Perfluorocycloalkene
{{Short description|Class of chemical compounds}}
{{Primary sources|date=January 2024}}
A perfluorocycloalkene (PFCA) fluorocarbon structure with a cycloalkene core. PFCAs have shown reactivity with a wide variety of nucleophiles including phenoxides, alkoxides, organometallic, amines, thiols, and azoles.{{cite journal |title=Chiral Discrimination in Photochromic Helicenes |journal=Journal of the American Chemical Society |volume=127 |issue=20 |pages=7272–3 |year=2005 |last1=Wigglesworth |first1=Tony J. |last2=Sud |first2=David |last3=Norsten |first3=Tyler B. |last4=Lekhi |first4=Vikram S. |last5=Branda |first5=Neil R. |pmid=15898750 |doi=10.1021/ja050190j|bibcode=2005JAChS.127.7272W }} They or their derivatives are reported to have nonlinear optical activity,{{cite journal |title=Synthesis of azo chromophores containing a perfluorocyclo-alkenyl moiety and their second-order optical nonlinearity |journal=Journal of Fluorine Chemistry |volume=97 |pages=207–12 |year=1999 |last1=Matsui |first1=Masaki |last2=Tsuge |first2=Michinori |last3=Funabiki |first3=Kazumasa |last4=Shibata |first4=Katsuyoshi |last5=Muramatsu |first5=Hiroshige |last6=Hirota |first6=Kazuo |last7=Hosoda |first7=Masahiro |last8=Tai |first8=Kazuo |last9=Shiozaki |first9=Hisayoshi |last10=Kim |first10=Misa |last11=Nakatsu |first11=Kazumi |issue=1–2 |doi=10.1016/S0022-1139(99)00050-0|bibcode=1999JFluC..97..207M }} and be useful as lubricants,{{cite web |title=Organometallic Derivatives Of Perfluorocycloalkenes - Minnesota Mining Mfg Co,Us |website=Freepatentsonline.com |date=1971-08-25 |url=https://www.freepatentsonline.com/3787461.html |access-date=2017-01-05}} etching agents,{{cite journal |title=Radical kinetics for polymer film deposition in fluorocarbon (C4F8, C3F6 and C5F8) plasmas |journal=Thin Solid Films |volume=374 |issue=2 |pages=303–10 |year=2000 |last1=Takahashi |first1=Kazuo |last2=Itoh |first2=Atsushi |last3=Nakamura |first3=Toshihiro |last4=Tachibana |first4=Kunihide |bibcode=2000TSF...374..303T |doi=10.1016/S0040-6090(00)01160-3}} components of fuel cells,{{cite web |title=Patent US20140162173 - Sulfonated perfluorocyclopentenyl polymers and uses thereof - Google Patents |website=Google.com |date=2013-10-09 |url=https://patents.google.com/patent/US20140162173 |access-date=2017-01-05}} low-dielectric materials, and superhydrophobic and oleophobic coatings.{{cite journal |title=Ultra low dielectric, self-cleansing and highly oleophobic POSS-PFCP aryl ether polymer composites |journal=Journal of Materials Chemistry C |volume=1 |issue=43 |pages=7222–7 |year=2013 |last1=Sharma |first1=Babloo |last2=Verma |first2=Rajneesh |last3=Baur |first3=Cary |last4=Bykova |first4=Julia |last5=Mabry |first5=Joseph M. |last6=Smith |first6=Dennis W. |doi=10.1039/C3TC31161A |url=https://figshare.com/articles/journal_contribution/2830519}}
File:Tetrafluorocyclopropene.png|Tetrafluorocyclopropene
File:Hexafluorocyclobutene.png|Hexafluorocyclobutene
File:Octafluorocyclopentene.png|Octafluorocyclopentene
File:Decafluorocyclohexene.png|Decafluorocyclohexene
Reactivity
Derivatization of these PFCA rings via displacement of fluorine atoms with nucleophiles occurs through an addition-elimination reaction in the presence of a base. Attack of the nucleophile on the PFCA ring generates a carbanion which can eliminate a fluoride ion, resulting in vinyl substituted and allyl substituted products (Scheme 1). The ratio of vinylic to allylic products depends on the ring size, reaction conditions, and nucleophile.{{cite journal |title=Triarylamine-enchained semifluorinated perfluorocycloalkenyl (PFCA) aryl ether polymers |journal=Applied Petrochemical Research |volume=5 |page=35 |year=2014 |last1=Sharma |first1=Babloo |last2=Faisal |first2=Mohammad |last3=Liff |first3=Shawna M. |last4=Smith |first4=Dennis W. |doi=10.1007/s13203-014-0063-0 |doi-access=free}}
Under favorable conditions, a good nucleophile can replace all the fluorine atoms on PFCA ring (Scheme 2).{{cite journal |title=Azoles as Reactive Nucleophiles with Cyclic Perfluoroalkenes |journal=Chemistry: A European Journal |volume=15 |issue=40 |pages=10554–62 |year=2009 |last1=Garg |first1=Sonali |last2=Twamley |first2=Brendan |last3=Zeng |first3=Zhuo |last4=Shreeve |first4=Jean'ne M. |pmid=19746368 |doi=10.1002/chem.200901508}}
File:Multi-substitution on PFCA ring.jpg or 1,2,4-triazole onto PFCA ring]]
PFCAs have a huge potential to be used as a monomer to produce a variety of polymers. The polycondensation of bisphenols with PFCAs can be done. A unique class of aromatic ether polymers containing perfluorocyclopentenyl (PFCP) enchainment was prepared from the simple step-growth polycondensation of commercial available bisphenols and octafluorocyclopentene (OFCP) in the presence of triethylamine (Scheme 3 and 4).{{cite journal |title=Perfluorocyclopentenyl (PFCP) Aryl Ether Polymers via Polycondensation of Octafluorocyclopentene with Bisphenols |journal=Macromolecules |volume=45 |issue=2 |pages=766–71 |year=2012 |last1=Cracowski |first1=Jean-Marc |last2=Sharma |first2=Babloo |last3=Brown |first3=Dakarai K. |last4=Christensen |first4=Kenneth |last5=Lund |first5=Benjamin R. |last6=Smith |first6=Dennis W. |bibcode=2012MaMol..45..766C |doi=10.1021/ma2024599}}
File:Perfluorocyclopentenyl (PFCP) aryl ether polymer synthesis.jpg
File:Bis(heptafluorocyclopentenyl) aryl ether monomers synthesis and polymerization.jpg
Fluoropolymers, namely, perfluorocyclohexenyl (PFCH) aryl ether polymers, may be formed via step-growth polycondensation of commercial bisphenols and decafluorocycloalkene (DFCH) in the presence of triethylamine (Scheme 5).{{cite journal |title=Perfluorocyclohexenyl aryl ether polymers via polycondensation of decafluorocyclohexene with bisphenols |journal=Journal of Polymer Science Part A: Polymer Chemistry |volume=52 |issue=2 |pages=232–8 |year=2014 |last1=Sharma |first1=Babloo |last2=Hill |first2=Sarah C. |last3=Liff |first3=Shawna M. |last4=Pennington |first4=William T. |last5=Smith |first5=Dennis W. |bibcode=2014JPoSA..52..232S |doi=10.1002/pola.26995 |url=https://figshare.com/articles/journal_contribution/2830120}}
File:Perfluorocycloalkenyl (PFCA) aryl ether polymer synthesis.jpg
