N.M.R. measurement of the equilibrium constants between boron fluoride ethyl ether complex and some cyclic ethers.

Okada, Masahiko; Suyama, Katsuhiko; Yamashita, Yuya

doi:10.1016/s0040-4039(00)90185-0

Cited by 14 publications

(6 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Extensive rotation (or disordering) of the methyl groups at room temperature would make it unlikely that localized hydrogen atoms would be observed. However, at low temperature short contacts (of 1.93 Á) between hydrogen atoms on the methyl groups and bridging hydrogen atoms on the tetrahydroborate groups (Hq(3) to Hg (7) and the symmetryrelated pair) would lock in the methyl groups with the ordered tetrahydroborate configuration. Table X lists all significant intramolecular and intermolecular contacts (together with esd's) based on the geometry of the low-temperature structure.…”

Section: Discussionmentioning

confidence: 99%

“…A total difference Fourier synthesis showed no peak with height greater than 0.44 electron/A3 (approximately 0.08 of the height of a boron atom in an observed synthesis). Tables V and VI list the atomic positions and vibrations, respectively, together with their standard errors; the large standard Ho(l) -0,148 (6) 0.107 (12) 0.160 (7) Ho(2) 0.137 (5) 0.288 (9) 0.164 (6) Ho (3) 0.060 (5) 0.057 (9) 0.101 (7) H0(4) 0.057 (7) 0.363 (15) 0.034 (9) Hg (5) 0.170 (6) 0.150 (12) 0.006 (8) Hg( 6) 0.282 (5) 0.007 (11) 0.167( 7) Hq( 7 Observed Structure Amplitudes and Calculated Structure Factors errors on the hydrogen atom isotropic temperature factors show that no significance can be attached to their absolute values. Table XT I lists observed structure amplitudes and calculated structure factors on the scale of electron units.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Crystal structure of aluminum tetrahydroborate-trimethylamine at 25 and -160.deg.

Bailey¹,

Bird²,

Wallbridge³

1968

Inorg. Chem.

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Crystal structure of aluminum tetrahydroborate-trimethylamine at 25 and -160.deg.

Bailey¹,

Bird²,

Wallbridge³

1968

Inorg. Chem.

View full text Add to dashboard Cite

“…Also, the buffers of benzeneboronic acid which were used for this purpose were made from the acid with carbonate-free potassium hydroxide. 7 All experiments were carried out with reaction mixtures at 25.0 ± 0.1°and at ionic strength 1.0 M, adjusted withKCl.…”

Section: Methodsmentioning

confidence: 99%

Search for the addition of monodentate nucleophiles to boric and benzeneboronic acids in water

Koehler¹,

Jackson²,

Lienhard³

1972

J. Org. Chem.

View full text Add to dashboard Cite

A spectrophotometric search for the addition of a variety of monodentate oxygen, nitrogen, sulfur, and carbon nucleophiles to boric and benzeneboronic acids in aqueous solution was made. None of the nucleophiles appeared to react significantly with boric acid. Among the nucleophiles which were tested with benzeneboronic acid, only 1-methylimidazole, imidazole, hydrazine, and probably 2,2,2-trifluoroethoxide ion reacted. The equilibrium constant for the addition of trifluoroethoxide ion to benzeneboronic acid was estimated to be 3500 M~\ at 25°and 1 M ionic strength. The equilibrium constants for the addition of 1-methylimidazole and imidazole were determined spectrophotometrically and, in one case, potentiometrically and have values of 12.2 and 10.7 Hi-1, respectively, at 25°and 1 M ionic strength. Apparent acid dissociation constants for boric and benzeneboronic acids in the presence of some salts and organic solutes are reported.

show abstract

“…Stirring was continued for 12 hr a t 0' and 12 hr at 25", at which time the reaction was complete as revealed by tlc in solvent A. This product was not crystalline: yield 80 mg (11%); nrnr (CDCl3) 6 1.13, 1.14 (s, 6, a,b), 1.61-1.5 (m, 2, d,e), 3.60 (s, 3 OF nmr data indicate that complexing first occurs solely at the A-ring carbonyl group. A saturated aqueous solution of sodium bicarbonate was then gradually added to neutralize the acetic acid liberated.…”

Section: Methodsmentioning

confidence: 89%

Photocyclization of Oxo-D-fructose pentaacetate and Oxo-L-sorbose pentaacetate

Whistler¹,

Doner²

1973

J. Org. Chem.

View full text Add to dashboard Cite

Ultraviolet irradiation of both 1,3,4,~,6-penta-o-acety~-keto-~-fructose (1) and 1,3,4,5,6-penta-o-acetyl-keto-L-sorbose (2) (epimeric at the y carbon) has been found to produce crystalline 1 (S),4(S)-diacetoxymethyl-2(S),-3(S),4-triacetoxycyclobutan-l-o1 (3), the former giving a yield of 11.6% and the latter a yield of 26.2%. Reaction is envisioned from 1,4 biradicals in the triplet state, but no other diastereoisomers resulted. The cyclic photoproduct was converted to its hexaaoetate and was also deacetylated to a hexose isomer, CleHllOe. The deacetylated material was converted to a tetra-p-toluenesulfonylate, in which all but the tertiary hydroxyl functions were derivatized. This derivative was reduced by lithium aluminum hydride to 1 (S),4(S)-dimethyl-3(S)-cyclobutanetriol. A minor photoproduct was produced in a 0.9% yield from 1. It presumably resulted from 6-hydrogen abstraction and formation of a 1,j-biradical intermediate, which underwent ring closure to meso-( 1,2,3/~,5)-2-acetoxymeth~l-1,3,4,5-tetraacetoxycyclopentan-2-ol(4).

show abstract

N.M.R. measurement of the equilibrium constants between boron fluoride ethyl ether complex and some cyclic ethers.

Cited by 14 publications

References 9 publications

Crystal structure of aluminum tetrahydroborate-trimethylamine at 25 and -160.deg.

Crystal structure of aluminum tetrahydroborate-trimethylamine at 25 and -160.deg.

Search for the addition of monodentate nucleophiles to boric and benzeneboronic acids in water

Photocyclization of Oxo-D-fructose pentaacetate and Oxo-L-sorbose pentaacetate

Contact Info

Product

Resources

About