Sulfur geometry

Heterocyclic Compounds, Five- and Six-Membered, Containing Oxygen or Sulfur, Geometry and Conformational Properties of (Romers, Altona, Buys asiA Havinga) 4 39... 

Monophosphams. The similar tetrahedral geometry and bond lengths of tetracoordinate phosphoms(V) compared to those of sulfur(VI) suggested that phosphonic and phosphinic acid groups might act as biososteres for the sulfonic acid moiety in the parent monobactams. The... 

Electrophilic attack on the sulfur atom of thiiranes by alkyl halides does not give thiiranium salts but rather products derived from attack of the halide ion on the intermediate cyclic salt (B-81MI50602). Treatment of a s-2,3-dimethylthiirane with methyl iodide yields cis-2-butene by two possible mechanisms (Scheme 31). A stereoselective isomerization of alkenes is accomplished by conversion to a thiirane of opposite stereochemistry followed by desulfurization by methyl iodide (75TL2709). Treatment of thiiranes with alkyl chlorides and bromides gives 2-chloro- or 2-bromo-ethyl sulfides (Scheme 32). Intramolecular alkylation of the sulfur atom of a thiirane may occur if the geometry is favorable the intermediate sulfonium ions are unstable to nucleophilic attack and rearrangement may occur (Scheme 33). 

The two types of vessel geometries employed are vertieal and horizontal. In most of the fine ehemieals proeesses the leaves are fitted into vertieal vessels whereas horizontal vessels are used in the heavier process industries sueh as the preparation of sulfur in phosphoric acid plants. The leaves inside horizontal tanks may be positioned either along the tank axis or perpendieular to the axis. In order to utilize the tank volume for maximum filtration area the width of the leaves is graduated so they fit to the eireular eontour of the tank. 

Verify, by making molecular models, that the bonds to sulfur are arranged in a trigonal pyramidal geometry in sulfoxides and in a tetrahedral geometry in sulfones. Is phenyl vinyl sulfoxide chiral What about phenyl vinyl sulfone ... 

Reaction of the allylborane 147 with 148 then workup with KOH gave the E isomer, while the workup with sulfuric acid gave the Z isomer 149. Heating the azidodiene 149 in CDCI3 in a sealed tube afforded 150 in one step. The stereoselectivity of the reaction was found to be slightly dependent on the geometry of the diene (89TL6661) (Scheme 29). 

The pneumatic tire has the geometry of a thin-wallcd toroidal shell. It consists of as many as fifty different materials, including natural rubber and a variety ot synthetic elastomers, plus carbon black of various types, tire cord, bead wire, and many chemical compounding ingredients, such as sulfur and zinc oxide. These constituent materials are combined in different proportions to form the key components of the composite tire structure. The compliant tread of a passenger car tire, for example, provides road grip the sidewall protects the internal cords from curb abrasion in turn, the cords, prestressed by inflation pressure, reinforce the rubber matrix and carry the majority of applied loads finally, the two circumferential bundles of bead wire anchor the pressnrized torus securely to the rim of the wheel. 

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