Ethyl Chloroformate Links

Nitrophenyl chloroformate activation. The reaction of polysaccharides with chloroformates forming reactive carbonate derivatives has often been used to link bioactive compounds, such as affinity ligands and enzymes, onto polysaccharide matrixes. It was reported that upon reaction with ethyl chloroformate cyclic carbonate as well as ethyl-carbonate structures are formed (9-13). Activation with N-succinimi-do chloroformate (14), 2,4,5-trichloroformate (14) and 4-nitrophenyl chloroformate (14, 15) reportedly led to the introduction of pending carbonate moieties. 

The basic concepts of competitive-binding solid phase EIA have been described elsewhere.The required separation of antibody from the assay mixture can be accomplished in a variety of ways. Double-antibody techniques are quite popular and involve the use of a second antibody, an antibody to the principal antibody, to induce separation. Cross-linking the second antibody serum - with ethyl chloroformate forms an insoluble suspension of small particles, which still maintain a high degree of im-munoreactivity toward the first antibody. Addition of such particles to an EIA assay mixture pulls the first antibody from solution along with enzyme-labeled molecules bound to the antibody. Such a process is depicted in Fig. 1 and employed for all separations in this work. Measurement of enzyme activity in the bound solid phase is desirable because complete purification of the labeled substance is not necessary. 

Cross-linking with a bifunctional reagent. Examples of such reagents are ethyl chloroformate [7], glutaraldehyde [8] or ethyl maleic anhydride [9]. Column properties of supports prepared this way are generally low, and due to the presence of unreacted functional groups in the matrix non-specific adsorption can be high. 

Linear non-cross-linked polystyrene has been used for organic synthesis since it is readily soluble in common organic solvents (i.e., dichloromethane, chloroform, tetrahydrofuran, toluene, ethyl acetate, and pyridine) but precipitates upon addition of water or methanol [123-126]. However, no examples of the use of this polymer in conjunction with microwave chemistry have been reported. 

In this section the use of polystyrene and copolymers of styrene with various cross-linking agents as supports for solid-phase organic synthesis is discussed. Copolymers of styrene with divinylbenzene are the most common supports for solid-phase synthesis. Depending on the kind of additives used during the polymerization and on the styrene/divinylbenzene ratio, various different types of polystyrene can be prepared. However, non-cross-linked polystyrene has also been used as a support for organic synthesis [10,16-22], Linear, non-cross-linked polystyrene is soluble in organic solvents such as toluene, pyridine, ethyl acetate, THF, chloroform, or DCM, even at low temperatures, but can be selectively precipitated by the addition of methanol or water. 

A number of industrial chemicals have been linked to cardiotoxicity. Aldehydes and primary alcohols that can be metabolically oxidized to aldehydes have exhibited cardiodepressant effects. Acute exposure to ethanol has caused arrhythmia. Isopropyl alcohol (2-propanol), a widely used industrial chemical and personal care product, may cause cardiovascular depression and excessively rapid heartbeat. Some halogenated hydrocarbons, including chloroform, ethyl bromide, and trichlo-rofluoromethane, have been implicated in cardiovascular disorders, including arrhythmia. 

Other approaches for insolubilization have been proposed by Francotte more stable CSPs could be obtained by cross-linking polysaccharide derivatives photochemical I y initiated ] 163] or thermally initiated ] 164] (Tables 9.5 and 9.6) using a radical reaction. The new CSPs exhibited improved separations for many racemates, predominantly through the ability to use chloroform and other co-solvents. Further, compounds that were insoluble in the commonly used /)-heptane-2-propanol eluents could be easily separated into individual enantiomers, and for many enantioseparations run times can be reduced with chloroform, ethyl acetate or THF containing mobile phases. These improved CSPs are about to be commercialized. 

Iodoform, CHI3, tri-iodomethane, is formed when alcohol and certain other compounds (66) are treated with iodine in the presence of an alkali. It can be prepared by adding iodine to a warm aqueous solution of alcohol or acetone which contains sodium carbonate. The iodoform, which separates as a yellow precipitate, is purified by crystallization from dilute alcohol. It crystallizes in yellow, lustrous, six-sided plates, which melt at 119 , and have a peculiar, very characteristic odor. The reactions by which alcohol is converted into iodoform are analogous to those as the result of which chloroform is obtained from alcohol. The formation of iodoform is often used as a test for ethyl alcohol, but as other substances, such as acetone, isopropyl alcohol, and aldehyde yield iodoform when warmed in alkaline solution with iodine, the test is not reliable unless it is known that the other substances which respond to it are absent. Most of the compounds which yield iodoform when treated in this way contain the group CH3.C linked to oxygen. 

Menet et al. have computed the Viow and Kp values for the 15 solvent systems smdied by Ito, along with 6 not previously studied [i.e., dimethyl sulfoxide (DMSO)-heptane (1 1, v/v), dimethyl formamide (DMF)-heptane (1 1, v/v), toluene-water (1 1, v/v), O-xylene-water (1 1, v/v), heptane-acetic acid-methanol (1 1 1, v/v) and chloroform-ethyl acetate-water-methanol (2 2 2 3, v/v)]. All the results have allowed them to define ranges of settling velocities linked to the hydrophobic, intermediate, or hydrophilic behavior of the solvent system. They have demonstrated the most reliable scale was that based on V p, which is the description of the rise of a droplet of the lighter phase in a continuous heavier one. 

Casting a film can refer to picking people to be in a movie, but here it refers to a method of preparing polymers for infrared transmission analysis. In this technique, the polymer is first dissolved in a volatile solvent, which is required because the solvent is evaporated later. Examples of solvents that work well include acetone, methyl ethyl ketone, chloroform, methylene chloride, tetrahydrofuran, and toluene. The polymer can be in any form, be it a sheet, formed part, chunk, or pellet. As long as the polymer will dissolve in a volatile solvent, in theory its spectrum can be measured. Thermoset polymers, which consist of three-dimensional cross-linked polymer networks, do not dissolve in solvents and hence cannot be analyzed using this technique. The amount of polymer and solvent used can be eyebaUed, but more consistent results are obtained if the amount of polymer and solvent are measured. 

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