Butatrien durch Thermolyse von Propiolsäure-(2-propinyl)ester

✍ Scribed by Vanda Bilinski; André S. Dreiding; Hans Hollenstein

• Publisher: John Wiley and Sons
• Year: 1983
• Tongue: German
• Weight: 471 KB
• Volume: 66
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19830660743

✦ Synopsis

Flow thermolysis of 2‐propynyl propiolate (5) at 580° afforded butatriene (6) (ca. 50%) and, as by‐products, 4‐methylene‐2‐cyclobuten‐1‐one (7), 2‐ethynylpropenal (8), 1‐penten‐4‐yn‐3‐one (9), 4‐penten‐2‐ynal (10) (total ca. 10%), along with some propynal, acetylene, CO~2~ and CO. In the same way, propiolic acid (1,1‐D~2~)‐2‐propynyl propiolate (11) led to (1,1‐D~2~)‐butatriene (12) and a little 4‐((D~2~)methylene)‐2‐cyclobuten‐1‐one (13). A mechanism is proposed for the transformation of 5 into 6 and of 11 into 12, which also accounts for the formation of 7,8,9 and 10, as well as 13. The position of one of the published ^13^C‐NMR signals of butatriene (6) must be revised. Thermolysis of methyl‐(1) and ethyl propiolate (2) resulted in small yields of 2‐buten‐4‐olide (3) and 2‐penten‐4‐olide (4).