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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Biotransformations of Turpentine Constituents : Oxygenation and Esterification

Lindmark-Henriksson, Marica January 2003 (has links)
<p>This thesis describes methods to obtain value–addedcompounds from TMP-turpentine obtained from the spruce, Piceaabies. The methodology focuses on biotransformations using twoapproaches: an oxygenation approach (i.e. oxygenation ofterpene hydrocarbons by cell cultures) and an esterificationapproach (i.e. lipase-catalysed transesterification of vinylacetate with terpene alcohols, and a further fractionation ofthe TMP-turpentine).</p><p>The main constituents of the turpentine, a-pinene, b-pineneand limonene, were subjected to a P. abies suspension culture.Allylic oxidation formed the major products for α-pineneand β-pinene, which were further oxidised to theirrespective aldehyde or ketone. One of the minor products froma-pinene, cis-verbenol, was not only transformed into verbenonebut also isomerised to trans-verbenol. Limonene gavelimonene-(1,2)-epoxide as the major product.</p><p>Fractionation of monoterpenes is accomplished throughphysical separation methods, chromatography and distillation,and lipase-catalysed transesterification of vinyl acetate withterpene alcohols. The esters of myrtenol and trans-pinocarveolwere separated from the more slowly reacting alcohols such asborneol and carveol by use of a combination of the Mucor mieheilipase and Candida antarctica lipase A as catalysts.Furthermore, the non-reacting tertiary terpene alcohols wereseparated from the reacting alcohols in a single step byCandida antarctica lipase A.</p><p>Lipase-catalysed (Candida antarctica lipase B andPseudomonas cepacia lipase) transesterification of vinylacetate with sterically hindered secondary alcoholsunexpectedly yielded hemiacetals or hemiacetal esters. Thereaction conditions required to obtain these side products havebeen studied.</p><p><b>Keywords:</b>Picea abies, Pinaceae, Essential oilscomposition; Terpene alcohol; Hemiacetal; Hemiacetal ester,TMP-turpentine; Monoterpene; α-Pinene; β-Pinene;Limonene; Verbenol; Pinocarveol; Borneol; Myrtenol; Suspensioncell culture; Biotransformation; Lipase-catalysed; Oxidation;Allylic oxidation; Transesterification; Autoxidation;Separation.</p>
12

Propriedades farmacolÃgicas dos monoterpenos &#945;- e &#946;-pineno no mÃsculo liso gastrintestinal de ratos: efeito miorrelaxante e prÃ-cinÃtico / Pharmacological properties of the monoterpenes &#945;- and &#946;-pinene on rat gastrointestinal smooth muscle: myorelaxant and prokinetic effects

