Ethyl chloride conformations

Example 6. Type D. Category 4. Zlamal and Kazda [2g] have reported that, when isobutene was polymerised by aluminium chloride at -78 °C in a mixture of ethyl chloride and benzene, the DP of the polymers went through a minimum when the solvent contained about 5% by weight of benzene. In conformity with the ideas developed in the previous example, we interpret this effect as being due to an impurity, G, in the benzene which reacts with aluminium chloride to form two complexes, thus ... 

But we start with a compound that is so simple that it has only one conformation because it has no rotatable bonds dichloromethane. You may have wondered why it is that, while methyl chloride (chloromethane) is a reactive electrophile that takes part readily in substitution reactions, dichloromethane is so unreactive that it can be used as a solvent in which substitution reactions of. other alkyl halides take place. You may think that this is a steric effect indeed, Cl is bigger than H. But CH2CI2 is much less reactive as an electrophile than ethyl chloride or propyl chloride there must be more to its unreactivity. And there is dichloromethane benefits from a sort of permanent anomeric effect . One lone pair of each chlorine is always anti-periplanar to the other C-Cl bond so that there is always stabilization from this effect. 

Let us return to ethyl chloride (Sec. 13.7), and focus our attention on the methyl protons. If, at any instant, we could look at an individual molecule, we would almost certainly see it in conformation I. One of the methyl protons is anti to... 

There are three conformations of ethyl chloride, II, III, and IV, identical except that a different individual proton occupies the anti position. Being of equal stability, the three conformations are exactly equally populated one-third of the molecules in each. In one of these conformations a given proton is anti to chlorine, and in two it is gauche. 

PROBLEM 2.12 Write Newman projections for the staggered conformations of ethyl chloride (CH3—CHj—Cl) and 1,2-dichloroethane (Cl—CHj—CH2—Cl). 

Active Figure 17.20 Dehydrochlorination of menthyl and neomenthyl chlorides, (a) Neomenthyl chloride loses HCI directly from its more stable conformation, but (b) menthyl chloride must first ring-flip before HCI loss can occur. The abbreviation "Et represents an ethyl group. Sign in at www.thomsonedu.com to see a simulation based on this figure and to take a short quiz. 

Problem 9.21 Write the structure of the preferred conformation of (a) trans-l-ethyl-3-isopropylcyclohexane, (ft) cis-2-chloro-c/s-4-chlorocyclohexyl chloride. 

Problem 9.41 Explain why (a) a carbene is formed by dehydrohalogenation of CHCI, but not from methyl, ethyl, or -propyl chlorides b) m-1,3- and /rawj-l,4-di-/ert-butylcyclohexane exist in chair conformations, but their geometric isomers, lrans-1,3- and cis-1,4-, do not. <... 

All data obtained on the rate of reaction of [Ni(NiL2)2]Cl2 with alkyl halides— i.e., methyl iodide, benzyl bromide, benzyl chloride, p-nitrobenzyl chloride, p-chlorobenzyl chloride, ethyl bromide, ethyl iodide, n-propyl bromide, and n-propyl iodide—conform closely to a pseudo-first-order rate law. Almost all experiments were carried out in the presence of an excess of alkyl halide. Since methanol solutions of the alkylated complexes have only negligible absorption at 495 m//, rates were obtained by graphs of log A0—A vs. time. The graphs are linear over the entire time interval, which corresponds to more than two half lives in most cases, passing through the origin at zero time. The rate is essentially the same whether measured by the spectrophotometric or conductivity method. 

The electrophilic nature of sulfuryl chloride is validated in a study on the chlorination of anthracene derivatives the observed substituent effects conform well with molecular orbital modeling859. Chlorination of ethyl 3,4,5-trialkylpyrrole-2-carboxylates results in a substantial amount of / -side-chain chlorinated products in addition to the expected a-side-chain chlorination860. This has been ascribed to the electrophilic nature of the reagent861 and the mechanism proposed involves an allylic migration of the halogen from the a-sigma adduct to the adjacent / -side chain. 

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