UCLA team shows century-old law is full of hot air; Europe’s nuclear rockets go zoom; and China’s magnetic milestone

A rethink of Bredt’s rule, NEP could be the future of interplanetary exploration, and a hybrid magnet in China sets new world record.

 An illustration of a nuclear electric propulsion spacecraft. | Photo Credit: Tractebel/European Space Agency  

100-year-old rule in organic chemistry broken

Chemists at the University of California, Los Angeles (UCLA) have just found that a fundamental rule of organic chemistry that has been around for 100 years is not true. It is time to rewrite the textbooks, they say.

Organic molecules are made primarily of carbon and have specific shapes and arrangements of atoms. Molecules known as olefins, or alkenes, have double bonds between two carbon atoms. The atoms, and those attached to them, ordinarily lie in the same 3D plane, and any contrary geometry is uncommon.

A rule known as Bredt’s rule, which dates back to 1924, states that molecules cannot have a carbon-carbon double bond at the ring junction of a bridged bicyclic molecule, also known as the “bridgehead” position. Bicyclic molecules occur widely—camphor, for example—and feature two joined rings. Olefins are useful in pharmaceutical research, but Bredt’s rule constrained the kind of synthetic molecules scientists could imagine making with them and prevented possible applications of their use in drug discovery.

Now, a paper published by UCLA chemists in Science has invalidated that idea. They have shown how to make several kinds of molecules that violate Bredt’s rule, called anti-Bredt olefins ( ABOs), allowing wider practical applications.

“People aren’t exploring anti-Bredt olefins because they think they can’t,” said Neil Garg of UCLA and the corresponding author of the paper. “We shouldn’t have rules like this—or if we have them, they should only exist with the constant reminder that they are guidelines, not rules.”

“There’s a big push in the pharmaceutical industry to develop chemical reactions that give three-dimensional structures like ours because they can be used to discover new medicines,” he added. “What this study shows is that contrary to one hundred years of conventional wisdom, chemists can make and use anti-Bredt olefins to make value-added products.”

Garg’s laboratory treated molecules called silyl (pseudo)halides with a fluoride source to induce an elimination reaction that forms ABOs. Because ABOs are highly unstable, they included another chemical that can “trap” the unstable ABO molecules and yield products that can be isolated. The resulting reaction indicated that ABOs can be generated and trapped to give new structures of practical value.

 The C8, C9, and C11 bicyclic alkanes. The bridgehead atoms are the carbons from which three bonds radiate, like spokes: bicyclo[2.2.2]octane, bicyclo[3.3.1]nonane, bicyclo[3.3.3]undecane. | Photo Credit: Durfo/Wikipedia  

 Nuclear electric propulsion for European space missions  

A project on nuclear electric propulsion (NEP) for space exploration, called RocketRoll (or “Preliminary European Reckon on Nuclear Electric Propulsion for Space Applications”), commissioned by the European Space Agency to a consortium led by the Belgian engineering firm Tractebel has defined a comprehensive technology road map, including a candidate design for a demonstrator spacecraft, to equip Europe with advanced propulsion systems capable of undertaking long-duration missions.

According to Tractebel, the technology demonstrator could fly by 2035.

The project, , brought together leading stakeholders in aerospace and nuclear energy within the consortium that included the French Alternative Energies and the Atomic Energy Commission, ArianeGroup, Airbus, and Frazer Nash. The project was commissioned last year and completed in October.

The partners studied the feasibility of a NEP system where the electricity produced by a nuclear power reactor powers electric ion thrusters wherein a gas is ionised and the ions are accelerated, which are then ejected to generate thrust. This method’s thrust is lower but continuous, and with far greater fuel efficiency, it has higher speeds and could cut 60 per cent of the travel time to Mars compared with traditional chemical rockets, according to a press release.

“Thanks to its huge energy density, NEP offers disruptive advantages in terms of speed, autonomy, and flexibility,” Tractebel said. “This innovative propulsion technology has the potential to transform space exploration and space mobility by enabling longer-duration missions, potentially shaping the future of interplanetary exploration.”

“NEP would enable exploration and in-space logistics in Earth Orbit and beyond on a scale that neither chemical nor electrical propulsion could ever provide,” the ESA said. “The ultimate raison d’être of NEP is to explore beyond Mars orbit where solar power is limited.”

The 42 tesla resistive magnet at the the High Magnetic Field Laboratory of the Hefei Institutes of Physical Science, Chinese Academy of Sciences.  | Photo Credit: CHMFL

China’s resistive magnet sets a new world record

On September 22, 2024, a resistive magnet developed in China produced a steady magnetic field of 42 tesla (T), setting a new world record for magnets of this kind. This is another major breakthrough by the High Magnetic Field Laboratory of the Hefei Institutes of Physical Science, Chinese Academy of Sciences, after its success in 2022 in making the world’s most powerful hybrid magnet, which produced a field strength of 45.22 T (Frontline, September 9, 2022).

Magnets are of two types: permanent magnets and electromagnets. A permanent magnet, such as the ones we stick to our refrigerators, is made from a solid ferromagnetic metal like iron, nickel, and cobalt that is magnetised to have its own persistent magnetic field. Electromagnets are made of coils of wire wound around a normal metal and can be turned on and off whereas a permanent magnet is not easily turned on and off.

There are two types of permanent magnets: superconducting and resistive. The first has superconducting wire and requires very little power but has a limit on how high a magnetic field it can generate. The limit is the point when the wire stops becoming a superconductor. Resistive magnets can generate higher fields but require a large amount of electric power. The best way to get to the ultimately high fields is a combination of the two, and this is a hybrid magnet.

After nearly four years of unremitting efforts, Chinese scientists and engineers innovated the structure of the magnet, optimised its manufacturing process, and finally produced a steady magnetic field of 42 T at a power supply of 32.3 MW, breaking the record of 41.4 T set by the US National High Magnetic Laboratory in 2017. The work was reported in a recent issue of Nature.

A high magnetic field is an extreme experimental condition required for material science research and a powerful tool for major scientific discoveries. High fields are useful for experiments that rely on very sensitive measurements because they boost the resolution and make it easier to see faint phenomena, says Alexander Eaton, a University of Cambridge condensed-matter physicist. According to him, every extra tesla is exponentially better than the last.

The development of magnet technology has become an important research field. Currently, there are five steady high magnetic field laboratories in the world, located in China, France, Japan, the Netherlands, and the US.