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Shiina macrolactonization (or Shiina lactonization) is an organic chemical reaction that synthesizes cyclic compounds by using aromatic carboxylic acid anhydrides as dehydration condensation agents. In 1994, Prof. Isamu Shiina ( Tokyo University of Science , Japan) reported an acidic cyclization method using Lewis acid catalyst , [ 1 ] [ 2 ...
Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH 3 CO) 2 O. Commonly abbreviated Ac 2 O, it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis. It is a colorless liquid that smells strongly of acetic acid, which is formed by its reaction with ...
An acid anhydride is a type of chemical compound derived by the removal of water molecules from an acid. In organic chemistry, organic acid anhydrides contain the functional group −C(=O)−O−C(=O)−. Organic acid anhydrides often form when one equivalent of water is removed from two equivalents of an organic acid in a dehydration reaction.
To balance the reaction, each TFBA accepts the atoms of one water molecule from its starting materials, i.e., the carboxylic acid and alcohol, and then changes itself into two molecules of 4-trifluoromethylbenzoic acid at the end of the reaction. Since the Lewis acid catalyst is reproduced at the end of the reaction, only a small proportion of ...
The following figure shows the reaction mechanism: [2] Reaktionsmechanismus Albright-Goldman-Oxidation. First, dimethyl sulfoxide (1) reacts with acetic anhydride to form a sulfonium ion. It reacts with the primary alcohol in an addition reaction. Furthermore, acetic acid is cleaved, so that intermediate 2 is formed. The latter reacts upon ...
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 ...
In even a slight presence of water, carbonic acid dehydrates to carbon dioxide and water, which then catalyzes further decomposition. [6] For this reason, carbon dioxide can be considered the carbonic acid anhydride. The hydration equilibrium constant at 25 °C is [H 2 CO 3]/[CO 2] ≈ 1.7×10 −3 in pure water [12] and ≈ 1.2×10 −3 in ...
A common type of organic acid anhydride is a carboxylic anhydride, where the parent acid is a carboxylic acid, the formula of the anhydride being (RC(O)) 2 O. Symmetrical acid anhydrides of this type are named by replacing the word acid in the name of the parent carboxylic acid by the word anhydride. [2] Thus, (CH 3 CO) 2 O is called acetic ...