Bromobenzene, nitration sodium

Even though the reaction conditions may lead to formation of the metal enolate in high yield, further reduction may occur during the quenching step of the reaction. Alcohols such as methanol and ethanol convert metal enolates to saturated ketones much faster than they react with metals in ammonia, and quenching of reduction mixtures with these alcohols will usually lead to partial or complete conversion to alcoholic product rather than to the saturated ketone. Rapid addition of excess solid ammonium chloride is the commonly employed quench procedure if ketonic products are desired,but other reagents that destroy solvated electrons before neutralization may be employed, such as sodium ben-zoate, iron(III) nitrate, - sodium nitrite, bromobenzene, sodium bromate, 1,2-dibromoethane and acetone. 

Tin triethyl phenyl is obtained as an oil, B.pt. 254 C., from the reaction mixture derived from heating together tin triethyl iodide (1 moL), bromobenzene (1 mol.), and metallic sodium. It forms a colourless liquid, which has to be distilled in hydrogen, since it is partially oxidised in the air, has a fairly pleasant odour, burns with a sooty flame, depositing metallic tin. It is highly refractive, and has a density 1-2639 at 0 C., is easily soluble in alcohol and ether, but insoluble in water. With alcoholic silver nitrate, iodine, fuming hydrochloric acid, and stannic chloride, the following reactions take place —... 

In practical terms, it is usually possible to get high yields of para products from electrophilic substitution reactions of halobenzenes. Both nitration and sulfonation of bromobenzene give enough material to make the synthesis worthwhile. Although mixtures of products are always bad in a synthesis, electrophilic aromatic substitution is usually simple to carry out on a large enough scale to make separation of the major product, ideally by crystallization, a workable method. A 68% yield of sodium p-bromobenzenesulfonate can be achieved by recrystallization of the sodium salt from water and a 70% yield of p-bromonitrobenzene by separation from the ortho isomer by recrystallization from EtOH. 

The bromination of phenyl n-pentyl ether is more para-selective in anionic micelles than it is in water. This contrasts with the lower para-selectivity of nitration of bromobenzene in the cationic micelles formed by dissolving lauric acid in 95% H2S04. It is not clear whether these effects are due to substrate orientation or to micelle-induced changes in the selectivity parameter for electrophilic aromatic substitution. The rates of solvolysis of alkyl p-trimethyl-ammoniumbenzenesulphonate trifluoromethanesulphonates (42) are strongly inhibited by anionic micelles of sodium lauryl sulphate or sodium dodecanoate. In water, homomicelles of (42) or sodium dodecanoate micelles, undergo inversion of stereochemistry, but in sodium lauryl sulphate 22% retention of... 

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