M-Bromoacetophenone

Because the position of electrophilic attack on an aromatic nng is controlled by the direct ing effects of substituents already present the preparation of disubstituted aromatic com pounds requires that careful thought be given to the order of introduction of the two groups Compare the independent preparations of m bromoacetophenone and p bromoace tophenone from benzene Both syntheses require a Friedel-Crafts acylation step and a bromination step but the major product is determined by the order m which the two steps are carried out When the meta directing acetyl group is introduced first the final product IS m bromoacetophenone... 

Problem 19.4 How would you carry out the following reactions More than one step may be required, (a) 3-Hexvne 3-Hexanone, (b) Benzene —> m-Bromoacetophenone I (c) Bromobenzene —> Acetophenone (d) 1-Methylcyclohexene — 2-Methylcyclohexanone... 

Acetophenone, Azido Derivatives,C H,NsO, mw 161.16, N26.07%. Two isomers are described in the literature a -Azidoaceto-phenone, Triazoacetophenone, Phenacyl Azide, Benzoylazidomethane, N3-CHa CO" CeHs plates (from eth + petr eth), mp 17°. Reacts very explosively with coned sulfuric acid. Was prepd by prolonged shaking of m-bromoacetophenone with Na azide inaq ale, with cooling... 

A solution of 40 g. (0.30 mole) of m-aminoacetophenone (p. 7) in 122 ml. of 36% aqueous hydrobromic acid and 120 mb of water is diazotized by treatment at a temperature below 0 , with a solution of 21.2 g. (0.31 mole) of sodium nitrite in 36 ml. of water. Sulfur dioxide is passed into a solution of 54.2 g. of copper sulfate and 27.2 g. of potassium bromide in 250 ml. of water until reduction is complete. Tbe resulting solution of cuprous bromide is added to tbe diazonium salt solution, and after being beated in a water batb for a short period tbe mixture is steam-distilled. The m-bromoacetophenone is extracted from the distillate with ether, and the ethereal solution is washed with dilute alkali, dilute acid, and water. Drying the resulting solution and distilling gives a 54% yield of product, b.p. 131°/16 mm. 

Compare the independent preparations of m-bromoacetophenone and p-bromoace-tophenone from benzene. Both syntheses require a Friedel-Crafts acylation step and a bromination step, but the major product is determined by the order in which the two... 

The analysis is often straightforward one simply disconnects one of the substituents from the ring of the target molecule and examines the ring with respect to the directing properties of the remaining substituent. Consider m-bromoacetophenone ... 

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