Studies in Solvolysis. Part VI. An Examination of the Heat Capacity of Activation for the Hydrolysis of 4-Methoxybenzyl Trifluoroacetate

1975 ◽  
Vol 53 (7) ◽  
pp. 1051-1055 ◽  
Author(s):  
June Gertrude Winter ◽  
John Patrick Barron ◽  
John Marshall William Scott
Keyword(s):  
Heat Capacity ◽  
The Other ◽  
Relative Importance ◽  
Reaction Paths ◽  
Enthalpy Of Activation ◽  
Hydrolysis Of

The heat capacity of activation for the hydrolysis of 4-methoxybenzyl trifluoroacetate in water containing 9.05 × 10−2 mol fraction of acetone has been measured and shown to be positive. This unusual result is consistent with the notion that the ester reacts by two distinct routes: one involving acyl–oxygen fission, the other, alkyl–oxygen fission. The relative importance of the two paths for the 4-methoxy ester has been established quantitatively via a Hammett σ–ρ correlation for a series of 4-substituted-benzyl trifluoroacetates. Such an assessment allows the observed heat capacity, entropy, and enthalpy of activation to be factored into parts appropriate to each of the two reaction paths.

Ion pairs and heat capacity of activation for 2,2-disubstituted cyclopropyl bromides

1976 ◽  
Vol 54 (8) ◽  
pp. 1246-1252 ◽  
Author(s):  
Surendra Singh ◽  
Ross Elmore Robertson
Keyword(s):  
Heat Capacity ◽  
Transition State ◽  
Relative Rate ◽  
Ion Pairs ◽  
Water Structure ◽  
Ion Pair ◽  
External Effects ◽  
Enthalpy Of Activation ◽  
Rate Ratios ◽  
Hydrolysis Of

The temperature dependence of the rates of hydrolysis of 2,2-dimethylcyclopropyl bromide, 2,2-cis-vinyl-trans-methylcyclopropyl bromide and 2,2-cis-methyl-trans-vinylcyclopropyl bromide have been determined in water. The temperature coefficient of the enthalpy of activation (ΔCp≠) for these compounds was determined to be −52, −27 and −37 cal deg−1 mol−1 respectively. The relative rate ratios for hydrolysis of the 2,2-methylvinylcyclopropyl bromides with respect to the appropriate 2-vinylcyclopropyl bromide isomer indicate a considerable progress towards allyl cations at the transition state in contrast to the indications of the ΔCp≠ values.The ΔCp≠ term for such reactions in water depends to an important degree on the external effects of charge development on water structure but is insensitive to internal electrostatic effects. In the three examples of ΔCp≠ reported in this study, all tend to show small external effects in spite of evidence which might suggest larger. The differences in ΔCp≠ are attributed to the particular shape and charge distribution of the quasi-ion pair.

A FACILE SYNTHESIS AND REACTIONS OF AMINO SELENOLO[2,3-b]PYRIDINE CARBOXYLATE

2015 ◽  
Vol 12 (1) ◽  
pp. 3910-3918 ◽  
Author(s):  
Dr Remon M Zaki ◽  
Prof Adel M. Kamal El-Dean ◽  
Dr Nermin A Marzouk ◽  
Prof Jehan A Micky ◽  
Mrs Rasha H Ahmed
Keyword(s):  
Biological Activity ◽  
Carbonyl Compounds ◽  
Mass Spectra ◽  
The Other ◽  
Pyridine Derivatives ◽  
Facile Synthesis ◽  
High Biological Activity ◽  
Basic Hydrolysis ◽  
Pyridine Carboxylate ◽  
Hydrolysis Of

 Incorporating selenium metal bonded to the pyridine nucleus was achieved by the reaction of selenium metal with 2-chloropyridine carbonitrile 1 in the presence of sodium borohydride as reducing agent. The resulting non isolated selanyl sodium salt was subjected to react with various α-halogenated carbonyl compounds to afford the selenyl pyridine derivatives 3a-f  which compounds 3a-d underwent Thorpe-Ziegler cyclization to give 1-amino-2-substitutedselenolo[2,3-b]pyridine compounds 4a-d, while the other compounds 3e,f failed to be cyclized. Basic hydrolysis of amino selenolo[2,3-b]pyridine carboxylate 4a followed by decarboxylation furnished the corresponding amino selenolopyridine compound 6 which was used as a versatile precursor for synthesis of other heterocyclic compound 7-16. All the newly synthesized compounds were established by elemental and spectral analysis (IR, 1H NMR) in addition to mass spectra for some of them hoping these compounds afforded high biological activity.

