Study on the reaction between bisphenol A and dimethyl carbonate over organotin oxide

Organotin oxide was used to catalyze the reaction between BPA (bisphenol A) and DMC (dimethyl carbonate), and Ph₂SnO (diphenyltin oxide) displays the excellent catalytic performance in transesterification and O-methylation. However, Bu₂SnO (dibutyltin oxide), (PhCH₂)₂SnO (dibenzyltin oxide) and (C₆H₁₁)₂SnO (dicyclohexyltin oxide) exhibited weaker catalytic activity but higher selectivity for C-methylation product formation. The π–π function between Ph₂SnO and BPA provided more chances for their interaction, and π–d interaction between phenyl ring and Sn resulted in catalyst having higher activity in transesterification and O-methylation. O-methylation product formation over Ph₂SnO comes from transesterification product decomposition not from direct methylation of BPA with DMC.     

4、6-二甲氧基-2-甲砜基嘧啶的合成研究

以硫脲、丙二酸二甲酯为原料,经缩合、O-烷基化和氧化反应合成了4、6-二甲氧基-2-甲砜基嘧啶,产品总收率59.1%,纯度96.0%。通过熔点测定、红外光谱、元素分析验证了中间体及目标分子结构。     

6-丙基-2-萘酚的合成研究

以2-萘酚为起始原料,经过O-甲基化、酰化、黄鸣龙还原、脱甲基等一系列反应,得到目标产物6-丙基-2-萘酚,总收率为52.3%。其结构经IR、1H NMR、MS分析确证。     

由碳酸二甲酯合成芳香醚的绿色工艺

综述了酚类化合物与碳酸二甲酯(DMC)甲基化反应合成芳香醚的绿色工艺。气相连续流动法和液相间歇法是2种有效的由DMC合成芳香醚的方法。在气液相转移催化和液固相转移催化的条件下,酚与DMC甲基化反应的产率和选择性均很高。酚与DMC甲基化反应的均相催化剂一般选择叔胺、叔膦、季铵盐及Schiff碱等有机碱,多相催化剂为碱金属碳酸盐、沸石、氧化铝及附载有金属盐的氧化铝和煅烧的Mg-Al水滑石。     

Chemical derivatization of Athabasca oil sand asphaltene for analysis of hydroxyl and carboxyl groups via nuclear magnetic resonance spectroscopy

Athabasca oil sand asphaltene was methylated with different base catalyst/solvent combinations in order to find an optimum procedure for analysis of the number and types of hydroxyl and carboxyl functional groups. High resolution carbon-13, fluorine-19, and silicon-29 NMR spectra were used to monitor the degree of methylation, trifluoroacetylation, trimethylsilylation, and aromaticity of asphaltene. Tetra-n-butylammonium hydroxide as phase transfer base catalyst and tetrahydrofuran or dichloromethane as solvent result in enhanced O-methylation of asphaltene. At least two types of acidic oxygen containing functionality have been detected, viz. hydroxyl and carboxyl (aliphatic and aryl). On average there are few, ≤4-8, hydroxyl containing groups (including COOH) per asphaltene molecule. ¹³C NMR lineshapes suggest a broad asymmetric distribution of acidic sites. The NMR and elemental analyses allow for oxygen containing functionalities to be included in an average molecular structure. A sludge phase collected from aqueous and hydrochloric acid extractions of asphaltene has also been analyzed. A correlation is observed between the degree of O-methylation and the dielectric permittivity of the solvent and the acidity of the substrate reaction site.     

三唑啉（硫）酮并环庚胺的合成

三唑啉（硫）酮是一类重要的杂环化合物,具有较高的生物活性和产品附加值。本路线以己内酰胺为起始原料,经过硫酸二甲酯的甲基化反应得到中间体（Ⅰ）,该中间体与肼基甲酸甲酯或肼基二硫代甲酸甲酯通过环化反应可得到三唑啉（硫）酮并环庚胺类杂环化合物。该化合物结构经过~1HNMR和MS表征。该合成方法具有条件温和、分离纯化简单、各步收率较高的优点,是合成此类杂环的一种好方法,适合工业化生产。     

