bluuebunny/crossref_metadata_2025_split huggingface dataset:
N‐Acetylation as a Means to Activate Polyfluoroarylamines for Selective ortho‐Hydrodefluorination by Zinc in Aqueous Ammonia: A Concise Route to Polyfluorobenzo Azaheterocycles
Authors: Laev Sergey S. , Gurskaya Larisa Yu. , Selivanova Galina A. , Beregovaya Irina V. , Shchegoleva Lyudmila N. , Vasil’eva Nadezhda V. , Shakirov Makhmut M. , Shteingarts Vitalij D. 
Published: November 2006

AbstractN‐Acetylation of polyfluoroarylamines is proposed as a meansto remove the amino group blocking effect of their hydrodefluorination by zinc in aqueous ammonia. With pentafluoroacetanilide, the Zn ion specific effect has been demonstrated to be responsible for ortho hydrodefluorination. This regiochemistry is accompanied by the removal of a fluorine atom from the para position, which occurs predominantly in the initial phase of the process in the absence of deliberately added zinc salt. The CuCl2 additive has been found to accelerate the reaction and to propel it to double defluorination. Quantum chemical calculations suggest a diminished electron affinity of pentafluoroaniline, which is responsible for its inertness in relation to the hydrodefluorination reaction. The pentafluoroaniline radical anion, which essentially has a nonplanar structure, is prone to easy fragmentation to give an aminotetrafluorophenyl radical. For pentafluoroacetanilide, CVA experiments and quantum chemical calculations predict that the pentafluorophenyl moiety serves as the electron receptor and that the acetamido group is twisted out of coplanarity with the benzene ring; thus, together with the electron‐withdrawing effect of the acetyl group, the amino group blocking effect is suppressed. On this ground, the selective ortho hydrodefluorination of polyfluoroacetanilides is developed as an important protocol for the expeditious and general synthesis of polyfluorobenzo azaheterocycles via readily accessible polyfluoroarylamines from base polyfluoroarenes. Its applicability has been illustrated by preparing quinolines that possess a polyfluorinated benzene moiety by the Skraup synthesis utilizing crude polyfluoroacetanilide hydrodefluorination products as starting materials. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Analysis of biologically active amines by CE
Authors: Chiu Tai‐Chia , Lin Yang‐Wei , Huang Yu‐Fen , Chang Huan‐Tsung 
Published: November 2006

AbstractThis paper provides an overview on the current status of the analysis of biogenic amines by CE. The basic CE separation and detection strategies for the analysis of biogenic amines are briefly described. CZE and MEKC that provide highly efficient and reproducible analysis of biogenic amines are particularly surveyed. With respect to the detection of biogenic amines, we focus on LIF, UV‐visible absorption, electrochemiluminescence, and MS. Derivatization strategies, indirect methods, and on‐line concentration techniques such as field‐amplified sample stacking, sweeping, and use of polymer solution are described. To show the practicality of CE, we highlight currently developed techniques for the determinations of biogenic amines in biological samples, including foods, beverages, cerebrospinal fluids, urine, and single cells.
Unusual essential oils with aromatic properties—I. Volatile components of Stevia rebaudiana bertoni
Authors: Martelli A. , Frattini C. , Chialva F. 
Published: November 2006

AbstractBy combination of liquid‐solid chromatography, capillary GLC and mass spectrometry, the essential oil obtained by steam distillation from the dried leaves of Stevia rebaudiana Bertoni (Asteraceae) imported from Brazil, was analyzed. Caryophyllene oxide and spathulenol accounted for about 43% of the oil, which contained more than a hundred compounds, most of which were present only in traces; 54 components were identified.Also the essential oil obtained by steam distillation from fresh plants of Stevia, cultivated in the Botanical Garden of Turin University, was analyzed.
The leaf oil terpene composition of eastern white pine, Pinus strobus L
Authors: Rudloff Ernst Von 
Published: November 2006

AbstractAnalysis by an on‐line computerized gas‐chromatrographic (g.c.)‐mass spectral method of the steam‐volatile leaf oil of eastern white pine confirmed that α‐ and β‐pinene, and myrcene are the main monoterpenes, with lesser amounts of camphene, car‐3‐ene, β‐phellandrene, limonene, terpinolene, α‐terpineol, and bornyl acetate. In addition, germacrene‐D and caryophyllene were identified as the main sesquiterpenes; lesser amounts of humulene and δ‐cadinene were also found. Small or trace amounts of hexanal, hex‐2‐enal, tricyclene, o‐cymene, α‐phellandrene, α‐terpinene, p‐cymene, γ‐terpinene, α‐fenchol, pinocamphone, terpinen‐4‐ol, a cadinol isomer, manoyl oxide, and a kauranol isomer were identified. Germacrene‐D tended to rearrange to other sesquiterpenes on all but highly deactivated g.c. columns.
Essential oils from fijian Ocimum basilicum L
Authors: Brophy J. J. , Jogia M. K. 
Published: November 2006