Davi Matthews Jucà 20 July 2007 (has links)
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / The monoterpenes &#945;- and &#946;-pinene are constituents commonly found in several essential oils obtained from plants in Brazilian northeast such as âmalva-santaâ and âeucaliptoâ, which are used in folk medicine to treat respiratory and gastrointestinal dysfunctions. Myorelaxant actions are due to the presence of these constituents in their essential oils. The present work aimed to further study the pharmacological effects of these compounds on smooth muscle gastrointestinal contractility as well as on liquid gastric emptying in rats. Wistar rats (200-250 g) were used, sacrificed by cervical dislocation. Strips were carefully obtained from gastric fundus, duodenum and ileum, and were maintained in Tyrodeâs solution. Isometric contractions were recorded through force transducers coupled to a computerized data acquisition system. Solutions containing &#945;- or &#946;-pinene were prepared with Tween 80 (final concentration &#8804; 0,2% v/v). Solely used, &#945;- or &#946;-pinene decreased duodenal basal tonus with IC50 value corresponding to 655.1 ÂM and 810.2 ÂM, respectively. Submaximal contractions induced by K+ (60 mM, K60) or acetylcholine (ACh, 3 ÂM) were inhibited, in a concentration-dependent manner (p < 0.001, ANOVA), with IC50 values of 790.0 [580.2-1007.4] e 760.0 [650.6-870.8] ÂM, respectively to &#945;-pinene and 770.1 [500.3-1180.5] e 620.7 [520.9-750.2] ÂM, respectively to &#946;-pinene. In tissues pre-treated with &#945;- (1 mM) or &#946;-pinene (1 mM) in medium without Ca2+ with EGTA (0.2 mM), ACh (3 ÂM)-induced phasic contractions were inhibited from 18.4  3.3% to 7.7  1.5% and 5.0  1.2% of K60, respectively. In tissues maintained under Ca2+-free conditions (in medium containing EGTA 0.2 mM) and in presence of K+ (60 mM) or ACh (3 ÂM), tonic contractions induced by Ca2+ addition were reduced from 50.2  3.3% and 53.9  5.2%, respectively to values corresponding to 10.6  2.6 % and 24.4  4.1 % to experiments with &#945;-pinene and 6.6  1.1 % and 10.9  3.5 % to experiments with &#946;-pinene, respectively. In tissues pre-treated with &#945;- (1 mM) or &#946;-pinene (1 mM), ACh (60 ÂM)-induced tonic contractions, in verapamil (3 ÂM)-containing medium, were inhibited from 29.0  4.1 % to 10.6  2.7 % and 12.5  2.2 % of the K60, respectively. The caffeine (20 mM)-induced contractile response in normal Tyrodeâs solution was potentiated from 47.8  3.2 % to 72.1  9.0 and 88.8  10.6 % of the control response in virtue of &#945;- (1 mM) or &#946;-pinene (1 mM) presence, respectively. In EGTA-containing Ca2+-free medium, the contractile response to caffeine was reduced to 9.5  3.5%. Under these conditions, and in presence of &#945;- (1 mM) or &#946;-pinene (1 mM), this response was not significantly altered, with values corresponding to 7.2  2.2 e 4.7  1.3 %, respectively. In verapamil- and EGTA-containing Ca2+-free medium, after depletion of the intracellular Ca2+ stores by CCh (100 ÂM), the contractions induced by Ca2+ addition were potentiated by the presence of &#945;- (1 mM) or &#946;-pinene (1 mM) from 30.7  2.1 % to 80.6  4.7 and 51.3  7.6 %, respectively (p < 0.05, Bonferroniâs test). In gastrointestinal dye fractional retention studies, &#945;- or &#946;-pinene increased the rat liquid gastric emptying. On the other hand, they did not alter the ACh-induced contractions on gastric fundus strips. Our study firstly shows that, both &#945;- and &#946;-pinene have prokinetic properties in rats. In isolated tissues, they did not affect cholinergic contractions on gastric fundus strips, but are myorelaxant compounds on rat duodenal preparations, probably by an interference with cellular mechanisms mediated by IP3 release. Moreover, &#945;- and &#946;-pinene activate capacitative Ca2+ entry to intracellular milieu after Ca2+ stores depletion / &#945;- e &#946;-pineno sÃo monoterpenos constituintes do Ãleo essencial de plantas encontradas no Nordeste do Brasil como a malva-santa e o eucalipto que, na medicina popular, sÃo usadas no tratamento de distÃrbios intestinais e respiratÃrios. As aÃÃes miorrelaxantes desses Ãleos essenciais sÃo atribuÃdas à presenÃa de &#945;- e de &#946;-pineno. Nosso objetivo foi estudar mais detalhadamente os efeitos desses constituintes sobre a contratilidade do mÃsculo liso gastrintestinal e sobre o esvaziamento gÃstrico de lÃquido em ratos. No presente estudo, foram usados ratos Wistar machos (200-250g) sacrificados por deslocamento cervical. Tiras de duodeno, Ãleo e fundo de estÃmago foram cortados e mantidos em Tyrode. As contraÃÃes isomÃtricas foram registradas atravÃs de transdutores de forÃa conectados a sistema computadorizado. SoluÃÃes contendo &#945;- ou &#946;-pineno foram preparadas em Tween 80 (concentraÃÃo final &#8804; 0,2% v/v). Usados isoladamente, &#945;- e &#946;-pineno diminuÃram o tÃnus basal em duodeno com CI50 de 655,1 e 810,2 ÂM, respectivamente. ContraÃÃes submaximais induzidas por K+ (60 mM, K60) ou acetilcolina (ACh, 3 ÂM) foram inibidas, de maneira concentraÃÃo-dependente (p < 0,001, ANOVA), com valores de CI50 correspondentes a 790,0 [580,2-1007,4] e 760,0 [650,6-870,8] ÂM, respectivamente, para o &#945;-pineno e 770,1 [500,3-1180,5] e 620,7 [520,9-750,2] ÂM para o &#946;-pineno, respectivamente. Em preparaÃÃes prÃ-tratadas com 1 mM de &#945;- ou &#946;-pineno, a contraÃÃo fÃsica induzida por ACh (3 ÂM) em meio sem Ca2+ contendo EGTA (0,2 mM) foi reduzida de 18,4  3,3 % para 7,7  1,5 % e 5,0  1,2 % da contraÃÃo K60, respectivamente. A contraÃÃo tÃnica induzida por adiÃÃo de Ca2+ (2 mM) em preparaÃÃes mantidas na presenÃa de K+ (60 mM) ou ACh (3 ÂM), em meio sem Ca2+ contendo EGTA (0,2 mM), foi reduzida de 50,2  3,3 % e de 53,9  5,2 % para 10,6  2,6 % e 24,4  4,1 % pelo &#945;-pineno e 6,6  1,1 % e 10,9  3,5 % pelo &#946;-pineno, respectivamente. Em preparaÃÃes prÃ-tratadas com 1 mM de &#945;- ou &#946;-pineno, a contraÃÃo tÃnica induzida por ACh (60 ÂM) em Tyrode normal contendo verapamil (3 ÂM) foi reduzida de 29,0  4,1 % para 10,6  2,7 % e 12,5  2,2 % da K60, respectivamente. A resposta contrÃtil induzida pela cafeÃna (20 mM) em Tyrode normal foi potencializada de 47,8  3,2 % para 72,1  9,0 e 88,8  10,6 % da resposta controle pelo prÃ-tratamento da preparaÃÃo com &#945;- ou &#946;-pineno, respectivamente. Em meio sem Ca2+ com EGTA, a resposta contrÃtil da cafeÃna (20 mM) foi reduzida para 9,5  3,5 %. Sob essa condiÃÃo e, na presenÃa de &#945;- ou &#946;-pineno, a resposta nÃo foi alterada significativamente, correspondendo a 7,2  2,2 e 4,7  1,3 %, respectivamente. ApÃs esgotamento dos estoques intracelulares com CCh (100 mM), a contraÃÃo induzida por adiÃÃo de Ca2+ (2 mM), em meio sem Ca2+ com EGTA (0,2 mM) e verapamil (3 ÂM), foi potencializada pela adiÃÃo prÃvia de &#945;- ou &#946;-pineno de 30,7  2,1 % para 80,6  4,7 e 51,3  7,6 %, respectivamente (p < 0,05, teste de Bonferroni). Em estudos de retenÃÃo fracional de corante no trato gastrintestinal, o &#945;- e o &#946;-pineno aumentaram o esvaziamento gÃstrico, porÃm, a contratilidade induzida por ACh (3 ÂM) em tiras de fundo de estÃmago in vitro nÃo foi alterada pela presenÃa prÃvia de &#945;- e &#946;-pineno. O presente trabalho demonstra, pela primeira vez, que os monoterpenos &#945;- e &#946;-pineno apresentam efeito procinÃtico em ratos. Em tecidos isolados, nÃo afetam a contraÃÃo colinÃrgica em tiras de estÃmago, mas apresentam atividade miorrelaxante em tecido duodenal, por provÃvel interferÃncia com os mecanismos celulares mediados pela formaÃÃo de IP3. AlÃm disso, como demonstrado em Ãleo de rato, esses monoterpenos provavelmente ativam as vias de entrada de Ca2+ para a cÃlula em situaÃÃes de depleÃÃo dos estoques intracelulares
13

Bioprospecting For Genes That Confer Biofuel Tolerance To Escherichia Coli Using A Genomic Library Approach

Tomko, Timothy 01 January 2017 (has links)
Microorganisms are capable of producing advanced biofuels that can be used as ‘drop-in’ alternatives to conventional liquid fuels. However, vital physiological processes and membrane properties are often disrupted by the presence of biofuel and limit the production yields. In order to make microbial biofuels a competitive fuel source, finding mechanisms for improving resistance to the toxic effects of biofuel production is vital. This investigation aims to identify resistance mechanisms from microorganisms that have evolved to withstand hydrocarbon-rich environments, such as those that thrive near natural oil seeps and in oil-polluted waters. First, using genomic DNA from Marinobacter aquaeolei, we constructed a transgenic library that we expressed in Escherichia coli. We exposed cells to inhibitory levels of pinene, a monoterpene that can serve as a jet fuel precursor with chemical properties similar to existing tactical fuels. Using a sequential strategy of a fosmid library followed by a plasmid library, we were able to isolate a region of DNA from the M. aquaeolei genome that conferred pinene tolerance when expressed in E. coli. We determined that a single gene, yceI, was responsible for the tolerance improvements. Overexpression of this gene placed no additional burden on the host. We also tested tolerance to other monoterpenes and showed that yceI selectively improves tolerance. Additionally, we used genomic DNA from Pseudomonas putida KT2440, which has innate solvent-tolerance properties, to create transgenic libraries in an E. coli host. We exposed cells containing the library to pinene, selecting for genes that improved tolerance. Importantly, we found that expressing the sigma factor RpoD from P. putida greatly expanded the diversity of tolerance genes recovered. With low expression of rpoDP. putida, we isolated a single pinene tolerance gene; with increased expression of the sigma factor our selection experiments returned multiple distinct tolerance mechanisms, including some that have been previously documented and also new mechanisms. Interestingly, high levels of rpoDP. putida induction resulted in decreased diversity. We found that the tolerance levels provided by some genes are highly sensitive to the level of induction of rpoDP. putida, while others provide tolerance across a wide range of rpoDP. putida levels. This method for unlocking diversity in tolerance screening using heterologous sigma factor expression was applicable to both plasmid and fosmid-based transgenic libraries. These results suggest that by controlling the expression of appropriate heterologous sigma factors, we can greatly increase the searchable genomic space within transgenic libraries. This dissertation describes a method of effectively screening genomic DNA from multiple organisms for genes to mitigate biofuel stress and shows how tolerance genes can improve bacterial growth in the presence of toxic biofuel compounds. These identified genes can be targeted in future studies as candidates for use in biofuel production strains to increase biofuel yields.
14

The use of new technologies to develop environmentally benign processes

Chamblee, Theresa S. 07 June 2004 (has links)
No description available.
15

Synthesis of Cyclic N-Sulfonylamidines through Ritter Type Reaction using Carene and Pinene Derivatives via Carbocation Rearrangement

Ganesh, V January 2007 (has links)
No description available.
16

Bioprospecting For Genes That Confer Biofuel Tolerance To Escherichia Coli Using A Genomic Library Approach

Tomko, Timothy 01 January 2017 (has links)
Microorganisms are capable of producing advanced biofuels that can be used as ‘drop-in’ alternatives to conventional liquid fuels. However, vital physiological processes and membrane properties are often disrupted by the presence of biofuel and limit the production yields. In order to make microbial biofuels a competitive fuel source, finding mechanisms for improving resistance to the toxic effects of biofuel production is vital. This investigation aims to identify resistance mechanisms from microorganisms that have evolved to withstand hydrocarbon-rich environments, such as those that thrive near natural oil seeps and in oil-polluted waters. First, using genomic DNA from Marinobacter aquaeolei, we constructed a transgenic library that we expressed in Escherichia coli. We exposed cells to inhibitory levels of pinene, a monoterpene that can serve as a jet fuel precursor with chemical properties similar to existing tactical fuels. Using a sequential strategy of a fosmid library followed by a plasmid library, we were able to isolate a region of DNA from the M. aquaeolei genome that conferred pinene tolerance when expressed in E. coli. We determined that a single gene, yceI, was responsible for the tolerance improvements. Overexpression of this gene placed no additional burden on the host. We also tested tolerance to other monoterpenes and showed that yceI selectively improves tolerance. Additionally, we used genomic DNA from Pseudomonas putida KT2440, which has innate solvent-tolerance properties, to create transgenic libraries in an E. coli host. We exposed cells containing the library to pinene, selecting for genes that improved tolerance. Importantly, we found that expressing the sigma factor RpoD from P. putida greatly expanded the diversity of tolerance genes recovered. With low expression of rpoDP. putida, we isolated a single pinene tolerance gene; with increased expression of the sigma factor our selection experiments returned multiple distinct tolerance mechanisms, including some that have been previously documented and also new mechanisms. Interestingly, high levels of rpoDP. putida induction resulted in decreased diversity. We found that the tolerance levels provided by some genes are highly sensitive to the level of induction of rpoDP. putida, while others provide tolerance across a wide range of rpoDP. putida levels. This method for unlocking diversity in tolerance screening using heterologous sigma factor expression was applicable to both plasmid and fosmid-based transgenic libraries. These results suggest that by controlling the expression of appropriate heterologous sigma factors, we can greatly increase the searchable genomic space within transgenic libraries. This dissertation describes a method of effectively screening genomic DNA from multiple organisms for genes to mitigate biofuel stress and shows how tolerance genes can improve bacterial growth in the presence of toxic biofuel compounds. These identified genes can be targeted in future studies as candidates for use in biofuel production strains to increase biofuel yields.
17

