Large-scale yielding

Hydroxylation. Olefins can be oxidized to cw-diols by this reagent in anhydrous CH2CI2 at - 70°. This reaction should not be carried out on a large scale. Yields of diols are generally higher than those obtained with KMn04 in the presence of a phase-transfer catalyst or a crown ether. 

An experimental investigation was performed on a laminate and separately on the individual components of the laminate. Peak load, energy dissipation at onset of fracture and at fast fracture were investigated. Fracture toughness cannot easily be defined because of very large scale yielding. Therefore an alternative toughness measurement was proposed. 

Newman and Sttella 18 Cold Flow and Large Scale Yielding... 

The fracture of most semicrystalline polymers, notably polyethylene, polypropylene and nylon, cannot be described by LEFM based on the theory of Griffith and Irwin because large-scale yielding occurs at the crack tip prior to failure. For these materials and for toughened polymers and polymer blends other approaches have been developed, three of which will be discussed in detail ... 

Electrolysis of molten NaCl is also carried out on a large scale, yielding sodium metal at the cathode rather than hydrogen. Still other processes involve the electrolysis of fused magnesium chloride (MgCU) or the oxidation of hydrogen chloride by oxygen or air in the presence of a copper catalyst. 

Although the Kac criterion has been applied with some notable successes, there are still numerous unresolved issues. These include the development of methods for treating time-dependent response, large-scale yielding, three-dimensional comers, and the development of a criterion that can be applied when the comer stress state is not characterized by a single Ka. Furthermore, a clearly desirable goal is the development of an approach for calculating /fac ftom more fundamental quantities. 

Electrolysis of hydrochloric acid yields hydrogen at the cathode and oxygen at the anode from the dilute acid, but chlorine at the anode (of carbon) from the concentrated acid. Electrolysis of the concentrated acid is used on the large scale to recover chlorine. 

The syntheses given are also useful for connecting porphyrins with other chroihophores and reactive groups, e.g., quinoncs. If the reported yields are reproducible, large electron donor-acceptor supramolecules should become accessible on a large scale. 

High yields of the enantiomerically pure alcohol and enantiomerically pure ester are reg ularly achieved The growing interest m chiral drugs (see the boxed essay on this topic p 296) has stimulated the development of large scale enzymatic resolution as a com mercial process... 

The ratio of reactants had to be controlled very closely to suppress these impurities. Recovery of the acrylamide product from the acid process was the most expensive and difficult part of the process. Large scale production depended on two different methods. If soHd crystalline monomer was desired, the acrylamide sulfate was neutralized with ammonia to yield ammonium sulfate. The acrylamide crystallized on cooling, leaving ammonium sulfate, which had to be disposed of in some way. The second method of purification involved ion exclusion (68), which utilized a sulfonic acid ion-exchange resin and produced a dilute solution of acrylamide in water. A dilute sulfuric acid waste stream was again produced, and, in either case, the waste stream represented a... 

Only a few of the wide variety of synthetic procedures which yield aldehydes as products are used for large-scale commercial preparation. A more complete discussion of syntheses can be found ia the Hterature (10,11). 

Although none of these survived commercially for more than a few years, their development led to an increased understanding of the inflation process and the identification of conditions which could yield a continuously hoUow staple fiber in large-scale production (43). 

Early in the twentieth century, the first attempts to manufacture formamide directiy from ammonia and carbon monoxide under high temperature and pressure encountered difficult technical problems and low yields (23). Only the introduction of alkaU alkoxides in alcohoHc solution, ie, the presence of alcoholate as a catalyst, led to the development of satisfactory large-scale formamide processes (24). 

The stoichiometry (4 mol lithium hydride to 1 mol LiAlH ) makes this an inherently expensive process, even though high yields of pure product are obtained. For large-scale production, metathesis from NaAlH is economically preferred. 

Most large-scale industrial methacrylate processes are designed to produce methyl methacrylate or methacryhc acid. In some instances, simple alkyl alcohols, eg, ethanol, butanol, and isobutyl alcohol, maybe substituted for methanol to yield the higher alkyl methacrylates. In practice, these higher alkyl methacrylates are usually prepared from methacryhc acid by direct esterification or transesterification of methyl methacrylate with the desired alcohol. 

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