Study of acid hydrolysis of bromazepam

2004 ◽  
Vol 82 (8) ◽  
pp. 1260-1265 ◽  
Author(s):  
Tatjana Damjanović ◽  
Gordana Popović ◽  
Srđan Verbić ◽  
Lidija Pfendt
Keyword(s):  
Acid Hydrolysis ◽  
Least Squares Method ◽  
Bond Cleavage ◽  
Equilibrium Constants ◽  
Spectrophotometric Analysis ◽  
Virtual Experiments ◽  
Experimental Approaches ◽  
Hydrolysis Of ◽  
Azomethine Bond ◽  
Solution Acidity

Quantitative study of an acid hydrolysis of bromazepam, which in acidic solution simultaneously undergoes reversible 4,5-azomethine bond cleavage and protolytic reactions, was performed (t = 25 °C). When an equilibrium is established, four species are simultaneously present in solution. Two approaches, both based on theoretically derived dependence between the absorbance (A) and the solution acidity ([H3O+]), were used to determine appropriate equilibrium constants. In the first, the least-squares method was used to fit experimentally obtained (A, [H3O+]) value pairs to a derived function. With values obtained as fitting parameters, the probability distribution for equilibrium constants was calculated with the virtual experiments performed using Monte Carlo simulations. In the second one, spectrophotometric analysis indicated an existence of two distinct pH intervals, both with three dominant species involved. Spectral data were used to calculate equilibrium constants by a linear curve fitting analysis. Values obtained for equilibrium constants from the numerical and the experimental approaches are in good accordance and were used to calculate distribution of all the species as a function of pcH. Key words: bromazepam, acid hydrolysis, equilibrium constants.

Kinetics of acid-catalysed hydrolysis of the α and β Carbonato(4,7-dimethyltriethylenetetramine) cobalt(III) ions

1974 ◽  
Vol 27 (2) ◽  
pp. 269 ◽  
Author(s):  
DJ Francis ◽  
GH Searle
Keyword(s):  
Acid Hydrolysis ◽  
Perchloric Acid ◽  
Rate Constants ◽  
Dissociation Constants ◽  
Bond Cleavage ◽  
Acid Dissociation ◽  
Acid Dissociation Constants ◽  
Rate Laws ◽  
Kinetics Of ◽  
Hydrolysis Of

The synthesis and separation of the complexes α-[Co(dmtr)CO3] ClO4 and β-[Co(dmtr)CO3] C1O4,H2O (dmtr = 4,7-dimethyltriethylenetetramine or N,N'-bis(2-aminoethyl)-N,N'-dimethylethane-1,2-diamine) are described. The kinetics of the acid hydrolysis of both complexes, studied in perchloric acid at 25�C and μ = 1.0M (LiC1O4), follow rate laws of form -d[complex]dt=(k0 + k1[H+I)[complex] The values of ko and k1 for the K-complex are 1.0 x 10-3 s-1 and 1.8 x 10-2 1. mol-1 s-1 respectively, while for the β-complex the corresponding values are 3.6 x 10-5 s-1 and 5.6 x 10-4 1. mol-1 s-1. Comparisons of these rate constants with the values for similar carbonato(tetramine)cobalt(111) complexes previously studied suggest that the ko path could involve O-C bond cleavage in the present dmtr complexes. The values of the acid dissociation constants of dmtr,4HCl, determined by potentiometric titration, are 1.61, 5.86, 8.18 and 9.95.

DETERMINATION OF MICRO-AMOUNTS OF 5β-PREGNAN-3α-OL-20-ONE IN URINE USING INFRARED-SPECTROMETRY

1962 ◽  
Vol 41 (2) ◽  
pp. 234-246 ◽  
Author(s):  
H. J. van der Molen
Keyword(s):  
Infrared Spectrum ◽  
Quantitative Determination ◽  
Acid Hydrolysis ◽  
Chromatographic Separation ◽  
Pure Form ◽  
Infrared Spectrometry ◽  
Hydrolysis Of

ABSTRACT A procedure for the quantitative determination of 5β-pregnan-3α-ol-20-one in urine is described. After acid hydrolysis of the pregnanolone-conjugates in urine, the free steroids are extracted with toluene. Pregnanolone is isolated in a pure form as its acetate; after chromatographic separation of the free steroids on alumina, the fraction containing pregnanolone is acetylated and rechromatographed on alumina. Quantitative determination of the isolated pregnanolone-acetate is carried out with the aid of the infrared spectrum recorded by a micro KBr-wafermethod. The reliability of the method under various conditions is discussed under the headings, specificity, accuracy, precision and sensitivity. It is possible to determine 30–40 μg pregnanolone in a 24-hours urine portion with a precision of 25%.

