Tetracarboxylates

Tiripicchio, A. J. Carty, and G. E. Toogood, Butterfly cluster complexes of the group VIII transition metals, Prog. Inorg. Chem., 35, 437 (1987). 

Kharas and L. F. Dahl, Ligand-stabilized metal clusters Structure, bonding, fluxionality, and the metallic state, Adv. Chem. Phys., 70, 1 (1988). 

Lemoine, Progress in cluster electrochemistry, Coord. Chem. Reo., 83, 169 (1988). 

The molybdenum(II) carboxylates, Mo2(02CR)4, are key derivatives containing molybdenum-molybdenum quadruple bonds.1 First described by Wilkinson and coworkers in the early 1960s,2 they remain the key starting materials in (Mo2)4 + chemistry and they have been the objects of numerous physical and theoretical studies.1 The most commonly used method of preparation is the reaction between molybdenum hexacarbonyl and a carboxylic acid in an inert solvent such as 1,2-dichlorobenzene (DCB) [eq. (I)].3 Excellent yields of Mo2(02CR)4 can be obtained by 

The formate complex W2(02CH)4 has recently been isolated by photolysis of W2(CH2Ph)2(02CH)4in benzene-cyclohexadiene.12 In the following section, we describe the syntheses of W2(02CCF3)4, W2(02C-t-Bu)4, and W2(02CCH3)4, which were developed in our laboratory. 

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This tetra ethyl ester is difficult to hydrolyse the corresponding tetra-methyl ester can, however, be hydrolysed to give ethane tetracarboxylic acid, (HOOC)jCH CH(COOH)j. The latter readily loses 2 molecules of carbon dioxide (on being heated or even on boiling with water) to give succinic acid, HOOCCHjCHjCOOH. 

Ethane tetracarboxylic ethyl ester can be regarded as composed of two malonic ester residues, each acting as a mono-alkyl substituent to the other. The two remaining hydrogen atoms therefore still retain acidic properties, and consequently the ester gives with sodium ethoxide a di-sodium derivative. 

The addition of active methylene compounds (ethyl malonate, ethyl aoeto-acetate, ethyl plienylacetate, nltromethane, acrylonitrile, etc.) to the aP-double bond of a conjugated unsaturated ketone, ester or nitrile In the presence of a basic catalyst (sodium ethoxide, piperidine, diethylamiiie, etc.) is known as the Michael reaction or Michael addition. The reaction may be illustrated by the addition of ethyl malonate to ethyl fumarate in the presence of sodium ethoxide hydrolysis and decarboxylation of the addendum (ethyl propane-1 1 2 3-tetracarboxylate) yields trlcarballylic acid ... 

In the above reaction one molecular proportion of sodium ethoxide is employed this is Michael s original method for conducting the reaction, which is reversible and particularly so under these conditions, and in certain circumstances may lead to apparently abnormal results. With smaller amounts of sodium alkoxide (1/5 mol or so the so-called catal3rtic method) or in the presence of secondary amines, the equilibrium is usually more on the side of the adduct, and good yields of adducts are frequently obtained. An example of the Michael addition of the latter type is to be found in the formation of ethyl propane-1 1 3 3 tetracarboxylate (II) from formaldehyde and ethyl malonate in the presence of diethylamine. Ethyl methylene-malonate (I) is formed intermediately by the simple Knoevenagel reaction and this Is followed by the Michael addition. Acid hydrolysis of (II) gives glutaric acid (III). 

Tricarballylic acid. Place 228 g. (204 ml.) of ethyl propane-1 1 2 3-tetracarboxylate and 240 ml. of 1 1 hydrochloric acid in a 1-litre threenecked flask, fitted with a mechanical stirrer and a fractionating column with condenser set for downward distillation attach a receiver with side tube to the condenser and connect the side tube to a wash bottle containing water. Boil the mixture, with continual stirring, at such a rate that the... 

Ethyl propane-1 1 3 3-tetracarboxylate. Cool a mixture of 320 g. (302 ml.) of redistilled diethyl malonate and 80 g. of 40 per cent, formaldehyde solution ( formalin ) contained in a 1-htre round-bottomed flask to 5° by immersion in ice, and add 5 g. (7 ml.) of diethylamine. Keep the mixture at room temperature for 15 hours and then heat under a reflux condenser on a boiling water bath for 6 hours. Separate the aqueous layer, dry the organic layer with anhydrous magnesium sulphate, and distil under reduced pressure. Collect the ethyl 1 1 3 3-tetracarboxylate at 200-215°/20 mm. The yield is 250 g. 

The dicarboxylation of cyclic alkenes is a useful reaction. All-c.vo-methyl-7-oxabicyclo(2.2.1]heptane-2,3,5,6-tetracarboxylate (233) was prepared from the cyclic alkene 232 using Pd on carbon and CuCh in MeOH at room temperature with high diastereoselectivity[216]. The dicarbonylation of cyclopentene... 

Dimethyl acetylenedicarboxylate (DMAD) (125) is a very special alkyne and undergoes interesting cyclotrimerization and co-cyclization reactions of its own using the poorly soluble polymeric palladacyclopentadiene complex (TCPC) 75 and its diazadiene stabilized complex 123 as precursors of Pd(0) catalysts, Cyclotrimerization of DMAD is catalyzed by 123[60], In addition to the hexa-substituted benzene 126, the cyclooctatetraene derivative 127 was obtained by the co-cyclization of trimethylsilylpropargyl alcohol with an excess of DMAD (125)[6l], Co-cyclization is possible with various alkenes. The naphthalene-tetracarboxylate 129 was obtained by the reaction of methoxyallene (128) with an excess of DMAD using the catalyst 123[62],... 

