Vicinal elements

Cox AL, Johnston JN (2001) Use of the Vicinal Element Effect for Regiochemical Control of Quinone Substitutions and Its Implication for Convergent Mitomycin Construction. Org Lett 3 3695... 

The vicinal element effect (the leaving groups on neighbouring carbons) Park s carbanionic theory... 

An additional type of element effect, which will be called the vicinal element effect is possible when two leaving groups are attached at both ends of the same double bond. Whether X or Y leaves earlier, or which one leaves alone when only monosubstitution occurs, depends on the preferred position of the attack of the nucleophile, and on the reversibility of this step. For irreversible attack, the (19)/(20) ratio would be determined by the relative electrophilicity of the a- and the /l-carbon... 

Beit-Yannai, M., Rappoport, Z., Shainyan, B.A., and Danilevich, Y.S. (1997) Intramolecular geminal and vicinal element effects in substitution of simple bromo(chloro)alkenes by methoxide and thiolate ions. An example of a single step substitution Journal of Organic Chemistry, 62, 8049-8057. 

From an electrochemical viewpoint, stable pit growtli is maintained as long as tire local environment witliin tire pit keeps tire pit under active conditions. Thus, tire effective potential at tire pit base must be less anodic tlian tire passivation potential (U ) of tire metal in tire pit electrolyte. This may require tire presence of voltage-drop (IR-drop) elements. In tliis respect the most important factor appears to be tire fonnation of a salt film at tire pit base. (The salt film fonns because tire solubility limit of e.g. FeCl2 is exceeded in tire vicinity of tire dissolving surface in tlie highly Cl -concentrated electrolyte.)... 

Elements of the matrix —are usually small in the vicinity of a conical intersection and can be added to to give a corrected diabatic energy matrix. As can be seen, whereas in Eq. (15) contains both the singular... 

Yarkoni [108] developed a computational method based on a perturbative approach [109,110], He showed that in the near vicinity of a conical intersection, the Hamiltonian operator may be written as the sum a nonperturbed Hamiltonian Hq and a linear perturbative temr. The expansion is made around a nuclear configuration Q, at which an intersection between two electronic wave functions takes place. The task is to find out under what conditions there can be a crossing at a neighboring nuclear configuration Qy. The diagonal Hamiltonian matrix elements at Qy may be written as... 

The acceptance of the name was premature because both Russian and American efforts now completely rule out the possibility of any isotope of Element 102 having a half-life of 10 min in the vicinity of 8.5 MeV. Early work in 1957 on the search for this element, in Russia at the Kurchatov Institute, was marred by the assignment of 8.9 +/- 0.4 MeV alpha radiation with a half-life of 2 to 40 sec, which was too indefinite to support discovery claims. 

Electrochemical Process. Several patents claim that ethylene oxide is produced ia good yields ia addition to faradic quantities of substantially pure hydrogen when water and ethylene react ia an electrochemical cell to form ethylene oxide and hydrogen (206—208). The only raw materials that are utilized ia the ethylene oxide formation are ethylene, water, and electrical energy. The electrolyte is regenerated in situ ie, within the electrolytic cell. The addition of oxygen to the ethylene is activated by a catalyst such as elemental silver or its compounds at the anode or its vicinity (206). The common electrolytes used are water-soluble alkah metal phosphates, borates, sulfates, or chromates at ca 22—25°C (207). The process can be either batch or continuous (see Electrochemicalprocessing). 

Figure 2 Standard output of an EDS spectrum. The horizontal axis is the energy scale is and the vertical axis is the number of photons per energy interval. The X-ray identification, element and line, is indicated in the vicinity of the peaks.

Particulate emissions have their greatest impact on terrestrial ecosystems in the vicinity of emissions sources. Ecological alterations may be the result of particulate emissions that include toxic elements. Furthermore, the presence of fine particulates may cause light scattering, known as atmospheric haze, reducing visibility and adversely affecting transport safety, property values, and aesthetics. 

The person responsible for the design must know drill string performance properties, data from wells already drilled in the nearest vicinity and current prices of the drill string elements. 

A valve that closes in case of fire should be inserted in the oil fuel line to the oil-burning equipment and fitted as close to the tank as possible. It may be held open mechanically, pneumatically or electrically. Temperature-sensitive elements should be arranged to close the valve at a fixed maximum temperature, and sited close to the oil-fired plant and well above floor level. The operating temperature of the heat-sensitive elements should not be greater than 68°C (155°F) except where ambient temperatures in the vicinity of the plant may exceed 418°C (120°F), in which case the operating temperatures may be 183°C (200°F). 

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