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Benthic-pelagic coupling are processes that connect the benthic zone and the pelagic zone through the exchange of energy, mass, or nutrients. These processes play a prominent role in both freshwater and marine ecosystems and are influenced by a number of chemical, biological, and physical forces that are crucial to functions from nutrient cycling to energy transfer in food webs.
Cross-couplings are a subset of the more general coupling reactions. Often cross-coupling reactions require metal catalysts. One important reaction type is this: R−M + R'−X → R−R' + MX (R, R' = organic fragments, usually aryl; M = main group center such as Li or MgX; X = halide) These reactions are used to form carbon–carbon bonds but ...
In one important reaction type, a main group organometallic compound of the type R-M (where R = organic group, M = main group centre metal atom) reacts with an organic halide of the type R'-X with formation of a new carbon-carbon bond in the product R-R'. The most common type of coupling reaction is the cross coupling reaction. [1] [2] [3]
As with oceans, the benthic zone is the floor of the lake, composed of accumulated sunken organic matter. The littoral zone is the zone bordering the shore; light penetrates easily and aquatic plants thrive. The pelagic zone represents the broad mass of water, down as far as the depth to which no light penetrates. [9]
In chemistry, a reaction mechanism is the step by step sequence of elementary reactions by which overall chemical reaction occurs. [ 1 ] A chemical mechanism is a theoretical conjecture that tries to describe in detail what takes place at each stage of an overall chemical reaction.
This coupling reaction is stereoselective with a propensity for trans coupling as the palladium halide group and the bulky organic residue move away from each other in the reaction sequence in a rotation step. The Heck reaction is applied industrially in the production of naproxen and the sunscreen component octyl methoxycinnamate.
Water is the medium of the oceans, the medium which carries all the substances and elements involved in the marine biogeochemical cycles. Water as found in nature almost always includes dissolved substances, so water has been described as the "universal solvent" for its ability to dissolve so many substances.
This reductive coupling can be viewed as involving two steps. First is the formation of a pinacolate (1,2- diolate ) complex, a step which is equivalent to the pinacol coupling reaction . The second step is the deoxygenation of the pinacolate, which yields the alkene , this second step exploits the oxophilicity of titanium.