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In it, Zaytsev proposed a purely empirical rule for predicting the favored regiochemistry in the dehydrohalogenation of alkyl iodides, though it turns out that the rule is applicable to a variety of other elimination reactions as well. While Zaytsev's paper was well referenced throughout the 20th century, it was not until the 1960s that ...
In chemistry, dehydrohalogenation is an elimination reaction which removes a hydrogen halide from a substrate. The reaction is usually associated with the synthesis of alkenes , but it has wider applications.
Such reactions give alkenes in the case of vicinal alkyl dihalides: [2] R 2 C(X)C(X)R 2 + M → R 2 C=CR 2 + MX 2. Most desirable from the perspective of remediation are dehalogenations by hydrogenolysis, i.e. the replacement of a C−X bond by a C−H bond. Such reactions are amenable to catalysis: R−X + H 2 → R−H + HX
Using a carboxylate-to-iodine ratio of 1:1 leads to an alkyl iodide product, in line with Borodin's findings and the modern understanding of the Hunsdiecker reaction. However, a 2:1 ratio favours the formation of an ester product that arises from decarboxylation of one carboxylate and coupling the resulting alkyl chain with the other. [9] [10]
In a related chemical test, known as the Herzig–Meyer alkimide group determination, a tertiary amine with at least one methyl group and lacking a beta-proton is allowed to react with hydrogen iodide to the quaternary ammonium salt which when heated degrades to methyl iodide and the secondary amine. [5]
“It’s not what you feed, it’s the way you feed it,” explains Burton. “Your treat delivery technique can have a powerful impact on the outcome of your training.”
The iodide anion is a good nucleophile and will displace chloride, tosylate, bromide and other leaving groups, as in the Finkelstein reaction. Alcohols can be converted to the corresponding iodides using phosphorus triiodide. Illustrative is the conversion of methanol to iodomethane: [15] PI 3 + 3 CH 3 OH → 3 CH 3 I + "H 3 PO 3 "
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