Synthèse de cétones encombrées via réduction de nitriles tertiaires en présence de métaux alcalins

1978 ◽  
Vol 56 (21) ◽  
pp. 2731-2736 ◽  
Author(s):  
Jean-Paul Mazaleyrat
Keyword(s):  
Radical Anion ◽  
Alkali Metals ◽  
Simple Method ◽  
Hydrolysis Of ◽  
Tertiary Alkyl

The reaction of alkali metals with tertiary alkyl nitriles eventually gives, after protonation, an imine. α-tert-Alkylketones are produced by the hydrolysis of these imines. This reaction, involving radical anion intermediates, is a simple method for the synthesis of highly hindered symmetric ketones.

scholarly journals A simple method for the determination of the cholesterol esterase activity.

2013 ◽  
Vol 60 (3) ◽  
Author(s):  
Agnieszka Ewa Stępień ◽  
Mykhailo Gonchar
Keyword(s):  
Human Serum ◽  
Esterase Activity ◽  
Cholesterol Oxidase ◽  
Cholesterol Esterase ◽  
Cholesterol Esters ◽  
Simple Method ◽  
Bacterial Enzyme ◽  
Low Costs ◽  
Hydrolysis Of

The proposed method determines the activity of cholesterol esterase (CEH) and takes advantage of its ability to catalyze the hydrolysis of cholesterol esters naturally present in human serum. The assay is based on Allain's method of spectrophotometric determination of cholesterol by means of cholesterol oxidase, peroxidase, but using 3,5-dichloro-dihydroxybenzenesulfonic acid (DHBS) as phenolic chromogen and human serum as a source of substrate for the CEH as a novelty. Furthermore, it is characterized by low costs and high precision. It can be employed to control the activity of CE preparations used for the preparation of enzymatic kits for the determination of cholesterol or for screening of potential bacterial enzyme producers.

scholarly journals Acidic hydrolysis of astilbin and its application for the preparation of taxifolin from Rhizoma Smilacis Glabrae

2020 ◽  
pp. 174751982094835
Author(s):  
Xiao-Lin Qiu ◽  
Qing-Feng Zhang
Keyword(s):  
Activation Energy ◽  
Kinetic Parameters ◽  
Hydrolysis Reaction ◽  
Simple Method ◽  
Acidic Hydrolysis ◽  
A Value ◽  
Hcl Concentration ◽  
Hydrolysis Of

The acidic hydrolysis of astilbin to produce its aglycone, taxifolin, was investigated in this study. The effects of aq. HCl concentration and temperature on the reaction were studied, and the kinetic parameters were calculated. The results showed that with higher aq. HCl concentration and temperature, the hydrolysis of astilbin became faster. The activation energy of the hydrolysis reaction under 1 mol L−1 aq. HCl was calculated with a value of 148.6 kJ mol−1. The reaction was successfully applied to produce taxifolin from a sample of Rhizoma Smilacis Glabrae. A simple method for the purification of taxifolin from Rhizoma Smilacis Glabrae was developed with purity of 97.5%.

scholarly journals A Simple Method for the Quantification of Free Isocyanates on the Surface of Cellulose Nanocrystals upon Carbamation using Toluene Diisocyanate

Surfaces ◽  
2019 ◽  
Vol 2 (2) ◽  
pp. 444-454 ◽  
Author(s):  
Hatem Abushammala
Keyword(s):  
Elemental Analysis ◽  
Cellulose Nanocrystals ◽  
Toluene Diisocyanate ◽  
Hydroxyl Group ◽  
Simple Method ◽  
Complete Hydrolysis ◽  
Amine Groups ◽  
Ph Increase ◽  
Hydrolysis Of ◽  
Cellulose Surface

In many reports, cellulose and nanocellulose have been carbamated using 2,4-toluene diisocyanate (2,4-TDI) to allow the grafting of molecules or polymers onto their surfaces. Such a process usually involves the reaction of the more reactive isocyanate group of TDI (para-NCO) selectively with a hydroxyl group from the cellulose surface, followed by the reaction of the free isocyanate (ortho-NCO) with a desired molecule. After the first step, it is not possible, using elemental analysis, to determine the amount of ortho-NCO on the cellulosic surface, as an ideal para/ortho selectivity is difficult to obtain. This paper presents a simple method for the quantification of ortho-NCOs on the surface of cellulose nanocrystals upon TDI-based carbamation. It relies on the pH increase upon a complete hydrolysis of ortho-NCOs to amine groups using acidified dimethylsulfoxide. The method was found to be accurate and valid for a degree of substitution of up to 20%.

