THE BROMINATION AND HALOGENOMETHOXYLATION OF D-GLUCAL TRIACETATE

1964 ◽  
Vol 42 (3) ◽  
pp. 532-538 ◽  
Author(s):  
R. U. Lemieux ◽  
B. Fraser-Reid
Keyword(s):  
Silver Acetate ◽  
Silver Carbonate

The bromination of D-glucal triacetate gave a mixture of tri-O-acetyl-2-bromo-2-deoxyglycopyranosyl bromides containing about 60% and 30% of the compounds with the α-D-gluco and α-D-manno configurations, respectively. Reaction of the bromides with methanol in the presence of silver carbonate proceeded almost entirely with inversion of the reacting anomeric centers. Hydrogenolysis of the product of methanolysis gave methyl 2-deoxy-β-D-glucopyranoside. Reaction of D-glucal triacetate with either bromine, chlorine, or iodine in methanol containing silver acetate gave in each case about 60–65% and 35–40% yields of the corresponding methyl 2-deoxy-2-halogeno-α-D-mannopyranoside and -β-D-glucopyranoside triacetates. The mechanisms of the reactions are discussed.

A COMPARISON OF THE PROPERTIES OF PENTAACETATES AND METHYL 1,2-ORTHOACETATES OF GLUCOSE AND MANNOSE

1955 ◽  
Vol 33 (1) ◽  
pp. 109-119 ◽  
Author(s):  
R. U. Lemieux ◽  
Carol Brice
Keyword(s):  
Acetic Acid ◽  
Hydrochloric Acid ◽  
Zinc Chloride ◽  
Main Product ◽  
Stannic Chloride ◽  
Aqueous Acetic Acid ◽  
Silver Acetate ◽  
Silver Carbonate ◽  
Ethyl Mercaptan ◽  
Glucose Pentaacetate

The rates of exchange of acetate—concurrent with anomerization—between the C1-acetoxy groups of the pentaacetates (0.05 M) of D-glucose and D-mannose and stannic trichloride acetate (0.05 M) in chloroform containing stannic chloride (0.05 M) were determined at 40 °C. using isotopically labelled acetate. 1,2-trans-α-D-Mannose pentaacetate underwent exchange seven times more rapidly than the β-1,2-cis-anomer but eight times less rapidly than 1,2-trans-β-D-glucose pentaacetate. The latter compound was 450 times more reactive than the α-1,2-cis-anomer. In accordance with these results, the D-mannose pentaacetate underwent mercaptolysis in ethyl mercaptan containing zinc chloride at rates intermediate to those found for the D-glucose pentaacetates. The main product from the mannose pentaacetates was in each case ethyl 1,2-trans-α-D-1-thiomannopyranoside tetraacetate (60–70% yield). Tetra-O-acetyl-β-D-glucopyranosyl chloride with silver acetate gave β-D-glucose pentaacetate when the reaction was carried out in dry acetic acid but gave 2,3,4,6-tetra-O-acetyl-α-D-glucose in 90% aqueous acetic acid. Tetra-O-acetyl-β-D-glucopyranosyl chloride with methanol and silver carbonate gave a sirupy product with the properties expected for methyl 1,2-ortho-O-acetyl-α-D-glucopyranose triacetate. The substance was hydrolyzed by 0.005 N hydrochloric acid in 95% dioxane 18 times more rapidly than the corresponding derivative of β-D-mannose. The significance of these observations toward an understanding of the effect of configuration on reactivity is discussed.

Stereoselective deprotonation of tropinone and reactions of tropinone lithium enolate

1992 ◽  
Vol 70 (10) ◽  
pp. 2618-2626 ◽  
Author(s):  
Marek Majewski ◽  
Guo-Zhu Zheng
Keyword(s):  
Acetic Acid ◽  
Ring Opening ◽  
Aldol Reaction ◽  
Ethyl Chloroformate ◽  
Lithium Diisopropylamide ◽  
Silver Acetate ◽  
Lithium Amides ◽  
Lithium Enolate ◽  
The Absolute ◽  
Absolute Stereochemistry

Tropinone (6) was deprotonated with lithium diisopropylamide and with chiral lithium amides (18–24) and the resulting enolates (two enantiomers) were treated with electrophiles. The aldol reaction with benzaldehyde and deuteration were both diastereoselective. The former yielded only one isomer (exo, anti) of the aldol 8a; the latter proceeded from the exo face. This selectivity permitted us to probe the deprotonation of tropinone with lithium amides; it was concluded that the reaction involves predominantly the exo axial protons. The reaction of tropinone enolate with ethyl chloroformate led, via a ring opening, to the cycloheptenone derivative 9. The reaction with methyl cyanoformate yielded, in the presence of silver acetate and acetic acid, the β-ketoester 8b; however, in the absence of these additives, and especially when 12-crown-4 was added to the enolate, a ring opening leading to the pyrrolidine derivative 10 occurred instead. Deprotonation of tropinone with chiral lithium amides proceeded with modest enantioselectivity. A synthesis of non-racemic anhydroecgonine via this strategy allowed establishing the absolute stereochemistry of deprotonation.

