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Terminal alkynes, like acetylene itself, are mildly acidic, with pK a values of around 25. They are far more acidic than alkenes and alkanes, which have pK a values of around 40 and 50, respectively. The acidic hydrogen on terminal alkynes can be replaced by a variety of groups resulting in halo-, silyl-, and alkoxoalkynes.
The order of reactivity of unsaturated substrates is: alkynes, allenes > terminal or strained alkenes > substituted alkenes. Trans alkenes react more rapidly than cis alkenes in general. The reactivity difference between alkynes and alkenes is usually not great enough to isolate intermediate alkenes; however, alkenes can be isolated from allene ...
The stronger the donation is, the stronger the back bonding from the metal d orbital to π* anti-bonding orbital of the alkene. This effect lowers the bond order of the alkene and increases the C-C bond length. One example is the complex PtCl 3 (C 2 H 4)] −. These complexes are related to the mechanisms of metal-catalyzed reactions of ...
A straight-chain alkane will have a boiling point higher than a branched-chain alkane due to the greater surface area in contact, and thus greater van der Waals forces, between adjacent molecules. For example, compare isobutane (2-methylpropane) and n-butane (butane), which boil at −12 and 0 °C, and 2,2-dimethylbutane and 2,3-dimethylbutane ...
The following is a list of straight-chain alkanes, the total number of isomers of each (including branched chains), and their common names, sorted by number of carbon atoms. [ 1 ] [ 2 ] Number of C atoms
Unsaturated hydrocarbons, which have one or more double or triple bonds between carbon atoms. Those with one or more double bonds are called alkenes. Those with one double bond have the formula C n H 2n (assuming non-cyclic structures). [1]: 628 Those containing triple bonds are called alkyne. Those with one triple bond have the formula C n H ...
Alkenes also react with halogens (X 2) to form haloalkanes with two neighboring halogen atoms in a halogen addition reaction. Alkynes react similarly, forming the tetrahalo compounds. This is sometimes known as "decolorizing" the halogen, since the reagent X 2 is colored and the product is usually colorless and odorless.
The reaction is predominantly applied to alkenes, but alkynes and azo compounds are also susceptible to cleavage. The outcome of the reaction depends on the type of multiple bond being oxidized and the work-up conditions. [1] Detailed procedures have been reported. [2] [3] [4]