甘油酯(PGMA),然后通过硫脲与PGMA的环氧基的开环反应制得硫脲改性D301树脂(TD301)。对TD301进行了扫描电子显微镜、傅里叶变换红外光谱、元素分析等表征,研究了硫脲改性条件对TD301吸附性能的影响,并考察了TD301对AuCl_4~–的吸附动力学行为。结果表明,TD301适宜的硫脲改性条件为硫脲用量2 g,反应温度90℃,反应时间8 h;在环境温度25℃,氯金酸溶液pH值为2的情况下,所制得的TD301对AuCl_4~–的吸附量可以达到300.4 mg/g;此外,TD301具有优良的再生与重复使用性能。     

Inhibition and polarization studies of some substituted urea compounds for corrosion of aluminium in nitric acid

Inhibition and polarization properties of urea, thiourea (TU), acetyl thiourea (AcTu), phenyl thiourea (PhTu), o-tolyl thiourea (o-tol Tu), m-tolyl thiourea (m-tol Tu), p-tolyl thiourea (p-tol Tu), 1:3-diphenyl thiourea (di-phTu), 1:3-di-o-tolyl thiourea (di-o tol Tu), 1:3-di-m-tolyl thiourea (di-m-tol Tu) and 1 : 3-di-p-tolyl thiourea (di-p-tol Tu) have been studied in relation to the corrosion of aluminium (1060) in 20% nitric acid. The polarization experiments were carried out using potentiostatic method. The inhibition efficiencies of the inhibitors were determined at 25°, 35° and 45°C and it has been observed that the percentage inhibition efficiencies of the inhibitors increase with increase in temperature. All the inhibitors except urea obey the Langmuir adsorption isotherm below the inhibitor concentration of 300 ppm, but in no case are slopes equal to unity observed. At and above the concentration of 300 ppm, the effectiveness of the compounds decreases, which is attributed to their action as cathodic depolarizers. The inhibitive performance of the compounds is discussed in the light of electronic effects in the thioureas. The potentiostatic anodic polarization curves in the presence of the inhibitors shift towards lower current density region as compared with the curve of the uninhibited solution, but there is no proper correlation between the inhibition efficiencies and the current densities required for the passivation of aluminium.     

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     

Influence of thiourea and thiourea ageing on the electrodeposition of copper from acid sulfate solutions studied by the ring-disc technique

The influence of the additive thiourea in freshly made and aged solutions on copper deposition from acid sulfate solutions was studied using a Pt/Pt rotating ring-disc electrode. In fresh thiourea solutions copper deposition is retarded, but the most distinct effect of thiourea is seen during dissolution of the deposits. The intermediate in copper dissolution, Cu⁺, is partly complexed with adsorbed thiourea. Thus Cu⁺ is adsorbed at the electrode surface and the current peak at the ring due to dissolving Cu⁺ becomes very small. The small peak indicates that active additive is present in the deposit. Thiourea containing solutions aged for only a few days have a distinct effect on the electrode reactions. At low concentrations of thiourea (1 mg dm^–3 ) a correlation between ageing and growth of the Cu⁺ peak at the ring is clearly seen. At high thiourea concentrations (100 mg dm^–3) a small growth of the Cu⁺ peak is seen during the first few days but upon further ageing of the thiourea solution copper deposition becomes strongly inhibited. The ring current can be used as a qualitative diagnostic criterion for the concentration and state of thiourea in copper sulfate solutions.     

提高二氧化硫脲产品收率研究

二氧化硫脲 (简称 TD)的国内收率为 80 % ,产品成本高 ,利润低 ,通过对其现有生产工艺的改进 ,产品收率可达 88%～ 90 %以上 ,产品保质期也由原来的 1～ 3个月延长至 18～ 2 4个月     

Electrochemical stripping of gold from Au-Ni-Cu electronic connector scrap in an aqueous solution of thiourea

The electrochemical behaviour of a gold-plated connector from electronic scrap in aqueous thiourea solution has been investigated. An attempt was made to recover gold from scrap in a nontoxic thiourea medium by an electrochemical method rather than the traditional cyanide process. Linear sweep voltammetry indicated that thiourea extraction of gold is more efficient in acidic solution than in neutral and alkaline. Hydrochloric acid is preferable to control the pH of the solutions; the optimum concentration of thiourea is 2.5% (0.33 m). Analysis of voltammetric data yielded a critical potential (0.40 V vs SCE), which is the upper limit for significant extraction of gold from scrap. Higher potentials should be avoided in practice to prevent decomposition of thiourea and its passivation of the scrap. Electrolysis at constant potential indicated that gold was extracted selectively in the range 0.20–0.30 V vs SCE. Electrolysis at potentials either less than 0.15 V vs SCE or greater than 0.40 V vs SCE is not recommended, because of slow dissolution in the former and severe passivation in the latter.     