AbstractThe composition of the steam‐volatile leaf oils of Fijian Ocimum basilicum L. (sweet basil) has been determined by the use of capillary gas‐liquid chromatography and mass spectrometry. The major components of the oils are methyl cinnamate, linalool, methyleugenol and eugenol.
The effect of heat on beef aroma: Comparisons of chemical composition and sensory properties
Authors: Macleod Glesni , Ames Jennifer M. 
Published: November 2006

AbstractAroma volatiles of fresh cooked ground beef subjected to varying degrees of heating were adsorbed on to Tenax TA, and the desorbed aromas analysed sensorially‐and chemically. Cooked meaty character, when present, was being sampled on to the Tenax and desorbed from it under the analytical conditions used. Several of the components identified by combined capillary gas chromatography‐mass spectrometry have not been reported previously from heated beef. Data is presented to support the generalization that the higher the degree of heating, the greater the concentrations of aliphatic aldehydes (especially Strecker aldehydes), benzenoids, aliphatic polysulphides, heterocyclic compounds and lipid‐derived volatiles, whilst smaller contributions to the isolates arise from aliphatic ketones and alcohols (of non‐lipid origin) and aliphatic mono‐sulphur components. By sensory analysis, eight odour qualities were frequently used during gas chromatographic odour port assessment, namely buttery, caramel, burnt, green, fragrant, oily/fatty, nutty and meaty. Components associated with the former seven qualities are aroma modifiers whereas compounds contributing meaty quality are character impact compounds, e.g. 2‐methyl‐3‐(methylthio)furan and 3‐methylcyclopentanone. Additionally, several unsaturated alicyclic ketones were present which resemble the cyclohexenones previously known to be significant in meat aroma.
Gas chromatographic analysis of absolutes and volatile oil isolated from Turkish and foreign jasmine concretes
Authors: Anac Olcay 
Published: November 2006

AbstractJasmine absolutes of concrete samples from the Antalya district of Turkey and foreign countries were analysed by capillary gas chromatography; the yields and some physicochemical properties were also measured. According to the data obtained, it seems that the quality of Turkish jasmine concrete and absolute could compete with that of other countries.
Essential oil of Zanthoxylum rhetsa
Authors: Joy M. T. , Verghese J. , Retamar J. A. , Talenti E. C. J. , Catalán C. A. N. , Gros E. G. 
Published: November 2006

AbstractThe volatile oil of Zanthoxylum rhetsa, D.C. has been analysed by a combination of gas chromatography and gas chromatography/mass spectrometry. Thirteen new components were identified. (‐)‐Sabinene comprised ∼50% of the oil.
The volatile leaf oils of the junipers of cuba: Juniperus lucayana britton and Juniperus saxicola Britton and Wilson
Authors: Adams Robert P. , Almirall Antonio Lopez , Hogge Lawrence 
Published: November 2006

AbstractThe junipers of Cuba are Juniperus lucayana and J. Saxicola, the latter being endemic to Pico Turquino in Cuba. In this first report on the oils of the junipers of Cuba, the leaf oils were first extracted and then analysed by GC‐MS. Juniperus lucayana from mainland Cuba and the Isle of Pines had oil yields (oven dry weight basis) of 0.58% (2 h) and 2.33% (24 h), and 0.40%(2 h), and 1.58% (24 h), respectively. The oils are dominated by α‐pinene (25–27%), limonene (23–27%), sabinene (11–12%) with small amounts of sesquiterpenes. The volatile leaf oil of J. saxicola was obtained in yields (oven dry weight basis) of 0.30% (2 h) and 0.72% (24 h). Its oil is dominated by sabinene (25%) and α‐pinene (24%), and is more similar to J. lucayana than other species of the Caribbean. The oil compositions of other junipers of the Caribbean are included to aid in making comparisons.
Direct capture of volatiles emitted by living plants
Authors: Bicchi C. , D'Amato A. , David F. , Sandra P. 
Published: November 2006

AbstractThe direct capture of volatiles emitted by living plants and their analysis by capillary gas chromatography (CGC) is discussed. Preliminary results are presented on the construction of a sampling assembly, on the possibilites of open traps (very thick film FSOT column) to capture the volatiles and on the desorption using a single or a double oven GC instrument.
Monoterpene glycosides, state‐of‐the‐art
Authors: Stahl‐Biskup E. 
Published: November 2006

