Synthesis of carbamates from amines and dialkyl carbonates: Influence of leaving and entering groups
A number of carbamates were synthesised through a halogen-free process by reacting amines with symmetrical and unsymmetrical carbonates. The results obtained showed a specific trend of preferred leaving groups (in the dialkyl carbonates) depending on whether a catalyst or a base was used. On the other hand, investigations conducted on the preferred entering groups (amines) for the synthesis of carbamates showed the same trend regardless of whether a catalyst or a base was used. Finally, in accordance with the results obtained, it was possible to synthesise sterically hindered carbamates in high yield by transesterification of methyl carbamate with a sterically hindered alcohol. Georg Thieme Verlag Stuttgart New York.
Tundo, Pietro,McElroy, C. Robert,Aricò, Fabio
supporting information; experimental part
p. 1567 - 1571
(2010/09/05)
Alkoxycarbonylation of alcohols and phenols by nitrosoformates
Unstable neutral radicals [ROCONHO?] 2 and nitrosoformates 3 are formed by oxidation of N-hydroxycarbamates with lead dioxide. In the presence of alcohols or phenols and water they solvolyzed to mixtures of symmetrical 4 and asymmetrical 5 carbonates. The content of asymmetrical carbonates 5 increases with increasing reactivity of the nitrosoformates 3 formed, temperature, the content of water in the reaction mixture, and with decreasing reactivity of alcohol. The reactivities of individual alcohols have been evaluated with the help of competitive alcoholysis. The new method of alcohol or phenol alkoxylation has been verified experimentally by preparing six asymmetrical carbonates which were obtained in 34 to 47% yields.
Mindl, Jaromir,Halama, Ales,Cernosek, Zdenek
p. 1053 - 1063
(2007/10/03)
Anodic Oxidation. Part 17. The Formation of Alkyl Methyl Carbonates in the Hofer-Moest Reaction in Methanol
The liquid products from the electrolysis of sodium butanoate in methanol containing methyl sodium carbonate at a graphite anode include propyl and 1-methylethyl methyl carbonates. 1,1-Dimethylethyl methyl carbonate is amongst the liquid products from the electrolysis of sodium 2,2-dimethylpropanoate in methanol at a platinum anode in the presence or absence of methyl sodium carbonate.Typical secondary products derived from propene or 2-methylpropene are also present in the liquid products from each of these electrolyses.
Brettle, Roger,Khan, M. Akhram,Rowbottom, John D.
p. 2927 - 2929
(2007/10/02)
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