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Master's Dissertation
DOI
10.11606/D.54.1982.tde-14102009-114949
Document
Author
Full name
Sandra Helena Pulcinelli
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 1982
Supervisor
Title in Portuguese
Determinação da estrutura cristalina e molecular de um produto natural extraído de Emmotum Nitens (Benth) Miers [ (2R, 3S) - 2 - Hidroxi - 3 (2¹Hidroxi-Isopropil) - 5 Hidroximetil-8 Metoximetil-1Ceto -1,2,3,4 - Tetrahidronaftaleno].
Keywords in Portuguese
Difração de raios x
Monocristais
Abstract in Portuguese
A presente dissertação consta de quatro capítulos, sendo que nos dois primeiros apresentamos alguns tópicos dos métodos diretos para determinação de estruturas e nos dois últimos, o desenvolvimento experimental e os resultados finais obtidos na determinação da estrutura cristalina e molecular de um produto natural extraído de E. Nitens, o (2R, 3S) - 2-hidroxi-3-(2’ - hidroxi-isopropil) - 5-hidroximetil-8-metoximetil-1-ceto-1, 2, 3, 4-tetrahidronaftaleno, conhecido pelo nome vulgar Emotina B. A Emotina B, C16H22O5, cristaliza no sistema triclínico, grupo espacial P1. Os parâmetros da cela unitária encontrados foram: a=7,474(2), b=8,922(5), c=12,405(4)Å, α=87,68(4), β=78,96(3), γ=67,40(4)° V=715,042Å3; dcalc=1,37g/cm3; Z=2 moléculas por cela unitária. Foram coletadas em 1667 reflexões únicas, utilizando o difratômetro automático CAD-4, com radiação monocromatizada de MoKα, das quais foram mantidas 1010 reflexões, consideradas observadas segundo o critério I> 2δ(I). A estrutura foi resolvida por métodos diretos (MULTAN-80) e por síntese de Fourier-diferenças sucessivas e refinadas por mínimos quadrados (SHELX-76) até um índice de discordância, R=0,054 para apenas as reflexões observadas e 0,067 para todas as reflexões.As moléculas são aproximadamente planas com variações conformacionais significativas apenas na parte alifática. Relacionam-se através de um pseudo-centro de inversão parcial localizado em (0,0846; 0,0622; 0,4174). Os esquemas de ligação hidrogênio são diferentes nas moléculas A e B e consistem de ligações intra e intermoleculares.
Title in English
Determination of the crystalline and molecular structure of a natural product extracted from Emmotum Nites (Benth) Miers [(2R, 3S)-2-Hydroxyl-3-(2,4-Hydroxyl-Isopropil)-5-Hydroxymethil-8-Methoxymetil-1-Ceto-1,2,3,4-tetrahydronaftalen]
Keywords in English
Single crystal
X-ray diffraction
Abstract in English
This dissertation consists of four chapters. Chapters 1 and 2 present some theoretical aspects of direct methods for crystal structure determination. Chapters 3 and 4 present the description of the experimental work and the crystal structure determination of a natural product obtained from E. Nitens, the (2R, 3S)-2-hydroxy-3-(2’-hydroxy-isopropyl)-5-hydroximethyl-8-methoxymethyl-1-ceto-1, 2, 3, 4-tetrahydronapghtalen (Emmotin - B). Emmotin - B, C16H22O5, crystallizes in the triclinic system, space group P1. Cell dimensioned are: a=7,474(2), b=8,922(5), c=12,405(4)Å, α=87,68(4), β=78,96(3), γ=67,40(4)° V=715,042Å3; dcalc=1,37g/cm3; Z=2 molecules/unit cell. The intensities of 1667 unique reflexions were collected using a CAD-4 automatic diffractometer with monochromated MoKα radiations of which only 1010 with I> 2δ(I) were considered observed. The structure was solved by direct methods (MULTAN-80) and successive applications of difference-Fourier calculations. It was refined by least square methods (SHELX-76). The final agreement index was R=0.054, considering only the observed reflexions and 0.067, considering all reflexions. The two independent molecules are almost identical showing discrepancies only in conformation of the aliphatic side chains. They are mutually related by a partial pseudo center of symmetry located at (0.0846, 0.0622, 0.4174). The hydrogen bonding schemes are different in both A and B molecules and consist of intra and intermolecular bonds.
 
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Publishing Date
2009-10-23
 
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