Methylsteroids. VII. Factors Affecting the Hydrolysis of 7α- and 11β-Acetoxylanostanes

1961 ◽  
Vol 14 (1) ◽  
pp. 48
Author(s):  
CS Barnes ◽  
BD Beilby
Keyword(s):  
Carbonyl Group ◽  
Carbonyl Groups ◽  
Factors Affecting ◽  
Steric Crowding ◽  
Methylene Groups ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of ◽  
Methylene Group

Doubly bonded methylene groups have been introduced into 7α- and 11β-acetoxylanostanes and the rate of hydrolysis compared with compounds having a hydroxy or carbonyl group at the same position as the methylene group. It was found that methylene groups facilitate hydrolysis of the hindered acetoxy groups in the same way, but not to the same extent, as carbonyl groups. It is concluded that the facilitation in each case results from a conformational disturbance, but that there is some other factor involved in carbonyl facilitation. It was not possible to demonstrate a similar effect resulting from steric crowding of substituents.

LYCOPODIUM ALKALOIDS: IV. REACTIONS OF α-CYANOBROMOLYCOPODINE AND ITS DERIVATIVES

1956 ◽  
Vol 34 (11) ◽  
pp. 1519-1527 ◽  
Author(s):  
L. R. C. Barclay ◽  
David B. MacLean
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Group ◽  
Lycopodium Alkaloids ◽  
Hydrolysis Of ◽  
Methylene Group

The hydrogenolysis and hydrolysis of α-cyanobromolycopodine to the secondary tricyclic base, α-des-dihydrolycopodine, is reported. The latter compound was converted to the methiodide in poor yield so that further degradations of the molecule through this derivative were not feasible. Hydride reductions of α-cyanobromolycopodine and some of its derivatives are recorded. The presence of a methylene group adjacent to the carbonyl group in lycopodine has been proved. Evidence is presented which suggests that the carbonyl group and the nitrogen atom are relatively close to one another in the molecule.

USE OF YEAST BETA-GALACTOSIDASE IN MILK AND MILK PRODUCTS1

1971 ◽  
Vol 34 (6) ◽  
pp. 294-299 ◽  
Author(s):  
W. L. Wendorff ◽  
C. H. Amundson ◽  
N. F. Olson ◽  
J. C. Garver
Keyword(s):  
Maximum Rate ◽  
Inhibitory Effect ◽  
Potassium Sulfate ◽  
Factors Affecting ◽  
Milk Products ◽  
Dry Milk ◽  
Rate Of Hydrolysis ◽  
Milk Solids ◽  
Hydrolysis Of ◽  
Beta Galactosidase

Experiments were carried out to study factors affecting the enzyme activity of β-galactosidase of Saccharomyces fragilis NRRL Y-1109 in milk products. Both the type of lactose-containing substrates and their method of preparation greatly affected β-galactosidase activity. Lactose in an aqueous solution was hydrolyzed more easily than it was in milk products. Of milk products tested, whey was the best substrate for the enzyme. Milk solids, other than lactose, exhibited some inhibitory effect on hydrolysis of lactose by the S. fragilis β-galactosidase. The maximum rate of hydrolysis in milk products was obtained when milk or whey was fortified with 0.1 M potassium sulfate and 10−4 M manganese chloride. Nonfat dry milk and whey powders, in which portions of the lactose were hydrolyzed to simple sugars, were prepared. These products were of good flavor, appearance, and stability.

Factors affecting the rate of hydrolysis of starch in legumes

1985 ◽  
Vol 42 (1) ◽  
pp. 38-43 ◽  
Author(s):  
S Wong ◽  
K Traianedes ◽  
K O'Dea
Keyword(s):  
Factors Affecting ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

scholarly journals ALKYLATION OF TRIETHYL ESTER OF PHOSPHONOACETIC ACID AND DIETHOXYCYANOMETHYLPHOSPHONATE WITH HALOIDACETALS AND PRODUCTS OF THEIR TRANSFORMATION

2017 ◽  
Vol 60 (2) ◽  
pp. 13
Author(s):  
Valekh M. Ismailov ◽  
Niftaly N. Yusubov ◽  
Nurlana D. Sadykhova ◽  
Gezal G. Ibragimova ◽  
Iskander A. Mamedov
Keyword(s):  
Nmr Spectroscopy ◽  
Carbon Atom ◽  
Carbonyl Group ◽  
Organic Compounds ◽  
Phosphonoacetic Acid ◽  
Ir And Nmr Spectroscopy ◽  
High Reaction ◽  
Hydrolysis Of ◽  
Active Methylene ◽  
Methylene Group

The method was developed for synthesis of hard-to-reach phosphorylated aldehides with hidden carbonyl group. As compounds with active methylene group triethyl ethers of phosfonacetic acid and diethoxycianomethyl phosfonate were used at the condensation with bromo- and chloroacetals to produce the corresponding acetals. It was found that in the mentioned phosphonates the alkylation by haloid acetal occurs exceptionally on the carbon atom of active methylene group, not touching the nitrile and ester groups. The hydrolysis of obtained phosphorylated acetals led to preparation of phosphorylated aldehydes. It was found that an application of chlorinated acetals led to decreasing the yield of final products. On the basis of obtained aldehydes the corresponding hydrozones were prepared. The latter in the course of reaction undergoes the conversion occurring on the nitrile and ester groups. The high reaction activity of synthesized phosphorylated acetals was used in the further synthesis of different kind of phosphoroganic compounds.  The reaction of phosphorylated aldehydes with hydrazine led to obtaining the nitrogen and phosphor containing organic compounds. The structures of synthesized compounds were studied and proved by IR and NMR spectroscopy methods. Forcitation:                                                                                                                    Ismailov V.M., Yusubov N.N., Sadykhova N.D., Ibragimova G.G., Mamedov I.A. Alkylation of triethyl ester of phosphonoacetic acid and diethoxycyanomethylphosphonate with haloidacetals and products of their transformation. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 2. P. 13-16.

