Carbene Synthesis
Carbene Synthesis - Related Videos
19:58
Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
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Cited by 1 •
2017
Detailed and generalized protocols are presented for the synthesis and subsequent purification of four palladium N-heterocyclic carbene complexes from benzimidazolium salts. The complexes were tested for catalytic activity in arylation and Suzuki-Miyaura reactions. For each reaction investigated, at least one of the four complexes successfully catalyzed the reaction.
10:44
Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
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Cited by 5 •
2019
We present protocols for the isolation of stable heterocyclic carbenes. The synthesis of a cyclic (alkyl)(amino) carbene (CAAC) and an N-heterocyclic carbene (NHC) is demonstrated using filter cannulas and Schlenk technique. We furthermore present the synthesis of the related oxygen-sensitive, electron-rich mixed “Wanzlick dimer” and the reduced stable organic radical.
14:07
Preparation and Use of Carbonyl-decorated Carbenes in the Activation of White Phosphorus
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Cited by 2 •
2014
Here, we present a protocol for the synthesis of two carbonyl-decorated carbenes. The protocol makes these interesting compounds readily available to chemists of all skill levels. In addition to the synthesis of these two carbenes, their use in the activation of white phosphorus is also described.
12:19
Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
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Cited by 2 •
2018
We describe a protocol to photogenerate N-heterocyclic carbenes (NHCs) by UV irradiation of a 2-isopropylthioxanthone/imidazolium tetraphenylborate salt system. Methods to characterize the photoreleased NHC and elucidate the photochemical mechanism are proposed. The protocols for ring-opening metathesis photopolymerization in solution and miniemulsion illustrate the potential of this 2-component NHC photogenerating system.
08:33
Hydrogel Synthesis
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2023
Source: Amber N. Barron, Ashlea Patterson, and Taylor D. Sparks, Department of Materials Science and Engineering, The University of Utah, Salt Lake City, UT Hydrogels are a versatile class of cross-linked polymers produced through relatively simple procedures and with generally inexpensive materials. They can be formed from solution and involve a polymer backbone formed from monomer reagents, an initiator which makes the polymer reactive and a crosslinking species which binds the polymer chains...
FAQs
Thermolysis uses heat, whereas photolysis uses light to decompose diazo compounds and release carbene intermediates. These approaches provide different ways to control when the reactive species forms during a synthesis. Selecting thermal or photochemical activation allows chemists to match carbene generation with the surrounding reaction conditions and the intended transformation.
Carbenes can be generated in singlet or triplet states, and the reaction conditions influence which state predominates. This electronic distinction is important because it changes the character of the intermediate available for subsequent chemistry. Controlling the favored state therefore helps chemists understand and direct carbene-mediated cyclopropanation, bond insertion, or rearrangement reactions.
The precursor, activation mode, and reaction conditions all influence how carbenes form and which electronic state predominates. Heat, light, base-induced elimination, and metal catalysis provide distinct routes for generating the intermediate. Adjusting these variables helps coordinate carbene formation with the desired reaction, which is especially important because the species is highly reactive.
Base-induced elimination forms a carbene by removing suitable components from an appropriate precursor under basic conditions, while metal-catalyzed decomposition uses a metal catalyst to promote formation from a precursor. Both routes generate the same broad class of reactive intermediate, but they rely on different activation principles and offer different ways to control the reaction environment.
A typical planning sequence begins by selecting a suitable carbene precursor, then choosing thermolysis, photolysis, base-induced elimination, or metal-catalyzed decomposition as the generation strategy. Chemists next adjust conditions so formation occurs in the intended reaction setting and immediately consider the desired transformation, such as cyclopropanation, bond insertion, or rearrangement.
Once generated, carbenes can participate in cyclopropanation, insertion into carbon-hydrogen or heteroatom-hydrogen bonds, and rearrangement reactions. These reaction classes allow a transient intermediate to create new ring systems, form bonds at existing C–H or heteroatom–H sites, or reorganize molecular structures. Consequently, carbene synthesis supports the construction of more complex molecules.
Beyond individual bond-forming reactions, controlled carbene generation supports organometallic catalysis and the development of selective synthetic methods. In medicinal chemistry, these capabilities help construct complex molecular frameworks, while organometallic applications use carbene chemistry within catalytic strategies. The broader value lies in connecting reactive intermediate control with selective molecular construction.