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  2. Phosphorus tribromide - Wikipedia

    en.wikipedia.org/wiki/Phosphorus_tribromide

    For example, with a Lewis acid such as boron tribromide it forms stable 1 :1 adducts such as Br 3 B · PBr 3. At the same time PBr 3 can react as an electrophile or Lewis acid in many of its reactions, for example with amines. An important reaction of PBr 3 is with alcohols, where it replaces an OH group with a bromine atom to produce an alkyl ...

  3. Heterogeneous water oxidation - Wikipedia

    en.wikipedia.org/wiki/Heterogeneous_Water_Oxidation

    Of the two half reactions, the oxidation step is the most demanding because it requires the coupling of 4 electron and proton transfers and the formation of an oxygen-oxygen bond. This process occurs naturally in plants photosystem II to provide protons and electrons for the photosynthesis process and release oxygen to the atmosphere, [ 1 ] as ...

  4. Water splitting - Wikipedia

    en.wikipedia.org/wiki/Water_splitting

    Atmospheric electricity utilization for the chemical reaction in which water is separated into oxygen and hydrogen. (Image via: Vion, US patent 28793. June 1860.) Electrolyser front with electrical panel in foreground. Electrolysis of water is the decomposition of water (H 2 O) into oxygen (O 2) and hydrogen (H 2): [2] Water electrolysis ship ...

  5. Oxygen reduction reaction - Wikipedia

    en.wikipedia.org/wiki/Oxygen_reduction_reaction

    Rather than combustion, organisms rely on elaborate sequences of electron-transfer reactions, often coupled to proton transfer. The direct reaction of O 2 with fuel is precluded by the oxygen reduction reaction, which produces water and adenosine triphosphate. Cytochrome c oxidase affects the oxygen reduction reaction by binding O 2 in a heme ...

  6. Woodward–Hoffmann rules - Wikipedia

    en.wikipedia.org/wiki/Woodward–Hoffmann_rules

    Thermolysis converts 1 to (E,E) geometric isomer 2, but 3 to (E,Z) isomer 4.. The Woodward–Hoffmann rules (or the pericyclic selection rules) [1] are a set of rules devised by Robert Burns Woodward and Roald Hoffmann to rationalize or predict certain aspects of the stereochemistry and activation energy of pericyclic reactions, an important class of reactions in organic chemistry.

  7. Photosystem II - Wikipedia

    en.wikipedia.org/wiki/Photosystem_II

    Photosynthetic water splitting (or oxygen evolution) is one of the most important reactions on the planet, since it is the source of nearly all the atmosphere's oxygen. Moreover, artificial photosynthetic water-splitting may contribute to the effective use of sunlight as an alternative energy-source.

  8. Hell–Volhard–Zelinsky halogenation - Wikipedia

    en.wikipedia.org/wiki/Hell–Volhard–Zelinsky...

    An example of the Hell–Volhard–Zelinsky reaction can be seen in the preparation of alanine from propionic acid.In the first step, a combination of bromine and phosphorus tribromide is used in the Hell–Volhard–Zelinsky reaction to prepare 2-bromopropionic acid, [3] which in the second step is converted to a racemic mixture of the amino acid product by ammonolysis.

  9. Photodissociation - Wikipedia

    en.wikipedia.org/wiki/Photodissociation

    This occurs by oxidation of water in the case of oxygenic photosynthesis. The electron-deficient reaction center of photosystem II (P680*) is the strongest biological oxidizing agent yet discovered, which allows it to break apart molecules as stable as water. [4] The water-splitting reaction is catalyzed by the oxygen-evolving complex of ...