硝基麝香香气化合物结构与香气性能关系的量子化学研究

ＡＭ１法计算结果表明，４个麝香香气合物的晶体结构与其最稳定结构符合得相当好。以稳定结构为基础研究总结其典型结构特征，用麝香香气分子共平面模型对其香气性能作了合理解释。     

麝香酮合成进展

麝香酮(3-甲基环十五烷酮)是天然麝香的组成成份,具有天然麝香的某些重要药理作用,又是天然麝香珍奇香气的主要来源。麝香酮在     

合成麝香与生态风险

简介了硝基麝香、多环麝香、大环麝香和脂环麝香的结构、香气特点及应用情况,说明了合成麝香的污染源和硝基麝香、多环麝香的生态风险。笔者认为大环麝香是当前合成麝香的研究热点,脂环麝香将有广阔的应用前景。     

香水百合香气成分的气相色谱保留指数三维定量构效关系研究

采用比较分子场分析（CoMFA）和比较分子相似性指数分析（CoMSIA）方法,研究了香水百合中38种香气成分分子结构与气相色谱保留指数值之间的定量构效关系。用外部测试集验证法和留一交叉验证法对模型的稳健性和预测能力进行了检验,并通过CoMSIA模型和CoMFA模型的分子场三维等势图研究了这些化合物分子中不同化学结构对保留指数值的影响。检验结果表明,所建立的CoMSIA模型和CoMFA模型都具有较好的稳健性和预测能力,且能够合理解释结构对保留指数值的影响,可应用于对香水百合香气成分的色谱保留指数值的预测。与CoMFA模型相比,CoMSIA模型的预测准确度更高,在香水百合香气成分的色谱定量构效关系研究中,显然有更好的应用前景。     

可溶解的聚氨酯交联大分子的合成及其特殊的溶液行为

到目前为止，交联过程之所以难以控制是因为在交联聚合体系中，没有一个与交联过程相竞争的反应．本文利用大分子在溶液中是无规线团的特征，设计了含有分子内和分子间反应的交联聚合体系，分子间反应即交联过程，而分子内反应使分子问反应受到抑制，使交联过程的链增长不能无限发展，从而合成了可溶解的具有交联结构的大分子．     

数值微扰分子轨道法的研究进展*

本文介绍了分子内和分子间各类定量微扰分子轨道(PMO) 法数值计算的发展和现状。简要地介绍了Salem ,Wolfe,Bernardi, Imamura 和Morokuma 等对PMO 理论发展的贡献     

臭氧分子中的极性探讨

采用abinitio方法对O3分子的电子结构进行了计算,构型优化的结果与文献符合的较好,并根据计算结果分析了O3分子中键的极性和分子的极性。     

应用分子形貌理论研究类SN2反应

应用分子形貌理论, 研究了类SN2反应过程中的沿着IRC路径上固定点的分子形貌的特征, 计算给出了形状和电子密度特征参数以及各键的Dpb值. 应用Matlab程序绘制了分子特征边界轮廓上的电子密度分布的三维图像, 即分子形貌像, 给出了这类反应的动态变化过程.     

关于分子特征形状的理论--Ⅱ.几个典型有机分子的内禀特征轮廓

借助于分子中电子运动的经典转折点,定义了分子的内禀特征轮廓.文中以甲烷、甲醇和甲酸为例,详细介绍了分子内禀特征轮廓理论方法.对分子轮廓的特征截面的具体分析,可以给出形成分子过程中原子的空间变化信息.首次计算和绘出了上述分子轮廓上的电子密度分布图,它与分子的化学性质密切相关,给出了对分子边界的新认识.     

关于分子特征形状的理论

借助于分子中电子运动的经典转折点, 定义了分子的内禀特征轮廓. 文中以甲烷、甲醇和甲酸为例, 详细介绍了分子内禀特征轮廓理论方法. 对分子轮廓的特征截面的具体分析, 可以给出形成分子过程中原子的空间变化信息. 首次计算和绘出了上述分子轮廓上的电子密度分布图, 它与分子的化学性质密切相关, 给出了对分子边界的新认识.     

