Malonic acid plants

Hydrochloric acid [7647-01-0], which is formed as by-product from unreacted chloroacetic acid, is fed into an absorption column. After the addition of acid and alcohol is complete, the mixture is heated at reflux for 6—8 h, whereby the intermediate malonic acid ester monoamide is hydroly2ed to a dialkyl malonate. The pure ester is obtained from the mixture of cmde esters by extraction with ben2ene [71-43-2], toluene [108-88-3], or xylene [1330-20-7]. The organic phase is washed with dilute sodium hydroxide [1310-73-2] to remove small amounts of the monoester. The diester is then separated from solvent by distillation at atmospheric pressure, and the malonic ester obtained by redistillation under vacuum as a colorless Hquid with a minimum assay of 99%. The aqueous phase contains considerable amounts of mineral acid and salts and must be treated before being fed to the waste treatment plant. The process is suitable for both the dimethyl and diethyl esters. The yield based on sodium chloroacetate is 75—85%. Various low molecular mass hydrocarbons, some of them partially chlorinated, are formed as by-products. Although a relatively simple plant is sufficient for the reaction itself, a si2eable investment is required for treatment of the wastewater and exhaust gas. 

Flavonoids are the largest class of phenylpropanoids in plants. The basic flavonoid structure is two aromatic rings (one from phenylalanine and the other from the condensation of three malonic acids) linked by three carbons (Fig. 3.6). Chalcone is converted to naringenin by the enzyme chalcone isomerase, which is a key enzyme in flavonoid synthesis. This enzyme, like PAL and chalcone synthase (CHS), is under precise control and is inducible by both internal and external signals. Naringenin is the... 

Condensation of coumaric acid with malonic acid yields the basic chalcone and stilbane skeletons (see Fig. 3.6). Stilbenes are found in most vascular plants, where they exhibit fungicidal and to a lesser extent antibiotic properties. They function as both constitutive and inducible defense substances. Some stilbenes inhibit fungal spore germination and hyphal growth, whereas others are toxic to insects and parasitic nematodes (round-worms). They also possess antifeeding and nematicide properties in mammals. For example, resveratrol (a stilbene in red wine) suppresses tumor formation in mammals. 

Certain plants accumulate897 very high levels of nickel in their tissues Hybanthus floribundus contains up to 1.3% nickel on a dry mass basis, while Psychotria douarrei has up to 44% nickel in the plant ash. AUysum is also known as a nickel accumulator. A large part of the nickel in these plants is water soluble, and in the last case is associated with malic and malonic acids.898 In Hybanthus floribundus, the nickel is largely accumulated in the leaves, where it is associated with pectic carbohydrates. 

In the reaction of the isatins 7 [154, 155], 54 [17, 154, 155], or 186 [155, 158, 159] with malonic acid in the presence of sodium acetate [155, 158] or in acetic acid [17, 154, 155, 159] the reaction products were 2-hydroxy-4-quinolinecarboxylic acids, which usually exist in the form of the 2-quinolone derivatives 187, as a result of decarboxylation of the initially formed dicarboxylic acids. Compound 187 with R = R1 = R2 = H and R3 = Me was patented as a plant growth regulator (Aureorysin) [158],... 

Most xenobiotic GSH conjugates In plants are metabolized at least to cysteine conjugates and cysteine conjugates appear to be the pivotal point In metabolism. Cysteine conjugates may be end-products of metabolism, as observed In methldathlon metabolism In tomato and peanut cell suspension culture, or aclfluorfen metabolism In soybean and peanut cell suspension culture (16). Xenobiotic cysteine conjugates are frequently N-acylated with malonic acid as shown In Equation 25. This was demonstrated with the following... 

Miscellaneous Conjugates. Several xenobiotic acids conjugate with malonic acid alone. Since 0-amlno acids often are sequestered as IJ -malonyl derivatives by plants, it is not surprising that D-gj-fluorophenylalanlne is converted to such a malonate by tobacco cell cultures (103). is a metabolite of carboxin in a... 

Indol-3-ylacrylic acid, a tryptophane metabolite found in animals and in plants has been C-iabelled at the 2-position of the indole nucleus in order to investigate the possibility of its light-initiated covalent binding to DNA and its capability of photoinactivating phage ". [2- C]Indole 175 has been formylated at the 3-position with phosphorous oxychloride/DMF and the aldehyde 174 obtained was condensed with malonic acid in pyridine/piperidine " (equation 64) yielding the title compound 173. 173 labelled with C in the a-position is obtained using C-labelled malonic acid and non-labelled 174. It has been found that 173-[ C binds photolytically to DNA . ... 

Malonic acid (3) is particularly abundant in the Leguminosae although its function is still not entirely clear. Li and Copeland [17] described a study of the temporal and spatial distribution of organic acids in chickpea plants and investigated the different kinds of abiotic stress on organic acid... 

It has been known for some time that tolerance towards high levels of both essential and toxic metals in a local soil environment is exhibited by species and clones of plants that colonize such sites. Tolerance is generally achieved by a combination of exclusion and poor uptake and translocation. Some species can accumulate large quantities of metals in their leaves and shoots at potentially toxic levels, but without any harmful effects. These metal-tolerant species have been used in attempts to reclaim and recolonize metal-contaminated wastelands. More recently such species have attracted the attention of inorganic chemists. There is abundant evidence that the high metal levels are associated with carboxylic acids, particularly with nickel-tolerant species such as Allysum bertolonii. The main carboxylic acids implicated are citric, mahc and malonic acids (see refs. 30 and 31 and literature cited therein). Complexation of zinc by malic and oxalic acids has been reported in the zinc-tolerant Agrostis tenuis and oxalic acid complexation of chromium in the chromium-accumulator species Leptospermum scoparium ... 

R. 5 -malonic acid ester (c), C20H22N4O9, Mr 462.42, is the pigment of the blue light receptor and is responsible for phototropism in plants. 

In the period from 1817 to 1820, these two men and their students isolated many of the alkaloids, which continue to be of major importance. Included in that avalanche of purified natural products was caffeine, which they obtained from the coffee bean. This substance is the target compound that you will be isolating directly from the raw plant in this experiment. A little more than 75 years later, caffeine was first synthesized by Fischer in 1895 from dimethylurea and malonic acid. 

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