4-Octyne, also known as dipropylethyne, is a type of alkyne with a triple bond at its fourth carbon (the '4-' indicates the location of the triple bond in the chain). Its formula is C8H14.

4-Octyne forms with 5-decyne, 3-hexyne, and 2-butyne a group of symmetric alkynes.

Preparation

One method for synthesizing 4-octyne is the reaction between acetylene and two equivalents of 1-bromopropane. Acetylene is first deprotonated by a base to give an anion, which then undergoes nucleophilic substitution with the bromopropane. The resulting alkyne is again deprotonated and reacts similarly with a second molecule of bromopropane. This reaction can be carried out in liquid ammonia at −70 °C with sodium amide as the base.[1]

Another synthetic route is the elimination reaction of 4,5-dibromooctane, which can be done in similar conditions.[2]

Properties

4-octyne is a colorless liquid at room temperature. Its density at 25 °C and otherwise stable conditions is 0.751 g/mL. The boiling point is 131–132 °C. The average molar mass is 110.20 g/mol.[3]

References

  1. ^ Seifert, H. (1948-05-01). "Olefinsynthesen in der C6- bis C11-Reihe". Monatshefte für Chemie und verwandte Teile anderer Wissenschaften (in German). 79 (3): 198–215. doi:10.1007/BF00899394. ISSN 1434-4475.
  2. ^ Miller, Harold N.; Greenlee, Kenneth W.; Derfer, John M.; Boord, Cecil E. (1954). "Mono- and Di-Alkylacetylenes from Vicinal Dihalides and Sodium Amide in Liquid Ammonia1". The Journal of Organic Chemistry. 19 (12): 1882–1888. doi:10.1021/jo01377a003. ISSN 0022-3263.
  3. ^ Lide, David R. (2010). "Physical Constants of Organic Compounds". CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, FL: CRC Press/Taylor and Francis. pp. 3–406.
Allikas: https://en.wikipedia.org/wiki/4-Octyne
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