Structure–sweetness relationships for fructose analogs. Part II. Synthesis and properties of 1,6-dihydroxy-2-hexanone, a simple analog of the ketohexoses, and X-ray structure determination of the corresponding dianhydrides

1985 ◽  
Vol 63 (6) ◽  
pp. 1222-1227 ◽  
Author(s):  
Walter A. Szarek ◽  
Olivier R. Martin ◽  
Robert J. Rafka ◽  
T. Stanley Cameron
Keyword(s):  
Structure Determination ◽  
Deuterium Oxide ◽  
Crystallographic Analysis ◽  
Open Chain ◽  
X Ray ◽  
Acidic Conditions ◽  
Simple Analog

Labile 1,6-dihydroxy-2-hexanone (4) was prepared from the corresponding triol by selective di-O-tritylation, Collins oxidation, and careful detritylation of the resulting keto compound 3 under mild, acidic conditions. As shown by its 1Hmr and 13Cmr spectra, 4 exists as a 3:2 mixture of open-chain and cyclic forms, respectively, at equilibrium in deuterium oxide (25 °C). Upon standing, 4 is slowly converted into a hemiacetalic dimer. Under acidic conditions, dehydrative dimerization takes place to give the corresponding tricyclic dianhydride, one or both of the possible isomers (1:1 mixture) of which being formed according to the presence or absence of water in the medium. The structure (trans) of the thermodynamic isomer 5 was firmly established by an X-ray crystallographic analysis.

Structure Determination of Triplet Diphenylcarbenes by in Situ X-ray Crystallographic Analysis

2007 ◽  
Vol 129 (8) ◽  
pp. 2383-2391 ◽  
Author(s):  
Masaki Kawano ◽  
Katsuyuki Hirai ◽  
Hideo Tomioka ◽  
Yuji Ohashi
Keyword(s):  
Structure Determination ◽  
Crystallographic Analysis ◽  
X Ray

Synthesis and Structure Determination of 2,3-Diphenyl-2H-1,4-Benzoxazin-2-ol

2007 ◽  
Vol 2007 (9) ◽  
pp. 548-551 ◽  
Author(s):  
Katayoun Marjani ◽  
Jafar Asgarian ◽  
Mohsen Mousavi
Keyword(s):  
Elemental Analysis ◽  
Structure Determination ◽  
Main Product ◽  
Crystallographic Analysis ◽  
Spectroscopic Methods ◽  
X Ray

A stable hemiacetal, 2,3-diphenyl-2H-1,4-benzoxazin-2-ol, was isolated as the main product from the reaction of benzil and o-aminophenol in THF. The structure of the product is confirmed by elemental analysis, common spectroscopic methods, and X-ray crystallographic analysis.

scholarly journals On the diterpenoids of Andrographis paniculata: X-ray crystallographic analysis of andrographolide and structure determination of new minor diterpenoids.

1984 ◽  
Vol 32 (6) ◽  
pp. 2117-2125 ◽  
Author(s):  
TETSURO FUJITA ◽  
RYUJIRO FUJITANI ◽  
YOSHIO TAKEDA ◽  
YOSHIHISA TAKAISHI ◽  
TOSHIHIDE YAMADA ◽  
...  
Keyword(s):  
Structure Determination ◽  
Crystallographic Analysis ◽  
Andrographis Paniculata ◽  
X Ray

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

scholarly journals Radical Ion Salts and Complexes, Part XVII. TCNQ Salts of 1,4-Dimethylpyridine and 2,3-Bis(1-methyl-4-pyridinio)butane

1999 ◽  
Vol 23 (3) ◽  
pp. 196-197
Author(s):  
Timothy J. Houghton ◽  
Stephen C. Wallwork
Keyword(s):  
Structure Determination ◽  
X Ray ◽  
Electrical Conductivities ◽  
Complex Salts ◽  
Radical Ion Salts

X-Ray structure determination of the complex salts [MeNC5H4Me]+[TCNQ2]- [1,4-dimethylpyridinium 2(7,7,8,8-tetracyanoquinodimethane) (1-); I] and [Me(NC5H4)(Me)CH-CH(Me)(C5H4N)Me]2+[TCNQ4]2- [ meso-2,3-bis( N-methyl-4-pyridyl)butane(2+) 4(7,7,8,8-tetracyanoquinodimethane) (2-); II], where TCNQ=(CN)2C(C6H4)C(CN)2, shows that, although in both salts the TCNQ moieties are stacked in columns, lateral shifts break these columns into diads for I and tetrads for II causing their electrical conductivities to be only moderate (Σ = 2–4 × 10−3 ohm−1 cm−1).

ChemInform Abstract: TRANSFER METAL-CATALYZED SELF-CONDENSATION OF (E)-BENZALDOXIME AND X-RAY CRYSTALLOGRAPHIC STRUCTURE DETERMINATION OF A PRODUCT

1977 ◽  
Vol 8 (39) ◽  
pp. no-no
Author(s):  
A. GIEREN ◽  
B. DEDERER ◽  
I. UGI ◽  
S. STUEBER
Keyword(s):  
Structure Determination ◽  
Crystallographic Structure ◽  
X Ray ◽  
Metal Catalyzed

Syntheses, X-ray, MSn, NMR and CD structure determination of nickel(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide and aromatic α-amino acids

Polyhedron ◽  
2008 ◽  
Vol 27 (17) ◽  
pp. 3477-3483 ◽  
Author(s):  
Milan Nádvorník ◽  
Vratislav Langer ◽  
Robert Jirásko ◽  
Michal Holčapek ◽  
Tomáš Weidlich ◽  
...  
Keyword(s):  
Amino Acids ◽  
Schiff Bases ◽  
Structure Determination ◽  
X Ray ◽  
Determination Of Nickel
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