ETHYLENE BLUE

Davison and Lishman [105] described a method in which sulphide is released from the sediment using 5.93mol L 1 hydrochloric acid, and the resulting solution is separated from the sediment by filtration in a sealed system of syringes. The concentrated sulphide is determined spectrophotometrically at 670nm as ethylene blue. The limit of detection is 2mg kg-1 expressed as mass of sulphide in dry mass of sediment. The relative standard deviation was 5% for a sediment containing 118mg kg 1 sulphide. 

Another method used in the manufacture of the so-called ethylene blue consists in treating nitrosodimethylaniline in sulphuric acid solution (sp. gr. 1 4) with zinc sulphide. Leuco-methylene blue is produced, and yields the dyestuff on oxidation. 

The Methylene (and Ethylene) Blue method has been applied in determinations of sulphur in plants [86], biological materials [87], waters [12,88], air [5,12,16,20], hydrocarbons [89], iron alloys [90,91], cobalt and zirconium [91], titanium [92], thallium and its halides [93], arsenic [94], selenium [95], and various reagents (including barium chloride) [14]. Flow-injection analysis has been applied in the determination of sulphur by the Methylene Blue method [96]. 

The liquid becomes progressively darker in colour, and then effervesces gently as ethylene is evolved. Allow the gas to escape from the delivery-tube in T for several minutes in order to sweep out the air in F and B. Now fill a test-tube with water, close it with the finger, and invert the tube in the water in T over the delivery-tube so that a sample of the gas collects in the tube. Close the tube again with the finger, and then light the gas at a Bunsen burner at a safe distance from the apparatus. If the tube contains pure ethylene, the latter burns with a clear pale blue (almost invisible) flame if the ethylene still contains air, the mixture in the test-tube ignites with a sharp report. Allow the... 

FIGURE 6 4 Electro static potential maps of HCI and ethylene When the two react the interaction is between the electron rich site (red) of ethylene and electron poor region (blue) of HCI The electron rich region of ethylene is associ ated with the tt electrons of the double bond and H IS the electron poor atom of HCI... 

Polyethylene terephthalate [25038-59-9] (8) is a polyester produced by the condensation polymerization of dimethyl terephthalate and ethylene glycol. Polyethylene terephthalate sutures are available white (undyed), or dyed green with D C Green No. 6, or blue with D C Blue No. 6. These may be coated with polybutylene adipate (polybutilate), polyydimethylsiloxane, or polytetrafiuoroethylene [9002-84-0]. The sutures are distributed under the trade names Ethibond Exel, Mersdene, Polydek, Silky II Polydek, Surgidac, Tevdek II, Polyester, and Tl.Cron. 

Deflagration pressure can be reduced substantially by suppression. Figure 26-30 shows the pressures measured in an ethylene-air explosion and a sodium bicarbonate-suppressed ethylene-air explosion. Fike Corporation, Blue Springs Missouri, and Fenwal Safety Systems, Marlborough, Mass., supply explosion suppression systems. 

Aromatic steroids are virtually insoluble in liquid ammonia and a cosolvent must be added to solubilize them or reduction will not occur. Ether, ethylene glycol dimethyl ether, dioxane and tetrahydrofuran have been used and, of these, tetrahydrofuran is the preferred solvent. Although dioxane is often a better solvent for steroids at room temperature, it freezes at 12° and its solvent effectiveness in ammonia is diminished. Tetrahydrofuran is infinitely miscible with liquid ammonia, but the addition of lithium to a 1 1 mixture causes the separation of two liquid phases, one blue and one colorless, together with the separation of a lithium-ammonia bronze phase. Thus tetrahydrofuran and lithium depress the solubilities of each other in ammonia. A tetrahydrofuran-ammonia mixture containing much over 50 % of tetrahydrofuran does not become blue when lithium is added. In general, a 1 1 ratio of ammonia to organic solvents represents a reasonable compromise between maximum solubility of steroid and dissolution of the metal with ionization. 

Xthyl at, n. ethylate, -atber, m. ethyl ether, >azetat, n, ethyl acetate, -blau, n, ethyl blue. AthyleQi n, ethylene, -bindung, /, ethylene linkage, double bond, -jodid, n. ethylene iodide, -oryd, n. ethylene oxide, -reihe, /. ethylene series, -verbindung, /. ethylene compound,... 

Figure 1.14 The structure of ethylene. Orbital overlap of two sp hybridized carbons forms a carbon-carbon double bond. One part of the double bond results from a (head-on) overlap of sp2 orbitals (green), and the other part results from (sideways) overlap of unhybridized p orbitals (red/blue). The ir bond has regions of electron density on either side of a line drawn between nuclei.

To illustrate this rule, consider the ethylene (C2H4) and acetylene (C2H2) molecules. You will recall that the bond angles in these molecules are 120° for ethylene and 180° for acetylene. This implies sp2 hybridization in C2H4 and sp hybridization in C2H2 (see Table 7.4). Using blue lines to represent hybridized electron pairs,... 

Bonding orbitals in ethylene (CH2=CH2) and acetylene (CH=CH). The sigma bond backbones are shown in blue. The pi bonds (one in ethylene and two in acetylene) are shown in red. Note that a pi bonding orbital consists of two lobes. 

Anthracene, B. D. H. (blue fluorescence), was used. Traces of ethylene glycol, glycerol, ethanol, or water considerably retard the reaction and lead to unsatisfactory results. 

Release of tetracycUne hydrochloride from PCL fibers was evaluated as a means of controlled administration to periodontal pockets (69). Only small amounts of the drug were released rapidly in vitro or in vivo, and poly(ethylene-co-vinyl acetate) gave superior results. Because Fickian diffusion of an ionic hydrochloride salt in a UpophiUc polymer is unlikely, and because PCL and EVA have essentially identical Fickian permeabilities, we attribute this result to leaching of the charged salt by a mechanism similar to release of proteins from EVA (73). Poly-e-caprolactone pellets have been found unsuitable for the release of methylene blue, another ionic species (74,75). In this case, blending PCL with polyvinyl alcohol (75% hydrolyzed) increased the release rate. 

Prussian blue (iron hexaferrocyanate) came into contact with ethylene oxide at 20 C. The reaction was very violent and the residue formed combusted spontaneously in air. 

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