Estudo fitoquímico de Croton grewioides Baill. e revisão da ocorrência das principais classes de metabólitos do gênero Croton

Medeiros, Vivianne Marcelino de 06 June 2012 (has links)
Made available in DSpace on 2015-05-14T12:59:51Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 16644791 bytes, checksum: 69ff0a5dda92d534738f14cc7f745210 (MD5) Previous issue date: 2012-06-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Euphorbiaceae is the sixth largest family of plants in the world and it is represented by 300 genera and approximately 7500 species. Among the many genus that composes this family, Croton stands as the second largest, with about 800 species, possessing a neotropical distribution. It is one of the genus more studied, largely due to promising bioactive compounds produced by this group. To contribute to the chemotaxonomic study of family Euphorbiaceae and genus Croton, the extract of C. grewioides was subjected to a phytochemical study to isolate its chemical constituents, through usual chromatographic methods, and then to identify them by means of spectroscopic methods such as infrared, NMR1H and 13C and uni-dimensional, mass spectrometry, and comparison with literature data. The chemical study of aerial parts of C. grewioides resulted in the identification of thirteen compounds (ent-2-oxo-cleroda-3,13-dien-15α,16-olide-21-ate, ent-2-oxo-cleroda- 3,13-dien-15β,16-olide-21-ate, ent-15,16-epoxy-2-oxo-3,13(16),14-clerodatriene, ent-15,16- epoxy-20-acetoxy-2-oxo-3,13(16),14-clerodatriene, ent-15,16-epoxy-2-oxo-3,13(16),14- clerodatrien-20-oic acid, 2-oxo-5α,8α-cleroda-3,13-dien-15,16-olide, cleroda-3,13-dien- 15,16-olide-8-oic acid, ent-kaur-16-en-19-oic acid, ent-7α-acetoxytraquiloban-18-oic, octasyl trans-ferulate, 4-alyl-1,2-dimethoxybenzene, 2-hidroxy-4,6-dimethoxy-acetofenone e estigmast-4-en-3-one), and three first described in the literature, isolates the first time in gender and eight first reported in the species. The chemical composition of essential oil showed eighteen components, among which α-pinene (47.43%) showed up with major compound. Essential oil C. grewioides and α-pinene were tested for toxicity against Staphylococcus aureus SA-1199B and IS-58.The essential oil C. grewioides and α-pinene tested did not show any significant antibacterial activity against Staphylococcus aureus strains used, but were able to modulate the bacterial resistance to drugs. / A família Euphorbiaceae é a sexta maior família de vegetais do mundo representada por 300 gêneros e 7500 espécies. Dentre os inúmeros gêneros que compõe esta família, o gênero Croton se destaca como o segundo maior, com cerca de 800 espécies, possuindo uma distribuição neotropical. Esse gênero tem sido um dos mais estudados, em grande parte devido aos compostos químicos promissores produzido por este grupo. Visando contribuir para o estudo quimiotaxonômico da família Euphorbiaceae e do gênero Croton, o extrato de C. grewioides foi submetido a um estudo fitoquímico para isolar seus constituintes químicos, através de métodos cromatográficos usuais, e depois para identificá-los por meio de métodos espectroscópicos, tais como Infravermelho, RMN de 1H e 13C uni e bidimensionais, espectométricos, espectometria de massas, além de comparação com dados da literatura. O estudo químico das partes aéreas de C. grewioides resultou na identificação de treze substâncias (ent-2-oxo-cleroda-3,13-dien-15α,16-olideo-21-ato, ent-2-oxo-cleroda-3,13-dien- 15β,16-olideo-21-ato, ent-15,16-epoxi-2-oxo-3,13(16),14-clerodatrieno, ent-15,16-epoxi-20- acetoxi-2-oxo-3,13(16),14-clerodatrieno, ácido ent-15,16-epóxi-2-oxo-3,13(16),14- clerodatrien-20-óico, 2-oxo-5α,8α-cleroda-3,13-dien-15,16-olideo, ácido cleroda-3,13-dien- 15,16-olideo-8-óico, ácido ent-caur-16-en-19-óico, ent-7α-acetoxitraquiloban-18-óico, ferulato de octila, 4-alil-1,2-dimetoxibenzeno, 2-hidroxi-4,6-dimetoxi-acetofenona e estigmast-4-en-3-ona), sendo destes, três descritos pela primeira vez na literatura, dois isolados pela primeira vez no gênero e oito relatados pela primeira vez na espécie. A composição química do óleo essencial apresentou dezoito componentes, dentre os quais, α- pineno (47,43%) mostrou-se com o composto majoritário. O óleo essencial de C.grewioides e o α-pineno foram testados para a toxicidade contra Staphylococcus aureus SA-1199B e IS-58. O óleo essencial de C.grewioides e o α-pineno testado não mostraram qualquer atividade antibacteriana significativa contra as cepas Staphylococcus aureus usados, mas foram capazes de modular a resistência bacteriana a drogas.
18

