Acrylic acid Catalyst types

Asymmetric hydrogenation has been achieved with dissolved Wilkinson type catalysts (A. J. Birch, 1976 D. Valentine, Jr., 1978 H.B. Kagan, 1978). The (R)- and (S)-[l,l -binaph-thalene]-2,2 -diylblsCdiphenylphosphine] (= binap ) complexes of ruthenium (A. Miyashita, 1980) and rhodium (A. Miyashita, 1984 R. Noyori, 1987) have been prepared as pure atrop-isomers and used for the stereoselective Noyori hydrogenation of a-(acylamino) acrylic acids and, more significantly, -keto carboxylic esters. In the latter reaction enantiomeric excesses of more than 99% are often achieved (see also M. Nakatsuka, 1990, p. 5586). 

We make polyethylene resins using two basic types of chain growth reaction free radical polymerization and coordination catalysis. We use free radical polymerization to make low density polyethylene, ethylene-vinyl ester copolymers, and the ethylene-acrylic acid copolymer precursors for ethylene ionomers. We employ coordination catalysts to make high density polyethylene, linear low density polyethylene, and very low density polyethylene. 

The effects of added C02 on mass transfer properties and solubility were assessed in some detail for the catalytic asymmetric hydrogenation of 2-(6 -meth-oxy-2 -naphthyl) acrylic acid to (Sj-naproxen using Ru-(S)-BINAP-type catalysts in methanolic solution. The catalytic studies showed that a higher reaction rate was observed under a total C02/H2 pressure of ca. 100 bar (pH2 = 50bar) than under a pressure of 50 bar H2 alone. Upon further increase of the C02 pressure, the catalyst could be precipitated and solvent and product were removed, at least partly by supercritical extraction. Unfortunately, attempts to re-use the catalyst were hampered by its deactivation during the recycling process [11]. 

Diels-Alder catalyst.2 The acrylates (4) of three chiral alcohols (1-3) have been found to undergo asymmetric Diels-Alder reactions with cyclopentadiene (equation I) in the presence of a Lewis acid catalyst. For this purpose, catalysts of the type TiCl2(X2) are superior to TiCl4 because they do not promote polymerization of the acrylate. The final products (6) all have the enrfo-orientation the configuration (R) or (S) depends upon the chiral alcohols. Those derived from 1 all have (S)-configuration ... 

Lewis acid catalysts were discussed in the acrylic monomer section. They are used at about 10% concentration vs monomer. Although no significant research has been done with them, other than looking for new ones, they most likely work by activating the monomers. Type Y zeolites catalyze GTP at about 25% concentration vs initiator. Conversions are quantitative and... 

FIG. 6. Asymmetric homogeneous hydrogenation of a-substituted acrylic acids with a Wilkinson-type catalyst under extended conditions (higher temperature and pressure than usual). 

One-step partial oxidation of propane to acrylic acid (an essential chemical widely used for the production of esters, polyesters, amides, anilides, etc.) has been investigated so far on three types of catalysts, namely, vanadium phosphorus oxides, heteropolycompounds and, more successfully, on mixed metal oxides. The active catalysts generally consist of Mo and V elements, which are also found in catalysts used for the oxidation of propene to acrolein and that of acrolein to acrylic acid. 

Quite a surprising reaction has recently been reported [74]. With a catalyst of palladium metal on carbon in aqueous phase, propene is oxidized with oxygen to give acrylic acid, probably via allyl alcohol in a allylic-type oxidation (for allylic oxidation see Section 3.3.14). In the presence of chloride or oxidants the normal Wacker-type reaction product acetone arises. 

In recent years heteropolycompounds have been studied for the oxidation of propane to acrylic acid and of isobutane to methacrylie aeid. Rohm Haas Company was the first in 1981 to claim the one-step oxidation of isobutane to methacrolein and methacrylie acid (55). Even though no reference is made to heteropolycompounds, the claimed catalyst compositions correspond to Keggin-type structures. In the patents later issued by Sumitomo (56,57) an important role was claimed to be played by vanadium (in an anionic position), by cesium (in a cationic position), as well as by an excess of phosphorus with respect to the stoichiometric composition. These catalysts gave selectivities to methacrylie acid plus methacrolein close to 70 %, with isobutane conversions in the 10 to 13 % range. Besides carbon oxides, acetic acid was the main by-product. 

A new type of boron catalyst 14 is obtained by addition of a controlled amount of diboranc to a monoacylated tartaric acid. This system gives excellent enantioselectivities in the [44-2] cycloaddition reactions of a broad range of dienes and dienophiles (including acrylic acid), being especially effective for the addition of methacrolein25,26. 

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