Nazarov Cyclizations Catalyzed by BINOL Phosphoric Acid Derivatives: Quantum Chemistry Struggles To Predict the Enantioselectivity

2021 ◽  
Author(s):  
Yuk Ping Chin ◽  
Elizabeth H. Krenske
Keyword(s):  
Phosphoric Acid ◽  
Quantum Chemistry ◽  
Nazarov Cyclizations

Chiral phosphoric acid catalysis: from numbers to insights

2018 ◽  
Vol 47 (4) ◽  
pp. 1142-1158 ◽  
Author(s):  
Rajat Maji ◽  
Sharath Chandra Mallojjala ◽  
Steven E. Wheeler
Keyword(s):  
Phosphoric Acid ◽  
Quantum Chemistry ◽  
Acid Catalysis ◽  
Asymmetric Reactions ◽  
Computational Quantum Chemistry ◽  
Chiral Phosphoric Acid ◽  
Computational Quantum ◽  
Phosphoric Acids

Chiral phosphoric acids (CPAs) have emerged as powerful organocatalysts for asymmetric reactions, and applications of computational quantum chemistry have revealed important insights into the activity and selectivity of these catalysts.

The concerted use of SEM, TEM, and SCM for examination of resin-dentin interfaces

1994 ◽  
Vol 52 ◽  
pp. 476-477
Author(s):  
B. Van Meerbeek ◽  
L. J. Conn ◽  
E. S. Duke
Keyword(s):  
Surface Layer ◽  
Stress Distribution ◽  
Phosphoric Acid ◽  
Bonding Mechanism ◽  
Restorative Dentistry ◽  
Dental Adhesive ◽  
Low Viscosity ◽  
Dentin Adhesives ◽  
Acid Etch ◽  
Tooth Tissue

Restoration of decayed teeth with tooth-colored materials that can be bonded to tooth tissue has been a highly desirable property in restorative dentistry for many years. Advantages of such an adhesive restorative technique over conventional techniques using non-adhesive metal-based restoratives include improved restoration retention with minimal sacrifice of sound tooth tissue for retention purposes, superior adaptation and sealing of the restoration margins in prevention of caries recurrence, improved stress distribution across the tooth-restoration interface throughout the whole tooth, and even reinforcement of weakened tooth structures. The dental adhesive technology is rapidly changing. An efficient resin bond to enamel has already long been achieved. Its bonding mechanism has been fully elucidated and has proven to be a durable and reliable clinical treatment. However, bonding to dentin represents a greater challenge. After the failures of a dentin acid-etch technique in imitation of the enamel phosphoric-acid-etch technique and a bonding procedure based on chemical adhesion, modern dentin adhesives are currently believed to bond to dentin by a micromechanical hybridization process. This process is developed by an initial demineralization of the dentin surface layer with acid etchants exposing a collagen fibril arrangement with interfibrillar microporosities that subsequently become impregnated by low-viscosity monomers. Although the development of such a hybridization process has well been documented in the literature, questions remain with respect to parameters of-primary importance to adhesive efficacy.

Phosphoric Acid from Slags

1884 ◽  
Vol 18 (457supp) ◽  
pp. 7298-7298
Author(s):  
C. Scheibler
Keyword(s):  
Phosphoric Acid

MOTIONS IN A VISCOUS INORGANIC LIQUID : FERROUS ION IN COLD PHOSPHORIC ACID

1976 ◽  
Vol 37 (C6) ◽  
pp. C6-739-C6-743 ◽  
Author(s):  
P. A. FLINN ◽  
B. J. ZABRANSKY ◽  
S. L. RUBY
Keyword(s):  
Phosphoric Acid ◽  
Ferrous Ion

Quantum Chemistry.

