Dimethyl from plants

Further thymol derivatives have been isolated from plant sources 49.3% of the oil from Eupatorium triplinerve consists of thymohydroquinone dimethyl ether (166), ° and esters of 1-hydroxythymol methyl ether (167) and 1-hydroxy-... 

The bioactivities of precocene I, 7-methoxy-2,2-dimethyl chromene, and precocene II, 6,7-dimethoxy-2,2-dimethyl chromene, are well established (Fig. (7)). These two compounds have been isolated from plants throughout the family Asteraceae [129-136, 154]. The chemical data for these compounds and references for their synthesis are compiled in Appendix IV, Tables 13 and 14. There is a wealth of information on the effects of these compounds on various insect species [42, 137]. For simplicity, we will focus on the effects of precocene II on the susceptible Hemipteran bug, Oncopeltus fasciatus. 

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. 

In a similar appHcation, Cape Industries has announced its intention to commission a solvent extraction plant to recover acetic acid from an effluent generated at its dimethyl terephthalate [120-61-6] faciHty (Wilmington, North Carolina) (44,45). The plant was commissioned in Eebmary 1995. In this case, the solvent will be CYANEX 923 extractant [100786-00-3], CYANEX 923 is also a phosphine oxide, but unlike TOPO is a Hquid and can be used without a diluent (46,47). This has the benefit of reducing plant size, capital, and operating costs. 

An analogue of the transesterification process has also been demonstrated, in which the diacetate of BPA is transesterified with dimethyl carbonate, producing polycarbonate and methyl acetate (33). Removal of the methyl acetate from the equihbrium drives the reaction to completion. Methanol carbonylation, transesterification using phenol to diphenyl carbonate, and polymerization using BPA is commercially viable. The GE plant is the first to produce polycarbonate via a solventiess and phosgene-free process. 

Processes involving oxygen and nitrogen oxides as catalysts have been operated commercially using either vapor- or Hquid-phase reactors. The vapor-phase reactors require particularly close control because of the wide explosive limit of dimethyl sulfide in oxygen (1—83.5 vol %) plants in operation use Hquid-phase reactions. Figure 2 is a schematic diagram for the Hquid-phase process. The product stream from the reactor is neutralized with aqueous caustic and is vacuum-evaporated, and the DMSO is dried in a distillation column to obtain the product. 

Sulfur dioxide occurs in industrial and urban atmospheres at 1 ppb—1 ppm and in remote areas of the earth at 50—120 ppt (27). Plants and animals have a natural tolerance to low levels of sulfur dioxide. Natural sources include volcanoes and volcanic vents, decaying organic matter, and solar action on seawater (28,290,291). Sulfur dioxide is beHeved to be the main sulfur species produced by oxidation of dimethyl sulfide that is emitted from the ocean. 

Manske has isolated from several papaveraceous plants an alkaloid aurotensine (items 9, 19, 23, 44, 47, 48 list, pp. 170-3) which occius in rhombic plates, m.p. 128° [a]n — 69-9° and appears to be an addition compound of I- and di-scoulerine (Manske ). Its dimethyl ether caseanine item 10 list, p. 170), m.p. 115-6° (hydrated) or 142° (ex benzene) must be tetrahydropalmatine (p. 292) and casealutine, found with caseanine, was shown later by Manske to be i-isocorypalmine. 

The external-loop slurry airlift reactor was used in a pilot plant (3000 t/a) for one-step synthesis of dimethyl ether (DME) from syngas. Specially designed internals were used to intensify mass transfer and heat removal. This new technology is highly efficient and easy to scale-up to industrial. 

The condensed reaction mixture is evaporated in film evaporator 16 under vacuum. The crude l-(2,6-dimethyl)-phenoxy-2-aminopropane hydrochloride is precipitated in tank 17 using HCl dissolved in organic solvent //, separated in centrifuge 18, and dried in tray drier 19. The final purification by crystallization from solvent III occurs in crystallizer M. Pure l-(2,6-dimethyI)-phenoxy-2-amino-propane hydrochloride is separated in centrifuge 21 and dried in tray drier 22. The plant is equipped with typical solvent recovery and storage facilities not shown in the figures. 

The plant is strongly aromatic on account of an essential oil which comprises cis-a-ocimene (25.11%), 3,7-dimethyl-l,6-octadien-3 ol (16.85%), and trans-nerolidol (13.89%), hence the use of the plant in aromatherapy. A methanolic extract of bark of Litsea cubeba (Lour.) Pers. and its fractions (0.01 mg/mL) from bark inhibit NO and PGE2 production in LPS-activated RAW 264.7 macrophages without significant cytotoxicity at less than 0.01 mg/mL concentration. The methanol extract decreased the enzymatic activity of myeloperoxidase (0.05 mg/mL). These findings suggest that L. cubeba is beneficial for inflammatory conditions and may contain compound(s) with anti-inflammatory properties (63). Can we expect the vasorelaxant laurotetanine (64) isolated from the plant to exert such activity ... 

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