نتایج جستجو برای: acidity constant
تعداد نتایج: 227783 فیلتر نتایج به سال:
The arylxenonium cation in the salt [C6F5X e]+ [AsF6]" is isoelectronic to C6F5I, but coordinatively unsaturated with respect to N-bases like MeCN and pyridines. Co-ordination of strongly basic pyridines causes weakening of the Xe-C bond and C6F5 radical formation. The thermal decomposition of pyridine co-ordinated arylxenonium cations gives three groups of products: C-pentafluorophenylated pyr...
A series of ionic liquids containing anions of differing coordination strength were investigated as solvents for the condensation reaction of an alkyl amine and an aromatic aldehyde. As predicted, the rate constant of the process was found to increase with the proportion of the ionic liquid in the reaction mixture. Temperature-dependent kinetic analyses demonstrated that by varying the ability ...
A chiral cyclophane–type macrocycle bearing two thiol groups has been prepared by chemical modification of S,S-(+)-tetrandrine. Cleavage of p-nitrophenyl acetate by deprotonated form of this macrocycle proceeds with a rate constant expected for a simple thiol anion of similar basicity, but the reactivity toward p-nitrophenyl esters of N-protected amino acids is one order of magnitude higher tha...
Background & Aim: Herbal extracts contain the important useful natural compounds. In the food industry are great important due to properties flavoring and aroma's, as well as delaying the corruption and are widely used as condiments, flavorings, preservatives and antioxidants. Experimental: The extract of Tragopogon graminifolius was added to milk prepared for yogurt producti...
glucose. The influence of the solution acidity on the deconstruction of Miscanthus giganteus was examined by varying the 1-butylimidazole to sulfuric acid ratio. Increased acidity led to shorter preteatment times and resulted in reduced hemicellulose content in the pulp. Addition of water to the ionic liquid resulted in enhanced saccharification yields. The ability to tune acidity through the u...
Three main, interrelated reasons for widespread digestive disorders in the modern world might be chronic metabolic acidosis, low exocrine pancreatic function, and intestinal dysbiosis. Chronic metabolic acidosis mainly distresses two alkaline digestive glands: the liver and pancreas, which secrete alkaline bile and pancreatic juice with a great amount of bicarbonate. The acidic shift in the bil...
The minerals from which a soil is formed partly determine whether it is acid or alkaline. Soils formed from acidic rocks have a lower pH than those formed from basic rocks or alkaline parent material. Rainfall affects soil acidity development by leaching basic elements such as calcium, magnesium, potassium, and sodium from the soil profile, leaving the acidic elements: hydrogen, aluminum and ma...
Two complementary models of Lewis molecular acidity are introduced and tested in a wide series of 45 room temperature ionic liquids (RTIL). They are defined in the context of the conceptual density functional theory. The first one, which we tentatively call the excess electronic chemical potential, assesses the electron accepting power of the RTIL by relating the H-bond donor acidity with the c...
Lakes developing in former coal mine pits are often characterized by high concentrations of sulfate and iron and low pH. The review focuses on the causes for and fate of acidity in these lakes and their watersheds. Acidification is primarily caused by the generation of ferrous iron bearing and mineralized groundwater, transport through the groundwater-surface water interface, and subsequent iro...
-Existing methods of measuring atmospheric aerosol strong acidity adequately prevent neutralization of fine-particle acidity by removing coarse alkaline particles and gaseous ammonia from air samples. However, these techniques do not consider particle interactions on the collection medium; therefore, they may still underestimate the actual aerosol acidity. Assessment of acid neutralization due ...
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