合成樟脑的进展

樟脑有天然樟脑和合成樟脑之分。我国台湾、福建、浙江等省的天然樟脑加起来约占世界总产量的首位。为满足国内和国际市场上的日益需要,从五十年代起,我国就已研究成功合成樟脑,弥补了天然樟脑之不足,并逐步建立了相当规模的合成樟脑工业。其产品绝大部分供外贸出口,远销三十多个国家。其中包括传统生产合成樟脑的如英国、西德、美国等国。     

合成樟脑

樟脑系二环单萜莰族类,故又名莰酮-[2]或1,7,7-三甲基双环[2:2:1]庚酮-[2]。或它存在于樟树的各部分中,通常用水气蒸馏法蒸出,分开樟脑油后,再用升华法精制,便得所谓天然樟脑。我国台湾的天然樟脑约占世界总产量60—70％,居世界第一位。本世纪初日本军国主义利用霸占我国台湾的特权,对天然樟脑加以垄断,而樟脑又是国防工业、医药卫生、赛璐珞及电影胶片等方面不可缺少的原料。这样就刺激     

光学活性金属卟啉的磁手性效应研究

磁光学活性与自然光学活性均可用介质对左右圆偏振光的吸收之差来表示 .但自然光学活性和磁光学活性的物理机制是截然不同的 ,前者源于镜象不能互相重叠介质的非定域光学响应 ( nonlocaloptical response) ,而后者则是由于介质的时间反演对称性 ( time- reversal symmetry)被磁场打破所致 .理论分析表明 ,当介质的两种光学活性同时存在时 ,将会出现一个新的附加光学效应 ,这种磁光学活性与自然光学活性之间的交叉效应称为磁手性效应 ( magneto- chiral effect)或磁手二色性 ( magneto-chiral dichroism) [1,2 ] .磁手性效应通常很弱 ,直到 1…     

对羰基选择性特别高的不对称还原反应

生物活性的天然化合物几乎都是光学活性体。用不对称还原非光学活性化合物中的对映面,而得到光学活性化合物的反应,从合成方法来说可以认为是理想的反应。可是实际上能满足化学得率及不对称得率两方面的反应尚未发现。     

甾体CD环合成原的不对称合成及其在全合成上的应用

光学活性的甾体口服避孕药已被广为应用。许多结构改变的光学活性甾体口服避孕药,例如D-18-甲基炔诺酮可从不对称合成获得。本文报道通过微生物不对称还原合成了四个光学活的C,D环合成原。其中两个是新的。我们并利用这些光学活性合成原全合成     

光学异构体拆分方法的进展

光学活性异构体物质广泛存在于自然界的生物体内,为生命起源的基本物质。蛋白质和酶等物质,就是由许多光学活性的氨基酸组成。     

光学活性α-氨基烃基膦酸的合成

由光学活性的α-氨基酸制备得光学活性α-氨基烃基膦酸, 且表示其关键反应步骤Michaelis-Arbuzov反应机理为SN2反应.     

高分子载体氧化铬试剂在樟脑合成中的应用

我国幅员辽阔,自然资源丰富。合理地综合利用和开发各种资源是我们的重要任务。松节油在我国产量很大,用途很广。合成樟脑是其目前的主要用途之一。合成樟脑的性能与天然樟脑相似。它是香料、化工、塑料工业的重要原料。     

二价过渡金属配合物催化的醇酮缩合

以酸或碱催化的醇酮缩合反应,通常得到的是α,β-不饱和酮.Watanabe等人以对硝基苯甲醛与丙酮缩合为标准反应,研究了光学活性的L-酪氨酸乙酯-金属离子(主要是Zn~(2+)离子)催化体系催化的醇酮缩合反应,得到有光学活性的β-醇酮产物。并初步研究了β-CD对该催化体系的协助效应。在L-酪氨酸-Zn~(2+)-β-CD的催化下,水溶液中反应得到无光学活性的β-醇酮产物。     

含偶氮苯光学活性侧基聚合物研究进展

综述了含偶氮苯光学活性侧基聚合物近年来的发展概况 ,介绍了多种聚合体系的类型。由于偶氮苯光于活性侧基的存在 ,使得这些聚合物具有光致变色性、非线性光学活性、光学各向异性等光学性能 ,在光信息存储材料、非线性光学材料、液晶材料、光电子器件、生物分子活性光调控、纳米技术等诸多领域都有广泛的应用。     

固相微萃取-气相色谱-质谱法分析香樟籽挥发性成分

采用固相微萃取-气相色谱-质谱法分离和鉴定香樟籽的挥发性成分,用归一化法测定其相对含量。共分离出76种组分,鉴定出47种化合物,其含量占总挥发性成分的97.4%。主要挥发成分为樟脑(57.89%)、柠檬烯(12.68%)、α-蒎烯(4.42%)、莰烯(2.69%)、香橙烯(2.34%)、伞花烃(2.26%)及β-蒎烯(2.12%)。     