Optimization of technological modes of cold acid hydrolysis of potato starch

2020 ◽  
Vol 26 (3) ◽  
pp. 222-233
Author(s):  
M. Alekseenko ◽  
V. Litvyak ◽  
A. Sysa ◽  
E. Hrabovska ◽  
O. Galenko
Keyword(s):  
Acid Hydrolysis ◽  
Potato Starch ◽  
Hydrolysis Of

FLOWTHROUGH ACID HYDROLYSIS OF RAPESEED STALKS

2012 ◽  
Vol 11 (12) ◽  
pp. 2313-2318
Author(s):  
Theodor Malutan ◽  
Adina Elena Panzariu
Keyword(s):  
Acid Hydrolysis ◽  
Hydrolysis Of

scholarly journals Tagasaste, leucaena and paulownia: three industrial crops for energy and hemicelluloses production

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Alberto Palma ◽  
Javier Mauricio Loaiza ◽  
Manuel J. Díaz ◽  
Juan Carlos García ◽  
Inmaculada Giráldez ◽  
...  
Keyword(s):  
Activation Energy ◽  
Acid Hydrolysis ◽  
Energy Production ◽  
Combustion Process ◽  
Operating Conditions ◽  
Raw Material ◽  
Energy Of Combustion ◽  
Increasing Temperature ◽  
Hydrolysis Of ◽  
Chamaecytisus Proliferus

Abstract Background Burning fast-growing trees for energy production can be an effective alternative to coal combustion. Thus, lignocellulosic material, which can be used to obtain chemicals with a high added value, is highly abundant, easily renewed and usually inexpensive. In this work, hemicellulose extraction by acid hydrolysis of plant biomass from three different crops (Chamaecytisus proliferus, Leucaena diversifolia and Paulownia trihybrid) was modelled and the resulting solid residues were used for energy production. Results The influence of the nature of the lignocellulosic raw material and the operating conditions used to extract the hemicellulose fraction on the heat capacity and activation energy of the subsequent combustion process was examined. The heat power and the activation energy of the combustion process were found to depend markedly on the hemicellulose content of the raw material. Thus, a low content in hemicelluloses resulted in a lower increased energy yield after acid hydrolysis stage. The process was also influenced by the operating conditions of the acid hydrolysis treatment, which increased the gross calorific value (GCV) of the solid residue by 0.6–9.7% relative to the starting material. In addition, the activation energy of combustion of the acid hydrolysis residues from Chamaecytisus proliferus (Tagasaste) and Paulownia trihybrid (Paulownia) was considerably lower than that for the starting materials, the difference increasing with increasing degree of conversion as well as with increasing temperature and acid concentration in the acid hydrolysis. The activation energy of combustion of the solid residues from acid hydrolysis of tagasaste and paulownia decreased markedly with increasing degree of conversion, and also with increasing temperature and acid concentration in the acid hydrolysis treatment. No similar trend was observed in Leucaena diversifolia (Leucaena) owing to its low content in hemicelluloses. Conclusions Acid hydrolysis of tagasaste, leucaena and paulownia provided a valorizable liquor containing a large amount of hemicelluloses and a solid residue with an increased heat power amenable to efficient valorization by combustion. There are many potential applications of the hemicelluloses-rich and lignin-rich fraction, for example as multi-components of bio-based feedstocks for 3D printing, for energy and other value-added chemicals.

scholarly journals Paving the Way to Food Grade Analytical Chemistry: Use of a Natural Deep Eutectic Solvent to Determine Total Hydroxytyrosol and Tyrosol in Extra Virgin Olive Oils

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 677
Author(s):  
Vito Michele Paradiso ◽  
Francesco Longobardi ◽  
Stefania Fortunato ◽  
Pasqua Rotondi ◽  
Maria Bellumori ◽  
...  
Keyword(s):  
Analytical Chemistry ◽  
Acid Hydrolysis ◽  
Virgin Olive Oil ◽  
Deep Eutectic Solvent ◽  
Spectrophotometric Analysis ◽  
Health Claim ◽  
Food Grade ◽  
Olive Oils ◽  
Natural Deep Eutectic Solvent ◽  
The Way

Extra virgin olive oil (EVOO) is well known for containing relevant amounts of healthy phenolic compounds. The European Food Safety Authority (EFSA) allowed a health claim for labelling olive oils containing a minimum amount of hydroxytyrosol (OHTyr) and its derivatives, including tyrosol (Tyr). Therefore, harmonized and standardized analytical protocols are required in support of an effective application of the health claim. Acid hydrolysis performed after extraction and before chromatographic analysis has been shown to be a feasible approach. Nevertheless, other fast, green, and easy methods could be useful for on-site screening and monitoring applications. In the present research, a natural deep eutectic solvent (NADES) composed of lactic acid and glucose was used to perform a liquid/liquid extraction on EVOO samples, followed by UV-spectrophotometric analysis. The spectral features of the extracts were related with the content of total OHTyr and Tyr, determined by the acid hydrolysis method. The second derivative of spectra allowed focusing on three single wavelengths (i.e., 299 nm, 290 nm, and 282 nm) significantly related with total OHTyr, total Tyr, and their sum, respectively. In particular, the sum of OHTyr and Tyr could be determined with a root mean square error of prediction of 29.5 mg kg−1, while the limits of quantitation and detection were respectively 11.8 and 4.9 mg kg−1. The proposed method, therefore, represents an easy screening tool, with the use of a green, food-derived solvent, and could be considered as an attempt to pave the way for food grade analytical chemistry.

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