Phenyl- -ketone

The first application of the time-resolved CIDNP method by Closs and co-workers involved tire Norrish 1 cleavage of benzyl phenyl ketone [24, 25]. Geminate RPs may recombine to regenerate the starting material while escaped RPs may fonn the starting ketone (12), bibenzyl (3), or benzil (4), as shown below. 

TTie true ketones, in which the >CO group is in the side chain, the most common examples being acetophenone or methyl phenyl ketone, C HjCOCH, and benzophenone or diphenyl ketone, C HjCOC(Hj. These ketones are usually prepared by a modification of the Friedel-Crafts reaction, an aromatic hydrocarbon being treated with an acyl chloride (either aliphatic or aromatic) in the presence of aluminium chloride. Thus benzene reacts with acetyl chloride... 

The dienone 858 is synthesized by coupling of the alkenyl copper reagent 856 with crotyl chloride (857) in the presence or absence of ZnCl2[731], Tetrabutyllead (859) reacts with benzoyl chloride to afford butyl phenyl ketone[732]. 

Oxidation of carbon side-chains has resulted in the synthesis of dithiazolyl ketone (82) and thiazolyl phenyl ketone (83). The hydrocarbon chain can also be dehydrogenated in acetic acid in the presence of... 

If the a carbon atom of an aldehyde or a ketone is a chnality center its stereo chemical integrity is lost on enolization Enolization of optically active sec butyl phenyl ketone leads to its racemization by way of the achiral enol form... 

Enol form [achiral may be converted to either (R) or (S) sec butyl phenyl ketone]... 

Each act of proton abstraction from the a carbon converts a chiral molecule to an achi ral enol or enolate ion The sp hybridized carbon that is the chirality center m the start mg ketone becomes sp hybridized m the enol or enolate Careful kinetic studies have established that the rate of loss of optical activity of sec butyl phenyl ketone is equal to Its rate of hydrogen-deuterium exchange its rate of brommation and its rate of lodma tion In each case the rate determining step is conversion of the starting ketone to the enol or enolate anion... 

Write an equation showing how you could prepare ethyl phenyl ketone from propanenitrile and a Grignard reagent What is the structure of the imine intermediate ... 

Can you think of how bromomethyl phenyl ketone might be prepared" ... 

Analyzing the target molecule in this way reveals that the required alkyl halide IS an a halo ketone Thus a suitable starting material would be bromomethyl phenyl ketone... 

Intermediates benzene to ethyl phenyl ketone to ethyl m nitrophenyl ketone to m aminophenyl ethyl ketone to ethyl m fluorophenyl ketone Reagents propanoyl chloride AICI3 HNO3 H2SO4 Fe HCl then HO NaN02 H2O HCl then HBF4 then heat... 

The A/-carboxyl group is lost duting the reaction, and no additional deprotection step is requited (104). Benzene reacts with A/-carboxyglyciae anhydride to give aminomethyl phenyl ketone however, it does not react with other A/-carboxy-a-amino acid anhydrides (105). 

Acetophenone. Acetophenone [98-86-2] (methyl phenyl ketone) is a colorless Hquid that forms laminar crystals at low temperature (mp 20°C). It has a characteristic sweet orange blossom odor, and is soluble in alcohols and ethers. It is found in nature in oil of casatoreum, obtained from beavers oil of labdanum, recovered from plants and in buds of balsam poplar. It can be prepared by the Friedel-Crafts reaction (qv) of acetyl chloride with benzene in the presence of aluminum chloride however, this route is of Htde commercial significance. 

Propiophenone. Propiophenone [93-55-0] (ethyl phenyl ketone) is a colorless Hquid with a flowery odor. It can be prepared by the Friedel-Crafts reaction of benzene and propionyl chloride in the presence of aluminum chloride (346), or by the catalytic reaction of benzoic acid and propionic acid in the presence of water (347). Propiophenone is commercially available (348), and is sold in Japan at 2700 Y/kg (349). It is used in the production of ephedrine, as a fragrance enhancer, and as a polymerization sensitizer. 

Electrophilic attack on phenyl groups Phenyl Undergo electrophilic substitution in the meta and para positions (ca. 1 1) Phenyl ketones... 

Acid treatment or thermolysis of aziridinyl phenyl ketone oxime generated a 2-isoxazoline (74JAP(K)74i 17462), while treatment of a diphenylcyclopropene (486) with NOCl generated a 2-isoxazoline in contrast to dialkylcyclopropene (487) which produced addition across the double bond (Scheme 126) (73MI41605). 

Diphenylthiirene 1-oxide reacts with hydroxylamine to give the oxime of benzyl phenyl ketone (79JA390). The reaction probably occurs by addition to the carbon-carbon double bond followed by loss of sulfur monoxide (Scheme 80). Dimethylamine adds to the double bond of 2,3-diphenylthiirene 1,1-dioxide with loss of sulfur dioxide (Scheme 81) (75JOC3189). Azide ion gives seven products, one of which involves cleavage of the carbon-carbon bond of an intermediate cycloadduct (Scheme 81) (80JOC2604). 

Acetophenone Methyl phenyl ketone 1.34 CgHgO Hydrogen bromide 226 HBr... 

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