乙酰丙酮氧钒催化氧化α-蒎烯一步转化成龙脑烯醛

以乙酰丙酮氧钒为催化剂,过氧化氢为氧化剂,研究了由α-蒎烯直接合成龙脑烯醛的反应。考察了溶剂、温度、催化剂用量、反应时间等因素对催化性能的影响。结果表明,乙酰丙酮氧钒与H2O2反应得到的高价态V5+是优良的氧化还原-Lewis酸双功能催化剂,易使α-蒎烯经氧化、2,3-环氧蒎烷异构得到龙脑烯醛。在n(H2O2):n(α-蒎烯):n(乙酰丙酮氧钒)=2.5:1:0.01、反应温度为20℃、丙酮为溶剂、反应2h条件下,α-蒎烯转化率为50.2%,龙脑烯醛的选择性达58.7%,反应6h后α-蒎烯转化率可达73.0%,主要产物龙脑烯醛和马鞭草烯酮的选择性分别为47.2%和13.2%。     

蒙古蒿精油化学成份的研究I.

The chemical constituents of the essential oil from the leaves of artemisia mongolica Fisch. were separated by gas chromatography employing glass capillary eolumns and identified by GC-MS-COM. 30 components have been separated and identified, i.e. 2-methyl-2-butene, methylene cyclopentane, 7,7-dimethyl-3-methylen-bicyclo-(3, 1, 1) heptane, α-thujene, α-pinene, camphene, 1-octen-3-o1, β-thujene, β-pinene, α-phellandrene, bornylene, p-cymene, terpinen-1-o1, artemisia ketone, γ-terpinene, β-terpineol, 3,7,7-trimethyl-bicyclo-(3, 1,1)-2-heptanol, α-terpinolene, verbenone, linalool iso-thujone, thujone, camphor, isopulegone, isoborneol, terpinen-4-o1, α-terpineol, myrtenol, trans- carveol, cis-carveol.     

Microbial Oxidation of (-)-α-pinene to Verbenol Production by Newly Isolated Strains

Verbenol is a bicyclicbicycle secondary allylic alcohol, with pronounced camphor and mint flavor notes, mainly used as food flavoring. This compound is also used to control harmful insects, and hence has potential for using in agriculture, and is an intermediate in the synthesis of valuable perfume and medicinal substances. This work is focused on the microbial oxidation of (-)-α-pinene to verbenol production. To carry out the present study, 405 microorganisms were tested for their ability to bioconvert the substrate. From the isolated microorganisms, 193 were selected in the pre-screening using mineral medium for limonene degradation. At the screening step, 31 strains were able to convert (-)-α-pinene in verbenol. The highest concentration in verbenol from (-)-α-pinene was about 125.6 mg/L for yeast isolated from orange juice industrial residue.     

Determination of Volatile Terpenes in Coriander Cold Pressed Oil by Vacuum Assisted Sorbent Extraction (VASE)

Cold-pressed plant oils are of high interest to consumers due to their unique and interesting flavors. As they are usually only pressed at low temperatures and filtered, without further processing stages (as refining), they preserve their character that originates from the plant the oil was extracted from. Coriander cold pressed oil is gaining popularity as a novel product, obtained from its fruits/seeds; due to the high amount of terpenes, it has very characteristic flavor. A novel, vacuum-assisted sorbent extraction (VASE) method was used to extract terpenes from coriander cold pressed oil. Optimal parameters were determined. The profile of compounds extracted using VASE was compared with that of classic hydrodistillation method. Moreover, 17 monoterpene hydrocarbons and alcohols were identified with β-linalool as the main compound, followed by α-pinene, γ-terpinene, camphor, sylvestrene, β-pinene, and o-cymene. Differences were noted between profiles of terpenes after hydrodistillation and VASE extraction. For 8 out of 17 terpenes, VASE was used for their quantitative analysis. Regarding simplicity of the method, small sample requirement (200 mg) and short extraction time (5 min), VASE combined with GC/MS is well suited for characterization of terpenes in such matrix as plant oils.     

Chemical composition and antimicrobial activities of Perovskia artemisioides Boiss. essential oil

The Perovskia artemisioides Boiss. essential oil obtained by hydrodistillation method of flowers growing wild in the north of Iran. The study led to the identification of 29 compositions by a combination of HP-5 GC–FID and GC–MS analytical techniques. The constituents were identified in P. artemisioides essential oil with 1,8-cineole (29.9%), camphor (29.5%) and α-pinene (7.8%) as main constituents as well as δ-3-carene (5.1%), camphene (3.3%) and β-pinene (2.7%). The oil was identified by a much larger amount of monoterpenes (87.7%) and sesquiterpenes (6.3%). The results of antimicrobial activity exhibit that the extracted essential oil has presented a high inhibiting activity against five microbial strains up to 18 mm. Also, the MIC and MBC results displayed that Staphylococcus aureus, Escherichia coli and Salmonella typhi were inhibited by P. artemisioides essential oil. Therefore, determination of essential oils in this research showed a relatively similar pattern to those published for the other species of Perovskia.     

