Search results
Results from the WOW.Com Content Network
The reaction is often carried out without a solvent (particularly when a large reagent excess of the alcohol reagent is used) or in a non-polar solvent (e.g. toluene, hexane) that can facilitate Dean–Stark distillation to remove the water byproduct. [4] Typical reaction times vary from 1–10 hours at temperatures of 60–110 °C.
The addition of the two molecules typically proceeds in a step-wise fashion to the addition product, usually in equilibrium, and with loss of a water molecule (hence the name condensation). [3] The reaction may otherwise involve the functional groups of the molecule, and is a versatile class of reactions that can occur in acidic or basic ...
The classic example of a dehydration reaction is the Fischer esterification, which involves treating a carboxylic acid with an alcohol to give an ester RCO 2 H + R′OH ⇌ RCO 2 R′ + H 2 O. Often such reactions require the presence of a dehydrating agent, i.e. a substance that reacts with water.
The term alcohol originally referred to the primary alcohol ethanol (ethyl alcohol), which is used as a drug and is the main alcohol present in alcoholic drinks. The suffix -ol appears in the International Union of Pure and Applied Chemistry (IUPAC) chemical name of all substances where the hydroxyl group is the functional group with the ...
The first part of this reaction is an Aldol reaction, the second part a dehydration—an elimination reaction (Involves removal of a water molecule or an alcohol molecule). Dehydration may be accompanied by decarboxylation when an activated carboxyl group is present.
Because an alcohol (which acts as the leaving group) and water (which acts as the nucleophile) have similar pK a values, the forward and reverse reactions compete with each other. As in transesterification, using a large excess of reactant (water) or removing one of the products (the alcohol) can promote the forward reaction.
Transesterification is the process of exchanging the organic functional group R″ of an ester with the organic group R' of an alcohol. These reactions are often catalyzed by the addition of an acid or base catalyst. [1] Strong acids catalyze the reaction by donating a proton to the carbonyl group, thus making it a more potent electrophile.
Ammonolysis refers to solvolysis by ammonia, but can also describe nucleophilic attack by ammonia more generally. Ammonia boils at −33 °C, and, as such, is rarely used as a solvent in its pure form. It is, however, readily miscible with water, and is commonly used in the form of a saturated aqueous solution. For this reason, ammonolysis may ...