XIII Other methods

Other methods proposed in the literature are, e.g., the piezoelectric method [vi-x], the exten-someter method [xi-xii], and the meniscus-rise technique [i.xiii]. 

The reaction was found particularly useful as a relatively selective and mild nitration method, for example allowing mononitration of durene and other highly alkylated benzenes, which with mixed acid usually undergo dinitration. (Table XIl). Methyl nitrate-boron trifluoride can also be used to achieve dinitration of tet-ramethylbenzenes by using two and three molar excess of methyl nitrate, respectively. Relative yields of mono- and dinitro product compositions are shown in Table XIII. Other Friedel-Crafts type catalysts can also be used, but boron trifluoride was found to be the most suitable. Aluminum trichloride and titanium (IV) chloride in the nitration of pentamethylbenzene caused formation of significant amounts of chlorinated derivatives, whereas sulfuric acid led to nitrodemethylation products. 

A number of other syntheses of coniine have been effected, of which that of Diels and Alder is of special interest. The initial adduct of pyridine and methyl acetylenedicarboxylate, viz., tetraraethylquinolizine-1 2 3 4-tetracarboxylate (IX) on oxidation with dilute nitric acid is converted into methyl indolizinetricarboxylate (X). This, on hydrolysis and decarboxylation, furnishes indolizine, the octahydro-derivative (XI) of which, also known as octahydropyrrocoline, is converted by the cyanogen bromide method (as applied by Winterfeld and Holschneider to lupinane, p. 123) successively into the broraocyanoamide (XII), cyanoaraide (XIII) and dZ-coniine (XIV). A synthesis of the alkaloid, starting from indolizine (pyrrocoline) is described by Ochiai and Tsuda. ... 

It so happens that the great majority of compounds separated as acetates are alditols or other polyhydric compounds, and this Section is therefore concerned with the problems of reduction and acetylation. There is no a priori reason why alditols and other polyols should not be separated as their trimethylsilyl ethers, and such methods are known (see Section VII,l,p. 57 Section XIII, p. 90 Table Va, p. 119 and Table Xlla, p. 151), but experience shows that the resolution of acyclic O-trimethylsilyl derivatives is less satisfactory than that of cyclic compounds. 

If, however, aqueous or alcoholic caustic alkali is used, by combining with the acid as formed, it shifts the equilibrium point of the reaction, and almost complete hydrolysis occurs. This reaction could also have been dealt with under Chapter XIII, since alcohols are simultaneously formed however, the hydrolysis is more usually undertaken to obtain the acid. Other special cases of hydrolysis have been dealt with elsewhere (see Reaction LXVII.). The general method of procedure will be clear from the following. 

In 1956, a successful synthesis of a vinyl co-polymer with optical activity due to the main chain was made by Schuerch etal. [9]. According to this method, l-ce-methylbenzyl mathacrylate (X) and maleic anhydride at 1 3 molar ratio were photopolymerized with azobisisobutyronitrile in dioxane. The obtained polymer (XII) changed to an optically inactive one, when the optically active side chain of the homopolymer (XI) from monomer (X) was cleaved by PH4I on the other hand copolymer (XIII), from monomer (X) and maleic anhydride, still remained optically active after cleavage of the side chain. 

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