The Chemical Constituents of the Wood of Pinus Luchuensis Mayer

From the hexane extractive of the wood of Pinus luchuensis Mayer, α-pinene, β-pinene, camphene, camphor, 4-terpineol, α-terpineol, carvacrol, tetracosanol, hexacosanol, octacosanol, β-sitosterol, stigmasterol, methyl dehydroabietate, pinosylvin monomethylether, pimaric acid, dehydroabietic acid and straight chain hydrocarbons C₂₃-C₃₅ were isolated.     

Stability assessment of gas mixtures containing terpenes at nominal 5 nmol/mol contained in treated aluminum gas cylinders

Studies of climate change increasingly recognize the diverse influences exerted by terpenes in the atmosphere, including roles in particulates, ozone formation, and their oxidizing potential. Measurements of key terpenes suggest atmospheric concentrations ranging from low pmol/mol (parts per trillion) to nmol/mol (parts per billion), depending on location and compound. To accurately establish concentration trends, assess the role of terpenes in atmospheric chemistry, and relate measurement records from many laboratories and researchers, it is essential to have good calibration standards. The feasibility of preparing well-characterized, stable gas cylinder standards for terpenes at the nmol/mol level is not yet well established. Several of the world’s National Metrology Institutes (NMIs) are researching the feasibility of developing primary and secondary reference gas standards at the nmol/mol level for terpenes. The US NMI, the National Institute of Standards and Technology, has prepared several nmol/mol mixtures, in treated aluminum gas cylinders, containing terpenes in dry nitrogen at nominal 5 nmol/mol for stability studies. Overall, 11 terpenes were studied for stability. An initial gas mixture containing nine terpenes, one oxygenate, and six aromatic compounds, including benzene as an internal standard, was prepared. Results for four of the nine terpenes in this initial mixture indicate stability in these treated aluminum gas cylinders for over 6 months and project long term (years) stability. Interesting results were seen for β-pinene, which when using a linear equation rate decline predicts that it will reach a zero concentration level at day 416. At the same time, increases in α-pinene, d-limonene (R-(+)-limonene), and p-cymene were observed, including camphene, a terpene not prepared in the gas mixture, indicating a chemical transformation of β-pinene to these species. Additional mixtures containing combination of either α-pinene, camphor, α-terpinene, and benzene indicate a second-order quadratic rate decline for the α-pinene and α-terpinene, a linear rate decline for camphor, and a second-order quadratic rate increase of camphene.     

Synthesis of β-Pinene/THF Block Copolymers

The living cationic polymerization of β-pinene was carried out with α-chloroethylbenzene(PEC)/TiCl₄/Ti(OiPr)₄ initiating system in CH₂C1₂ at -40℃. After 25 min of reaction(β-pinene conversion~100%),the resulted living poly(β-pinene) was capped with a few units of styrene and then the polymerization was quenched to give β-pinene macroinitiator with benzenyl chloride chain end (P(β-p)-St-Cl). The structure of the macroinitiator was confirmed by ¹H NMR (Fig.l). The macroinitiator, in conjunction with AgSbF₆ or AgC1O₄,was used to initiate the ring-opening cationic polymerization of THF in the presence of propylene oxide promoter. GPC analysis of the obtained polymers showed that AgSbF₆ system led to almost pure block copolymers of β-pinene with THF, whereas AgC1O₄ system gave mixtures of block copolymers and low molecular weight homopolymers of THF and unreacted macroinitiator (Fig.2). ¹H NMR analysis further confirmed the formation of β-pinene/THF block copolymers with macroinitiaor/AgSbF₆ system (Fig.3).     

Optimization of Algerian rosemary essential oil extraction yield by supercritical CO2 using response surface methodology

The present study deals with the determination of optimal values of operating parameters such as temperature and pressure leading to the best yield of a supercritical CO₂ extraction of essential oil from local rosemary plants, using the response surface methodology (RSM). The maximum of essential oil recovery percentage relative to the initial mass of leaf powder was 3.52 wt%, and was obtained at 313 K and 22 MPa.A second-order polynomial was used to express the oil recovery and the calculated mass of recovered oil using the RSM was very close to the experimental value, confirming the reliability of this technique.The chemical composition of the Algerian rosemary oil under the obtained optimal conditions (313 K and 22 MPa), determined by GC–MS analysis, revealed the presence of camphor (major compound) (52.12%), 1,8-cineole (9.65%), camphene (7.55%), α-pinene (6.05%), borneol (3.52%), aroma dendrene (2.11%), verbenone (1.97%), α-caryophyllene (1.71%), and others.