Many addition-reactions of acetylenic ethers have been studied 1 in the past. In accordance with the expected polarisation of ethoxy- ethyne (I) 2 it was found that nucleophilic reagents always become attached to the acarbon atom, whereas electrophilic reagents interact with the p-carbon atom. The acid-catalysed additions of water, alcohols, etc. also fit into this picture because the catalysing electro- philic hydrogen ion becomes bound to the p-carbon atom.