Silver Acetate as an Amphoteric Base.

1951 ◽  
Vol 55 (8) ◽  
pp. 1299-1302 ◽  
Author(s):  
Sigfred Peterson ◽  
Edward K. Dienes
Keyword(s):  
Silver Acetate

Surface modified silver-carbonate mixed conducting membranes for high flux CO2 separation with enhanced stability

2014 ◽  
Vol 453 ◽  
pp. 36-41 ◽  
Author(s):  
Lingling Zhang ◽  
Yunhui Gong ◽  
Jacob Yaggie ◽  
Siwei Wang ◽  
Kevin Romito ◽  
...  
Keyword(s):  
Co2 Separation ◽  
High Flux ◽  
Silver Carbonate ◽  
Surface Modified ◽  
Conducting Membranes ◽  
Enhanced Stability

Silver acetate catalysed cycloadditions of isocyanoacetates

Tetrahedron ◽  
1999 ◽  
Vol 55 (7) ◽  
pp. 2025-2044 ◽  
Author(s):  
Ronald Grigg ◽  
Mark I. Lansdell ◽  
Mark Thornton-Pett
Keyword(s):  
Silver Acetate

Thermal decomposition of silver carbonate

1991 ◽  
Vol 183 ◽  
pp. 279-287 ◽  
Author(s):  
Yutaka Sawada ◽  
Noriyuki Kanou ◽  
Nobuyasu Mizutani
Keyword(s):  
Thermal Decomposition ◽  
Silver Carbonate

Improved synthesis of anti-sesquinorbornene

1984 ◽  
Vol 62 (9) ◽  
pp. 1840-1844 ◽  
Author(s):  
Karl R. Kopecky ◽  
Alan J. Miller
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Lead Tetraacetate ◽  
Carboxyl Group ◽  
Silver Acetate ◽  
Benzenesulfonyl Chloride ◽  
Methoxide Ion ◽  
Hydrolysis Of ◽  
Monomethyl Ester

Treatment of methyl hydrogen decahydro-1,4:5,8-exo,endo-dimethanonaphthalene-4a,8a-dicarboxylate with lead tetraacetate in benzene – acetic acid replaces the carboxyl group by an acetoxy group. Hydrolysis of this product with 25% sulfuric acid at 130 °C forms 8a-hydroxydecahydro-1,4:5,8-exo,endo-dimethanonaphthalene-4a-carboxylic acid 10. The reaction between 10 and benzenesulfonyl chloride in pyridine containing triethylamine at 95 °C produces anti-sesquinorbornene 1 in 34% yield. In the absence of triethylamine 1 is converted to the hydrochloride. The iodohydroperoxide of 1 is converted by silver acetate at 0 °C to the diketone in a luminescent reaction. The 1,2-dioxetane could not be isolated. Decahydro-1,4:5,8-exo,exo-dimethanonaphthalene-4a,8a-dicarboxylic anhydride is converted slowly by methoxide ion in methanol at 150 °C to the monomethyl ester which then undergoes demethylation. The isomeric exo,endo anhydride undergoes reaction readily with methoxide ion at 80 °C.

Development and creation of zeta potential reference material of the particles in a liquid medium

2021 ◽  
pp. 58-62
Author(s):  
Dmitrii I. Belenkii ◽  
Dmitry V. Averkin ◽  
Dmitry V. Vishnevetskii ◽  
Svetlana D. Khizhnyak ◽  
Pavel M. Pakhomov
Keyword(s):  
Bovine Serum Albumin ◽  
Zeta Potential ◽  
Serum Albumin ◽  
Aqueous Solutions ◽  
Bovine Serum ◽  
Polystyrene Latex ◽  
Powder Materials ◽  
Silver Acetate ◽  
Supramolecular Systems ◽  
Standard Samples

A comprehensive study to develop and create standard samples of the zeta potential unit of particles in a liquid in accordance with the requirements of GOST ISO 13099-2-2016 in the range of measured values from minus 150 mV to plus 150 mV was carried out. The existing standard samples of zeta potential in Russia and the world have been investigated; the analysis of the applicability of the starting materials and components for the creation of new standard samples has done. Samples based on modified polystyrene latex microspheres, bovine serum albumin and supramolecular systems based on aqueous solutions of L-cysteine, N-acetylcysteine, and silver acetate were considered as promising standard samples of the zeta potential of particles. All studies were carried out on equipment from the State Primary Standard of Dispersed Parameters of Aerosols, Suspensions and Powder Materials GET 163-2020 using the method of electrophoretic light scattering and measuring the pH value. It was found that polystyrene latex microspheres do not correspond to the requirements of the work in terms of developing a set of standard samples. Samples based on suspensions of bovine serum albumin do not correspond to the requirements of GOST ISO 13099-2-2016. Supramolecular systems based on aqueous solutions of L-cysteine, N-acetylcysteine, and silver acetate were proposed as standard samples. Such systems are characterized by the ability to modify the initial potential-determining layer of particles without changing their aggregate stability. Studies of the long-term stability of the developed standard samples of the zeta-potential unit of particles in a liquid have been carried out.

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