2.6- lutidine-4-£ i-oxide

It is found in practice that for a number of compounds reacting ma the predominant species an almost horizontal plot is obtained. For compounds presumed to be nitrated via the free bases, such as 2,6-lutidine i-oxide and 3- and 5-methyl-2-pyridone, slopes of approximately unity are obtained. Since this type of plot allows for the incomplete ionisation of nitric acid, it can be used at higher acidities than plots using — ( H + logio Hjo) which break down when the condition is no longer true. 

These arguments were originally applied to the 4-nitration of 2,6-lutidine i-oxide and quinoline i-oxide, and use of the data available... 

Because of these difficulties, special mechanisms were proposed for the 4-nitrations of 2,6-lutidine i-oxide and quinoline i-oxide, and for the nitration of the weakly basic anilines.However, recent remeasurements of the temperature coefficient of Hq, and use of the new values in the above calculations reconciles experimental and calculated activation parameters and so removes difficulties in the way of accepting the mechanisms of nitration as involving the very small equilibrium concentrations of the free bases. Despite this resolution of the difficulty some problems about these reactions do remain, especially when the very short life times of the molecules of unprotonated amines in nitration solutions are considered... 

The main drawback of the oxidative cleavage of olefins by 0s04-NaI04 is the formation of side product such as a-hydroxy ketone derivatives presumably formed via the overoxidation of the diol intermediate. Jin and coworkers found that the use of 2,6-lutidine in dioxane-H20 enables higher chemical yield of the corresponding aldehydes by suppressing unwanted products (eq 75).i ... 

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