Exploration of Product Centric Factors in Telecom Industry

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Swati Ganeti ◽  
Rajat Agarwal ◽  
Murali Krishna Medudula ◽  
Mahim Sagar
Keyword(s):  
Service Quality ◽  
Service Provider ◽  
Service Providers ◽  
Network Connectivity ◽  
Factor Loading ◽  
The Other ◽  
Relative Importance ◽  
Network Connection ◽  
Telecom Service ◽  
Telecom Industry

Telecom industry is one of those industries which has changed dramatically during the past decade. With more and more players entering in this industry, competition is ever increasing. The war between these players is slowly shifting from the price to the augmentation. This paper aims at exploring such factors which influence a customers preference of one telecom service provider (TSP) over the other. It is a descriptive research where study has been conducted among the consumers of different telecom service providers (TSPs). By reviewing the existing literature in this domain, we explored different factors which affect the consumers decision to prefer one telecom service provider over the other. A consumer targeted questionnaire was designed where consumers were asked about the factors they consider (with their relative importance quantified using Likert scale), before buying a new network connection to know the relative importance of the various factors. Factor Analysis was performed to club various variables into distinct factors. Statistical techniques then helped in identifying the relative importance. From the Factor Loading matrix the following five factors were generated:- Overall service quality, Point of Purchase Differentiator, Promotion Measures, Tariff Plans and Size of the Network. Further study in the behavioural perceptions of consumer shows that the most important factor in influencing the customer buying behavior is Service Quality. The second most important factor is cost and various plans offered by the telecom service provider. Network connectivity was considered by almost all the respondents and consumers prefer the largest network player. The study also found that promotional measures dont influence the customers as expected.

THE ALDOBIOURONIC ACIDS OF HEMICELLULOSE B OF OAT HULLS

1956 ◽  
Vol 34 (3) ◽  
pp. 338-344 ◽  
Author(s):  
E. L. Falconer ◽  
G. A. Adams
Keyword(s):  
Glucuronic Acid ◽  
The Other ◽  
Partial Hydrolysis ◽  
Oat Hulls ◽  
Hydrolysis Of

Partial hydrolysis of hemicellulose B from oat hulls yielded two aldobiouronic acids, which were identified as 2-O-(4-O-methyl-α-D-glucopyruronosyl)-D-xylose and 2-O-(α-D-glucopyruronosyl)-D-xylose respectively. In addition, two aldotriouronic acids were isolated, one yielding on hydrolysis xylose and 4-O-methyl-glucuronic acid, and the other, xylose, galactose, and glucurone.

Heat capacity of activation for the hydrolysis of methanesulfonyl chloride and benzenesulfonyl chloride in light and heavy water

1969 ◽  
Vol 47 (22) ◽  
pp. 4199-4206 ◽  
Author(s):  
R. E. Robertson ◽  
B. Rossall ◽  
S. E. Sugamori ◽  
L. Treindl
Keyword(s):  
Heat Capacity ◽  
Free Energy ◽  
Temperature Dependence ◽  
Heavy Water ◽  
Bond Formation ◽  
Sulfonyl Chlorides ◽  
Benzenesulfonyl Chloride ◽  
Methanesulfonyl Chloride ◽  
Hydrolysis Of ◽  
Parameter Temperature Dependence

Rates of solvolysis of methanesulfonyl chloride and benzenesulfonyl chloride have been determined in H2O and D2O. The free energy, enthalpy, entropy, and heat capacity of activation were calculated. The exceptional accuracy of the data permitted an estimation of dΔCp≠/dT from a four parameter temperature dependence of the kinetic rates.From these data we conclude that both sulfonyl chlorides hydrolyse by the same mechanism (Sn2) The change in R from CH3 to C6H5 in RSO2Cl did not alter ΔCp≠ but ΔS≠ (20°) was changed from −8.32 to −13.25 cal deg−1 mole−1, respectively. The significance of this difference is attributed to the probability of bond formation rather than to differences in solvent reorganization.

scholarly journals Fertility and its relation to social conditions A study of the vital statistics of London in 1930–1932

1937 ◽  
Vol 37 (1) ◽  
pp. 108-123 ◽  
Author(s):  
K. Mitra
Keyword(s):  
Birth Rate ◽  
Western Europe ◽  
Vital Statistics ◽  
Considerable Extent ◽  
The Other ◽  
Rapid Decline ◽  
Relative Importance ◽  
Absolute Size ◽  
The Military

The rapid decline of the birth-rate in nearly all countries of western Europe has naturally attracted much attention. Some have studied the probable effects upon the absolute size and the age constitution of the population, and the consequence entailed upon the military and economic strength of a nation. Others have drawn attention to resulting change's in the relative importance of diseases of young, adult and old ages. Changes in mere numbers depend wholly, and the other changes to a considerable extent, upon quantitative factors; they must occur even if the quality of those born differs in no way from that of those produced when fertility was at a higher level. But, if the quality of births changes with their quantity, then the consequences of decrease of numbers may be better or worse than mere numerical changes would involve.

scholarly journals Estructura de preferencias de los consumidores de vino y actitudes hacia los vinos con denominación de origen. El caso de Castilla-La Mancha

2011 ◽  
Vol 5 (9) ◽  
pp. 57 ◽  
Author(s):  
R. Bernabéu ◽  
M. Olmeda ◽  
M. Díaz
Keyword(s):  
Consumer Preferences ◽  
The Other ◽  
Consumer Attitude ◽  
Relative Importance ◽  
La Mancha ◽  
The One

