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Typical polar protic solvents include water and alcohols, which will also act as nucleophiles, and the process is known as solvolysis. The Y scale correlates solvolysis reaction rates of any solvent ( k ) with that of a standard solvent (80% v/v ethanol / water ) ( k 0 ) through
Sigmatropic rearrangements are concisely described by an order term [i,j], which is defined as the migration of a σ-bond adjacent to one or more π systems to a new position (i−1) and (j−1) atoms removed from the original location of the σ-bond. [3]
Reverse electron flow (also known as reverse electron transport) is a mechanism in microbial metabolism. Chemolithotrophs using an electron donor with a higher redox potential than NAD(P) + /NAD(P)H , such as nitrite or sulfur compounds, must use energy to reduce NAD(P) + .
In the second step, the nucleophilic reagent (Nuc:) attaches to the carbocation and forms a covalent sigma bond. If the substrate has a chiral carbon, this mechanism can result in either inversion of the stereochemistry or retention of configuration. Usually, both occur without preference. The result is racemization.
Run-and-tumble motion is a movement pattern exhibited by certain bacteria and other microscopic agents. It consists of an alternating sequence of "runs" and "tumbles": during a run, the agent propels itself in a fixed (or slowly varying) direction, and during a tumble, it remains stationary while it reorients itself in preparation for the next run.
In the Walden inversion, the backside attack by the nucleophile in an S N 2 reaction gives rise to a product whose configuration is opposite to the reactant. Therefore, during S N 2 reaction, 100% inversion of product takes place. This is known as Walden inversion. It was first observed by chemist Paul Walden in 1896.
A process flow diagram (PFD) is a diagram commonly used in chemical and process engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between major equipment of a plant facility and does not show minor details such as piping details and designations.
Those bacteria that stick firmly to the walls forming a biofilm are difficult to study under chemostat conditions. Mixing may not truly be uniform, upsetting the "static" property of the chemostat. Dripping the media into the chamber actually results in small pulses of nutrients and thus oscillations in concentrations, again upsetting the ...