Catalytic hydrogenation of aromatic nitriles and their properties of polyamides obtained from p-(?, ?'-diaminodiethylbenzene)

Structuring of bridged silsesquioxanes via cooperative weak interactions: H-bonding of urea groups and hydrophobic interactions of long alkylene chains

“…Moreover, this effect is also evident from the amide A (n NH # 3400 cm 21 ) vibration, where a shift towards lower wavenumbers corresponds to stronger H-bonding between the urea groups. 23 The results are in good agreement with those of the Dn values since the n NH values of M4-M6 range from 3353 to 3356 cm 21 . In contrast, those for M1-M3 are observed at higher wavenumbers (3370-3423 cm 21 ).…”

“…After drying over Na 2 SO4, the solvents were removed leading to a white solid. Yield: 84% (686 mg, 4.18 mmol); mp: 60 uC; IR (CHCl 3 , cm 1,4-Di(aminopropyl)benzene 21 (3). The same procedure as above was used with 901 mg (4.90 mmol) of 1,4-di(cyanoethyl)benzene.…”

“…We also examined the H-bonding strength of the urea groups by FT-IR studies of the hybrids. This can be probed by monitoring the positions of the amide 1 (n CO # 1650 cm 21 ) and amide 2 modes (d NH # 1570 cm 21 ). The difference between these two vibrations (Dn) gives a good indication of the strength of the H-bonds between the urea groups, [23][24][25] with a low Dn value indicating strong H-bonding interactions.…”

“…21 ): 1560 (d NH ), 1654 (n CO ) and 3370 (n NH );13 C NMR CPMAS (ppm): 10.7, 25.2, 43.4 (2 C), 127.4, 139.5, 160.1; 29 Si NMR CPMAS (ppm): 257.8, 265.7 (T 2 and T 3 sites); specific surface area: 8.9 m 2 g 21 . Found elemental analysis: C 44.25, H 6.23, N 12.86, Si 12.90.…”

“…21 ): 3358 (n NH );1 H NMR (200 MHz, CDCl 3 ): d 5 1.08 (m, 4H, NH 2 ), 2.69 (t, 4H, CH 2 ), 2.92 (t, 4H, NCH 2 ), 7.11 (s, 4H, H ar ); 13 C NMR (50 MHz, CDCl 3 ): d 5 39.7 (CH 2 ), 43.6 (CH 2 N), 128.9 (CH ar ) and 137.6 (C…”