Composição e variabilidade enantiomérica de &#945;-pineno em Constrictotermes cyphergaster (Silvestri, 1901) (Isoptera; Termitidae) / Composition and enantiomeric variability of &#945;-pinene in Constrictotermes Cyphergaster (Silvestri, 1901) (Isoptera; Termitidae)

OLIVEIRA NETO, Jerônimo Raimundo de 07 October 2011 (has links)
Made available in DSpace on 2014-07-29T15:12:46Z (GMT). No. of bitstreams: 1 Dissertacao Jeronimo R de O Neto.pdf: 732547 bytes, checksum: aec94205f1a668baad1af6da00c58d09 (MD5) Previous issue date: 2011-10-07 / Termites are eusocial insects of isoptera order that part in seven families. In this study we analyze the chirality of &#945;-pinene in the defensive secretion that C. cyphergaster (Isoptera, Termitidae, Nasutitermitinae) this compound showed that among the majority of termite volatile. Along with checking the chirality was made a study seeking to correlate the production of each enantiomer, R(+)-&#945;-pinene and S(-)-&#945;-pinene, soil and climate data in dry and wet seasons of year 2002 and 2003. In the statistical data were used some statistical techniques such as Detrended Correspondence Analysis, to predict the model, Analysis of Variance for multiple comparison of means, and Redundancy Analysis to show a correlation matrix by another and that have a preview of the separation of groups. The DCA analysis showed that the model is linear. The analysis of variance for both the original data and for the transformed data showed that the averages do not differ statically at 95%, because they have p>0,05. The analysis of redundancy was not possible to explain the environment by the response matrix, in the 95% level of confidence. There was a production of enantiomeric &#945;-pinene by the C. cyphergaster populations, which can be an important factor to assist in chemotaxonomic studies of these specimens. There is increased production of the (S) enantiomer, but it was not possible to correlate this trend with soil and climatic factors in statistically significant odds. The variation of the enantiomérica composition can be related to factors other than soil and climate, such as ecological factors, genetic, or eusocial. / Os térmitas (cupins) são insetos eusociais da ordem Isoptera que se subdividem em sete famílias. Neste trabalho analisamos a quiralidade do &#945;- pineno presente na secreção defensiva do Constrictotermes cyphergaster (Isoptera, Termitidae, Nasutitermitinae), composto este que se mostrou majoritário entre os voláteis deste térmita. Juntamente com a verificação da quiralidade foi feito um estudo buscando correlacionar a produção de cada enantiômero, R(+)-&#945;-pineno e S(-)-&#945;-pineno, com dados edáfico-climáticos nas estações de seca e de chuva dos anos de 2002 e 2003. No tratamento estatístico dos dados foram usadas algumas técnicas estatísticas tais como análise de correspondência destendenciada, para prever o modelo; análise de variância, para comparação múltipla das médias; análise de redundância, para ter uma visualização da separação dos grupos e para correlacionar variáveis das matrizes resposta e ambiental. A análise destendenciada revelou que linear é o modelo mais apropriado. A análise de variância tanto para os dados originais quanto para os dados transformados mostraram que as médias não se diferenciam estatisticamente ao nível de 95 %, pois apresentam p>0,05. Pelas análises de redundância não foi possível a explicação da matriz resposta pelo ambiente, ao nível de 95 % de confiança. Houve uma produção enantiomérica de &#945;-pineno por parte das populações de C. cyphergaster, que pode ser um fator importante para auxiliar em estudos quimiotaxonômicos desta espécie. Há maior produção do enantiômero (S), porém não foi possível correlacionar esta tendência com fatores edáfico-climáticos dentro de probabilidades estatisticamente significativas. A variação da composição enantiomérica pode estar relacionada a outros fatores que não os edáfico-climáticos, tais como: fatores ecológicos, genéticos e eusociais.
19