Oxidative weathering of Illinois No.6 coal

The exposure of freshly-mined Illinois No.6 bituminous coal (Monterey Mine No.1) to atmospheric oxygen at ambient conditions resulted in a slow oxidation reaction which appeared to be complete within two months to produce an oxidized coal product with ≈26% more organically bound oxygen than the fresh coal. An oxygen functional group analysis was performed to determine the carboxylic acid, hydroxyl and ether group content of the coal before, during and after the reaction. Infrared analysis showed no carbonyl production; however, ether functionality was being produced. O-methylation reactions which employed isotopically labelled methyl groups (both C-13 and deuterium) were used to identify and quantify O-H and CO₂H sites in the weathering coal samples. It was found that these acidic groups were not the products of oxidative weathering. Essentially all of the chemically incorporated oxygen eventually formed ether linkages. In a related study on this coal, hydroperoxide was detected as a transient intermediate in the early stages of the oxidation. A mechanism is proposed which involves the simultaneous formation under mild temperatures of a hydroperoxide and a carbon radical that undergoes a radical displacement producing the ether product directly. Solvent swelling studies revealed that these ethers act as cross-linking agents in the coal structure. The more highly cross-linked coal structure that resulted from weathering was responsible for the destruction of the plastic properties of this bituminous coal.     

Characterization of the biosynthesis gene cluster for alkyl-O-dihydrogeranyl-methoxyhydroquinones in Actinoplanes missouriensis

A polyketide biosynthesis gene cluster (agq) was found on the genome of a rare actinomycete, Actinoplanes missouriensis. Streptomyces lividans expressing agqA encoding a type III polyketide synthase produced alkylresorcinols mainly from C(16-17) fatty acids. Heterologous expression of the agq genes in S. lividans indicated the function of cognate polyketide modification enzymes; a monooxygenase AgqB hydroxylates the alkylresorcinols to yield 6-alkyl-2-hydroxyhydroquinones, a methyltransferase AgqC catalyzes O-methylation of the alkyl-hydroxyhydroquinones to yield 6-alkyl-2-methoxyhydroquinones, and a UbiA-like prenyltransferase AgqD attaches a prenyl group to the C-4 hydroxy group of the alkyl-methoxyhydroquinones to yield 6-alkyl-4-O-geranyl-2-methoxyhydroquinones and 6-alkyl-4-O-dihydrofarnesyl-2-methoxyhydroquinones derived from C(16-17) fatty acids. In contrast, A. missouriensis was found to produce 6-alkyl-4-O-dihydrogeranyl-2-methoxyhydroquinones derived from C(16-18) fatty acids by the function of the agq gene cluster. All of these prenylated phenolic lipids were novel compounds.     

Studies of the effects of O-methylation on the pyrolysis behaviour of four coals

O-methylation of coal was found to exhibit a noticeable effect on the pyrolysis behaviour of the original coal. Significant increases in tar yields and a low-temperature fraction, 150–300 °C, were found for the low-rank O-methylated coals. It is proposed that methylation prevents formation of new ether cross linkages through water elimination reactions of hydroxyl functional groups thus allowing for the release of a low-temperature fraction as well as a higher temperature tar. KBr studies of CD₃ labelled O-methylated coals using CD₃I as the methylating agent have resulted in the identification of three distinct i.r. absorptions in the C-D stretching region which have been assigned to methylated phenolic, methylated carboxylic and methylated aliphatic hydroxyl groups. Pyrolysis studies of the O-methylated coals have resulted in better insight into the decomposition mechanisms of different methylated hydroxyl functional groups. Methanol or formaldehyde are seen to be the principle products from the pyrolysis of methylated carboxylic and aliphatic hydroxyls. Decomposition of methylated phenolic groups occurs at a slightly higher temperature and produces principally methane and carbon monoxide.     

Rational Design of Resveratrol O-methyltransferase for the Production of Pinostilbene

Pinostilbene is a monomethyl ether analog of the well-known nutraceutical resveratrol. Both compounds have health-promoting properties, but the latter undergoes rapid metabolization and has low bioavailability. O-methylation improves the stability and bioavailability of resveratrol. In plants, these reactions are performed by O-methyltransferases (OMTs). Few efficient OMTs that monomethylate resveratrol to yield pinostilbene have been described so far. Here, we report the engineering of a resveratrol OMT from Vitis vinifera (VvROMT), which has the highest catalytic efficiency in di-methylating resveratrol to yield pterostilbene. In the absence of a crystal structure, we constructed a three-dimensional protein model of VvROMT and identified four critical binding site residues by applying different in silico approaches. We performed point mutations in these positions generating W20A, F24A, F311A, and F318A variants, which greatly reduced resveratrol’s enzymatic conversion. Then, we rationally designed eight variants through comparison of the binding site residues with other stilbene OMTs. We successfully modified the native substrate selectivity of VvROMT. Variant L117F/F311W showed the highest conversion to pinostilbene, and variant L117F presented an overall increase in enzymatic activity. Our results suggest that VvROMT has potential for the tailor-made production of stilbenes.     

