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Updated: May 4, 2026
Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source
Published on: August 17, 2018
Carbon dioxide incorporation into alkyne compounds mediated by silver catalysts
Satoshi Kikuchi1, Tohru Yamada
1Department of Chemistry, Keio University, Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan. yamada@chem.keio.ac.jp.
Abstract:
We have reported that a silver catalyst with a base was an effective system for the incorporation and utilization of carbon dioxide in organic syntheses under mild reaction conditions. The C≡C triple bond activation by the silver catalysts was assumed to be a key step in these reactions, which was supported by DFT calculations with a model substrate. Based on these reports, we recently developed three new CO2 incorporations under the mild reaction conditions using our silver catalyst system. In this Personal Account, we describe the silver-catalyzed CO2 incorporation with C-C bond formation to afford the corresponding γ-lactone derivatives and the synthesis of benzoxazin-2-one derivatives and 4-hydroxyquinolin-2(1H)-one derivatives from alkynylanilines with carbon dioxide catalyzed by silver salts.
Related Concept Videos
02:24Reduction 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.
02:27Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
02:34Preparation of Alkynes: Dehydrohalogenation
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
02:42Acidity of 1-Alkynes
The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.