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Sublimation is caused by the absorption of heat which provides enough energy for some molecules to overcome the attractive forces of their neighbors and escape into the vapor phase. Since the process requires additional energy, sublimation is an endothermic change.
In thermodynamics, the enthalpy of sublimation, or heat of sublimation, is the heat required to sublimate (change from solid to gas) one mole of a substance at a given combination of temperature and pressure, usually standard temperature and pressure (STP). It is equal to the cohesive energy of the solid.
into exo and endo ring closures, depending whether the bond broken during the ring closure is inside (endo) or outside (exo) the ring that is being formed; into tet, trig and dig geometry of the atom being attacked, depending on whether this electrophilic carbon is tetrahedral (sp 3 hybridised), trigonal (sp 2 hybridised) or diagonal (sp ...
A sublimatory [1] [2] or sublimation apparatus is equipment, commonly laboratory glassware, for purification of compounds by selective sublimation. In principle, the operation resembles purification by distillation , except that the products do not pass through a liquid phase .
They observed that while the endo isomer is formed more rapidly, longer reaction times, as well as relatively elevated temperatures, result in higher exo / endo ratios which had to be considered in the light of the remarkable stability of the exo-compound on the one hand and the very facile dissociation of the endo isomer on the other.
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 ...
another definition sublimation is a type of evaporation in which a solid changes directly to a gas without going through a liquid state. The definition in the article should read: " Sublimation of an element or compound is the direct transition from the solid to the gas phase".
The substituent to be classified is attributed with the exo descriptor when facing the bridge. It is endo configured when facing away from the bridge. If two different substituents are located on the same C atom, the exo/endo assignment is based on the substituent with higher priority according to the CIP rules.