See also Pyromellitic acid.) [PHTTiALIC ACID AND OTTiERBENZENEPOLYCARBOXYLIC ACIDS] (Vol 18) Benzene-1,2,4,5-tetracarboxylic dianhydride-3-carboxylic acid [59025-58-0]... 

Polyimides (PI) are polycondensation products (1) prepared from derivatives of tetracarboxylic acids and primary diamines (1—5). Descriptions of self-polycondensation polymers (2) based on aminodicarboxylic acid derivatives are also found in the literature (6—9). 

Diesters of Tetracarboxylic Acids with Diamines. Dianhydrides react with alcohols at a moderate temperature, producing the tetracarboxyhc acid diesters. Ben2ophenonetetracarboxyhc acid diester (BTTA diester) is obtained from B I DA as a mixture of three positional isomers. Partiy because it is an isomeric mixture, the diester of BTTA is soluble in methanol at high concentrations. A state-of-the-art thermoset polyimide,... 

Acetylenedicaiboxylic esteis also react with phenyUiydioxylamines to give pyrroles (28), eg, N-phenylpyrrole-2,3,4,5-tetracarboxylic acid, tetramethyl ester [37802-39 ] (14). 

IH-Azepine 1-oxide, 1-methyl- C NMR, 7, 498 <770MR<9)333) 2H-Azepine-2-selenone, hexahydro-l-methyl- C NMR, 7, 498 <79AJC567> 3H-Azepine-2,3,5,7-tetracarboxylic acid, 4,6-diphenyl-, tetramethyl ester X-ray, 7, 494 <72CB982) 3H-Azepine-2,4,6,7-tetracarboxylic acid, 3,5-diphenyl-, tetramethyl ester X-ray, 7, 494 <72CB982>... 

H,5H-Pyrrolo[l,2-c]thiazole-6,7,8,9-tetracarboxylic acid, 3,5-etheno-5-methyl-, tetramethyl ester H NMR, 6, 977 (80JOC5396)... 

IndoIe-4,5,6,7-tetracarboxylic acid, l-aryl-3a,6-dihydro-esters... 

Pyrido[2,l-/][l,2,4]triazine-5,6,7,8-tetracarboxylic acid, 4,4a-biphenyl-l-p-tolyl-synthesis, 3, 428 Pyridotropylium cations... 

A number of other syntheses of coniine have been effected, of which that of Diels and Alder is of special interest. The initial adduct of pyridine and methyl acetylenedicarboxylate, viz., tetraraethylquinolizine-1 2 3 4-tetracarboxylate (IX) on oxidation with dilute nitric acid is converted into methyl indolizinetricarboxylate (X). This, on hydrolysis and decarboxylation, furnishes indolizine, the octahydro-derivative (XI) of which, also known as octahydropyrrocoline, is converted by the cyanogen bromide method (as applied by Winterfeld and Holschneider to lupinane, p. 123) successively into the broraocyanoamide (XII), cyanoaraide (XIII) and dZ-coniine (XIV). A synthesis of the alkaloid, starting from indolizine (pyrrocoline) is described by Ochiai and Tsuda. ... 

P. Terech, P. Maldivi, C. Dammer. Living polymers in organic solvents Stress relaxation in bicopper tetracarboxylate/tert-butyl cyclohexane solutions. J Phys II (France) 4 1799-1811, 1994. 

Naphthalene-1,8-dicarboxylic add, its nitro-substituted derivatives, and naphthalene-1,4,5,8 tetracarboxylic acid, on treatment with sulfur tetrafluoride at 0 C, undergo dehydration to form quantitatively the corresponding anhydrides [218, 221] Unsubstituted and mononitrated monoanhydndes react further at 200-250 °C to give derivatives of 1,1,3,3-tetrafluoro-l// naphtho[I,8 c,d]pyran Dinitronaphthalene-l,8-di-carboxyhc acid anhydndes and naphthalene 1,4,5,8 tetracarboxylic acid dianhydnde give the respective tetra- and octafluoroethers only in the presence of an excess of anhydrous hydrogen fluoride [221] (equabons 113 and 114)... 

When the original reaction between the 1-methylpyrrole and dimethyl acetylenedicarboxylate was carried out on a larger scale with inadequate cooling, an exothermic reaction took place and none of the dihydroindole (48) could be detected among the products. However these included the mellitic ester (49) and the pyrrole (50), indicating that some of the dihydroindole (48) had formed and had combined with more of the acetylenic ester as already described. A decomposition product of the dihydroindole as yet unidentified, tetramethyl l-methylindole-2,3,6,7-tetracarboxylate (52), and tetramethyl prehnit-... 

Heating the 9-methyl-9aH-quinolizine (83) with 2-methylpyridine in methanol causes isomerization to the corresponding 9-methyl-4H-quinolizine (84), but with 3-methylpyridine the isomeric 7-methyl-4H-quinolizine (86) is obtained. Similarly the 9-methyl compound (83) and the corresponding 7,9-dimethyl derivative (82) with pyridine yield tetramethyl 47f-quinolizine-l,2,3,4-tetracarboxylate (78) with loss of the original alkylated pyridine. The mechanism of these reactions has not been established but the addition-elimination isomerization sequence for 3-methylpyridine accounts for the known cases of exchange of the pyridine (see Scheme 1). 

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