Ethynylhydroxycarbene (H-C≡C-C̈-OH)

Area of Science:

• Astrochemistry
• Physical Chemistry
• Organic Chemistry

Background:

• The C3H2O potential energy surface is significant in extraterrestrial chemistry.
• Previous studies have not characterized the ethynylhydroxycarbene isomer.

Purpose of the Study:

• To synthesize and characterize ethynylhydroxycarbene (1).
• To investigate the photochemical and thermal reactions of ethynylhydroxycarbene.
• To understand the role of tunneling in chemical reactions.

Main Methods:

• High-vacuum flash pyrolysis of ethynylglyoxylic acid ethyl ester.
• Trapping of the product in solid argon matrices at low temperatures (3 and 20 K).
• Photochemical irradiation at 436 nm and dark reactions.
• Computational chemistry (CCSD(T)/cc-pVTZ and B3LYP/def2-QZVPP).

Main Results:

• Ethynylhydroxycarbene (1) was successfully generated and trapped.
• Irradiation induced rearrangement of the trans-conformer to the cis-conformer.
• Dark reactions showed a conformer-specific [1,2]H-tunneling process leading to propynal formation with a half-life of approximately 70 hours.
• Computational results align with experimental observations.

Conclusions:

• The study successfully characterized ethynylhydroxycarbene, an important isomer in astrochemical contexts.
• Conformer-specific hydrogen tunneling is a key mechanism in the transformation of ethynylhydroxycarbene to propynal.
• The findings contribute to understanding reaction pathways in interstellar environments.