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Depending on the product structure, it could promptly react further to eject a leaving group to give the addition–elimination reaction sequence. Addition reactions are useful in analytic chemistry, as they can identify the existence and number of double bonds in a molecule. For example, bromine addition will consume a bromine solution ...
Also called Kharasch effect (named after Morris S. Kharasch), these reactions that do not involve a carbocation intermediate may react through other mechanisms that have regioselectivities not dictated by Markovnikov's rule, such as free radical addition. Such reactions are said to be anti-Markovnikov, since the halogen adds to the less ...
When allyl bromide reacted with HBr in vacuo (in the absence of air or other oxygen source), the average reaction time took about 10 days with an approximate yield of 88%, the majority of which was the expected (according to Markovnikov's rule) 1,2-dibromopropane (65-85%). In contrast, when the reaction was run in the presence of air or oxygen ...
The addition proceeds in an anti-Markovnikov fashion. Early work linked the addition to olefin polymerization. [4] This addition is a step in a protocol known as atom transfer radical polymerization. [5] An example of Kharasch addition is the synthesis of 1,1,3-trichloro-n-nonane from 1-octene and chloroform using an iron-based catalyst: [6]
This reaction produced the 1,6-addition product 2 in 0% yield, the 1,6-addition product 3 in approximately 99% yield, and the 1,4-addition product 4 in less than 2% yield. This particular catalyst and set of reaction conditions led to the mostly regioselective and enantioselective 1,6-Michael addition of ethyl sorbate 1 to product 3 .
A good example from solid-state chemistry is the adducts of ethylene or carbon monoxide of CuAlCl 4. The latter is a solid with an extended lattice structure . Upon formation of the adduct, a new extended phase is formed in which the gas molecules are incorporated (inserted) as ligands of the copper atoms within the structure.
Free-radical reactions depend on one or more relatively weak bonds in a reagent. Under reaction conditions (typically heat or light), some weak bonds homolyse into radicals, which then induce further decomposition in their compatriots before recombination. Different mechanisms typically apply to reagents without such a weak bond.
Darzens halogenation is the chemical synthesis of alkyl halides from alcohols via the treatment upon reflux of a large excess of thionyl chloride or thionyl bromide (SOX 2) in the presence of a small amount of a nitrogen base, such as a tertiary amine or pyridine or its corresponding hydrochloride or hydrobromide salt.