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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.
1

Obtenção de compostos intermediários para a síntese do agente anti-HIV Tenofovir, e de derivados do D-manitol

SIQUEIRA, Edmilson Clarindo de 13 April 2012 (has links)
Submitted by (lucia.rodrigues@ufrpe.br) on 2017-02-13T15:29:49Z No. of bitstreams: 1 Edmilson Clarindo de Siqueira.pdf: 4674633 bytes, checksum: c618a0d261dbc9f5432627199fd82f3a (MD5) / Made available in DSpace on 2017-02-13T15:29:49Z (GMT). No. of bitstreams: 1 Edmilson Clarindo de Siqueira.pdf: 4674633 bytes, checksum: c618a0d261dbc9f5432627199fd82f3a (MD5) Previous issue date: 2012-04-13 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this study we investigated the resolution of rac-1,2-propanediol and rac-2,3- isopropylidene glycerol using chiral amines (R)- and (S)-1-phenylethylamine (27). The alcohols are esterified to form hemi-phthalates, and treated with the enantiomers of 27 resulting in the following salts (R)-27.(±)-52 and (S)-27.(±)-52 in good yields. However, salts (R)-27.(±)-33 and (S)-27.(±)-33 did not form crystalline material. In addition we studied the resolution of (±)-14 and (±)-31 through the use of amino acids benzyl esters and brucine as auxiliaries. Attempts to obtain the benzyl ester of L-tryptophan (59) were negative; attempts to obtain benzyl esters of Lphenylalanine (58) and L-lysine (57) were also negative. In the case of brucine (35) there was no noticeable diastereoisomeric enrichment during repeated crystallizations. As an extension to this, we performed dehydration of D-mannitol (40) in an acid medium. Modifications of the published method resulted in obtaining a new derivative, the 2,5-anhydro-1,3-O-benzyl-D-mannitol (81) whose structure was established via x-ray study. / Neste trabalho foi avaliada a resolução dos alcoóis rac-1,2-propanodiol (14) e rac-2,3-isopropilideno glicerol (31) pelas aminas quirais (R)- e (S)-1-feniletilamina (27) via processo de dessimetrização: os alcoóis foram esterificados, na forma de ftalatos, e tratados com os enantiômeros de 27 que resultou nos seguintes sais (R)-27.(±)-52 e (S)-27.(±)-52 em bons rendimentos. Todavia, os sais (R)-27.(±)-33 e (S)-27.(±)-33 não foram isolados em sua forma cristalina. Adicionalmente, foi estudada a resolução de (±)-14 e (±)-31 através do uso de aminoácidos, na sua forma benzílica, e brucina como auxiliares quirais. Tentativas de obter o éster benzil de L-triptofano (59), foram negativas. Alternativas de usar Lfenilalanina (58) e L-lisina (57) também foram negativas. Condizente com este tipo de resolução foi ensaiada também o alcalóide brucina (35), porém não houve enriquecimento diastereoisomérico durante repetidas cristalizações. Como extensão ao trabalho realizado com os alcoóis, foi investigada a desidratação do D-manitol (40) em meio ácido. Modificações desta metodologia conduziram à obtenção de um novo derivado deste substrato, o 2,6-anidro-1,3-di-Obenzil- D-manitol (81), que foi caracterizado por raios-X.
2