The Effects of Amines on the Esterase Activities of Thrombin and Thrombokinase and on Several Clotting Tests

1974 ◽  
Vol 31 (02) ◽  
pp. 309-318
Author(s):  
Phyllis S Roberts ◽  
Raphael M Ottenbrite ◽  
Patricia B Fleming ◽  
James Wigand
Keyword(s):  
Choline Chloride ◽  
Polymerization Process ◽  
Ammonium Bromide ◽  
Bovine Thrombin ◽  
One Stage ◽  
Human Proteins ◽  
Rate Of Hydrolysis ◽  
The One ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Summary1. Choline chloride, 0.1 M (in 0.25 M Tris. HCl buffer, pH 7.4 or 8.0, 37°), doubles the rate of hydrolysis of TAME by bovine thrombokinase but has no effect on the hydrolysis of this ester by either human or bovine thrombin. Only when 1.0 M or more choline chloride is present is the hydrolysis of BAME by thrombokinase or thrombin weakly inhibited. Evidence is presented that shows that these effects are due to the quaternary amine group.2. Tetramethyl ammonium bromide or chloride has about the same effects on the hydrolysis of esters by these enzymes as does choline chloride but tetra-ethyl, -n.propyl and -n.butyl ammonium bromides (0.1 M) are stronger accelerators of the thrombokinase-TAME reaction and they also accelerate, but to a lesser degree, the thrombin-TAME reaction. In addition, they inhibit the hydrolysis of BAME by both enzymes. Their effects on these reactions, however, do not follow any regular order. The tetraethyl compound is the strongest accelerator of the thrombokinase-TAME reaction but the tetra-ethyl and -butyl compounds are the strongest accelerators of the thrombin-TAME reaction. The ethyl and propyl compounds are the best (although weak) inhibitors of the thrombokinase-BAME and the propyl compound of the thrombin-BAME reactions.3. Tetra-methyl, -ethyl, -n.propyl and -n.butyl ammonium bromides (0.01 M) inhibit the clotting of fibrinogen by thrombin (bovine and human proteins) at pH 7.4, imidazole or pH 6.1, phosphate buffers and they also inhibit, but to a lesser degree, a modified one-stage prothrombin test. In all cases the inhibition increases regularly as the size of the alkyl group increases from methyl to butyl. Only the ethyl com pound (0.025 M but not 0.01 M), however, significantly inhibits the polymerization of bovine fibrin monomers. It was concluded that inhibition of the fibrinogen-thrombin and the one-stage tests by the quaternary amines is not due to any effect of the com pounds on the polymerization process but probably due to inhibition of thrombin’s action on fibrinogen by the quaternary amines.

The effect of polymeric and model imidazolium halides on the rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid

1985 ◽  
Vol 50 (4) ◽  
pp. 845-853 ◽  
Author(s):  
Miloslav Šorm ◽  
Miloslav Procházka ◽  
Jaroslav Kálal
Keyword(s):  
Catalyst Concentration ◽  
Low Molecular Weight ◽  
Imidazolium Chloride ◽  
First Order ◽  
Nitrobenzoic Acid ◽  
Rate Of Hydrolysis ◽  
Acid Catalyzed ◽  
Hydrolysis Of ◽  
Ethanol In Water ◽  
Direct Attack

The course of hydrolysis of an ester, 4-acetoxy-3-nitrobenzoic acid catalyzed with poly(1-methyl-3-allylimidazolium bromide) (IIa), poly[l-methyl-3-(2-propinyl)imidazolium chloride] (IIb) and poly[l-methyl-3-(2-methacryloyloxyethyl)imidazolium bromide] (IIc) in a 28.5% aqueous ethanol was investigated as a function of pH and compared with low-molecular weight models, viz., l-methyl-3-alkylimidazolium bromides (the alkyl group being methyl, propyl, and hexyl, resp). Polymers IIb, IIc possessed a higher activity at pH above 9, while the models were more active at a lower pH with a maximum at pH 7.67. The catalytic activity at the higher pH is attributed to an attack by the OH- group, while at the lower pH it is assigned to a direct attack of water on the substrate. The rate of hydrolysis of 4-acetoxy-3-nitrobenzoic acid is proportional to the catalyst concentration [IIc] and proceeds as a first-order reaction. The hydrolysis depends on the composition of the solvent and was highest at 28.5% (vol.) of ethanol in water. The hydrolysis of a neutral ester, 4-nitrophenyl acetate, was not accelerated by IIc.

Kinetics of hydrolysis of peroxodisulphate ions in acidic medium to peroxomonosulphuric acid

1981 ◽  
Vol 46 (5) ◽  
pp. 1229-1236 ◽  
Author(s):  
Jan Balej ◽  
Milada Thumová
Keyword(s):  
Ionic Strength ◽  
Rate Constants ◽  
Acidic Medium ◽  
Measured Data ◽  
Molar Ratios ◽  
Starting Solution ◽  
Kinetics Of Hydrolysis ◽  
Rate Of Hydrolysis ◽  
Kinetics Of ◽  
Hydrolysis Of

The rate of hydrolysis of S2O82- ions in acidic medium to peroxomonosulphuric acid was measured at 20 and 30 °C. The composition of the starting solution corresponded to the anolyte flowing out from an electrolyser for production of this acid or its ammonium salt at various degrees of conversion and starting molar ratios of sulphuric acid to ammonium sulphate. The measured data served to calculate the rate constants at both temperatures on the basis of the earlier proposed mechanism of the hydrolysis, and their dependence on the ionic strength was studied.

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