Search results
Results From The WOW.Com Content Network
The rules apply when the nucleophile can attack the bond in question in an ideal angle. These angles are 180° (Walden inversion) for exo-tet reactions, 109° (Bürgi–Dunitz angle) for exo-trig reaction and 120° for endo-dig reactions. Angles for nucleophilic attack on alkynes were reviewed and redefined recently. [4]
The opposite is an endothermic reaction, which usually takes up heat and is driven by an entropy increase in the system. Examples As an example in everyday life, hand warmers make use of the oxidation of iron to achieve an exothermic reaction:
The opposite of an endothermic process is an exothermic process, one that releases or "gives out" energy, usually in the form of heat and sometimes as electrical energy. [1] Thus, endo in endothermic refers to energy or heat going in, and exo in exothermic refers to energy or heat going out. In each term (endothermic and exothermic) the prefix ...
The opposite of an exothermic process is an endothermic process, one that absorbs energy, usually in the form of heat. [2] The concept is frequently applied in the physical sciences to chemical reactions where chemical bond energy is converted to thermal energy (heat).
Exocytosis (/ ˌ ɛ k s oʊ s aɪ ˈ t oʊ s ɪ s / [1] [2]) is a form of active transport and bulk transport in which a cell transports molecules (e.g., neurotransmitters and proteins) out of the cell (exo-+ cytosis). As an active transport mechanism, exocytosis requires the use of energy to transport material.
According to Merriam-Webster dictionary, the term "exoenzyme" was first recognized in the English language in 1908. [6] The book "Intracellular Enzymes: A Course of Lectures Given in the Physiological," by Horace Vernon is thought to be the first publication using this word in that year. [ 7 ]
The chair conformation of six-membered rings have a dihedral angle of 60° between adjacent substituents thus usually making it the most stable conformer. Since there are two possible chair conformation steric and stereoelectronic effects such as the anomeric effect, 1,3-diaxial interactions, dipoles and intramolecular hydrogen bonding must be taken into consideration when looking at relative ...
One of the most widely recognized examples of the synthetic utility of radical cascades is the cyclization sequence employed in the total synthesis of (±)-hirsutene, in 1985 (Scheme 6). [4] [16] Herein, alkyl iodide 28 was converted to the primary radical intermediate 29, which underwent a 5-exo-trig cyclization to afford reactive species 30.