Pentene Sodium ethoxide

A-14. Compound A, on reaction with bromine in the presence of light, gave as the major product compound B (C9H19Br). Reaction of B with sodium ethoxide in ethanol gave 3-ethyl-4,4-dimethyl-2-pentene as the only alkene. Identify compounds A and B. 

Since compound A gives a single alkene on being treated with sodium ethoxide in ethanol, it can only be 3-bromo-2,4-dimethylpentane, and compound B must be 2,4-dimethyl-2-pentene. 

When the thermodynamic enolate of 2-methyl-3-pentanone, formed with sodium ethoxide in ethanol, was treated with 2i -bromopentane, one product was the expected alkylated ketone. Draw this product. Two other products were isolated and identified as 2 -pentene and 2Z-pen-tene. Speculate on a mechanism that accounts for the formation of these two alkenes. 

CHI CsHii-n with zinc powder and ammonium chloride in aqueous ethanol or hot ethanolic sodium ethoxide yields the alkane n-C7Fi5 C7Hj5-n and the olefin n-C7Fi5 CH=CH C5Hu-n, respectively. The results of detailed studies on free-radical (AZBN-initiated at 70 °C) addition of perfiuoroalkyl iodides across C=C bonds in cyclic olefins (cyclo-pentene, -hexene, and... 

Depending on the structure of the alkyl substrate, the E2 reaction can lead to cis-trans alkene mixtures, in some cases with selectivity. For example, treatment of 2-bromopentane with sodium ethoxide furnishes 51% trans- and only 18% cw-2-pentene, the remainder of the product being the terminal regioisomer. The outcome of this and related reactions appears... 

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