scholarly journals REGIO- AND STEREOSELECTIVE CYCLOPROPANE RING OPENING IN A TETRACYCLIC COMPOUND.exo-4-ACETOXY-4-HOMOISOTWISTANE (exo-4-ACETOXYTRICYCLO[5.3.1.03,8]UNDECANE) FROM 2,4-DEHYDRO-4-HOMOTWISTANE (TETRACYCLO[ 5.4.0.02,4.03,9]UNDECANE) IN ACETIC ACID UNDER SULFURIC ACID CATALYSIS

1978 ◽  
Vol 7 (8) ◽  
pp. 825-828 ◽  
Author(s):  
Naotake Takaishi ◽  
Yoshiaki Fujikura ◽  
Yoshiaki Inamoto
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Ring Opening ◽  
Acid Catalysis ◽  
Cyclopropane Ring

scholarly journals Aliphatic extractive effects on acetic acid catalysis of typical agricultural residues to xylo-oligosaccharide and enzymatic hydrolyzability of cellulose

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jianming Guo ◽  
Kaixuan Huang ◽  
Rou Cao ◽  
Junhua Zhang ◽  
Yong Xu
Keyword(s):  
Acetic Acid ◽  
Acid Catalysis ◽  
Cost Effective ◽  
Economic Benefits ◽  
Ethanol Extraction ◽  
Minimal Impact ◽  
Aliphatic Compounds ◽  
Organic Solvent Extraction ◽  
Promising Application ◽  
Poplar Sawdust

Abstract Background Xylo-oligosaccharide is the spotlight of functional sugar that improves the economic benefits of lignocellulose biorefinery. Acetic acid acidolysis technology provides a promising application for xylo-oligosaccharide commercial production, but it is restricted by the aliphatic (wax-like) compounds, which cover the outer and inner surfaces of plants. Results We removed aliphatic compounds by extraction with two organic solvents. The benzene–ethanol extraction increased the yield of acidolyzed xylo-oligosaccharides of corncob, sugarcane bagasse, wheat straw, and poplar sawdust by 14.79, 21.05, 16.68, and 7.26% while ethanol extraction increased it by 11.88, 17.43, 1.26, and 13.64%, respectively. Conclusion The single ethanol extraction was safer, more environmentally friendly, and more cost-effective than benzene–ethanol solvent. In short, organic solvent extraction provided a promising auxiliary method for the selective acidolysis of herbaceous xylan to xylo-oligosaccharides, while it had minimal impact on woody poplar.

Donor–Acceptor Cyclopropane Ring Opening with 6-Amino-1,3-dimethyluracil and Its Use in Pyrimido[4,5-b]azepines Synthesis

2021 ◽  
Author(s):  
Anna E. Vartanova ◽  
Irina I. Levina ◽  
Victor B. Rybakov ◽  
Olga A. Ivanova ◽  
Igor V. Trushkov
Keyword(s):  
Ring Opening ◽  
Cyclopropane Ring ◽  
Donor Acceptor

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.

The role of acidity profile in the nanotubular growth of polyaniline

2010 ◽  
Vol 64 (1) ◽  
Author(s):  
Elena Konyushenko ◽  
Miroslava Trchová ◽  
Jaroslav Stejskal ◽  
Irina Sapurina
Keyword(s):  
Acetic Acid ◽  
Sulfuric Acid ◽  
Reaction Temperature ◽  
Subsequent Growth ◽  
Subsequent Oxidation ◽  
Ammonium Peroxydisulfate ◽  
Aniline Oligomers ◽  
Positive Effect ◽  
Granular Morphology

AbstractConditions of polyaniline (PANI) nanotubes preparation were analyzed. Aniline was oxidized with ammonium peroxydisulfate in 0.4 M acetic acid. There are two subsequent oxidation steps and the products were collected after each of them. At pH > 3, neutral aniline molecules are oxidized to non-conducting aniline oligomers. These produce templates for the subsequent growth of PANI nanotubes, which takes place preferably at pH 2–3. At pH < 2, granular morphology of the conducting PANI is obtained. High final acidity of the medium should be avoided in the preparation of nanotubes, e.g., by reducing the amount of sulfuric acid which is a by-product. Reduction of the peroxydisulfate-to-aniline mole ratio was tested for this purpose in the present study. Lowering of the reaction temperature from 20°C to −4°C had a positive effect on the formation of nanotubes.

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.

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