Journal"FluorineNotes",Volume#2(105),March-April2016
Received:November2015
DOI10.17677/fn20714807.2016.02.01
Asynthesisofanewfluoroorganosilicon
compoundscontainingcyclobutanefragmentsand
studyofpropertiesofobtainedoligomers
YaroshA.А.,SakharovА.М.,GlazkovA.A.
N.D.ZelinskyInstituteofOrganicChemistryRussianAcademyofScience,
117991,Moscow,Leninskyprospect,47,
e-mail:[email protected],[email protected]
Abstract: At interation of perfluoroalkylvinyl ethers and butadiene there were synthesized a new
polyfluorinated compounds – 1-vinyl-2-ω-cianoperfluoroalkoxi-2,3,3-trifluorocyclobutanes. It was established
thatadditionofbutadienetoperfluoroalkylvinyletherwasgoingonunder"headtohead".Therewereobtained
corresponded chlorosilyl derivatives. There were obtained polyfluoroorganosiloxanes at hydrolysis of these
chlorosilylderivates.Therewerestudiessomepropertiesofpolyfluororganiloxanes.
Keywords: perfluoroalkyl vinyl ethers, butadiene. cycloaddition, hydrosilylation, polyfluororganosiloxane,
oligomerproperties.
Production of aliphatic polyfluorinated organo-silicon compounds is of a great scientific and
applicativeinterest.Themainmethodsofsynthesisoforgano-siliconcompoundscontainingfluorine's
atominorganicradicalweresummarizedinthemonographsofV.А.Ponomarenkoandtheirstuff.[1,2].
This work was devoted to the synthesis of polyfluoroorganosilanes and siloxanes containing nitrile
groups. Offered method of synthesis of fluoroorgano silicon compounds supposed two steps: thefirst
one is polyfluorinated cyclobutane derivative production containing multiple bond, the second one is
applicationofwellknownhydrosilylationreactionofunsaturatedcompound.
Itisknownthatfluoro-containingalkenescouldbeaddedtononfluorinatedunsaturatedcompounds
fareasierthendimerized[3,4].Inthereactionofnon-fluorinateddienescycloadditiontofluoroalkenes,
namely, to perfluoroalkylvinyl ether (PFAVE), it could be formed not only isomer (addition «head to
head» or «head to tail»), but also their stereo isomers. The isolation and exact characterization of
forming isomer is essentially complicated when they have a large molecular weight and high boiling
point. That is why it seems appropriate to establish the principle of their formation and structure, low
molecularweightanaloguesofthesecompounds.
InthisworkPFAVEwasusedasfluorinateddienesthatcontainednitrilegroup.Thegeneralmethod
isdescribedintheschemebelow1[5,6]:
Scheme1
Compound2wasobtainedanalogically,scheme2[6]:
Scheme2
AcycloadditonofPFAVEtobutadienecouldbedoneintworoutes:«headtohead»or«headtotail».
1Н and 19F NMR spectra of cyclodimerization products show that it could be realized in experiment
conditions,iftherewouldbeonlyonetypeofaddition,namely"headtohead"withequalcontentofcisandtrans-isomersrelativelytothecycle[4](scheme3):
Rf=-(CF2)5Compound3;-(CF2)3OCF(CF3)Compound4;
Scheme3
It was carried out the separation of cis- and trans -isomers -vinyl-2-perfluoropropyloxy-2,3,3trifluorocyclobutabe by HPLC (High-performance liquid chromatography) method for accurate
assignment of signals in NMR spectra and description of the stereochemical structure of obtained
products. As a result, we managed to isolate preparative pure isomers in order to identify their -19F
NMRspectra.Itwasestablishedthatthepeakwithearlyretentiontimecorrespondedtocis-isomer,and
withlateonecorrespondedto–trans-isomer[8].
Itisknownthatelectricfield'sduopolyofneighboringbondshasasignificantinfluenceonchemical
shiftof19Fnucleusacrossthespace,forexample,so-called«ortho-effect»influorobenzenes.Thesize
ofthiseffectdependsuponinteratomicdistance:assmallerinteratomicdistancebetween 1Н and 19F,
resonanceatoms 19Fisobservedinweakfield[9].Basedonit,thesignalsinthefield-120ppmcould
bereferredtofluorineatomof−CF−groupincis-isomer,andthesignalsinthefield-140ppmcouldbe
referredtothesamegroupintrans-isomer.
As a result of hydrosilylation of compounds 3 and 4 there were obtained corresponded
dichlorosilanesandoligosiloxanes(scheme4):
RfismentionedaboveinScheme3
Scheme4
As a result of hydrolysis of methyldichlorosilane derivates there were synthesized oligomers with
terminalssilanolgroups.Thestabilizationoflastonesbytrimethylchlorosilanegivesarisetooligomer
formationwithmolecularweight4500-5000(ebullioscopyinC6F6).Thetemperatureofsucholigomers
consistsof260°Сat10%lossofweight,itisaresultofdehydrofluorinationatheating[10].
AreactioncontrolwasmadebyNMRspectroscopy.Therewereappearedsignalsinthearea(ppm):
3.80(ОСН2); 1.02 (SiCH2); and 0.76 (SiCH3) in Proton magnetic resonance spectroscopy along with
conversion increase. In the same time there were disappeared the signals in the area (ppm): 5.30
(=СН2)and5.87(=СН).
Obtained silanes and siloxanes could be used for creation of different composition on their basis,
whichonecouldhavepotentiallyusefulpropertiesinpractice.
