An aluminum-based chemical reagent designed by a RIKEN scientist could prove to be a useful way of building complex carbon compounds, such as novel pharmaceuticals.
The aluminate reagent (i-Bu3Al(TMP)Li) is able to pluck a hydrogen atom away from a carbon atom to create a new carbon–aluminum bond. The aluminum can then be replaced by a wide variety of other chemical groups, allowing new compounds to be constructed.
Masanobu Uchiyama of RIKEN’s Advanced Science Institute in Wako, and colleagues at Tohuku University, Japan, and the University of Cambridge, UK, have now uncovered exactly how the aluminate reagent works, and for which reactions it is most suitable1.
Uchiyama and colleagues used density functional theory to calculate how chemical reactions involving the aluminum reagent were likely to proceed. This technique relies on quantum theory to determine how electrons are spread around the molecules involved in a reaction.
This revealed that it is specifically the ring-shaped TMP portion of the aluminate reagent that is responsible for removing a hydrogen atom at the beginning of the reaction; a conclusion confirmed by subsequent experiments.
The aluminate also requires only a single chemical step to remove the hydrogen atom from its target. But this process is markedly different when using an analogous zinc-based reagent investigated by the team.
By creating detailed computer models of both reagents caught in mid-reaction, the scientists found that their reaction pathways diverge because the aluminum atom is less able to attract electrons located on a nitrogen atom in a different part of the intermediate molecule.
The upshot is that while the zincate reagent tends to create the most energetically stable product molecule, the aluminate reagent simply replaces the most easily removed hydrogen atom, leading to a different end product.
Strong bases incorporating lithium or magnesium have been used traditionally for these reactions. But these reagents can inadvertently scramble part of the molecules involved in the reaction, and work only at very low temperatures.
Aluminates and zincates use much milder reaction conditions and are less likely to interfere with other parts of the reactant molecules, says Uchiyama. Choosing the appropriate reagent will give chemists the ability to control the course of chemical reactions that may have more than one possible product.
Knowing the precise path of the aluminate’s reaction should allow the scientists to improve the yields of compounds it generates, he adds. The team is now testing both reagents to assess how widely they can be used by chemists.
1. Naka, H., Morey, J.V., Haywood, J., Eisler, D.J., McPartlin, M., Garcia, F., Kudo, H., Kondo, Y., Uchiyama, M. & Wheatley, A.E.H. Mixed alkylamido aluminate as a kinetically controlled base. Journal of the American Chemical Society 130, 16193–16200 (2008).
The corresponding author for this highlight is based at the RIKEN Advanced Elements Chemistry Laboratory
Modern genetic sequencing tools give clearer picture of how corals are related
17.08.2017 | University of Washington
The irresistible fragrance of dying vinegar flies
16.08.2017 | Max-Planck-Institut für chemische Ökologie
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
17.08.2017 | Physics and Astronomy
17.08.2017 | Earth Sciences
17.08.2017 | Physics and Astronomy