Catalysis by heteropoly compounds. XXII. Reactions of esters and esterification catalyzed by heteropolyacids in a homogeneous liquid phase - effects of the central atom of heteropolyanions having tungsten as the addenda atom

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1288· OSTI ID:5155805

Hu, Changwen; Hashimoto, Masato; Okuhara, Toshio; Misono, Makoto ^[1]

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1. Univ. of Tokyo (Japan)

Decomposition of isobutyl propionate (IBP) (Reaction (1)), ester exchange of IBP with acetic acid (Reaction (2)), ester exchange of IBP with n-propyl alcohol (Reaction (3)), and esterification of propionic acid with isobutyl alcohol (Reaction (4)) have been studied in a homogeneous liquid phase using heteropolyacids H[sub m]XW[sub 12]O[sub 40] (X = P, Si, Ge, B, and Co) having the Keggin structure and H[sub 6]P[sub 2]W[sub 18]O[sub 62] having the Dawson structure. The results clearly indicated that the catalytic behavior of heteropolyacids remarkably depended on the kind of reaction system, namely, the basicity of reactants. For Reaction (1), the catalytic activities of the heteropolyacids were 60-100 times higher than those of H[sub 2]SO[sub 4] and p-toluenesulfonic acid. Among the heteropolyacids, the activity was in the order H[sub 3]PW[sub 12]O[sub 40] > H[sub 4]SiW[sub 12]O[sub 40] [approximately] H[sub 4]GeW[sub 12]O[sub 40] > H[sub 5]BW[sub 12]O[sub 40] > H[sub 6]CoW[sub 12]O[sub 40]. This order suggests that the activity follows the order of the acid strength of the solutions of heteropolyacids, which increases with the decrease in the negative charge of the polyanion. H[sub 6]P[sub 2]W[sub 18]O[sub 62] showed an activity between those of H[sub 5]BW[sub 12]O[sub 40] and H[sub 6]CoW[sub 12]O[sub 40]. Water molecules in the system retarded Reaction 1. For Reaction 2, the activity order was similar to that for Reaction 1 in the absence of water. However, contrary to Reaction 1, the addition of water greatly accelerated Reaction 2. It was presumed that, in the presence of water, Reaction 2 proceeds via the hydrolysis of IBP to propionic acid and isobutyl alcohol, followed by the esterification of isobutyl alcohol with acetic acid. 28 refs., 8 figs., 4 tabs.

• OSTI ID: 5155805
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 143:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACETIC ACID
ALCOHOLS
BORON COMPOUNDS
CARBOXYLIC ACIDS
CATALYSIS
CATALYTIC EFFECTS
CHEMICAL REACTIONS
COBALT COMPOUNDS
DECOMPOSITION
ESTERIFICATION
ESTERS
GERMANIUM COMPOUNDS
HETEROPOLY ACIDS
HOMOGENEOUS CATALYSIS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INORGANIC ACIDS
MONOCARBOXYLIC ACIDS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PHOSPHORUS COMPOUNDS
PROPANOLS
PROPIONIC ACID
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS