13423-63-7Relevant academic research and scientific papers
A Guiding Principle for Strengthening Crosslinked Polymers: Synthesis and Application of Mobility-Controlling Rotaxane Crosslinkers
Sawada, Jun,Aoki, Daisuke,Otsuka, Hideyuki,Takata, Toshikazu
, p. 2765 - 2768 (2019)
Three component mobility controlling vinylic rotaxane crosslinkers with two radically polymerizable vinyl groups (RC_Rs) were synthesized to prove that the mobility of the components of the RC_Rs plays a crucial role in determining the properties of rotaxane-crosslinked polymers (RCPs). RC_Rs (R=H, Me, or Et) were obtained from living ring-opening polymerization. RCP_Et was prepared using RC_Et, which exhibits the lowest component mobility. The low component mobility is reflected in inferior mechanical strength and stretching ability in tensile stress tests compared to components with good (R=Me) and high (R=H) mobility. However, RCP_Et exhibited significantly higher stress and strain values than the corresponding covalently crosslinked polymers (CCP_Rs). These results indicate that a suitable component mobility substantially enhances the mechanical strength of RCPs. This behavior could serve as a guiding principle for the molecular design of advanced RCs.
Selective pyrolysis of bifunctional compounds: gas-phase elimination of carbonate-ester functionalities
Al-Azemi, Talal F.,Dib, Hicham H.,Al-Awadi, Nouria A.,El-Dusouqui, Osman M.E.
, p. 4126 - 4134 (2008/09/20)
Compounds containing both carbonate and ester functionalities were synthesized and then subjected to online-GC gas-phase pyrolysis. The carbonate groups were cleaved selectively in all elimination reactions. The end products of the reaction were found to be affected by the nature of the substrate. The presence of hydrogen and carbonyl substituents on the carbon β to the carbonate group resulted in further product decomposition through a concerted six-membered transition state. Results from flash vacuum pyrolysis (FVP) and analysis of the GC data indicate that the cleavage of the carbonate group is fast, and that the slower secondary decomposition reactions are independent of the presence of the carbonate group. Spectroscopic analyses of the products are reported.
Di-tert-butyl dicarbonate and 4-(dimethylamino)pyridine revisited. Their reactions with amines and alcohols
Basel, Yochai,Hassner, Alfred
, p. 6368 - 6380 (2007/10/03)
The reaction of BOC2O in the presence and absence of DMAP was examined with some amines, alcohols, diols, amino alcohols, and aminothiols. Often, unusual products were observed depending on the ratio of reagents, reaction time, polarity of solvent, pK(a) of alcohols, or type of amine (primary or secondary). In reactions of aliphatic alcohols with BOC2O/DMAP, we isolated for the first time carbonic-carbonic anhydride intermediates; this helps explain the formation of symmetrical carbonates in addition to the O-BOC products. In the case of secondary amines, we succeeded to isolate unstable carbamic-carbonic anhydride intermediates that in the presence of DMAP led to the final N-BOC product. The effect of N-methylimidazole in place of DMAP was also examined.
PREPARATION OF CYCLIC CARBONATES AND 2-OXAZOLIDONES USING DI-2-PYRIDYL CARBONATE
Kim, Sunggak,Ko, Young Kwan
, p. 1625 - 1630 (2007/10/02)
Cyclic carbonates and 2-oxazolidones are conveniently prepared in high yields by the reaction of diols and β-amino alcohols with di-2-pyridyl carbonate.It is of synthetic significance that the formation of cyclic carbonates in refluxing toluene occurs under essentially neutral conditions.
