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propadiene

n. (context organic compound English) the simplest allene, CH2=C=CH2

Wikipedia
Propadiene

Propadiene is the organic compound with the formula HC=C=CH. It is the simplest allene or compound with two adjacent C=C double bonds, and can also be identified as allene. As a constituent of MAPP gas, it has been used as a fuel for specialized welding.