Pyridines piperidines

Blanco et al. (1994) reported measurements of the vapor pressure (P,at) for p-xylene, y-picoline, piperidine, pyridine and tetralin. The data for piperidine and pyridine are given in Table 3.4. A suitable equation to correlate these data is Antoine s relationship given next... 

Conversely, it can be seen on Fig. 1, that chemisorption of thiophenol (C6H5SH) at room temperature does not involve ail the surface Ni atoms. This behavior has already been obsen/ed for another similar molecule, benzene the fraction of occupied Ni surface atoms at room temperature was ca. 0.65 over a 4.2 % Al Ni Raney pretreated in vacuo at 250°C (ref. 13). This kind of study has been extended to a series of poisons such as thiophene (ref. 14), ammonia (ref. 15), piperidine, pyridine and 3.5 dimethyl piperidine (ref. 16). which also lead to a non-corrosive chemisorption, involving only a fraction of surface atoms. It has also been shown (ref. 14) that after poison saturation, the free Ni atoms are accessible to H2 chemisorption but not to large molecules such as benzene. In contrast, COS and CS2 chemisorptions at room temperature are corrosive as for the case for H2S chemisorption (ref. 14). 

The preparation of 45 was used by Verducci as the benchmark reaction to check polymer 43 containing 4-piperidine pyridine fragments. The activity of this catalyst used in 20mol.% was lower than that of DMAP. Although the catalyst was recycled ten times a 30% decrease in its efficiency was observed. The use of different spacers did not modify significantly the results, but the catalytic activity was clearly decreased by raising the catalyst loading [185]. 

Introductory surveys of these groups form parts of two chapters in an excellent general volume on the chemistry of alkaloids.1,2 A short review dealing with selected alkaloids of potential medicinal interest includes mention of a pyridine alkaloid.3 A review on the use of n.m.r. spectroscopy in structural and conformational elucidation of piperidine, pyridine, and monoterpenoid alkaloids is not readily accessible.4... 

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