allenen.

1875 Jrnl. Chem Soc. 13 1177 Two hydrocarbons having this composition can exist, (1) CH≡C—CH₃, allylene, and (2) CH₂=C=CH₂, which it is proposed to name allene.

1898 Science 30 Sept. 417/1 Itaconic acid was resolved by the current into symmetrical allene.

1922 J. J. Sudborough Bernthsen's Text-bk. Org. Chem. (new ed.) i. 56 Allene (propadiene),..is obtained by the electrolysis of itaconic acid.

1969 M. Julia in H. G. Viehe Chem. of Acetylenes v. 341 Acetylene itself with photolyzed diazomethane..gave propyne and allene.

2009 Photochem. 38 126 The probabilities of transitions between the states of allene and allylene in the process of the photochemical reaction have been calculated.

1889 Jrnl. Chem. Soc. 56 360 Monosubstituted acetylenes when acted on by alcoholic solution of the alkalis are converted into disubstituted acetylenes or non-symmetrical allenes.

1922 T. B. Johnson & D. A. Hahn tr. F. Henrich Theories Org. Chem. 316 Auwers undertook a systematic study of certain of the allenes and ketenes.

1977 J. March Adv. Org. Chem. (ed. 2) iv. 147 The smallest cyclic allene so far isolated is 1,2-cyclonanadiene, but cyclic allenes are in general less strained than their acetylenic isomers.

2003 Nature 13 Feb. p. vii Multiple bonds are common in carbon chemistry, in compounds such as acetylenes, nitriles, allenes and carbon dioxide.