Organophosphorverbindungen mit tertiären Alkylsubstituenten. III*: Synthese und Reaktionen Di-1-adamantylsubstituierter Phosphorverbindungen; Kristallstruktur von Di-1-Adamantylphosphinsäurechlorid / Organophosphorus Compounds with Tertiary Alkyl Substituents. Ill: Synthesis and Reactions of Di-1-adam antyl-Substituted Phosphorus Compounds; Crystal Structure of Di-1-adam antylphosphinic Chloride

1994 ◽  
Vol 49 (6) ◽  
pp. 801-811 ◽  
Author(s):  
Jens R. Goerlich ◽  
Axel Fischer ◽  
Peter G. Jones ◽  
Reinhard Schmutzler
Keyword(s):  
Organophosphorus Compounds ◽  
Phosphorus Compounds ◽  
Secondary Phosphine ◽  
Phosphine Oxides ◽  
X Ray ◽  
Dry Air ◽  
Nmr Data ◽  
Standard Procedures ◽  
Hydrolysis Of ◽  
Tertiary Alkyl

The reaction of adamantane with PCl3/A1Cl3, followed by hydrolysis, gave (1-Ad)2P(:O)Cl 1, which was converted to (1-Ad)2P(:O)F 2 and (1-Ad)2P(:S)Cl 3 by standard procedures. The structure of 1 was confirmed by a single crystal X-ray structure determination; despite the bulky substituents the P-C bond lengths are normal (184.0(3), 185.0(3) pm). Whereas chlorine-fluorine exchange in 3 with AsF3 furnished (1-Ad)2P(:S)F 4, desulfuration of 3 with Ph3P to give (1-Ad)2PCl 5 failed. The secondary phosphine oxides R 1R2P(:O)H (R1, R2 = 1-Ad: 6; R1 = 1-Ad, R2 = tBu: 7; R1, R2 = tBu: 8) were synthesized by reaction of 1, 1-AdP(:O)Cl2 and tBuP(:0)Cl2 with tBuLi. 6 and 8 reacted readily with chloral to give the adducts R2P(:O)CH(OH)CCl3 (R = 1-Ad: 9; R = tBu: 10). Silylation of 6 with Me2NSiMe3 in the presence of dry air led to (1-Ad)2P(:O)OSiMe3 11, which was hydrolyzed to give (1-Ad)2P(:O)OH 12. (1-Ad)2POSiMe3 13 was obtained by the reaction of 6 with n-BuLi, followed by Me3SiCl. No reaction took place upon heating 6 with Mo(CO)6. (1-Ad)2PCl 5 was synthesized in low yield by the reaction of 6 with PCl3. The action of tetrachloro-obenzoquinone (TOB) upon 6 furnished (1-Ad)2P(:O)(o-OH)C6Cl4 15, whereas the tbutyl analogue of 15, 16, was synthesized by hydrolysis of the TOB-adduct of di-tbutylfluorophosphine. Analogous 1-adamantyl- and tbutyl-phosphorus compounds are compared with regard to their 31P NMR data

scholarly journals Electrophoretic and zymographic techniques for production monitoring of two lipase forms from Candida antarctica DSM 70725

2012 ◽  
Vol 66 (2) ◽  
pp. 201-206
Author(s):  
Aleksandra Dimitrijevic ◽  
Dusan Velickovic ◽  
Ratko Jankov ◽  
Nenad Milosavic
Keyword(s):  
Molecular Weight ◽  
Large Scale ◽  
Fermentation Broth ◽  
Candida Antarctica ◽  
Simple Method ◽  
Wide Range ◽  
Work Production ◽  
Lipase A ◽  
Dimeric Form ◽  
Hydrolysis Of

Yeast Candida antarctica produces two lipase forms, which are widely used as catalysts in variety of organic reactions, many of which are applied on a large scale. In this work, production of two forms of lipase from C. antarctica DSM 70725 (CAL A and CAL B) was monitored during seven days of cultivation in the optimal medium using different electrophoretic and zymographic techniques. According to electrophoresis after silver staining, C. antarctica lipase A (molecular mass 45 kDa) was produced starting from the second day of cultivation. C. antarctica lipase B (CAL B) was also produced starting from the second day, but protein was present in the fermentation broth predominantly as dimer (molecular weight 66 kDa), while presence of monomeric form of CAL B (molecular weight of 33 kDa) was observed starting from the fourth day of cultivation. Both types of zymograms (based on hydrolysis and synthesis reactions) were used for detection of lipase activity in the fermentation broth. C. antarctica lipase A showed activity only in hydrolytic zymogram, when ?-naphtyl butyrate was used as substrate. In the same zymogram, with ?-naphtyl acetate as substrate no CAL A activity was detected. Similarly, CAL A showed no activity in synthesis based zymograms towards oleic acid and octanol as substrates, indicating that CAL A is not active towards very short or long-chain substrates. As opposite of CAL A, both monomeric and dimeric form of CAL B were detected in the all zymograms, suggesting that CAL B is active towards wide range of substrates, regardless to the chain length. Thus, zymogram based on hydrolysis of ?-naphtyl butyrate represents a simple method for monitoring the production of two forms of lipase from C. antarctica, that greatly differ in their characteristics.

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