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Updated: Dec 25, 2025
Preparation of Carbon Nanosheets at Room Temperature
Published on: March 8, 2016
Alkyne benzannulations in the preparation of contorted nanographenes
Kelsie M Magiera1, Vivek Aryal1, Wesley A Chalifoux1
1Department of Chemistry, University of Nevada, Reno, 1664 N. Virginia St., Reno, NV 89557, USA. wchalifoux@unr.edu.
Abstract:
Nanographenes are a popular area of research due to their promising properties for electronics. Over the last twenty years there has been a significant increase in interest in the development of contorted nanographenes. While many top-down techniques are employed in the synthesis of these planar nanographenes, the use of alkynes in bottom-up syntheses allows for easy functionalization and the development of contorted nanographenes. The syntheses of contorted nanographenes with a focus on utilizing alkynes is reviewed here.
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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.
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Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
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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.
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