128 research outputs found

    The lead tetra-acetate oxidations of some N-arylaminofumarates in the presence of trifluoroacetic acid

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    p-Chloroanilino-, p-acetylanilino-, and p-toluidinojumarates are oxidized by lead tetraacetate in low yields to give oxanzlate. Similar oxidation of p-acetylan Nnofumarate in the presence of trifluoroacetic add affords only oxanilate. p- Toluidino and p-chloroanilinojumarates with lead tetra-acetateltrifluoroacetic acid give mixtures of oxazin, azobenzene and anzlide

    Biological Activity of Some Malaysian Plant Extracts

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    Extracts obtained from three Malaysian Labiatae plants, including Ocimum sanctum, Mentha arvensis and Orthoshiophon staminea, were investigated for their biological activity. The volatile fraction of each plant was isolated and the major components were characterized by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS), and nuclear magnetic resonance (NMR). The antibacterial and antifungal activity, insecticidal activity and inhibition of the germination of seeds of the volatile fraction and residue were studied

    Pemprosesan Kimia ke atas Buangan Pertanian Padi

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    The production process of 2-furaldehyde (furfural) from agricultural wastes including the husk, leaf and straw was investigated chemically. Three types of pro tic acid were tested with respect to its cataly tic activity. The effect of hydrochloric acid concentration on the yield percentage was also investigated

    Chemical Conversion of the Oil Palm Wastes

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    The production of a 2-furaldehyde (furfural) from mesocarp fibre waste and oil palm sludge from a palm oil mill using protic acids was investigated. The effect of immersion of fibre in acid prior to heating was also studied. Production of furfural was completed in 3-4 hours when hydrochloric (HCI) or sulfuric (H2S04 ) acids were used as the catalyst whereas a longer reaction time was required in the case of phosphoric (H3P04 ) or oxalic (H2C20 4 ) acids. The experiment showed that the rates of furfural production were increased when higher acid concentrations were applied. Immersion of fibre in the acids for 24 hours prior to reaction increased the furfural yield. The chemical conversion of sludge from the palm oil mill was also investigated. A similar acid concentration effect on the rate was observed

    Toxicity Studies of Plant Extracts on Insects and Fish

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    Toxicity studies of several local plant extracts on insects and fish were carried out. The volatile fraction of some of plant extracts was isolated and the major components were characterized. The contact insecticidal activity and the toxicity test of the plant extract on fishes were studied

    Development of microwave system for extraction of essential oils from Mesua ferrea L. leaves and Jasminum samhac flowers

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    A microwave extraction system (MES) was developed for the extraction of essential oils from Mesua ferrea L. leaves and Jasminum sambac flowers. The performance of MES was compared with the conventional extraction method (CEM) for dry distillation (DD), wet distillation (WD), hydro distillation (HD) and steam distillation (SD) in terms of rapidity, quality and quantity of yield and its efficiency. Mesua ferrea L. extracted by HD contributed 0.035% of yield, WD 0.029%, DD 0.024% and SD 0.013%. For Jasminum sambac, DD contributed 0.10%, WD 0.06% while SD and HD both contributed 0.02%, respectively. Although more compounds were detected in CEM extract, substantial higher amounts of odoriferous compounds were present in MES extract. The project has successfully proved that MES is more efficient than CEM in terms of rapidity, quality and quantity of yield

    Comparison between conventional and microwave-assisted hydrodistillation methods towards extraction of essential oils from Murraya koenigii (Curry leaves)

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    Study on the extraction of essential oils from leaves of Murraya koenigii had been carried out by conventional hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD) methods. Time of the first oil droplet, percentage yield of the extracted oils and the chemical components of the extracted essential oils from both methods were compared. The running time for MAHD was set at one and half hour while running time for HD was 5 hours. The major components from the essential oils obtained from HD method were β-copaene (41.5%), α-selinene (10.0%) and α-humulene (8.4%). Meanwhile, major chemical components extracted from MAHD method were β-caryophyllene (19.5%), terpine-4-ol (17.6%) and linalool (9.8%). A total of 79.6% of chemical components were identified from essential oil extracted through HD method while MAHD method was 75.7%. The first oil droplet for HD method was found to be at 34 minutes and 20 minutes for MAHD method. MAHD is more preferable method for extracting essential oils from Murraya koenigii as it provides high extraction efficiency with less time taken

    Investigation on the Chemical Constituents of the Leaves of Ficus elastica Roxb. and Their Antimicrobial Activity

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    Four known compounds (emodin, sucrose, morin and rutin) were isolated from the leaves of Ficus elastica Roxb. The structures of the compounds were established by spectroscopic techniques and by comparison with published data. The compounds were screened for antimicrobial activity against two species of bacteria, Bacillus cereus (Gram-positve) and PseuiUlmonas aeruginosa (Gram-negative) and four species of fungi by using the disc diffusion method. The compounds showed antibacterial activity but no antifungal activity was observed against the tested organisms

    Screening of Tropical Plants for the Presence of Bioactive Compounds

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    The use of synthetic pesticides and herbicides to control insect and weed pests has posed substantial problems due to their persistence in the environment, insect resistance and high mammalian toxicity. On the other hand. plant-de1ived insecticide are more readily biodegraded, less likely to contaminate the environment and less toxic to non target organism.s. Hence, the search for new sources of such compounds from plants has gained popularity amongst researchers. A screening procedure far the presence of bioactive compounds from plant sources by using brim: shrimp as the general bio assay has been can;ed out and a number of plant species has been identified for further detailed studies. The crude extracts and purified samples were further tested using other more specific bioassay methods
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