AbstractBefore 1969, when Francis and Allcock reported the occurrence of geranyl, neryl, and citronellyl β‐D‐glucosides in rose petals, nothing was known about such non‐steam volatile forms of monoterpenoids in plant tissue, although the increase of essential oil content during storage and similar phenomena involved the existence of such compounds. To date, 25 different plants have been investigated, and 22 different monoterpene glycosides, mainly glucosides, have been detected.Geraniol, nerol, linalol and α‐terpineol represent the monoterpenoid aglycones most often detected, all four being key intermediates in monoterpene biosynthesis. This fact may indicate a close connection between the monoterpene glycosides and the monoterpene biosynthesis.Banthorpe and co‐workers consider monoterpene glucosides as structural equivalents to the carbonium ions in Ruzicka's hypothetical scheme of monoterpene biosynthesis, while Francis postulates geranyl glucoside to be an intermediate in the step from geranyl pyrophosphate to geraniol.Other results show the glycosides as a transport form of the free monoterpenes, on the one hand from the site of biosynthesis to the site of accumulation, on the other hand in the service of monoterpene turnover and catabolism. On account of their hydrophilic properties their role as a transport form seems plausible and opens a wide field for future research work.
Analysis of leaf oils from four varieties of sweet orange by combined gas chromatography‐mass spectrometry
Authors: Baaliouamer Aoumeur , Meklati Brahim Y. , Fraisse Daniel , Scharff Claude 
Published: November 2006

AbstractThe leaf oil of four varieties of Algerian sweet orange were examined by GC and GC‐MS. In total, 68 constituents were identified from which 50, 54, 38 and 43 compounds were found to be present in the leaf oils of Washington‐navel, Valencia, Sanguine and Portuguese varieties respectively. Of the 68 constituents, 34 were characterized in sweet orange leaf oil for the first time.
Piperine determination in pepper (Piper nigrum L.) and its oleoresins—a reversed‐phase high‐performance liquid chromatographic method
Authors: Wood A. B. , Barrow Maureen L. , James D. J. 
Published: November 2006

AbstractA reversed‐phase high‐performance liquid chromatographic (HPLC) method for the selective determination of piperine, in pepper or its oleoresins, is described and evaluated. It employs a fully‐capped, bonded C18 stationary phase (ODS‐2) and an acetonitrile ‐ aqueous acetic acid mobile phase, with ultraviolet (UV) detection. Piperine is extracted from ground pepper by refluxing 3h with ethanol (96% v/v), whilst homogenized oleoresins are simply dissolved in the same solvent. At all stages, light must as far as possible be excluded from the solutions, so as to minimize the photoisomerization of piperine. Quantitation, based on peak areas, is achieved by reference to purified piperine as external standard. Results obtained for a range of samples at four different detection wavelengths showed virtual wavelength‐independence, indicating a good degree of peak purity. All samples were also analysed by the ISO spectrophotometric method (ISO 5564, 1982), which invariably yielded higher results because of the contributions from other pepper alkaloids (e.g. piperyline and piperettine) to the UV absorption. Since some of these other alkaloids are believed to contribute to the pungency of pepper, the HPLC method is proposed as complementary to the spectrophotometric method, rather than as a replacement for it. The HPLC method gave results with relative standard deviations less than ±3% for black or white pepper, and piperine values between 75.8% and 90.9% of those yielded by spectrophotometry. Given suitable standards, its use could perhaps be extended to cover the quantitation of other pepper alkaloids, two of whose peaks were tentatively identified. Limited experiments on the use of a synthetic capsaicinoid as an internal standard for piperine determination gave encouraging results, and suggested that piperine might be determined satisfactorily with this means of standardization used in conjunction with an automatic injection system, provided that light could be adequately excluded from solutions awaiting injection.
Essential oil of Melissa officinalis L. subsp. altissima (Sibthr. et Smith) Arcang
Authors: Dawson Bernard S. W. , Franich Robert A. , Meder Roger 
Published: November 2006

AbstractThe essential oil derived by steam distillation of the leaves of Melissa officinalis L. subsp. altissima (Sibthr. et Smith) Arcang. naturalized in New Zealand has been shown by capillary column GLC combined with mass and Fourier‐transform infrared spectrometry to comprise β‐cubebene (39% of the oil) together with lesser amounts of other sesquiterpenes, including α‐ and β‐copaene, β‐bourbonene, β‐caryophyllene, and germacrene‐B and ‐D. Significant amounts of terpene alcohols were identified in the oil, viz. 4‐terpineol, α‐terpineol, and α‐ and T‐cadinol, and T‐muurolol, together with cis‐hex‐3‐en‐1‐ol. The fragrance of the essential oil is green and woody (pine‐like), with a floral (rosy) top note, probably attributable to the terpenes, terpineols and hexenol. The oil did not contain any geranial, neral, or citronellal typically found in M. officinalis L. subsp. officinalis.
Transformations of the pungent principles in extracts of ginger
Authors: McHale D. , Laurie W. A. , Sheridan J. B. 
Published: November 2006

