The efficient selective synthesis of secondary and tertiary amines has been achieved by means of Cp*Ir-catalyzed multialkylation of ammonium salts with alcohols without solvent: the reactions of ammonium acetate with alcohols gave tertiary amines exclusively, while those of ammonium tetrafluoroborate afforded secondary amines selectively. Using this method, secondary 5- and 6-membered cyclic amines were synthesized from ammonium tetrafluoroborate and diols in one pot.
Glass transition of core/shell capsules consisting of calcium carbonate whisker as a core and crosslinked polystyrene as a shell was studied by differential scanning calorimetry (DSC). The thickness of the crosslinked shell was in the range of 26-81 nm. The crosslinked shells were revealed to show higher glass transition temperatures (T g) than the corresponding bulk values. It was revealed that a thicker shell exhibits a lower T g than a thinner shell, and that capsules without core (hollow capsules) exhibit lower T g 's than the corresponding core/shell capsules. These results suggest that the interfacial molecular interaction plays a role in the segmental relaxation which is responsible for the glass transition. The difference in T g between the core/shell and hollow samples was reduced when a coupling agent, methacrylic acid 3-(tri-methoxysilyl)propyl ester was not included. This also suggests the interfacial effect on T g. However, the results still suggest that the enhancement of T g for the present crosslinked shells is not only due to the interfacial effect but also to the effects of chain configuration and heterogeneous crosslink.
A new atom-economical and selective synthetic method for secondary and tertiary alkylamines has been achieved by means of (pentamethylcyclopentadienyl)iridium (Cp*Ir) complex catalyzed multiple N-alkylations of ammonium salts with primary and secondary alcohols without solvent.
The choice of ammonium salt is crucial for the selective preparation of secondary or tertiary amines. The procedure allows a one-pot preparation of cyclic amines from diols (VIII). -(YAMAGUCHI*, R.; KAWAGOE, S.; ASAI, C.; FUJITA*, K.-I.; Org. Lett. 10 (2008) 2, 181-184; Grad. Sch. Hum. Environ. Stud., Kyoto Univ., Yoshida, Kyoto 606, Japan; Eng.) -R. Steudel 26-068
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