Labels vinyl

These new data acquired with double-labeled vinyl probes (13CH2=13CHBr and 13CH2=13CH2) determined first on Rh, but found to be similar for more common Fischer-Tropsch catalysts (Ru, Fe, Co) showed that these are readily incorporated into the alkene and the alkane products. In addition, an increase in the rate of hydrocarbon formation was observed during vinylic but not ethyl addition. These data indicate that the participation of vinyl intermediates is an integral part of the surface polymerization mechanism, specifically, vinyl (alkenyl) intermediates couple with surface methylene in hydrocarbon formation ... 

Vinyl chloride is generally transported via pipeline, and in railroad tank cars and tanker ships. Containers of vinyl chloride must be labeled "vinyl chloride," "extremely flammable gas under pressure," and "cancer-suspect agent" (146). Because hazardous peroxides can form on standing in air, especially in the presence of iron impurities, vinyl chloride should be handled and transported under an inert atmosphere. The presence of peroxide from vinyl chloride and air can initiate polymerization of stored vinyl chloride however, stabilizer can be added to prevent polymerization. Inhibitors such as hydroquinone [123-31-9] are often added, particularly when shipping long distances in warmer climates. 

It was also suggested that the fragmentation of the excited C3HeT+ ions which escape stabilization occurs predominantly according to processes (59) and (60). These produce, in addition to tritiated methane, labeled vinyl and allyl ions, whose consecutive reactions with cyclopropane lead to the formation of tritiated ethylene by two different routes ... 

This procedure has been utilized by Nicolaou to prepare the vinyl iodide (482) in the synthesis of lipo-toxins As and Bs (equation 111). The synthesis of vinyl iodides was also utilized by Bestmann in a stereospecific synthesis of (4 ,6 ,llZ)-hexadecatrienal. A Wittig reaction was used to create the ( )-al-kene (484), and the ( )-diene portion was synthesized via vinyl iodide (485) formation and coupling (Scheme 63). This method has been applied to the synthesis of > C-labeled vinyl iodide (488 equation 112). Labeled iodoform (486) was ma and the reaction conditions altered fhrni those employed by Takai and cowmkers in order to use smaller quantities of the valuable iodoform, relative to C1CI2. 

Another in vivo study with a negative result was performed by Simon et al. (58). After administration of (14C) vinyl acetate to male and female rats, either orally or by inhalation, no specific hepatic DNA adducts, known to occur after administration of labelled vinyl halides or vinyl carbamates, could be observed in liver. 

Antoni and Langstrom have recently reported the synthesis of carbon-11 labelled vinyl cyanides from H CN. This provides useful synthons because vinyl chlorides can undergo Michael additions to give a wide variety of carbon-11 labelled compounds. The carbon-11 labelled vinyl and cinnamyl cyanides have been prepared in 35% yield and greater than 99% radiochemical purity in 3 minutes by reacting CN with the appropriate bromide in the presence of a palladium catalyst and 18-crown-6 ether in acetonitrile (equation 71). 

An example illustrating the synthetic possibilities arising from the Michael addition reaction with these carbon-11 labelled vinyl cyanides is their addition to the carbanion formed from dimethyl malonate (equation 72). These compounds are useful from a... 

The ethynyl-7-lactone (XI), prepared from levulinic acid as indicated in Fig. 7, was partially tritiated to give the labeled vinyl-7-lactone (XII). 

Thermal Cope-type rearrangements between C-vinyl and nitrogen substituents bearing appropriately labeled unsaturation are also known, e.g. (147) -> (148) (67JA60S, 71JOC3076). 

Minimize stocks and segregate from other chemicals and work areas. Where appropriate, keep samples dilute or damp and avoid formation of large crystals when practicable. Add stabilizers if possible, e.g. to vinyl monomers. Store in specially-designed, well-labelled containers in No Smoking areas, preferably in several small containers rather than one large container. Where relevant, store in dark and under chilled conditions, except where this causes pure material to separate from stabilizer (e.g. acrylic acid). 

Several approaches have been disclosed to make release coatings that can be printed with ink jet or laser jet printers (e.g., to make linerless labels). For example, Khatib and Langan [164] disclose a blend of two different acrylate functional silicones, one with a high level of acrylate functionality to provide the printability and one with a low level of acrylate functionality to provide easy PSA release. Lievre and Mirou [165] describe an aqueous blend of a crosslinkable silicone and poly(vinyl alcohol-vinyl acetate) resins while Shipston and Rice describe a blend of acrylic resin and a surfactant [166]. 

Binder formulas for carpet backing, aluminum foil to paper, vinyl flooring, tire cord, paper labeling, masking tape, and oriented polypropylene tape applications are available from Midgley and Rea in Skiest [215]. 

Evidence for this mechanism comes from the observation that the rearrangement takes place with an inversion of the allyl group. That is, allyl phenyl ether containing a 14C label on the allyl ether carbon atom yields o-allylphenol in which the label is on the terminal vinylic carbon (green in Figure 18.1). It would be very difficult to explain this result by any mechanism other than a pericyclic one. We ll look at the reaction in more detail in Section 30.8. 

Evidence for migration of the arylthio group across the double bond comes from C-14 labeling studies on ester 213 and product studies from unsymmetrical vinyl sulfonates 214 (181). Complete scrambling of the C-14... 

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