From Acetylenes to Aromatics: Novel Routes – Novel Products

Hopf, Henning

doi:10.1002/3527601767.ch5

Cited by 6 publications

(4 citation statements)

References 44 publications

(59 reference statements)

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“…64 By now it seems clear that vinylidenes, being stabilised carbenes, have to be taken seriously, not only as intermediates in cyclopropene isomerisations, but also as potential intermediates in other high temperature hydrocarbon pyrolysis systems, such as those where alkynes and aromatics are involved. This is already recognised by a number of researchers, 62,65 but by no means everyone in the world of high temperature hydrocarbon chemistry. It may be that vinylidenes also play a role in fullerene and soot formation.…”

Section: Unfavourable Products and Processes (A) Allene Formationmentioning

confidence: 98%

The cyclopropene pyrolysis story

Walsh

2005

Chem. Soc. Rev.

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Cyclopropene is the last of the small strained ring hydrocarbons to have its thermal decomposition subjected to intensive investigation. This critical review describes the nearly 40 year history of this investigation largely by gas kinetic methods with chromatographic analysis. These studies have revealed that cyclopropenes can decompose by a variety of mechanisms involving diradicals, vinylcarbenes and vinylidenes. Much detailed information has been obtained about the reactivity of these intermediates which has wider implications for thermal hydrocarbon pyrolysis. Theory has also played a important role. Cyclopropene itself has been shown to be an intermediate in the allene --> propyne rearrangement. The story itself illustrates how the evolution of mechanistic understanding has been anything but straightforward.

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Section: Unfavourable Products and Processes (A) Allene Formationmentioning

confidence: 98%

The cyclopropene pyrolysis story

Walsh

2005

Chem. Soc. Rev.

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“…The first synthesis of benzene goes back to Berthelot's experiment in 1867, where aromatic materials were isolated upon heating acetylene (13). It was speculated that the multistep process was initiated by isomerization of acetylene to vinylcarbene, which reacts with acetylene to form vinylacetylene (20).…”

mentioning

confidence: 99%

“…Several mechanisms have been proposed to explain PAH growth (8)(9)(10)(11)(12)(13), typically based on coupling reactions between stable species like acetylene and reactive aromatic radicals. A prominent example is the well-known hydrogen abstraction C 2 H 2 addition mechanism, which is composed of two sequential steps.…”

mentioning

confidence: 99%

Ab initio dynamics and photoionization mass spectrometry reveal ion–molecule pathways from ionized acetylene clusters to benzene cation

Stein

Bandyopadhyay

Troy

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The growth mechanism of hydrocarbons in ionizing environments, such as the interstellar medium (ISM), and some combustion conditions remains incompletely understood. Ab initio molecular dynamics (AIMD) simulations and molecular beam vacuum-UV (VUV) photoionization mass spectrometry experiments were performed to understand the ion-molecule growth mechanism of small acetylene clusters (up to hexamers). A dramatic dependence of product distribution on the ionization conditions is demonstrated experimentally and understood from simulations. The products change from reactive fragmentation products in a higher temperature, higher density gas regime toward a very cold collision-free cluster regime that is dominated by products whose empirical formula is (C 2 H 2 ) n + , just like ionized acetylene clusters. The fragmentation products result from reactive ionmolecule collisions in a comparatively higher pressure and temperature regime followed by unimolecular decomposition. The isolated ionized clusters display rich dynamics that contain bonded C 4 H 4 + and C 6 H 6 + structures solvated with one or more neutral acetylene molecules. Such species contain large amounts (>2 eV) of excess internal energy. The role of the solvent acetylene molecules is to affect the barrier crossing dynamics in the potential energy surface (PES) between (C 2 H 2 ) n + isomers and provide evaporative cooling to dissipate the excess internal energy and stabilize products including the aromatic ring of the benzene cation. Formation of the benzene cation is demonstrated in AIMD simulations of acetylene clusters with n > 3, as well as other metastable C 6 H 6 + isomers. These results suggest a path for aromatic ring formation in cold acetylene-rich environments such as parts of the ISM.ion-molecule reactions | polycyclic aromatic hydrocarbons | molecular dynamics | quantum chemistry | photoionization mass spectrometry

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“…New approaches to the synthesis of aromatic molecules have proven repeatedly to yield more than just new structures. Advances in the understanding of pyrolysis have opened the door to fullerenes and carbon nanotubes and their rational synthesis [ 1 , 2 , 3 , 4 , 5 ]. Study of ring closures and the packing of small molecules have bolstered the reputation and uses of grapheme [ 6 , 7 , 8 ].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Acridines through Alkyne Addition to Diarylamines

et al. 2018

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A new synthesis of substituted acridines is achieved by palladium-catalyzed addition of terminal acetylenes between the aryl rings of bis(2-bromophenyl)amine. By including a diamine base and elevating the temperature, the reaction pathway favors the formation of acridine over a double Sonogashira reaction to form bis(tolan)amine. This method is demonstrated with several aryl-alkynes and alkyl-alkynes.

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From Acetylenes to Aromatics: Novel Routes – Novel Products

Cited by 6 publications

References 44 publications

The cyclopropene pyrolysis story

The cyclopropene pyrolysis story

Ab initio dynamics and photoionization mass spectrometry reveal ion–molecule pathways from ionized acetylene clusters to benzene cation

Synthesis of Acridines through Alkyne Addition to Diarylamines

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