Mechanism of photoprotection of wool with formaldehyde and thiol derivatives

The application of thiourea and formaldehyde offers significant reductions in photoyellowing for natural, bleached and fluorescent‐brightened wools. We have examined the use of alternative thiol derivates to thiourea and shown that a mixture of N‐acetylcysteine and formaldehyde is similarly effective. Photo‐induced chemiluminescence studies on treated wool fabrics show that the intensity of chemiluminescence following a brief exposure to ultraviolet A radiation is reduced for wool treated with thiourea and formaldehyde, N‐acetylcysteine–formaldehyde and thiourea dioxide–formaldehyde, but not for formaldehyde alone. This demonstrates that a lower population of free radicals is formed in irradiated thiol‐derivative formaldehyde‐treated wools because of free radical scavenging by the sulphur‐containing species. This free radical scavenging results in reduced photoyellowing. The effect of thiourea and formaldehyde treatment on the intrinsic fluorescence of wool is significantly different to N‐acetylcysteine–formaldehyde. Thiourea and formaldehyde quenches tryptophan fluorescence relative to untreated wool, whereas N‐acetylcysteine–formaldehyde treatment results in an increase in intensity probably because of a reduction in disulphide quenching.     

Rapid and highly efficient synthesis of thioureas in biocompatible basic choline hydroxide

A straightforward and convenient synthesis of symmetrical thiourea derivatives by the reaction of primary amines and carbon disulfide in biocompatible basic choline hydroxide is presented. A variety of biologically important thiourea derivatives can be obtained in good to excellent yields without a tedious work-up under mild reaction conditions. A series of primary aliphatic and aromatic amines with different substituted functional groups have been converted to thiourea derivatives under milder reaction conditions and short reaction times.     

硫脲对镀锌层硅酸盐钝化作用的影响

采用盐雾试验测试了锌镀层钝化膜的耐蚀性,研究了硫脲对镀锌层硅酸盐钝化作用的影响。实验结果表明,在硅酸盐钝化液中加入一定量的硫脲,可以使镀锌层转化膜的耐蚀性增强,但当其浓度较低时却会降低转化膜的耐蚀性。     

高稳定性碱性硫脲体系对不同类型金矿的适应性

为考察碱性硫脲体系对不同类型金矿浸出的适应性,选用理化性质不同的6种含金物料,分析了其化学组成及矿物物相,并对其浸出行为进行了研究. 结果表明,稳定剂Na2SO3和Na2SiO3大大降低了碱性硫脲的分解率,随稳定剂浓度的增大,硫脲分解率逐渐降低;而且Na2SiO3对碱性硫脲的稳定效果明显优于Na2SO3,当Na2SiO3浓度为0.3 mol/L时,硫脲的分解率由72.5%降至33.8%. 铁氰化钾为适合碱性硫脲浸金的温和氧化剂. 碱性硫脲体系中金矿物浸出前后物相基本无变化. 所选择的金矿物中均含有大量耗碱物质,使溶液的pH值由12.5很快降至中性,但稳定剂Na2SiO3能维持体系的pH值在12左右,有利于浸出过程的进行. 碱性硫脲体系中伴生金属浸出率小于0.1%,浸金具有显著的选择性. 碱性硫脲体系适合浸出经预处理的物相主要为SiO2的氧化矿,浸金率高达82.68%,为碱性硫脲成功应用于黄金工业生产提供了一定的理论依据.     

Comments on the paper “Electrooxidation of borohydride on platinum and gold electrodes: Implications for direct borohydride fuel cell” by E. Gyenge, Electrochim. Acta 49 (2004) 965: Thiourea, a poison for the anode metallic electrocatalyst of the direct borohydride fuel cell?