多环麝香的分子结构和香气之间的关系

本文综述了多环麝香的当前进展,并提出了系统的分类方法。对各种多环麝香(茚满型,萘满型,异色满型,氢化引达省型,苊型)香味与分子结构之间关系的研究进行了总结,还作了比较。并描述了多环分子中环上取代基的性质,数量和位置对麝香香味的影响。     

Compass: A shape-based machine learning tool for drug design

Summary Building predictive models for iterative drug design in the absence of a known target protein structure is an important challenge. We present a novel technique, Compass, that removes a major obstacle to accurate prediction by automatically selecting conformations and alignments of molecules without the benefit of a characterized active site. The technique combines explicit representation of molecular shape with neural network learning methods to produce highly predictive models, even across chemically distinct classes of molecules. We apply the method to predicting human perception of musk odor and show how the resulting models can provide graphical guidance for chemical modifications.     

What's Hot,What's Not: The Trends of the Past 20 Years in the Chemistry of Odorants

This review is the sequel to the 2000 report on the recent advances in the chemistry of odorants and it summarizes the developments in fragrance chemistry over the past 20 years. Following the olfactory spectrum set out in that report, trendsetting so‐called captive odorants (patent‐protected ingredients unavailable to the market) are presented according to the main odor families: “fruity”, “marine”, “green”, “floral”, “spicy”, “woody”, “amber”, and “musky”. The design of odorants, their chemical synthesis, and their use in modern perfumery are illustrated with prominent examples. Featured are new fruity odorants that provide signature in the top note, as well as precursor technology. In the green domain, focus is on leafy notes and green pear. New benzodioxepines and benzodioxoles have modernized the marine family and required a revision of the existing olfactophore models. The replacement of Lilial and Lyral kept the industry busy in the floral domain with a plethora of new “muguets”. There was continued activity in the domain of rose odorants, especially in the area of rose ketones. Biotechnology became significant, for example, with Clearwood and Ambrofix, and the principal odorants of vetiver oil in the woody family have been found. Fourth and fifth families of musk odorants were also discovered and populated. Thus, new avenues for further explorations into fragrance chemistry have been opened.     

New aromatic musk odorants: Design and synthesis

By appropriate structural modification of known musk odorants, new strong musk odorants have been discovered. Incorporation of supplementary CH₃ or CH₂ groups into the basic musk skeleton of type G only slightly modifies the global shape of the molecule but leads to densely packed structures of enhanced lipophilicity. For the construction of these highly substituted 1,2,3,4-tetrahydronaphthalenes, new annulation sequences (intramolecular mono- and dialkylations; see Schemes 3,6, and 8) have been developed and, in certain cases, the design of the target molecules was dictated by both structure-activity-relationship and synthetic considerations (e.g. 46 and 47 , Scheme 6). This work also presents an original solution to an analytical problem: the distinction between a C₂- and a C_s-symmetrical aromatic hydrocarbon (viz. 71 and 72 ) by conversion into a [Cr(CO)₃arene]complex.     

Devices for Assisting Human Olfaction: Some Fundamental Experiments

Olfactory assist systems that allow the user to sense smells with amplified sensitivities are reported. We have developed two types of systems. The first system, an olfaction augmenter, detects the presence of a volatile organic compound in the air using a gas sensor, and presents an odor with an amplified intensity to the user using an odor generator. The second system, an olfactory concentrator, collects odor molecules in the air using an adsorbent, and presents the concentrated odor to the user. Results of our initial experiments on a prototype concentrator are reported.     

On the unpredictability of odor

The relationship between molecular structure and odor has fascinated and puzzled chemists for more than a century. Despite a great deal of research on structure-odor relationships, prediction of the odor of a novel molecule remains a statistical exercise and models only provide a probability of the character, threshold, and intensity. Surprises are still commonplace, and serendipity continues to be an important factor in the discovery of novel fragrant molecules. Recent advances in our understanding of the mechanism of olfaction provide an explanation for this and suggest that our ability to predict odor properties of molecules will not improve significantly in the near future.     

