Nitric oxide cyclic ketones

In a 2-1. round-bottomed, 3-necked flask fitted with a stirrer and two large-bore condensers are placed 200 cc. of 50 per cent nitric acid and 0.25 g. of vanadium pentoxide. The flask is heated to 65-70° in a water bath (thermometer in water), and I cc. of cyclopentanone added. Oxidation is indicated by the production of brown fumes. The water bath is removed, and 42 g. (less the i cc.) of the cyclic ketone added from a dropping funnel through the condenser at the rate of a drop every three seconds. The heat of the reaction keeps the flask at about 70°. If the temperature drops, oxidation ceases until the ketone has accumulated, when it may proceed almost explosively. In such a case, or if the temperature is higher, much succinic acid is formed. After addition has been completed, the water bath... 

The effect of the nitric acid/hydrogen peroxide mixture on acetone when it is hot gives rise to an explosive oxidation, especially when the medium is confined. This situation also applies to a large number of ketones, and in particular, cyclic ketones. Cyclic di- and triperoxides form compounds that detonate, if there is no strict and very delicate thermal control. Accidents have been reported with butanone, 3-pentanone, cyclopentanone, cyclohexanone and methylcyclo-hexanones. 

Clearly such a method is of limited preparative value, but an important exception is the oxidation of cyclic secondary alcohols which on oxidation with nitric acid give good yields of dicarboxylic acids by way of the intermediate cyclic ketone, e.g. adipic acid from cyclohexanone, Expt 5.123. 

The cyclitols are resistant to oxidation with dilute nitric acid, but with concentrated acid, depending on the conditions, a variety of products may be obtained ranging from carbon dioxide to cyclic ketones. Reference will be made here, as well as in subsequent sections, to those instances in which the ring has remained intact or in which it has been opened and compounds retaining all the original carbons have been isolated. 

We review in this chapter the nature of the photodecomposition pathways of several of the major products of atmospheric oxidation of the hydrocarbons, namely, the acyclic aldehydes in section IX-B the aldehydes containing additional functional groups in section IX-C the acyclic ketones in section IX-D the cyclic ketones in section IX-E the ketones containing additional functional groups in section IX-F the acyl halides and carbonyl halides in section IX-G nitrous acid, the alkyl nitrites, the nitroalkanes, and the nitroso-compounds in section IX-H nitric acid and the alkyl nitrates in section IX-I the peroxyacyl nitrates in section IX-J the alkyl hydroperoxides in section IX-K and some oxygenates derived from the aromatic hydrocarbons in section IX-L. 

Dodecanedoic acid is obtained from cyclodo-decane by oxidation first with air to give cyclic alcohol and ketone and then with nitric acid to the dibasic acid. The cyclic C12 hydrocarbon is made by trimeri-zation of butadiene followed by hydrogenation. 

The oxidation of cyclohexanol by concentrated nitric acid is mechanistically complex. A reasonable mechanistic route to the dicarboxyUc acid is given here. The first stage of the oxidation is considered to proceed by a mechanism similar to that found in chromic acid oxidations of alcohols (see Experiment [33]).The reaction here involves the initial formation of a nitrate ester intermediate, which, under the reaction conditions, cleaves by proton abstraction to form the ketone. This reaction is accompanied by reduction of the nitrate to nitrite. The proton transfer may involve a cyclic intramolecular rearrangement during the oxidation-reduction cleavage step. A likely mechanism is outlined below ... 

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