Experimental
19F and 1Н
NMR spectra are registered on spectrometer “Bruker WN-250» with frequency 235
(external standard CFCl3) and 250 MHz (external standard TMS), accordingly. 29Si spectra were
registeredonspectrometer«Bruker-АС-200P»withfrequency39.76MHz(externalstandardTMS).IRspectrawereregisteredonspectrometer«SpecordIR-75».HPLCwasmadeonliquidchromatographer
LC21CP «Bruker», equipped with refractometric detector on semi-preparative silicagel column IBM
(10.0x250х5), eluent – hexane, 2 ml/min. GLC-analysis was made on chromatographer LHM-8MD
(column1000×3,5mm,carrierChromatone0.160-0.200mm,treatedby5%SiliconSE-30).Astarting
chlorsilanesweresuppliedbyAcrosOrganics,(puritynotlessthan96%).Acatalystwasmadeunder
thefollowingmethod:1gofH2PlCl6×Н2Оwasloadedintoflaskcontaining100mlofTHF,preliminary
distilled under СаН2, and obtained solution was kept in closed flask at room temperature within 168
hours.
Asynthesisofcompound1isdescribedin[4].Thecompound2wasobtainedbydebrominationinthe
presenceofZn-dustandmetaliodineindiglime,similartomethod[6].Yield87%,b.p.=105°С.
Generalmethodforfluorocyclobutanespreparation3and4:
0.05moleofPFAVEand0.05-0.006moleofbutadienewereloadedintosteelautoclavewithvolume
50ml.Anautoclavewasheatedupto120°andkeptatthistemperaturewithin6-8hours.In addition
autogenic pressure was increased to 10-12 atm. After cooling and pressure releasing the content of
autoclavewaspurifiedbyrectification.Theyieldofcompounds3and4consistedof70-75%.
Compound3
B.p.=71°С/10 torr. Elemental analysis: found, %: C 33.77; H 1.61; F 57.01. Calculated for
C12H6F13NO,%:C33.72;H1.40;F57.84.
1HNMRspectroscopy(δ,ppm):5.80m(1НСН=);5.30m(2Н=СН);3.30m(1НСНinthecycle);
2.80mand2.45m(2НСН2inthecycle).
19FNMRspectrum(δ,ppm):twoАВ-spectra:δ
А -77.7,δВ-85.9,JAB=152Hz;δА-80.1; δВ -84.9;
JAB=148Hz;(2FOCF2cis-andtrans-isomers);twoАВ-spectra:δА-107.5,δВ-110.0,JAB=208Hz;δА
-108.2; δВ -212; JAB= 148 Hz; (2F CF2 in the cycle, cis- and trans-isomers); -105.3 m (2F CF2CN);
-121.4m(2FCF2CF2CN);-122.2-125.3m(4F-CF2CF2-);-121.0m(cis);-138.9m(trans)(1FCF-O).
IRspectrum,ν,cm-1:2260(CN).
B.p.=80°С/16 torr. Elemental analysis: found, %: С 32.61; H 1.57; F 55.37. Calculated for
C12H6F13NO2,%:C32,52;H1,36;F55,34.
1HNMRspectroscopy(δ,ppm):5.80m(1НСН=);5.30m(2Н=СН);3.30m(1НСНinthecycle);
2.80mand2.45m(2НСН2inthecycle).
19F NMR spectrum (δ, ppm): -78.1;78.9;81.5;82.0 (OCF
2); 83.1 (CF3); 105.2; 109.2; 114.4; 118.0
(CF2inthecycle);120.0141.3(CFinthecycle,cis-andtrans);115.0CF-CN);128.6128.9(CF2CF2).
IR-spectrum,ν,cm-1:2260(CN).
Hydrosilylationoffluoro-containingcyclobutanebymethyldichlorosilane.
Intoafour-neckflaskequippedwithstirring,droppingfunnel,thermometerandrefluxcondenserwas
loaded 15.76 g (0.0355 mol) vinylcyclobutane 3. A flask was blown by argon. 0.5 ml 0.1N solutionof
H2PlCl6inTHFwasadded.Than8.2g(0.071mol)ofmethyldichlorosilanewasaddedatrapidmixing.
Thecontentofflaskwasheatedto60°Сandkeptwithin2hours.Areactionproductswerefractionated.
Itwasobtained16.1g(80.8%)ofcompound5.B.p.=90-91°С/1torr.
1H NMR spectroscopy (δ, ppm.): 0.63 (Si-CH
3); 0.70 -1.10 (Si-CH2); 1.5-2.00 (Si-CH2 CH2); 2.20-
2.70(СН2-СНinthecycle). 19FNMRspectrum(δ,ppm):78.1;-78.9;-81.5;-82.0(OCF2)-83.1(CF3);
-105.3;-114.4;-118.0(CF2inthecycle);-120.0;-141(CF–inthecycle);-115.0(СFCN);-128.6;-128.9
(CF2CF2).
29Si,NMRspectrum(δ,ppm):30.0.IRspectrum,ν,cm-1:1000-1200(СF);1410(CHinSiCH
3);2260
(CN);2800-3000(CH).
Acompound6wasobtainedanalogically,yield66,7%.B.p.=105-107°С/1torr.Chemicalshiftsin 1Н,
29SiNMRspectraofthiscompoundwerematchedinarangeofmeasurementaccuracyinaccordance
withcorrespondedareaofcompound6.19FNMRspectrum(δ,ppm.):-77.2;-78.5;-82.2;-83.1(OCF2);
-105.4(CF2CN);-109.4;-109.6;-114.2;-118.1(CF2inthecycle);-123.0;-124.4;-126.0(CF2CF2CF2);
-119.9;-141.9and-141.2(CFinthecycle).
IR-spectrum,ν,cm-1:2260(CN).
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RecommendedforpublicationbyProf.S.P.Krukovsky