Perfluorinated Cyclic Ethers

with charcoal and recrystallized four times from benzene. The final product was a white powder which melted a t 105 105.5'. I t did not depress the melting point of an authentic sample of di-n-octadecylphosphiiiic acid prepared frotn n-Ioctadecene and hypophosphorous acid2 (1n.p. 105.3--106°), but did depress the melting point of the original di-n-octadecylphosphine oxide b y 10'. Anal. Calcd. for ( C I ~ H S ~ ) ~ P ( O ) O neut. H : equiv., 571. Found: neut. equiv., for the sample from the phosphine oxide N O , for the satnple frorn hypophosphorous acid 583. S - K a y diffraction patterns indicated that t h e t \ v u acid .;aniples were essentially identical. I t was rintrtl iri taking t h r iniued iiirlting point of (1i-u-

octadecylphosphiiie oxide with di-72-octadecylphosphinic acid that 110 depression was obtained unless the samples were very intiniately mixed. After normal mixing of the samples melting points of 105106' mere obtained, but when these melts were solidified and again heated they melted 10' lower. Attempts t o oxidize di-n-octadecylphosphine oxide tyith 3 L ) ~ ohydrogen peroxide resulted in little or no reaction.

Acknowledgment.-The authors xish to acknowledge assistance extended by the management and rnelnbers of t h e Socoriy - \'~1cuutii T,aboratories. h'ACI~Sl?ORo,

YKlV

TERSEY

Perfluorinated Cyclic Ethers B Y h,I3nERT

L. HENNEAND

SIDNRY

13. I