Quinaldine, preparation

On acetylation it gives acetanilide. Nitrated with some decomposition to a mixture of 2-and 4-nitroanilines. It is basic and gives water-soluble salts with mineral acids. Heating aniline sulphate at 190 C gives sulphanilic add. When heated with alkyl chlorides or aliphatic alcohols mono- and di-alkyl derivatives are obtained, e.g. dimethylaniline. Treatment with trichloroethylene gives phenylglycine. With glycerol and sulphuric acid (Skraup s reaction) quinoline is obtained, while quinaldine can be prepared by the reaction between aniline, paraldehyde and hydrochloric acid. 

Quinaldine (or 2-methylquinoline) can be prepared by the Doebner.Miller Synthesis, which in some respects is closely similar to the Skraup Synthesis (p. 297) but has some significant differences. 

A number of improvements have been made in these syntheses. For example, the use of ethanoHc ferric chloride and zinc chloride produces a good yield of 2-isopropylquinoline [17507-24-3] from isovaleraldehyde (46). The purification of 2-methylquinoline is facHitated through precipitation. A cmde quinaldine—hydrochloride and zinc chloride complex is prepared and then treated with aqueous base (47). 

Polymers. Quinoline and its derivatives may be added to or incorporated in polymers to introduce ion-exchange properties (see Ion exchange). For example, phenol—formaldehyde polymers have been treated with quinoline, quinaldine, or lepidine (81) (see Phenolic resins). Resins with variable basic exchange capacities have been prepared by treating Amherlites with 2-methylquinoline (82). 

The quinaldine can also be separated from the crude mixture of bases by conversion into the zinc chloride double salt in the manner described in the case of quinoline. This furnishes a somewhat smaller yield of a purer preparation. 

Fig. 3.116. Preparation of D C Yellow No. 10 by condensing quinaldine, 1 with phtalic anhydride, 2 and sulphonating the condensation product, 3. Reprinted with permission from A. Weiszet al. [172].

Uses Preparation of 1-butanol, butyraldehyde, 2-ethylhexanol, quinaldine chemical warfare insecticides leather tanning alcohol denaturant solvent warning agent in fuel gases purification of lubricating oils organic synthesis. 

Into a second test tube is placed 4-9 c.c. of a sodium hydroxide solution approximately 0.01 N. The author has found that ordinary tap water may be used for a-, j8-, and -y-dinitrophenol and for quinaldine red. Comparison solutions of the methoxytri-phenylcarbinols are prepared in 0.1-0.5 N hydrochloric acid. A quantity of the same indicator, sufficient to produce a color approximately the same as that in the first tube, is then added. As a rule the stock solution of indicator will thus be diluted ten or twenty fold. It is best to employ for this purpose a burette graduated to 0.01 c.c. Then the solution is diluted with solvent (0.01 N NaOH, water, sodium carbonate, or hydrochloric acid, as the case may be) to the total volume of the first tube. The ratio of the quantity of indicator in the comparison solution and in the solution being studied is equal to the degree of coloration F. 

For the preparation of pyrido[2,3-d]pvrimidinc-2,4(l//,3//)-diones 28, an adaption of the Doebner-Miller quinaldine synthesis (cf. Houben-Weyl, Vol. E7a, p 363), can be used. The orientation of addition of oc,/5-unsaturated carbonyl compounds to pyrimidin-6-amines is governed by the attack of C5 of the pyrimidinamine at the carbon /5 to the carbonyl function.219 Besides pyrimidine-2,4,6-triamine,149 263 aminouracils are used as partners for the base-catalyzed reaction with a,/5-unsaturated ketones.148,219 264,570,571 Without the final oxidation step, which occurs mostly by air, the dihydro compounds are produced.265 Examples are the Michael additions of 4,4-dimethyl-l-phenylpent-l-en-3-one266 or of 1,3-diphenylprop-2-en-l-one264 to 6-amino-l,3-dimethylpyrimidine-2,4(l//,37T)-dione, which are followed by ring closure to give the corresponding pyrido[2,3-d]pyrimidme-2,4(l//,3//)-diones or their dihydro derivatives. 

Quinaldine N-oxide monohydrate treated with a freshly prepared 10%-soln. of K-methoxide in methanol, benzaldehyde added, and refluxed 4 hrs. 2-styryl-... 

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