And elimination of alkyl halides

Partially fluorinated vinyl ethers of fluoroolefins are quite susceptible to the action of Lewis acids. Reaction usually proceeds with ionization of the allylic C-F bond and results in formation of C=0 group and elimination of alkyl halide. Indeed, 3-chloro-2-methoxyhexafluoro-2-butene 82 reacts with A1C13 with formation of trichlorovinyl ketone 83, and cyclic alkoxyfluoroalkenes demonstrate similar behavior in reaction with aluminum or tin(IV) halides [170] ... 

Show how substitutions and eliminations of alkyl halides might be used to synthesize other types of compounds. 

These A -acyl phosphazenes also decompose further on heating to PhaMePO and RCN. The elimination of methyl iodide probably occurs by a course closely related to the elimination of alkyl halides in the Arbusov reaction, where the alkoxy-group undergoes nucleophilic attack by halide ion. 

This means that if a reaction is carried out on a compound that has no stereoisomers, it cannot be stereospecific but at most stereoselective. The concerted reactions, including SN2 displacements, E2 elimination of alkyl halides, anti and Syn addition to alkenes are all stereoselective. In the case of chiral or geometric substrates the nature of the product depends on the unique stereoelectronic requirement of the reaction. These are examples of stereospecific reactions. 

In contrast to the inner salts, the tertiary salts are sufficiently stable that they can be prepared and purified quite easily by the usual methods for handling somewhat hygroscopic materials. They are readily soluble in a number of solvents so, with the exception of the ferric salt which seems to give some difficulty, can be purified by crystallization. They decompose at their melting points with elimination of alkyl halide... 

The elimination of alkyl halides is done under basic conditions, the elimination of alcohols is done under acid conditions. Under basic conditions, an E2 elimination would require the loss of a hydroxide ion as a leaving group. Since the hydroxide ion is a strong base, it is not a good leaving group and so the elimination of alcohols under basic conditions is difficult to achieve. 

Introduction their functional groups. In this chapter, we consider the properties and reactions of alkyl halides. We use alkyl halides to introduce substitution and elimination, two of the most important types of reactions in organic chemistry. Stereochemistry (Chapter 5) will play a major role in our study of these reactions. Many other reactions show similarities to substitution and elimination, and the techniques introduced in this chapter will be used throughout our study of organic reactions. 

El eliminations of alkyl halides are rarely useful for synthetic purposes because they give mixtures of substitution and elimination products. Explain why the sulfuric acid-catalyzed dehydration of cyclohexanol gives a good yield of cyclohexene even though the reaction goes by an El mechanism. (Hint What are the nucleophiles in the reaction mixture What products are formed if these nucleophiles attack the carbocation What further reactions can these substitution products undergo )... 

Hydrogen and chlorine are anti to each other in the Z isomer and are syn in the E isomer. Since the Z isomer reacts fifty times faster than the E isomer, elimination must proceed more favorably when the substituents to be eliminated are anti to one another. This is the same stereochemical result that occurs in E2 eliminations of alkyl halides. 

If the monomers contain reactive groups that could be attacked by carbanions they will not be suitable for anionic polymerizations. Halogen-containing vinyl monomers are difficult to polymerize in these systems because of the elimination of alkyl halides. Interactions between many initiators and the carbonyl groups of methacrylates or acrylates necessitate the use of special reaction conditions, like very low temperatures, for the anionic polymerization of these monomers. 

What kind of reactions do alkyl halides undergo The characteristic reactions of alkyl halides are substitution and elimination. Because alkyl halides contain an electrophilic carbon, they react with electron-rich reagents— Lewis bases (nucleophiles) and Brpnsted—Lowry bases. 

The synthesis of stereodefined acyclic alkenes via 3-elimination reactions—such as (1) dehydration of alcohols, (2) base-induced eliminations of alkyl halides or sulfonates (tosyl or mesyl esters), and (3) Hofmann eliminations of quaternary ammonium salts—often suffers from a lack of regio- and stereoselectivity, producing mixtures of isomeric alkenes. 

The elimination of alkyl halide and the formation of dialkylthiophosphato complexes appears to be a fairly general feature of the reactions of transition-metal halides with trialkylthiophosphates (see also p. 6). VOCI2, for example, affords insoluble VOL2 (L = diethylthiophosphate or di-n-butylthiophosphate). A v(V=0) value in the range 972—990 cm Ms indicative of axial co-ordination of the vanadyl oxygen. 

Chapter 10 discusses the substitution reactions of alkyl halides. Of the different compounds that undergo substitution and elimination reactions, alkyl halides are examined first because they have relatively good leaving groups. You will also see the kinds of compounds biological organisms use in place of alkyl halides, since alkyl halides are not readily available in nature. 

Reagents that are classified as bases can be used with both Lewis and Brpnsted-Lowry acids and one application is the elimination of alkyl halides (E2 reactions sec. 2.9.A) in the presence of a base. Elimination involves conversion of a saturated moiety containing a leaving group to a molecule with a multiple bond. An example of this latter transform is ... 

Oxidative Addition and Reductive Elimination of Alkyl Halides... 

The thermal elimination of alkyl halides to form nitriles is perhaps the best known reaction of imidoyl chlorides. J. v. Braun investigated this reaction in detail over a period of 40 years, and he developed a host of useful new synthetic procedures for the synthesis of compounds, which are otherwise more difficult to obtain. Unfortunately, most of his work has been written up in detailed form in Chemische Berichte and it requires some effort to retrieve this information. However, he wrote one review article in 1934 which is most informative. The elimination of alkyl halides on heating of imidoyl chlorides was recognized by Wallach in 1877 and v. Pechmann and Ley and Holzweissig reported examples of this reaction prior to the work of J. v. Braun. The elimination reaction, in its most general terms, can be described by the following sequences ... 

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