Highly strained

Hoover W G, Ladd A J C and Moran B 1982 High strain rate plastic flow studied via nonequilibrium molecular dynamics Phys. Rev.L 48 1818-20... 

We illustrate the method for the relatively complex photochemistry of 1,4-cyclohexadiene (CHDN), a molecule that has been extensively studied [60-64]. There are four it electrons in this system. They may be paired in three different ways, leading to the anchors shown in Figure 17. The loop is phase inverting (type i ), as every reaction is phase inverting), and therefore contains a conical intersection Since the products are highly strained, the energy of this conical intersection is expected to be high. Indeed, neither of the two expected products was observed experimentally so far. 

Sulfonium ylides may be added to C N double bonds to yield aziridines in a formal [1 -t-2]-cycloaddition. Alkyl azides are decomposed upon heating or irradiating to yield ni-trenes, which may also undergo [ 1 + 2 -cycloaddition reactions to yield highly strained hetero-cycles (A.G. Hortmann, 1972). 

The novel intramolecular reaction of the alkenyl bromide with the terminal alkyne in 328, followed by intramolecular Diels-Alder reaction, afforded the highly strained dynemicin A structure 329 in one stepf237]. 

Hydroxy-THISs react with electron-deficient alkynes to give nonisol-able adducts that extrude carbonyl sulfide, affording pyrroles (23). Compound 16 (X = 0) seems particularly reactive (Scheme 16) (25). The cycloaddition to benzyne yields isoindoles in low- yield. Further cyclo-addition between isoindole and benzyne leads to an iminoanthracene as the main product (Scheme 17). The cycloadducts derived from electron-deficient alkenes are stable (23, 25) unless highly strained. Thus the two adducts, 18a (R = H, R = COOMe) and 18b (R = COOMe, R = H), formed from 7, both extrude furan and COS under the reaction conditions producing the pyrroles (19. R = H or COOMe) (Scheme 18). Similarly, the cycloadduct formed between 16 (X = 0) and dimethylfumarate... 

J. L. Edwards, B. H. Cranston, and G. Krauss, Metallic Fffects at High Strain Rates, Plenum Press, New York, 1973. 

Al—Mg—Mn. The basis for the alloys used as bodies, ends, and tabs of the cans used for beer and carbonated beverages is the Al—Mg—Mn alloy system. It is also used in other appHcations that exploit the excellent weldabiUty and corrosion resistance. These alloys have the unique abiUty to be highly strain hardened yet retain a high degree of ductOity. Some of the manganese combines with the iron to form AF(Fe,Mn) or constituent... 

V-methylpiperidine oxide [17206-00-7] does not undergo the reaction because of its inabihty to achieve the highly strained transition configuration, whereas the... 

Another type of experiment involves a fluid filament being drawn upward against gravity from a reservoir of the fluid (101,213,214), a phenomenon often called the tubeless siphon. The maximum height of the siphon is a measure of the spinnabiUty and extensional viscosity of the fluid. Mote quantitative measures of stress, strain, and strain rate can be determined from the pressure difference and filament diameter. A more recent filament stretching device ia which the specimen is held between two disks that move apart allows measurements ia low viscosity Hquids (215). AH of these methods are limited to spinnable fluids under small total strains and strain rates. High strain rates tend to break the column or filament. 

There is another technique that can be used with low viscosity (100 mPa-s) nonspinnable fluids and which allows high strain rates (>10 ). A... 

Rohde, R.W., B.M. Butcher, D.R. Holland, and C.H. Karnes (1973), Metallurgical Effects At High Strain Rates, Plenum, New York. 

Murr, L.E. (1981), Shock Waves and High-Strain-Rate Phenomena in Metals, Plenum, New York, pp. 1-1101. 

This phenomena has been attributed to the very high strain rates associated with shock loading and the subsonic restriction on dislocation velocity requiring the generation and storage of a larger dislocation density during the shock process than for quasi-static processes [1], [2], [12],... 

L.E. Murr, Metallurgical Effects of Shock and High-Strain-Rate Loading, in Materials at High Strain Rates (edited by T.Z. Blazynski), Elsevier/Applied Science, London, 1987, p. 1. 

P.S. Follansbee, High-Strain-Rate Deformation Mechanisms in Copper and Implications for Behavior during Shock-Wave Deformation, in Shock Waves in Con-... 

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