1958 ◽  
Vol 17 (3_4) ◽  
pp. 279-280
Author(s):  
Th. Förster
Keyword(s):  
Quantum Chemistry

Propagators in Quantum Chemistry

1975 ◽  
Vol 95 (4-6) ◽  
pp. 318-319
Author(s):  
W. A. Bingel
Keyword(s):  
Quantum Chemistry

CLINICAL INVESTIGATIONS OF A LONG-ACTING OESTRIOL (POLYOESTRIOL PHOSPHATE)

1961 ◽  
Vol 38 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Christian Lauritzen ◽  
Semih Velibese
Keyword(s):  
Side Effects ◽  
Phosphoric Acid ◽  
Quantitative Data ◽  
Water Soluble ◽  
Cholesterol Concentration ◽  
Experimental Investigations ◽  
Clinical Investigations ◽  
Prolonged Duration ◽  
High Doses ◽  
Long Acting

ABSTRACT A description is given of experimental investigations and preliminary clinical experience with the long-acting oestriol compound polyoestriol phosphate – a water-soluble polymere of oestriol and phosphoric acid. The compound seems to exert all the physiologically important effects of oestriol. Even with high doses the hormone causes no proliferation of the endometrium and no withdrawal bleeding. It has no untoward effect on metabolism. It decreases slightly the cholesterol concentration (to the extent of ⅓–⅕ of the effect produced by long-acting oestradiol esters). The compound has a wide therapeutic range. No side-effects have been observed. Doses of 10 mg or more have a prolonged duration. Additional prolongation of the effect is largely dependent on dosage. To ensure an effect lasting for 4 weeks 40 mg polyoestriol phosphate (corresponding with 30 mg oestriol) is required – an amount which roughly corresponds with physiological quantitative data. The compound, which involves an interesting new principle of prolongation, was most effectively used in the treatment of menopausal symptoms and genital organic disorders. For these indications it can be recommended without reservation.

EINE CHEMISCHE METHODE ZUR BESTIMMUNG VON 16-EPI-ÖSTRIOL IM URIN DES MENSCHEN

1963 ◽  
Vol 44 (1) ◽  
pp. 47-66 ◽  
Author(s):  
W. Nocke ◽  
H. Breuer
Keyword(s):  
Melting Point ◽  
Phosphoric Acid ◽  
Aqueous Alkali ◽  
Percentage Error ◽  
Organic Layer ◽  
Maximum Percentage ◽  
Chemical Determination ◽  
Routine Assay ◽  
Hydrolysis Of

ABSTRACT A method for the chemical determination of 16-epi-oestriol in the urine of nonpregnant women with a qualitative sensitivity of less than 0.5 μg/24 h is described. The separation of 16-epi-oestriol and oestriol is accomplished by converting 16-epi-oestriol into its acetonide, a reaction which is stereoselective for cis-glycols and therefore not undergone by oestriol as a trans-glycol. Following partition between chloroform and aqueous alkali, the acetonide of 16-epi-oestriol is completely separated with the organic layer whereas oestriol as a strong phenol remains in the alkaline phase. 16-epi-oestriol is chromatographed on alumina as the acetonide and determined as a Kober chromogen. This procedure can easily be incorporated into the method of Brown et al. (1957 b) thus making possible the simultaneous routine assay of oestradiol-17β, oestrone, oestriol and 16-epi-oestriol from one sample of urine. The specificity of the method was established by separation of 16-epi-oestriol from nonpregnancy urine as the acetonide, hydrolysis of the acetonide by phosphoric acid, isolation of the free compound by microsublimation and identification by micro melting point, colour reactions and chromatography. The accuracy of the method is given by a mean recovery of 64% for pure crystalline 16-epi-oestriol when added to hydrolysed urine in 5–10 μg amounts. The precision is given by s = 0.24 μg/24 h. For the duplicate determination of 16-epi-oestriol the qualitative sensitivity is 0.44 μg/24 h, the maximum percentage error being ± 100% The quantitative sensitivity (±25% error) is 1.7 μg/24 h.

The presence of new peptides containing D-ribulose and phosphoric acid in germ cells

Reproduction ◽  
1969 ◽  
Vol 18 (1) ◽  
pp. 160-160 ◽  
Author(s):  
H Amand ◽  
I Yanagisawa ◽  
T Asada
Keyword(s):  
Phosphoric Acid ◽  
Germ Cells
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