Pentacarbonylmanganese enolate and dienolate complexes. Preparative and mechanistic considerations

1990 ◽  
Vol 68 (3) ◽  
pp. 492-501 ◽  
Author(s):  
Andrew P. Masters ◽  
Ted S. Sorensen
Keyword(s):  
Nmr Spectroscopy ◽  
Nucleophilic Substitution ◽  
Reaction Products ◽  
Organic Products ◽  
Mechanism Of The Reaction ◽  
Model Reactions ◽  
Inorganic And Organic

Reactions of pentacarbonyl manganate anion with 4-halocrotonate esters or 2-halocarboxylate esters result in a complex set of inorganic and organic products, usually including the expected dienolate (or enolate) complexes. The reaction variables include the counterion, solvent, and halo group. The mechanism of the reaction has been investigated by conducting a thorough characterization of the reaction products under various conditions and also by carrying out model reactions. One can rationalize most of the non-organometallic products using either a radical or carbanion mechanism, but the latter seems to fit the available data better. Experimental procedures for optimizing the yield of the organometallic dienolate or enolate complexes have been worked out. Keywords: pentacarbonyl manganate, metalate nucleophilicity, enolate complex, nucleophilic substitution, 55Mn NMR spectroscopy.

Unambiguous structural characterization of hydantoin reaction products using 2D HMBC NMR spectroscopy

2007 ◽  
Vol 45 (3) ◽  
pp. 240-244 ◽  
Author(s):  
Mary M. Senior ◽  
Tze-Ming Chan ◽  
Guoqing Li ◽  
Ying Huang ◽  
Andrew Stamford
Keyword(s):  
Nmr Spectroscopy ◽  
Structural Characterization ◽  
Reaction Products

TEM characterization of reaction zone in a SiC fiber-reinforced titanium alloy

1988 ◽  
Vol 46 ◽  
pp. 738-739
Author(s):  
G. Das ◽  
R. E. Omlor
Keyword(s):  
Titanium Alloys ◽  
Reaction Zone ◽  
Carbon Layer ◽  
Fiber Reinforced ◽  
Reaction Products ◽  
Sic Fibers ◽  
Sic Fiber ◽  
The Matrix ◽  
Immense Potential

Fiber reinforced titanium alloys hold immense potential for applications in the aerospace industry. However, chemical reaction between the fibers and the titanium alloys at fabrication temperatures leads to the formation of brittle reaction products which limits their development. In the present study, coated SiC fibers have been used to evaluate the effects of surface coating on the reaction zone in the SiC/IMI829 system.IMI829 (Ti-5.5A1-3.5Sn-3.0Zr-0.3Mo-1Nb-0.3Si), a near alpha alloy, in the form of PREP powder (-35 mesh), was used a茸 the matrix. CVD grown AVCO SCS-6 SiC fibers were used as discontinuous reinforcements. These fibers of 142μm diameter contained an overlayer with high Si/C ratio on top of an amorphous carbon layer, the thickness of the coating being ∽ 1μm. SCS-6 fibers, broken into ∽ 2mm lengths, were mixed with IMI829 powder (representing < 0.1vol%) and the mixture was consolidated by HIP'ing at 871°C/0. 28GPa/4h.

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