29366-08-3Relevant academic research and scientific papers
Synthesis of Trialkylamines with Extreme Steric Hindrance and Their Decay by a Hofmann-like Elimination Reaction
Banert, Klaus,Hagedorn, Manfred,Heck, Manuel,Hertel, Raphael,Ihle, Andreas,Müller, Ioana,Pester, Tom,Shoker, Tharallah,Rablen, Paul R.
, p. 13630 - 13643 (2020/11/13)
A number of amines with three bulky alkyl groups at the nitrogen, which surpass the steric crowding of triisopropylamine considerably, were prepared by using different synthetic methods. It turned out that treatment of N-chlorodialkylamines with organometallic compounds, for example, Grignard reagents, in the presence of a major excess of tetramethylenediamine offered the most effective access to the target compounds. The limits of this method were also tested. The trialkylamines underwent a dealkylation reaction, depending on the degree of steric stress, even at ambient temperature. Because olefins were formed in this transformation, it showed some similarity with the Hofmann elimination. However, the thermal decay of sterically overcrowded tertiary amines was not promoted by bases. Instead, this reaction was strongly accelerated by protic conditions and even by trace amounts of water. Reaction mechanisms, which were analyzed with the help of quantum chemical calculations, are suggested to explain the experimental results.
Catalytic etherification of alcohols in Shilov system: C[sbnd]O versus C[sbnd]H bond activation
Khazipov, Oleg V.,Nykytenko, Denys V.,Krasnyakova, Tatyana V.,Vdovichenko, Alexander N.,Fuentes Frias, Dario A.,Mitchenko, Serge A.
, p. 490 - 498 (2016/12/16)
A novel catalytic reaction of alcohol etherification in the system ROH ? PtCl42? ‐ PtCl62? was found. Methanol easily transforms into dimethyl ether in the presence of catalytic amounts of PtII chloro complexes at 70?°C. Under the same conditions reaction of ethanol affords diethyl ether (catalytic) and π-ethylene PtII complex (stoichiometric). The reactions are accompanied by multiple H/D exchange, which is indicative of intermediacy of corresponding alkyl platinum derivatives. The plausible reaction mechanism involves oxidative addition of alcohol forming intermediate alkyl platinum(IV) derivative followed by decomposition of it via reductive elimination step under the action of alcohol giving the ether and regenerating catalyst. In the case of ethyl alcohol reaction, β-hydrogen abstraction from the intermediate Pt-ethyl species yields π-ethylene platinum(II) complex. Although it seems that the reaction does not involve the initial breaking of C[sbnd]H bonds of an alcohol, this system can be regarded as a model for studying of some peculiarities of Shilov chemistry, in particular, of isotope scrambling mechanisms in Shilov alkane activation. In contrast to reactions of dimethyl and diethyl ethers formation, tert-butyl ethers formation in CD3OH/t-BuOH medium is catalyzed by PtIV chloro complexes also and is not accompanied by isotope scrambling. These observations argue against intermediacy of alkyl platinum derivatives suggesting that acid-catalyzed mechanism operates in tert-butyl alcohol etherification.
