Aconitates

Oxalic (Hibdrate) Malonio Sttooinio Qluiaric Adipic Pimclic Suberic Aiclaic Scbacic Malic Mocic Fumaric Maleic Meaaoonic Citraconic Itaoonio Camphoric roC Tartaric mcco Tartaric d.Tartahc. Citric (hydrated) Aconitic... 

Aconitatc was obtained as a minor product in the carbonylation of propar-gyl alcohol[479]. However, in the two-step synthesis of methyl aconitate (536) from propargyl alcohol in 70% overall yield, the first step is the oxidative carbonylation under CO and air using Pdli and KI to giNe dimethyl hydro-xymethylbutenedioate (535), which is carbonylated further to give trimethyl aconitate (536) by u.sc of [Pd(Tu)4jl2 as a catalyst[480]. 

The enzyme acomtase catalyzes the hydration of aconitic acid to two products citric acid and isocitnc acid Isocitnc acid is optically active citric acid is not What are the respective con stitutions of citric acid and isocitnc acid" ... 

In the presence of the enzyme acomtase the double bond of aconitic acid undergoes hydra tion The reaction is reversible and the following equilibrium is established... 

Itaconic 2Lcid[97-65-4] (methylenebutanedioic acid, methylenesuccinic acid) is a crystaUine, high, melting acid (mp = 167-168) produced commercially by fermentation of carbohydrates (1 4). Itaconic acid is produced in the broth from citric acid (qv). Isolated from the pyrolysis products of citric acid in 1836, this a-substituted acryUc acid received its name by rearrangement of aconitic, the acid from which it is formed by decarboxylation. 

L-glutamic acid C. melassecola C. melassecola Glu A, citrate dehydrogenase, ppc, aconitate dehydratase ... 

Fermentation Feedstock. Sucrose, in the form of beet or cane molasses, is a fermentation feedstock for production of a variety of organic compounds, including lactic, glutamic, and citric acids, glycerol, and some antibiotics. Lesser amounts of itaconic, aconitic, and kojic acids, as well as acetone and butanol, are also produced (41,51—53). Rum is made by fermentation of cane molasses. Beet and cane molasses are used for production of baker s and brewer s yeast (qv). 

Decomposition. When heated above 175°C, citric acid decomposes to form aconitic acid [499-12-7] citraconic acid [498-25-7], itaconic acid [97-65 ], acetonedicarboxyhc acid [542-05-2], carbon dioxide, and water, as shown in Figure 1. 

For purification the acid is crystallized from about 150 cc. of glacial acetic acid, using an acid-resistant filter for the hot solution (Note 7). Aconitic acid separates as small, colorless needles weighing 50-60 g., and about 10 g. more can be secured by concentrating the mother liquor under reduced pressure to one-third of its volume. The material is dried in the air and then in a desiccator containing sodium hydroxide in order to remove all traces of acetic acid. One crystallization usually is sufficient to bring the point of decomposition to 198-199° (Note 6). 

By filtering at this point rather than at a lower temperature a separation from a small amount of low-melting material is accomplished without much loss of aconitic acid. 

When heated in a capillary tube aconitic acid decomposes rather suddenly with vigorous gas evolution at a temperature which is highly dependent upon the rate of heating and the temperature at which the sample is introduced. In the literature melting points ranging from 182.5° iQ4-5° > 16 recorded. The uncrystallized aconitic acid, when introduced at 180° into a small bath provided with mechanical agitation and heated at the rate of 2-3° per minute, usually decomposed at 189-190°. The... 

Aconitic acid has been prepared from citric acid by the action of sulfuric acid or hydrogen chloride, or by heating. It has been prepared also from methyl acetylcitrate and from acetylcitric anhydride. The method described is essentially that of Hentschel. Phosphoric acid (85 per cent) can be used in place of sulfuric acid, but much closer regulation of the conditions seems necessary and the yield is not greatly improved. 

Aconitine is also stated to occur in Portuguese aconite (A. Napellus Linn., sub-species lusitanicum), and it may also be present in an unidentified aconite from the Chumbi Valley, Tibet [cf. A. Ludlowii, below). 

Aconite roots marketed in India are apt to be from mixed species and botanical verification of such material is desirable. 

This kind of reaction was first recorded for aconitine (p. 675) and it serves to emphasise the parallelism in reactivity, and probably therefore in structure, which exists between aconitine and delphinine and possibly between the whole range of aconite and larkspur alkaloids. 

Sansemeria zeylanica. An alkaloid is present in the roots and rhizomes. The juice contains aconitic acid. (Scheindlin and Dodge, Amer. J. Pharm., 1947, 119, 232.)... 

Abrine, 484 Abrotine, 772 Abrtis precatorius, 484 Abuta spp., 371 Acacia spp., 771 Acetylcholine, 262, 518 Acetylomithine, 170, 171, 172 Achillea spp., 779 Achilleine achilletine, 779 Acolyctine, 686 Aconine, 673, 675, 679, 685 Aconines, nuclear structure, 693 Aconite alkaloids, 673 Aconitine, 673, 674, 775 oxidation products, 676 Aconitines, pharmacological action, 690 Aconitinone, 676 Aconitoline, 675... 

Citrate is isomerized to isocitrate by aconitase in a two-step process involving aconitate as an intermediate (Figure 20.7). In this reaction, the elements... 

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