This paper covers a dual objective. On the one hand, the relative importance was determined of the wine attributes that influence the formation of consumer preferences in Castilla-La Mancha. On the other, consumer attitude was analysed towards wine with Castilla-La Mancha’s most important Designation of Origin (D.O.) certifications (D.O. La Mancha and D.O. Valdepeñas), compared with the best-known wine in the national ambit (D.O. Rioja). As a result of the first objective, the most relevant attributes are price, colour (red, white), certification and origin, in this order. The second objective shows that D.O. La Mancha and D.O. Valdepeñas are considered cheaper wines, of habitual consumption and a lower prestige image, while D.O. Rioja wines are seen as prestigious and expensive, so their consumption is considered appropriate for special occasions.

scholarly journals On the Mechanism of Protection against Infective Disease

1928 ◽  
Vol 28 (2) ◽  
pp. 127-132
Author(s):  
M. Greenwood ◽  
E. M. Newbold ◽  
W. W. C. Topley ◽  
J. Wilson
Keyword(s):  
The Other ◽  
Relative Importance ◽  
Selective Mortality ◽  
Lethal Infection ◽  
Infective Disease ◽  
Subsequent Exposure ◽  
The Subject ◽  
The One

In the course of a paper by the present writers (this Journal, xxv, 336–53) an attempt was made to assess the relative importance of selective mortality on the one hand and sub-lethal infection on the other in increasing herd resistance to subsequent exposure to infection. The subject was further considered by one of us (E.M.N.) in a later report (this Journal, xxvi, 19–27).

Minimum Irreversibility Criteria for Heat Exchanger Configurations

1999 ◽  
Vol 121 (4) ◽  
pp. 241-246 ◽  
Author(s):  
F. E. M. Saboya ◽  
C. E. S. M. da Costa
Keyword(s):  
Heat Capacity ◽  
Heat Exchanger ◽  
Heat Exchangers ◽  
Cross Flow ◽  
Second Law Of Thermodynamics ◽  
The Other ◽  
Maximum Heat ◽  
Transfer Rates ◽  
Mass Flow Rates ◽  
Flow Heat

From the second law of thermodynamics, the concepts of irreversibility, entropy generation, and availability are applied to counterflow, parallel-flow, and cross-flow heat exchangers. In the case of the Cross-flow configuration, there are four types of heat exchangers: I) both fluids unmixed, 2) both fluids mixed, 3) fluid of maximum heat capacity rate mixed and the other unmixed, 4) fluid of minimum heat capacity rate mixed and the other unmixed. In the analysis, the heat exchangers are assumed to have a negligible pressure drop irreversibility. The Counterflow heat exchanger is compared with the other five heat exchanger types and the comparison will indicate which one has the minimum irreversibility rate. In this comparison, only the exit temperatures and the heat transfer rates of the heat exchangers are different. The other conditions (inlet temperatures, mass flow rates, number of transfer units) and the working fluids are the same in the heat exchangers.

scholarly journals Inositol phosphate release and steroidogenesis in rat adrenal glomerulosa cells. Comparison of the effects of endothelin, angiotensin II and vasopressin

1990 ◽  
Vol 271 (3) ◽  
pp. 791-796 ◽  
Author(s):  
E A Woodcock ◽  
P J Little ◽  
J K Tanner
Keyword(s):  
Angiotensin Ii ◽  
Metabolic Pathways ◽  
Inositol Phosphate ◽  
The Other ◽  
Relative Importance ◽  
Phosphate Release ◽  
Phosphatidylinositol Turnover ◽  
Transient Rise ◽  
Glomerulosa Cells ◽  
Stimulation Of

Endothelin has steroidogenic activity in adrenal glomerulosa cells, as do two other vasoconstrictor peptides, angiotensin II and vasopressin. The steroidogenic activities of angiotensin II and vasopressin are probably mediated via the phosphatidylinositol-turnover pathway and associated changes in cytosolic Ca2+ concentration. Endothelin caused a steroidogenic response, which was small compared with that to angiotensin II and quantitatively similar to the vasopressin response. Cytosolic free Ca2+ responses were similarly higher to angiotensin II than to either of the other two peptides. However, total inositol phosphate responses to endothelin and angiotensin II were similar when these were measured over 20 min, and were quantitatively greater than the vasopressin response. A detailed study has been made of the phosphatidylinositol-turnover response to endothelin in comparison with responses to angiotensin II and vasopressin. Each of the three peptides produced a rapid and transient rise in Ins(1,4,5)P3 (max. 5-15 s), followed by a slow sustained rise. Ins(1,4,5)P3 was metabolized by both dephosphorylation and phosphorylation pathways, but the relative importance of the two metabolic pathways was different under stimulation by each of the three peptides. These findings show that adrenal glomerulosa cells can distinguish between the stimulation of phosphatidylinositol turnover by three different effectors. These differences in the pathway may be associated with the observed different steroidogenic and Ca2+ responses to the three peptides.

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