Total synthesis of zoanthamine alkaloids

Zoanthamine alkaloids, isolated from organisms in the Zoanthus genus, constitute a distinctive family of marine metabolites. These molecules exhibit a broad spectrum of unique biological properties. For example, norzoanthamine inhibits interleukin-6, the key mediator of bone resorption in osteoporosis, providing a promising drug candidate for a disease that affects more than 10 million people over age 50 in the United States. In addition, these natural products are characterized by a densely functionalized heptacyclic framework, as exemplified by the structures of zoanthamine, norzoanthamine, and zoanthenol, which makes them extremely attractive targets for chemical synthesis. Prior to our first total synthesis of norzoanthamine in 2004, the densely functionalized and complex stereostructures of the zoanthamine alkaloids had impeded synthetic studies of these molecules. In this Account, we describe our synthetic approach toward the total synthesis of zoanthamine alkaloids, focusing on how we overcame various synthetic challenges. At the beginning of our synthetic studies, we aimed to develop an efficient route that was flexible enough to provide access to several members of the family while allowing the synthesis of various analogues for biological testing. Our first project was the total synthesis of norzoanthamine, and we established an efficient synthetic route based on a novel strategy involving the following key features. First, we used a sequential three-component coupling reactions and subsequent photosensitized oxidation of a furan moiety to synthesize the precursor for the key intramolecular Diels-Alder reaction. Second, the key intramolecular Diels-Alder reaction constructed the ABC-ring carbon framework bearing two adjacent quaternary asymmetric carbon atoms at the C12 and C22 positions in a single stereoselective step. Third, we installed the third quaternary asymmetric carbon center at the C9 position by an intramolecular acylation of a keto alcohol followed by successive O-methylation and C-methylation reactions with complete stereoselectivity. Through the exploitation of a deuterium kinetic isoptope effect, we then efficiently synthesized the alkyne segment. Next, a coupling reaction between the alkyne segment and the amino alcohol segment and several subsequent synthetic transformations afforded the bis-aminoacetalization precursor. Finally, bis-aminoacetalization reactions carried out in one-pot constructed the DEFG-ring system and culminated in the total synthesis of norzoanthamine. Our synthetic route to norzoanthamine also allowed access to other zoanthamine alkaloids from a common synthetic intermediate, by way of stereoselective introduction of the C19 methyl group for zoanthamine, and isoaromatization for construction of the aromatic A-ring in zoanthenol. The chemistry described here not only allowed us to overcome formidable synthetic challenges but also opened a completely chemical avenue to naturally occurring zoanthamine alkaloids and their synthetic derivatives.     

Regulated and unregulated emissions of a light duty vehicle operated on diesel/palm-based methyl ester blends over NEDC and a non-legislated driving cycle

In this study, regulated, unregulated exhaust emissions and fuel consumption with diesel fuel and palm-based biodiesel blends at proportions of 5%, 20% and 40% (v/v) have been investigated. A Euro 3 compliant light duty vehicle was tested on a chassis dynamometer over the new European driving cycle (NEDC) and the non-legislated Athens driving cycle (ADC). The experimental results showed that the addition of biodiesel increased NO_x emissions. This increase was more significant with the use of B20 over both cycles (13.7% and 23.2% over the NEDC and ADC, respectively). Biodiesel addition resulted to increases in CO emissions with the highest increase being 11.78% for B20 over NEDC and 11.62% for B40 over ADC. HC emissions increased with biodiesel over the NEDC, while over the ADC the addition of biodiesel led to reductions with the highest being with the use of B40 (about 26.47%). The same observation holds for PM emissions. Over the ADC the most beneficial reduction was in the order of 50% for the B40. CO₂ emissions and fuel consumption followed similar patterns. B20 led to increases up to 6.16% and 2.94% in fuel consumption over NEDC and ADC, respectively. Some PAH compounds demonstrated an increase with biodiesel, while nitro-PAHs decreased with most of them being almost undetectable. Most carbonyl emissions decreased with biodiesel.     

