Propionic acid metal complexes

Activators. Activators are chemicals that increase the rate of vulcanization by reacting first with the accelerators to form mbber soluble complexes. These complexes then react with the sulfur to achieve vulcanization. The most common activators are combinations of zinc oxide and stearic acid. Other metal oxides have been used for specific purposes, ie, lead, cadmium, etc, and other fatty acids used include lauric, oleic, and propionic acids. Soluble zinc salts of fatty acid such as zinc 2-ethyIhexanoate are also used, and these mbber-soluble activators are effective in natural mbber to produce low set, low creep compounds used in load-bearing appHcations. Weak amines and amino alcohols have also been used as activators in combination with the metal oxides. 

In chlorophyll iron as complex-forming metal is replaced by magnesium (Willstatter). The structure of chlorophyll differs from that of haemin as follows. In chlorophyll one propionic acid chain (a) in oxidised form has condensed with a methine carbon atom to form a cyclopentane ring which takes the position at (c) of the vinyl ethyl. Further the two carbonyl groups are esterified and one of the four pyrrole rings is partially hydrogenated... 

Noncatalytic oxidation to produce acetic acid can be carried out in the gas phase (350-400°C, 5-10 atm) or in the liquid phase (150-200°C). Liquid-phase catalytic oxidations are operated under similar mild conditions. Conditions for the oxidation of naphtha are usually more severe than those for n-butane, and the process gives more complex product mixtures.865-869 Cobalt and other transition-metal salts (Mn, Ni, Cr) are used as catalysts, although cobalt acetate is preferred. In the oxidation carried out in acetic acid solution at almost total conversion, carbon oxides, carboxylic acids and esters, and carbonyl compounds are the major byproducts. Acetic acid is produced in moderate yields (40-60%) and the economy of the process depends largely on the sale of the byproducts (propionic acid, 2-butanone). 

Propionic acid, a-[ 2-[(a-carboxy-2-hydroxybenzyl)-imino]ethyl imino]-metal complexes, 788 Propionic acid, 2,3-diamino-metal complexes, 750... 

Propionic acid, ethylenebis[(carboxymethyl)imino]di-metal complexes, 787 Propionic acid, ethylenediiminotetra-metal complexes, 787 Propionic acid, 3-hydroxy-metal complexes NMR, 467... 

This vitamin possesses the most complex structure of any of the vitamins and is unique in that it has a metallic element, cobalt, in the molecule (Figure 9-19). The molecule is a coordination complex built around a central tervalent cobalt atom and consists of two major parts—a complex cyclic stmcture that closely resembles the porphyrins and a nucleotide-like portion, 5,6-dimethyl-l-(a-D-ribofuranosyl) benzimidazole-3 -phosphate. The phosphate of the nucleotide is esterified with 1-amino-2-propanol this, in turn, is joined by means of an amide bond with the propionic acid side chain of the large cyclic stmcture. A second linkage with the large stmcture is through the coordinate bond between the cobalt atom and one of the nitro-... 

In the field of olefin carboxylation, stoichiometric reactions have been described to occur between non-activated alkenes, CO2 and an electron-rich transition-metal complexes, such as Ni(0) [3], Ti(II) [4] or Fe(0) [5]. A Pd-catalyzed CO2 fixation occurs into methylenecyclopropane derivatives affording lactones [6]. The reaction of carbon dioxide with ethylene is difficult and its carboxylation to propionic acid, catalyzed by Rh derivatives [7], needs drastic experimental conditions. 

The water-gas shift reaction is normally an unwanted side reaction of homogeneous catalysis when carbon monoxide is engaged as a substrate and if water is present as the medium or as a product. Both a pH-basic medium (formation of the nucleophilic [OH] ) and metals or metal complexes that deprotonate the water favor the shift reaction. For example, in the hydrocarboxylation process to make propionic acid directly from C2H4, CO, and H2O (eq. (14)), the formation of hydrogen via the water-gas shift reaction leads to (minor) hydrogenation and hydroformylation products (cf. Section 2.1.2.2). 

Distorted octahedral structures have been proposed for the 1 1 neutral complexes formed between bivalent transition-metal ions and hydroxymethyl-phosphonic acid, H0CH2P03H2. A series of new dialkylaminomethylenedi-phosphonic acids (H0)2P(0)CH(NR R )2P(0)(0H)2 has been prepared from phosphorus trihalides and NN-dialkylformamides. Acid dissociation constants and the complex behaviour toward Cu " for the phosphinyl-propionic acid Ph(H0)P(0)CMe(0H)(C02H) have been evaluated. ... 

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