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The curiosity in what have been recognized at the start as Friedel-Crafts polymerisations begun within the Nineteen Thirties and grew quickly from the Nineteen Forties lower than the effect of the USA man made Rubber Programme and from the Nineteen Fifties a result of Ziegler-Natta and comparable polymer advancements. From 1944 Professor Plesch has spent so much of his educational lifestyles, learning the character of what have been later known as cationic and, extra lately nonetheless, cationoid polymerisations.
The articles within the publication deal with stream instability and transition beginning with classical fabric handled in an cutting edge and rigorous manner, a few more moderen actual mechanisms defined for the 1st time and eventually with the very advanced subject of bombustion and two-phase stream instabilities.
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Extra info for Advances in Heterocycling Chemistry. Vol. 44
At -65"C, 50-55% of 78 was isolated, with none of the isomeric 4-aminoquinoline (125). At 15"C, 125 was formed in 60-65% yield with only 6-7% of 78. (781 (125) For quinoline derivatives substituted with electron-withdrawing groups, such as 3-nitroquinoline (126), the amide ion is not necessary for a-adduct formation. Liquid ammonia is a sufficiently strong nucleophile to attack the highly electron-deficient heterocycle (Scheme 50). The attack occurred at C-4 and was not dependent on temperature in the range of -45 to +20°C.
For example, 2-phenylpyridine was aminated in DMA with sodium amide to give 6-amino-2-phenylpyridine in 87:/, yield (72KGS1642). The yield was a function of reaction time and temperature; prolonged heating decreased the yield, and the optimum temperature was in the range 130-140°C (73MI1). Preferential attack at the 2-position of 3-substituted pyridines is a general phenomenon in the Chichibabin reaction (64CJC1627). 5: 1 ratio of 2amino-3-methylpyridine to 2-amino-5-methylpyridine (see Section IV,A).
A new catalytic procedure has made it possible to prepare alkyl sodium amides in good yields and in reasonable time. The ADVANCES I N T H E C H I C H I B A B I N R E A C T I O N Sec. B] n-BuNH, + Na catalyst PhCH, 33 d3uNHNa procedure involved refluxing sodium sand and the amine in toluene with a catalyst consisting of a 3- or 4-alkylpyridine, 3,3’-dialkyl-2,2’-bipyridine, or 3or 4-alkylquinoline. The preformed alkyl sodium amide underwent a normal Chichibabin reaction with evolution of hydrogen at lower temperatures than required for sodium amide (83USP4405790).
Advances in Heterocycling Chemistry. Vol. 44 by Author Unknown