AbstractGingerols, the pungent principles from ginger, are thermally labile. Two degradation pathways have been established: retro‐aldol condensation to zingerone and the appropriate aldehyde, and dehydration to shogaols. Evidence is now presented that suggests that the shogaols are also sensitive to certain processing conditions. A series of gingerols ethylated at the aliphatic hydroxyl group has been detected in commercial extracts of ginger. Ethanol is commonly used to extract the pungent principles from the rhizomes. The addition of ethanol to α‐β‐unsaturated ketones is well known and such a reaction with the shogaols is the likely origin of the O‐ethyl gingerols.
Seasonal studies on indian Citrus jambhiri lush leaf oil—a new chemotype
Authors: Agarwal S. G. , Lai S. , Thappa R. K. , Kapahi B. K. , Sarin Y. K. 
Published: November 2006

AbstractLeaf oil of Citrus jambhiri distributed in the sub‐Himalayas has been chemically investigated. Oil samples collected under the different phenological conditions during a year revealed a maximum yield of oxygenated terpenes at the early fruiting stage. The study also confirms that chemically this oil is altogether different from the Californian oil. The oil after deterpenation was found to be similar to Petitgrain citron oil.
The herb essential oil of Thymus glandulosus Lag. ex H. del villar
Authors: Adzet T. , Vila R. , Cañigueral S. , Ibàñez C. 
Published: November 2006

AbstractAir‐dried aerial parts of Thymus glandulosus Lag. ex H. del Villar, an endemic plant of southern Spain and northern Africa, yielded 0.9% (vol/wt) of essential oil. The oil which was investigated for the first time, contained p‐cymene as main component (58%).
Comparative study of the essential oils from hops of various Humulus lupulus L. Cultivars
Authors: Katsiotis S. T. , Langezaal C. R. , Scheffer J. J. C. , Verpoorte R. 
Published: November 2006

AbstractCultivars of the hop (Humulus lupulus L.) are of great interest for breweries. The lupulin glands of the hop cones contain a resinous fraction and an essential oil which are responsible for the bitter taste of beer and contribute to the flavour of it, respectively. The essential oils isolated by hydrodistillation from cones of ten hop cultivars were analysed by chromatographic methods. Two oils contained α‐humulene as main component (ca 40%), in seven oils β‐myrcene (42–58%) clearly predominated, and in one oil almost equal amounts of β‐myrcene (25%) and α‐humulene (27%) were present. The percentages of the quantitatively most important components of the oils are presented, while the composition of the oil of the cultivar ‘Hallertau mittelfruh’ is given in more detail.
Essential oil analysis of Nepeta teydea Webb. & Berth
Authors: Velasco‐Negueruela Arturo , Perez‐Alonso Maria Jose , Rodriquez Ana Buades 
Published: November 2006

AbstractThe volatile oil of Nepeta teydea Webb. & Berth., has been analysed by gas chromatography (GC) and infrared spectroscopy (IR). The essential oil derived from the leaves of Nepeta teydea harvested prior to flowering is characterized by a high content of 4aα‐,7α,7aα‐nepetalactone (89.54%) and by a much lower percentage of other components. Whereas oil extracted from the leaves and flowers collected once flowering had commenced contains as main components: β‐pinene (7.87%), 1,8‐cineole + limonene (14.67%), camphor (5.94%), α‐terpineol (12.64%) and smaller amounts of nepatalactone diasteroisomers as well as nepetalic acid and 5,9‐dehydronepetalactone. The tendency of nepetalactone to hydrolyse is also mentioned.
Quantitative determination of alcohols in essential oils
Authors: Konschake E. , Ziegler And E. , Hefendehl F. W. 
Published: November 2006

AbstractAttempts to determine mixtures of primary, secondary and tertiary alcohols with the currently used chemical methods often lead to wrong results. Using methoxalic anhydride,Bis(Methoxycarbonylacetic) anhydride.
a new method has been developed to esterify such mixtures quantitatively under relatively mild conditions. The free methoxalic acid formed can be determined quantitatively by alkalimetric titration.
Essential oil of curcuma longa l. leaves
Authors: Oguntimein Babajide O. , Weyerstahl Peter , Marschall‐Weyerstahl Helga 
Published: November 2006