The present discussion paper deals with the Gyenge's [E. Gyenge, Electrochim. Acta 49 (2004) 965] suggestion to add thiourea (H₂N-CS-NH₂) to the borohydride fuel of the direct borohydride fuel cell (DBFC). It is expected that thiourea inhibits the hydrogen evolution (stem from the borohydride hydrolysis, a side reaction) that occurs at the anode of the DBFC where in fact it is expected the direct oxidation of borohydride.However, thiourea is an organic sulphur compound and it is well known that the sulphur species are poisons for the metallic catalysts. Hence, the present discussion paper asks a question: may thiourea and the sulphur species stem from its decomposition act as poisons of metallic sites of catalysts used as DBFC anodes?     

尿素络合法分离费托合成产品中的正构烷烃

分别以费托合成直馏柴油和异构柴油为原料,通过尿素/硫脲对正构烷烃和异构烷烃进行分离,从而提高产品附加值。通过尿素或硫脲法分离直馏柴油中的正/异构烷烃实验可以看出,采用尿素法一次脱蜡得到的产品中正构烷烃含量达到97.0%（质量分数,下同）,二次脱蜡得到的正构烷烃含量达到98.0%;通过硫脲法分离正/异构烷烃,产品中正构烷烃含量为96.5%,但硫脲量使用量降低。通过对尿素法分离异构柴油的研究,可以看出尿素量增加有利于降低异构柴油的凝点。对比尿素法和硫脲法的分离结果,可以看出,尿素和硫脲均可与正/异构烷烃反应,但稳定性存在差异。相对而言,尿素与高碳异构烷烃或低碳正构烷烃形成络合物更稳定,硫脲与高碳正构烷烃或低碳异构烷烃形成络合物更稳定。     

手性硫脲对映选择性催化Henry反应研究

手性硫脲是不对称催化反应中一类典型的双功能有机小分子催化剂。文章合成了6种新型手性硫脲衍生物,以FT-IR和1H NMR进行了表征。同时以HPLC检测了手性硫脲催化剂在对映选择性催化Henry反应中的催化活性和对映选择性并获得了较高的产率和ee。实验证明,硫脲衍生物中氯元素取代基能够促进底物的活化,酰基硫脲的分子内氢键对催化剂的对映选择性催化具有较大的影响作用。     

A new secondary accelerator for the sulfur vulcanization of natural rubber latex and its effect on the rheological properties

The vulcanization of natural rubber (NR) latex can be effectively carried out at low temperatures by using binary accelerator systems containing thiourea (TU) as a secondary accelerator. It was reported that sulfur‐containing nucleophiles such as thiourea enable the primary accelerator to become effective even at low temperatures, indicating a nucleophilic reaction mechanism in such vulcanization reactions. In the present study, a derivative of thiourea [viz. aminoiminomethyl thiourea (AMT)], which is more nucleophilic than thiourea, is used as a secondary accelerator in the sulfur vulcanization of NR latex. One of the aims of this study was to give conclusive evidence for a nucleophilic reaction mechanism. The synergistic effect of the above thiourea derivative with primary accelerators such as tetramethylthiuram disulfide (TMTD), zinc diethyldithiocarbamate (ZDC), and cyclohexylbenzthiazyl sulfenamide (CBS) was studied at two different temperatures (viz. 100 and 120°C). These binary systems were found to be very effective in reducing the optimum cure time of the different mixes compared to control formulations containing TU. The optimum amount of the secondary accelerator required was also determined. Mechanical properties such as tensile strength and tear strength of the vulcanizates were also evaluated. Chemical characterization of the vulcanizates was carried out by determining the total crosslink density. Values of the cure characteristics evaluated support a nucleophilic reaction mechanism in these vulcanization reactions under review. The effect of this secondary accelerator on the rheological behavior of compounded latex is also studied and was found not to affect adversely. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2781–2789, 2004     

Contribution to the mechanism of sulphur-free thiuram vulcanisation

The influence of the concentration of tetramethylthiuram disulphide on the kinetics and degree of the sulphur-free vulcanisation of pale crepe in the absence and in the presence of thiourea has been investigated. Rate and degree of the vulcanisation increase with concentration of tetramethylthiuram disulfide to a certain limit. Exceeding this limit the values of the rate constant and the crosslinking density decrease. Due to the presence of thiourea the rate of the vulcanisation is increased and the final degree of vulcanisation is decreased. This effect of thiourea also depends on the concentration of tetramethylthiuram disulphide. On the basis of the above results the mechanism of the tetramethylthiuram disulphide vulcanisation is discussed.