2,3-二氯丙腈的合成研究

采用丙烯腈、液氯为原料 ,在无溶剂情况下 ,在催化剂作用下直接通氯气合成2 ,3 二氯丙腈 ;产品收率为 96 6% ,纯度≥ 92 .0 %。     

纳米钠基蒙脱土填充改性聚丙烯

采用熔融法把纳米钠基蒙脱土填充到聚丙烯中。研究了纳米钠基蒙脱土对聚丙烯的力学性能的影响。结果表明：添加适量的纳米钠基蒙脱土能够显著改善聚丙烯的力学性能;与纯聚丙烯相比,当纳米钠基蒙脱土含量达到3％（wt）-5％㈩时,冲击强度能增加30％以上,断裂伸长率增加了16％以上,拉伸强度增加了27％以上,弹性模量降低了17％以上。     

DOC-Ⅰ降烯烃催化剂小型提升管反应性能评价

采用小型提升管催化裂化试验装置评价研制的DOC-Ⅰ降烯烃催化剂的催化裂化反应性能。结果表明,在反应温度500 ℃、剂油质量比6和停留时间1.99 s条件下,DOC-Ⅰ催化剂上原料油的转化率达75.01%,较参比催化剂提高1.79个百分点,相应的液化气产率降低0.28个百分点,汽油产率增加2.9个百分点,烯烃含量下降5.21个百分点,异构烷烃和芳烃含量明显增加,产品分布有效改善。表明研制的DOC-Ⅰ催化剂具有较好的催化裂化性能和降烯烃能力。     

Racemization of (R)-(−)-10-methyl-Δ-octalin: Stereochemical requirements for double bond migration (isomerization) on metal catalysts

(R)-(−)-10-methyl-Δ¹⁽⁹⁾-octalin was synthesized in a mixture with cis- and trans-(R)-(−)-10-methyl-Δ¹⁽²⁾-octalin in a five step sequence. After removal of the cis- and trans-(R)-(−)-10-methyl-Δ¹⁽²⁾-octalins by hydrogenation over 5% Pt/C, 5% Rh/C, or 5% Pd/C, the remaining (R)-(−)-10-methyl-Δ¹⁽⁹⁾-octalin was monitored for racemization (double bond migration) during continued hydrogenation. No racemization occurs over these catalysts. However, slow racemization does occur in increasing amounts during hydrogenations over a series of 1% Pd/SiO₂ catalysts with dispersions increasing from 36%D to 84%D. The ratio of cis- to trans-9-methyldecalin changes from 1.8 over 5% Rh/C, 1.6 over 5% Pt/C, 1.1 over 5% Pd/C, to 1.0 over the 1% Pd/SiO₂ catalysts. Since double bond migration does not occur over the 5% catalysts, it cannot be used to account for differences in the ratio of cis- to trans- products. Congestion around the double bond inhibits addition, but double bond migration seems to require the allylic hydrogens to be nearly perpendicular to the planes of the double bond and the surface.     

乙二醇与二甘醇混合醇用杂多酸催化制取二氧六环

试验了用杂多酸为催化剂,以二甘醇与乙二醇的混合物为原料制取二氧六环,得到了适宜的催化剂和工艺条件。     

苯乙烯类热塑性弹性体的生产现状及发展趋势

苯乙烯与二烯烃嵌段共聚物类热塑性弹性体因性能优良而得到迅速发展,其产量已位居各类热塑性弹性体之首,消耗量占热塑性弹性体的５０％以上,预计今后产量将以年均约８％的速度递增。通过对其改性技术的研究,提高产品质量,降低生产成本,如开发高透明度,等性能优良或用途特殊的新产品。     

控释尿素与普通尿素掺混对小麦和玉米轮作产量及氮肥利用率的影响研究

对小麦/玉米轮作制下进行了控释尿素与普通尿素掺混比例试验.试验结果表明：控释尿素与普通尿素掺混处理的产量是在小麦、玉米上均以控释尿素70%＋普通尿素30%处理最好;小麦产量分别为8 000和8 150 kg/hm2,比100%控释尿素处理增产6.2%和7.2%,比100%普通尿素处理增产17.0%和16.7%,比对照增产39.9%和34.5%,它们之间的差异达1%显著水平;玉米产量分别为6 780和6 550 kg/hm2,比100%控释尿素处理增产5.1%和5.6%,比100%普通尿素处理增产16.2%和17.8%,比对照增产22.1%和20.8%,它们之间的差异达1%显著水平.     

Selective N-monomethylation of aniline with dimethyl carbonate over Y-zeolites

The methylation of aniline with dimethyl carbonate was studied and a very high selectivity for N-monomethylation was attained over alkali cation exchanged zeolites. Thus, a 93.5% selectivity for N-methylaniline was obtained at aniline conversion at 99.6% over KY at 453K.