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The amount of energy released during a hydrogenation reaction, known as the heat of hydrogenation, is inversely related to the stability of the starting alkene: the more stable the alkene, the lower its heat of hydrogenation. Examining the heats of hydrogenation for various alkenes reveals that stability increases with the amount of ...
This example showcases the "divide and duplicate rule" for double bonds. The vinyl group (C=C) or alkene portion has a higher priority over the alkane (C−C) portion. If an atom, A, is double-bonded to another atom, then atom A should be treated as though it is "connected to the same atom twice". [11]
For vinyl cations, relative stabilities can be compared with respect to their neutral alkene analogs. To obtain the stabilization properties of a-substituents, the isodesmic reaction was used to calculate enthalpy differences between the substituted vinyl cation and its neutral alkene precursor by getting its reaction enthalpy. This method is ...
In organosulfur chemistry, the thiol-ene reaction (also alkene hydrothiolation) is an organic reaction between a thiol (R−SH) and an alkene (R 2 C=CR 2) to form a thioether (R−S−R'). This reaction was first reported in 1905, [ 1 ] but it gained prominence in the late 1990s and early 2000s for its feasibility and wide range of applications.
Hyperconjugation can be used to rationalize a variety of chemical phenomena, including the anomeric effect, the gauche effect, the rotational barrier of ethane, the beta-silicon effect, the vibrational frequency of exocyclic carbonyl groups, and the relative stability of substituted carbocations and substituted carbon centred radicals, and the thermodynamic Zaitsev's rule for alkene stability.
In chemistry, chemical stability is the thermodynamic stability of a chemical system, in particular a chemical compound or a polymer. [1] Colloquially, it may instead refer to kinetic persistence , the shelf-life of a metastable substance or system; that is, the timescale over which it begins to degrade.
The inductive effect can be used to determine the stability of a molecule depending on the charge present on the atom and the groups bonded to the atom. For example, if an atom has a positive charge and is attached to a - I group its charge becomes 'amplified' and the molecule becomes more unstable.
This is because the bond angle for an alkene, C-C=C, is 122°, while the bond angle for an alkane, C-C-C, is 112°. When these carbons form a small ring, the alkene which has a larger bond angle will have to compress more than the alkane causing more bond angle strain. [4] Cycloalkenes have a lower melting point than cycloalkanes of the same size.