Metal carboxylates

References have been made above to dehydrations of Mn(HC02)2 2 H20 [91,212] and Cu(HC02)2 4 H20 [213]. The influence of the structure of dehydrated Ni(CH02)2 2 H20 [118,605] (E dehydration, is 105 kJ mole-1) on subsequent decomposition has been discussed [118] removal of the last traces of water probably influences decomposition nu-cleation [375]. 

Non-isothermal measurements of the temperatures of dehydrations and decompositions of some 25 oxalates in oxygen or in nitrogen atmospheres have been reported by Dollimore and Griffiths [39]. Shkarin et al. [606] conclude, from the similarities they found in the kinetics of dehydration of Ni, Mn, Co, Fe, Mg, Ca and Th hydrated oxalates (first-order reactions and all values of E 100 kJ mole-1), that the mechanisms of reactions of the seven salts are probably identical. We believe, however, that this conclusion is premature when considered with reference to more recent observations for NiC204 2 H20 (see below [129]) where kinetic characteristics are shown to be sensitive to prevailing conditions. The dehydration of MnC204 2 H20 [607] has been found to obey the contracting volume 

In an unusual type of study, Gardner [1264] investigated the dehydration reaction 

For many reactions in the subsequent sections, the product of dehydration constitutes the reactant in a decomposition. Account must be taken of the changes in structure and texture which accompany or follow withdrawal of water from the lattice (perhaps in several steps) in considering the kinetics of subsequent decompositions or interactions of the anhydrous solid. 

---

Carboxylic acids react with butadiene as alkali metal carboxylates. A mixture of isomeric 1- and 3-acetoxyoctadienes (39 and 40) is formed by the reaction of acetic acid[13]. The reaction is very slow in acetic acid alone. It is accelerated by forming acetate by the addition of a base[40]. Addition of an equal amount of triethylamine achieved complete conversion at 80 C after 2 h. AcONa or AcOK also can be used as a base. Trimethylolpropane phosphite (TMPP) completely eliminates the formation of 1,3,7-octatriene, and the acetoxyocta-dienes 39 and 40 are obtained in 81% and 9% yields by using N.N.N M -tetramethyl-l,3-diaminobutane at 50 in a 2 h reaction. These two isomers undergo Pd-catalyzed allylic rearrangement with each other. 

MOCR (a metal carboxylate a source of the nucleophilic anion RC—O )... 

Metal carboxylates are ionic and when the molecular weight isn t too high the sodium and potassium salts of carboxylic acids are soluble m water Carboxylic acids therefore may be extracted from ether solutions into aqueous sodium or potassium hydroxide... 

Color intensity and permanence are improved by metal carboxylate salts, especially 2inc salts (83), which cataly2e the dye development and stabili2e the dye in its colored form. The substituted novolak resin, along with extender and binder, can be apphed to the receiving sheet as a solution or aqueous dispersion. Aqueous dispersions are probably the most widely used they are manufactured by the resin suppher or the user from the base resin. 

Solution Deposition of Thin Films. Chemical methods of preparation may also be used for the fabrication of ceramic thin films (qv). MetaHo-organic precursors, notably metal alkoxides (see Alkoxides, metal) and metal carboxylates, are most frequently used for film preparation by sol-gel or metallo-organic decomposition (MOD) solution deposition processes (see Sol-GEL technology). These methods involve dissolution of the precursors in a mutual solvent control of solution characteristics such as viscosity and concentration, film deposition by spin-casting or dip-coating, and heat treatment to remove volatile organic species and induce crystaHhation of the as-deposited amorphous film into the desired stmcture. 

Because of the different vulcanization chemistry involved in each commercial ACM, a vulcanization system specific to the cure site present has to be adopted. Many cure systems for labile chlorine containing ACM have been proposed (45). Among these the alkali metal carboxylate—sulfur cure system, or soap—sulfur as it is called in the United States, became the mainstay of acryflc elastomer technology in the early 1960s (46), and continues to be widely used. 

If the starting material contains M-H or M-C bonds a further complication can arise due to the possibility of a CO2 insertion reaction. Thus, both [Ru(H)2(N2)(PPh3)3] and [Ru(H)2(PPh3)4] react to give the formate [Ru(H)(OOCH)(PPh3)3], and similar CO2 insertions into M-H are known for M = Co, Fe, Os, Ir, Pt. These normal insertion reactions are consistent with the expected bond polarities M +-H and 0 =C +=0, but occasionally abnormal insertion occurs to give metal carboxylic acids... 

In the case of metal carboxylates it may be the long -alkyl chains, normally incorporated to reduce volatil-... 

Replication avoids the problem of sample deterioration in the instrument, but it is destructive in that reaction of the material cannot be continued after the replica has been prepared. Transitory features cannot be detected unless a series of preparations are examined corresponding to increasing progress of the reaction considered. The textures of replicas have been shown [220] to be in satisfactory agreement with those of the original surface as viewed in the scanning electron microscope. The uses and interpretations of observations made through sample replication procedures are illustrated in the studies of decomposition of metal carboxyl-ates by Brown and co-workers [97,221—223]. 

Metal salts of carboxylic acids obviously possess some organic character, but decompositions of these substances can be considered in the present context. Many metal carboxylates decompose at a reactant—product interface and their nucleation and growth processes are similar to the behav-... 

The products of decomposition of metal carboxylates vary to some extent with the constituent cation and the final residue is usually either the metal or an oxide, occasionally the carbide and sometimes some elemental carbon deposit. Dollimore et al. [94] have described the use of Ellingham diagrams for the prediction of the composition of the solid products of oxalate decompositions. The complete characterization of residual material can be difficult, however, since the solids may be finely divided, pyrophoric [1010], metallic and amorphous to X-rays. 

The literature available constitutes neither a comprehensive nor a particularly systematic investigation of the kinetics of decompositions of metal carboxylates. (A comparable remark could also be made at the end of each of the Sections 1—4 and 6.) The simplest reactants have naturally been accorded the greatest interest. Reactions of certain formates and... 

The reactions of some aromatic metal carboxylates are on the borderline of classification as solid-state processes. While there is no evidence of liquefaction, rates of decomposition in the poorly crystallized or vitreous reactant obey kinetic expressions more characteristic of reactions proceeding in a homogeneous phase. 

Solvent extraction of metal carboxylates. H. Yamada and M. Tanaka, Adv. Inorg. Chem. Radiochem., 1985, 29,143 (159). 

Reaction between Alkali Metal Carboxylates and Dihaloalkanes... 

PET is the polyester of terephthalic acid and ethylene glycol. Polyesters are prepared by either direct esterification or transesterification reactions. In the direct esterification process, terephthalic acid is reacted with ethylene glycol to produce PET and water as a by-product. Transesterification involves the reaction of dimethyl terephthalate (DMT) with ethylene glycol in the presence of a catalyst (usually a metal carboxylate) to form bis(hydroxyethyl)terephthalate (BHET) and methyl alcohol as a by-product. In the second step of transesterification, BHET... 

Mehrotra, R. C. Bohra, R. (1983). Metal Carboxylates. London New York Academic Press. 

---