Related Experiment Video
Updated: Jul 19, 2026

Quantification of Hydrogen Concentrations in Surface and Interface Layers and Bulk Materials through Depth Profiling with Nuclear Reaction Analysis
Published on: March 29, 2016
High-level ab initio studies of hydrogen abstraction from prototype hydrocarbon systems
Berhane Temelso1, C David Sherrill, Ralph C Merkle
1Center for Computational Molecular Science and Technology, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, USA.
Ethynyl radicals efficiently abstract hydrogen atoms from various carbon types, with near-barrierless reactions on diamond surfaces. These findings support their use in mechanosynthesis for hydrogen abstraction.
Area of Science:
- Computational Chemistry
- Quantum Mechanics
- Chemical Kinetics
Background:
- Hydrogen abstraction reactions are fundamental in chemistry.
- Understanding these reactions is crucial for various chemical processes, including synthesis and materials science.
Purpose of the Study:
- To investigate hydrogen abstraction reactions using advanced ab initio electronic structure methods.
- To evaluate the efficacy of the ethynyl radical as a hydrogen abstraction agent.
- To explore the potential of ethynyl radicals in mechanosynthesis, particularly for diamondoid surfaces.
Main Methods:
- Utilized second-order Møller-Plesset perturbation theory (MP2) and coupled-cluster singles, doubles, and perturbative triples [CCSD(T)] methods.
- Employed large correlation consistent basis sets (cc-pVXZ, X=D,T,Q) for high accuracy.
- Calculated transition-state geometries, activation barriers, and thermodynamic properties.
Main Results:
- Ethynyl radical exhibits a high affinity for hydrogen atoms.
- Activation energy for hydrogen abstraction by ethynyl radical is below 3 kcal mol(-1) for sp(2) and sp(3) hybridized carbons.
- Hydrogen abstraction from a model diamond C(111) surface using the ethynyl radical is predicted to be barrierless.
Conclusions:
- Ethynyl radicals are highly effective hydrogen abstraction agents.
- The low activation barriers support their proposed role in mechanosynthesis for abstracting hydrogens from diamondoid surfaces.
- Computational results provide a strong basis for experimental investigations into ethynyl radical-mediated mechanosynthesis.
More Related Videos
Related Concept Videos
Radical Formation: Abstraction
Even though homolysis produces radicals, it is different from radical...
Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Electrophilic 1,2- and 1,4-Addition of HX to 1,3-Butadiene
Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
Radical Chain-Growth Polymerization: Chain Branching
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.