AbstractThe essential oil of the leaves of Curcuma longa L. (Zingiberaceae) was investigated by GC, NMR and MS. Major constituents are α‐phellandrene (47.7%) and terpinolene (28.9%). The oil is composed mainly of monoterpenes.
Composition of the essential oils from leaves of various Humulus lupulus L. cultivars
Authors: Katsiotis S. T. , Langezaal C. R. , Scheffer J. J. C. 
Published: November 2006

AbstractCultivars of hop, Humulus lupulus L., are of economic importance for breweries, since hop cones contain a resinous fraction, responsible for the bitter taste of beer, and a volatile fraction, which contributes to its flavour. Till now research on the presence of volatile compounds in the leaves of hop plants has not been reported.Dried leaves of ten cultivars were submitted to hydrodistillation, using the apparatus described in the European Pharmacopoeia. A trap of pentane was necessary to detect and to take up the oils, because hop leaves contain volatile compounds to a much lesser extent than hop cones (<0.05%).The oils were analysed by GC and GC–MS. Of the many components detected 36 were identified, among which were eleven alkanes. In all oil samples sesquiterpene hydrocarbons clearly predominated; α‐humulene (3‐23%) and β‐caryophyllene (5‐29%) were the main components. β‐Myrcene, one of the main components of the essential oils from the cones of the same cultivars, was found in the leaf oils in a concentration of 1% or less.
Review headspace‐gas chromatographic analysis of medicinal and aromatic plants and flowers
Authors: Bicchi Carlo , Joulain Daniel 
Published: November 2006

AbstractThis article reviews papers published during the period 1982‐88 on the headspace of medicinal and aromatic plants and flowers. Articles reported in Chemical Abstracts, the bibliography section of the Journal of Chromatography and Analytical Abstracts are discussed. Considering the large number of publications on this topic which have appeared in the literature over this period, we apologize in advance for any articles which may have been overlooked. Flower headspace analysis is treated as an especially dedicated subject, considering the peculiarity and specificity of this topic.
A new look at the spectroscopic properties of dihydrocarveol stereoisomers
Authors: Decouzon M. , Géribaldi S. , Rouillard M. , Sturla J.‐M. 
Published: November 2006

AbstractThe principal spectroscopic properties of the four dihydrocarveol diastereoisomers are reinvestigated. The interpretation of their 1H‐NMR spectra allows unambiguous differentiation of the diastereoisomers and the determination of their conformations. ‘Negative ion chemical ionization‐Collision‐induced dissociation’ experiments have been performed on the quasimolecular ions [M ‐ H]− using a FT‐ICR spectrometer. The daughter ion spectra of the alkoxide negative ions [M ‐ H]− of the four isomers show substantial differences which can be used for a diastereoisomeric differentiation and the confirmation of the conformations. The gas phase FT‐IR spectra are recorded. The MS and IR results can be used for essential oil analysis using GC–MS and/or GC‐FTIR techniques.
‘Mapo’ tangelo essential oil
Authors: Dugo Giacomo , Cotroneo Antonella , Verzera Antonella , Dugo Giovanni , Licandro Gianvincenzo 
Published: November 2006

AbstractThe volatile fraction of ‘Mapo’ tangelo essential oil was studied using chromatography on a neutral alumina column and gas chromatography with a SE 52 capillary column. Its composition has been compared with that of the essential oils of mandarin and grapefruit.The olfactory characteristics and the composition of the essential oil are in relation to the origin of tangelo which was obtained in Sicily by crossbreeding mandarin with grapefruit.
Structure‐odour correlation, part XI1: Studies on the patchouli character of camphor derivatives
Authors: Weyerstahl Peter , Gansau Christian , Claußen Tilo 
Published: November 2006

AbstractFrom camphor (1) the ketones 2–7 were prepared by α‐alkylation, and the tertiary alcohols 9–17 by Grignard reaction. The disubstituted (iso)borneols 21–26 could be obtained by Grignard reaction of 2–4 with MtMgI or allyl magnesium halide. Reaction of 2–4 with EtMgl afforded the secondary alcohols 18–20 by reduction. Olfactive evaluation showed that the α‐monoalkylated camphors 2–7 as well as the 2‐alkylisoborneols 9a–13a remained more or less within the camphor‐eucalyptus odour profile. However, 14a–16a and the disubstituted (iso)borneols 22–25 possess a strong patchouli scent. The structure of a sterically hindered, rigid tertiary alcohol with 13 to 15 C‐atoms should be responsible for this phenomenon.