Solid-phase microextraction as a novel air sampling technology for improved, GC-olfactometry-based assessment of livestock odors

Air sampling and characterization of odorous livestock gases is one of the most challenging analytical tasks. This is because of low concentrations, physicochemical properties, and problems with sample recoveries for typical odorants. Livestock operations emit a very complex mixture of volatile organic compounds (VOCs) and other gases. Many of these gases are odorous. Relatively little is known about the link between characteristic VOCs/gases and, specifically, about the impact of characteristic odorants downwind from sources. In this research, solid-phase microextraction (SPME) is used for field air sampling of odors downwind from swine and beef cattle operations. Sampling time ranges from 20 min to 1 h. Samples are analyzed using a commercial gas chromatography-mass spectrometry-olfactometry system. Odor profiling efforts are directed at odorant prioritization, with respect to distance from the source. The results indicate the odor downwind is increasingly defined by a smaller number of high-priority odorants. These "character defining" odorants appear to be dominated by compounds of relatively low volatility, high molecular weight, and high polarity. In particular, p-cresol alone appears to carry much of the overall odor impact for swine and beef cattle operations. Of particular interest is the character-defining odor impact of p-cresol as far as 16 km downwind of the nearest beef cattle feedlot. The findings are highly relevant to scientists and engineers working on improved air sampling and analysis protocols and on improved technologies for odor abatement. More research evaluating the use of p-cresol and a few other key odorants as a surrogate for overall odor dispersion modeling is warranted.     

Determination of major aroma impact compounds in fermented cucumbers by solid-phase microextraction--gas chromatography--mass spectrometry--olfactometry detection

Purge-and-trap, solid-phase extraction, and solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) sample preparation techniques for the analysis of odor impact chemicals in fermented cucumber brine are compared. SPME-GC-MS is coupled with detection frequency olfactometry experiments to determine key impact odor compounds in the brine. The most potent odorants that define the typical characteristic brine aroma are trans-4-hexenoic acid and cis-4-hexenoic acid. Confirmation of key impact odorants in brine is confirmed by recombination experiments.     

Characterization of volatile organic compounds and odorants associated with swine barn particulate matter using solid-phase microextraction and gas chromatography-mass spectrometry-olfactometry

Swine operations can affect air quality by emissions of odor, volatile organic compounds (VOCs) and other gases, and particulate matter (PM). Particulate matter has been proposed to be an important pathway for carrying odor. However, little is known about the odor-VOCs-PM interactions. In this research, continuous PM sampling was conducted simultaneously with three collocated TEOM 1400a analyzers inside a 1000-head swine finish barn located in central Iowa. Each TEOM was fitted with total suspended particulate (TSP), PM-10, PM-2.5 and PM-1 preseparators. Used filters were stored in 40 mL vials and transported to the laboratory. VOCs adsorbed/absorbed to dust were allowed to equilibrate with vial headspace. Solid-phase microextraction (SPME) Carboxen/polydimethylsiloxane (PDMS) 85 microm fibers were used to extract VOCs. Simultaneous chemical and olfactometry analyses of VOCs and odor associated with swine PM were completed using a gas chromatography-mass spectrometry-olfactometry (GC-MS-O) system. Fifty VOCs categorized into nine chemical function groups were identified and confirmed with standards. Five of them are classified as hazardous air pollutants. VOCs were characterized with a wide range of molecular weight, boiling points, vapor pressures, water solubilities, odor detection thresholds, and atmospheric reactivities. All characteristic swine VOCs and odorants were present in PM and their abundance was proportional to PM size. However, the majority of VOCs and characteristic swine odorants were preferentially bound to smaller-size PM. The findings indicate that a significant fraction of swine odor can be carried by PM. Research of the effects of PM control on swine odor mitigation is warranted.     

A rapid method for molecular shape comparison of medium-sized molecules. Conformational calculations on sandalwood odor,IV

Summary A fast method of a surface comparison of two or more molecules to be matched is presented. The Van der Waals surfaces of molecules are described by points calculated as the intersection of grid lines with the molecular surface. The mean surface of various molecules with the same biological activity can be constructed. It is used for further comparisons with similar molecules lacking this activity. Deviations of any molecular surface from the mean surface can be mapped onto the surface. The method was tested on a distinct group of sandalwood odor molecules and it was shown that such matching and comparison procedures are useful in the investigation of odor structure-activity relationships proposed as CAFD (computer aided fragrance design).Dedicated to Prof. Dr. W. Fleischhacker, on occasion of his 60th anniversary