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Synthesis of cis- and trans-alkenes from alkynes For the preparation multisubstituted alkenes, carbometalation of alkynes can give rise to a large variety of alkene derivatives. Rearrangements and related reactions
Being more unsaturated than alkenes, alkynes characteristically undergo reactions that show that they are "doubly unsaturated". Alkynes are capable of adding two equivalents of H 2, whereas an alkene adds only one equivalent. [12] Depending on catalysts and conditions, alkynes add one or two equivalents of hydrogen.
Metalation of terminal alkynes is a significant side reaction that occurs under these conditions. If metalation is desired, tertiary amine complexes of DIBAL-H are useful. [13] (5) The use of silyl acetylenes avoids the problem of competitive metalation of terminal alkenes.
In organic chemistry, syn-and anti-addition are different ways in which substituent molecules can be added to an alkene (R 2 C=CR 2) or alkyne (RC≡CR).The concepts of syn and anti addition are used to characterize the different reactions of organic chemistry by reflecting the stereochemistry of the products in a reaction.
Alkenes and alkynes give alkyl and vinyl silanes; aldehydes and ketones give silyl ethers, while esters provide alkyl silyl mixed acetals. Hydrosilylation has been called the "most important application of platinum in homogeneous catalysis."
A hydrohalogenation reaction is the electrophilic addition of hydrogen halides like hydrogen chloride or hydrogen bromide to alkenes to yield the corresponding haloalkanes. [ 1 ] [ 2 ] [ 3 ] If the two carbon atoms at the double bond are linked to a different number of hydrogen atoms, the halogen is found preferentially at the carbon with fewer ...
As a result, there are now numerous catalysts that can be utilised in the hydroamination of alkene, allene and alkyne substrates, including various metal based heterogeneous catalysts, early-transition metal complexes (e.g. titanium and zirconium), late-transition metal complexes (e.g. ruthenium and palladium), lanthanide and actinide complexes ...
Organoaluminum compounds can react with alkenes and alkynes, resulting in the net addition of one organyl group and the metal fragment across the multiple bond (carboalumination). This process can proceed in a purely thermal manner or in the presence of a transition metal catalyst.