Researchers break down plastic waste

May 26, 2017, Nagoya University
Design of a sterically confined bipyridine–ruthenium (Ru) framework allows controlled confinement of adsorbed H2 and its delivery to inert amides enabling catalytic hydrogenation of a wide range of amide bonds. Cleavage of both C=O and C–N lactam bonds achieved by activation of a single precatalyst. Credit: Nagoya University

What to do proteins and Kevlar have in common? Both feature long chain molecules that are strung together by amide bonds. These strong chemical bonds are also common to many other naturally occurring molecules as well as man-made pharmaceuticals and plastics. Although amide bonds can give great strength to plastics, when it comes to their recycling at a later point, the difficultly of breaking these bonds usually prevents recovery of useful products. Catalysts are widely used in chemistry to help speed up reactions, but breaking the kinds of amide bonds in plastics, such as nylon, and other materials requires harsh conditions and large amounts of energy.

Building on their previous work, a research team at Nagoya University recently developed a series of organometallic catalysts to break down even the toughest amide bonds effectively under mild conditions.

"Our previous catalysts could hydrogenate most amide bonds, but the reactions needed a long time at high temperature and high pressure. This new ruthenium can hydrogenate difficult substrates under much milder conditions," says lead author Takashi Miura.

Hydrogenation is the key step leading to breakdown of amide bonds. The catalyst features a ruthenium atom supported in an organic framework. This ruthenium atom can adsorb hydrogen and deliver it to the amide to initiate the breakdown. The team probed the position of hydrogen on the catalyst in the reaction pathway and modified the shape of the supporting framework. By making sure that the hydrogen molecule was is the best possible position for interaction with amide bonds, the team achieved much more effective hydrogenation.

Group leader Susumu Saito says, "The changes we made to the catalyst allowed some tricky amide bonds to be selectively cleaved for the first time. This catalyst has great potential for making designer peptides for pharmaceutics and could also be used to recover materials from waste plastics to help realize an anthropogenic chemical carbon cycle."

Explore further: Chemists find new way to break amide bonds

More information: Takashi Miura et al. Multifaceted catalytic hydrogenation of amides via diverse activation of a sterically confined bipyridine–ruthenium framework, Scientific Reports (2017). DOI: 10.1038/s41598-017-01645-z

Related Stories

Chemists uncover a means to control catalytic reactions

December 12, 2016

Scientists at the University of Toronto have found a way to make catalysis - the use of catalysts to facilitate chemical reactions - more selective, breaking one chemical bond 100 times faster than another. The findings are ...

Recommended for you

Simulations show how atoms behave inside self-healing cement

January 19, 2018

Researchers at Pacific Northwest National Laboratory (PNNL) have developed a self-healing cement that could repair itself in as little as a few hours. Wellbore cement for geothermal applications has a life-span of only 30 ...

A new polymer raises the bar for lithium-sulfur batteries

January 18, 2018

Lithium-sulfur batteries are promising candidates for replacing common lithium-ion batteries in electric vehicles since they are cheaper, weigh less, and can store nearly double the energy for the same mass. However, lithium-sulfur ...

Looking to the sun to create hydrogen fuel

January 18, 2018

When Lawrence Livermore scientist Tadashi Ogitsu leased a hydrogen fuel-cell car in 2017, he knew that his daily commute would change forever. There are no greenhouse gases that come out of the tailpipe, just a bit of water ...

The early bits of life

January 18, 2018

How can life originate before DNA and genes? One possibility is that there are natural processes that lead to the organisation of simple physical objects such as small microcapsules that undergo rudimentary forms of interaction, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.