Solubility and phase transitions in batch and laminar-flow tubular crystallizers

Mendez del Rio, Jose R. 03 December 2004 (has links)
The research addressed in this thesis focuses on monitoring and characterization of pharmaceutical compounds by laser backscattering. In particular, this study covers two topics: (1) the determination of naproxen sodium solubility in water, and its phase transition; and (2) comparisons of batch and laminar flow tubular crystallizers for the production of paracetamol (acetaminophen) and D-mannitol. Using a Lasentec™ Focused Beam Reflectance Measurement (FBRM) device, the solubility of naproxen sodium in aqueous solutions was determined over a temperature range from 15.2 to 39.7 ℃ With the determination of the solubilities of two pseudopolymorphs, anhydrous and dihydrated naproxen sodium, the phase transition point between these two forms of the pharmaceutical compound was determined to occur at 30.3 ℃ Enthalpy of solution and metastable zone widths were also determined for the experimental conditions. Crystallizations of paracetamol and D-mannitol were performed in a batch crystallizer and in a laminar flow tubular crystallizer (LFTC) system. In the latter system, supersaturation was generated rapidly in the solution being transported through a temperature-controlled tube and recovered in a batch vessel where product crystals were grown to equilibration. Because of the rapid rate at which supersaturation was generated in the LFTC, the resulting crystals were of smaller mean size than those obtained from batch crystallizations. The total time required for crystallization was significantly less with the LFTC than with the batch unit. Additionally, the rapid cooling in the LFTC led to the formation of two different polymorphs of paracetamol, Forms I and II.
3

Preparação e utilização de amino catalisadores - derivados do glicerol, D-manitol e L-aminoácidos - em reações de adição aldólica

Martins, Rafaela de Souza 03 August 2017 (has links)
Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-10-10T11:51:05Z No. of bitstreams: 1 rafaeladesouzamartins.pdf: 11994443 bytes, checksum: c42e2d285fd87e325b038e9bfe95bdf5 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-10-10T12:22:21Z (GMT) No. of bitstreams: 1 rafaeladesouzamartins.pdf: 11994443 bytes, checksum: c42e2d285fd87e325b038e9bfe95bdf5 (MD5) / Made available in DSpace on 2017-10-10T12:22:21Z (GMT). No. of bitstreams: 1 rafaeladesouzamartins.pdf: 11994443 bytes, checksum: c42e2d285fd87e325b038e9bfe95bdf5 (MD5) Previous issue date: 2017-08-03 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Neste trabalho descrevemos a preparação de oito amino catalisadores, obtidos na forma de sal do trifluoroacetato. Quatro destes catalisadores foram preparados na forma da mistura de dois estereoisômeros, a partir do glicerol e os aminoácidos L-leucina, L-valina, L-fenilalanina e a L-prolina. Os outros quatro amino catalisadores foram preparados, em sua forma estereoisomericamente pura, a partir do D-manitol e os aminoácidos L-leucina, L-valina, Lfenilalanina e a L-prolina. Os oito amino catalisadores foram capazes de catalisar a reação de adição aldólica entre a cicloexanona e o 4-nitrobenzaldeído. Os produtos de adição foram obtidos em rendimentos que variaram de 58-95 %, sendo a maior r.d. de 1 : 9,12 (sin:anti), determinada por RMN de 1H, e maior e.e. de 94 %, determinado por cromatografia líquida de alta eficiência. O melhor resultado, considerando o rendimento, a diastereo e a enantiosseletividade dos produtos formados, foi obtido quando o catalisador enantiomericamente puro derivado da L-prolina foi utilizado. / In this work we describe a preparation of eight amino-catalysts, obtained as a trifluoroacetate salt. Four of these catalysts were prepared, in the form of the mixture of two stereoisomers, from glycerol and the amino acids L-leucine, L-valine, L-phenylalanine and L-proline. The other four amino-catalysts were prepared in stereoisomerically pure form from D-mannitol and the amino acids L-leucine, L-valine, L-phenylalanine and L-proline. The eight aminocatalysts were able to catalyze the aldol addition reaction between cyclohexanone and 4nitrobenzaldehyde. The addition products were obtained in yields ranging from 58-95 %, the highest d.r. from 1:9.1 (sin: anti), determined by 1H NMR, and higher e.e. of 94 %, determined by high performance liquid chromatography. The best result, considering the yield, diastereomer and enantioselectivity of the formed products, was obtained when the enantiomerically pure L-proline derived catalyst was used.

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