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In specific acid catalysis, protonated solvent is the catalyst. The reaction rate is proportional to the concentration of the protonated solvent molecules SH +. [6] The acid catalyst itself (AH) only contributes to the rate acceleration by shifting the chemical equilibrium between solvent S and AH in favor of the SH + species. This kind of ...
In chemistry, protonation (or hydronation) is the adding of a proton (or hydron, or hydrogen cation), usually denoted by H +, to an atom, molecule, or ion, forming a conjugate acid. [1] (The complementary process, when a proton is removed from a Brønsted–Lowry acid, is deprotonation.) Some examples include The protonation of water by ...
These properties recommend DBU for use as a catalyst, for example as a curing agent for epoxy resins and polyurethane. It is used in the separation of fullerenes in conjunction with trimethylbenzene. It reacts with C 70 and higher fullerenes, but not with C 60. It is useful for dehydrohalogenations. [7]
The described bond formation and breaking process runs synchronous concerted without the appearance of a tetrahedral intermediate. The acetic acid formed will then protonate the DMAP. In the last step of the catalytic cycle the auxiliary base (usually triethylamine or pyridine) deprotonates the protonated DMAP, reforming the catalyst. The ...
In organic chemistry, ether cleavage is an acid catalyzed nucleophilic substitution reaction. Depending on the specific ether, cleavage can follow either S N 1 or S N 2 mechanisms. Distinguishing between both mechanisms requires consideration of inductive and mesomeric effects that could stabilize or destabilize a potential carbocation in the S ...
Following a second intramolecular proton transfer (20,21), the tetrahedral intermediate collapses, eliminating a phenol and forming an ester protonated at the carbonyl oxygen (22). Finally, deprotonation of the carbonyl oxygen yields the collected products and regenerates the acid catalyst (23). [5] Acid-catalyzed Dakin oxidation mechanism
The essence of Brønsted–Lowry theory is that an acid is only such in relation to a base, and vice versa. Water is amphoteric as it can act as an acid or as a base. In the image shown at the right one molecule of H 2 O acts as a base and gains H + to become H 3 O + while the other acts as an acid and loses H + to become OH −.
Aldol reactions may proceed by two distinct mechanisms. Carbonyl compounds, such as aldehydes and ketones, can be converted to enols or enol ethers. These species, being nucleophilic at the α-carbon, can attack especially reactive protonated carbonyls such as protonated aldehydes. This is the 'enol mechanism'.