Bicyclic Strained Allenes: Incorporation Of An Allene Unit Into Alpha-pinene And Benzonorbornadiene

Kilbas, Benan 01 January 2009 (has links) (PDF)
The synthesis of cyclic allenes with eight or less skeletal C-atoms, known as highly strained organic compounds, has for the past decades attracted increasing interest. The first part of study describes an investigation aimed at the incorporation of an allene unit into a natural compound, being &amp / #945 / -pinene, by using &amp / #946 / -elimination method. The two double-bond isomers 310 and 299b were synthesized as key compounds. Treatment of 310 with t-BuOK resulted in the formation of ketone 308 and diene 313. For the formation of 308, the cyclic allene 300 was proposed as an intermediate. Treatment of 299b, with t-BuOK gave arise to the diene 313 and the dimerization product 322. On the basis of density-functional-theory (DFT) calculations on the allene 300 and the alkyne 320, the formation of the latter as the intermediate was excluded. In the second part of study, the stability of endo-carbene 304 was investigated. Previous studies indicated, during the formation of intermediate 264, no exo-carbene 330 structure could be optimized in its free carbene form. At this point, we were curious about the stability of endo-cyclopropylidene 304 not discussed before in literature. First, addition of bromofluorocarbene to anti-7-ethylbenzonorbornadiene (352) was aimed to isolate the endo-adduct 302b. However, no carbene addition reaction was observed caused by pyramidalization on double bond respect to the methoxy derivative, 363b. Therefore, the bromine was introduced to C-7 carbon atom. Treatment of 302a with MeLi in the presence of furan, gave furan adduct 306a confirmed the formation of allene 305a as a reactive intermediate. Theoretical calculations showed endo-carbene 304a was optimized in the free carbene form . However, it readily isomerizes to allene 305a afforded furan adduct 306a.
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Bicyclic Strained Allenes: Incorporation Of An Allene Unit Into Alpha-pinene And Benzonorbornadiene

Azizoglu, Akin 01 June 2004 (has links) (PDF)
The first part of study describes an investigation aimed at the incorporation of an allene unit into a natural compound, being alpha-pinene, by using Doering-Moore-Skatteboel method. DFT computations show that both allene product and insertion product can be isolated if the reaction of methyllithium with 3,3-dibromo-2,7,7-trimethyl-tricyclo[4.1.1.02,4]octane is carried out at either low or high temperatures. One insertion product resulting from the intramolecular C-H insertion at the bridge and three allene dimers were isolated when this reaction was carried out at room temperature. In the second part of study, exo- and endo-cyclopropylidene incorporated into benzonorbornadiene were investigated by using theoretical and experimental methods. Theoretical calculations show that the endo-carbene would be stable and undergo some kind of insertion and addition reactions. On the contrary, the exo-carbene is not stable and isomerizes to the corresponding allene structure during the optimization process. For this purpose, the reaction of dibromocarbene and dichlorocarbene with 7-methoxybenzonorbornadiene was achieved to afford gem-dibromocyclopropane and gem-dichlorocyclopropane adducts, respectively. However, they suffer stereoelectronically-controlled ring opening under the reaction conditions to give the ring-expanded allylic dihalides, respectively. On the other hand, gem-bromofluorocyclopropane, obtained by the treatment of 7-methoxybenzonorbornadiene with bromofluorocarbene, provided one of the four possible [2+4] allene adducts upon treatment with MeLi in furan. The exact structure of the adduct has been elucidated on the basis of NMR spectral data. This result confirms the formation of the bicyclic allene as an reactive intermediate. No products were isolated derived from the endo-carbene.

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