Reactions of tetrafluoroethene oligomers. Part 4. Some reactions of the major hexamer oligomer with nucleophiles based on oxygen and sulphur

The major hexamer oligomer of tetrafluoroethene [perfluoro-2-(1-ethyl-1-methylpropyl)-3-methyl-pent-1-ene] (1) reacted with sodium hydroxide under vigorous conditions to afford perfluoro-[(1-ethyl-1-methylpropyl) (1-methylpropyl)]keten (3). Reaction of (1) with methoxide ion in methanol afforded 4-methoxycarbonyl-heneicosafluoro-3,5-dimethyl-5-ethyl-hept-3-ene (5) whereas reaction with methanol In the presence of triethylamine initially afforded (5), but on further reaction yielded (E, Z)-4H-heneicosafluoro-3,5-dimethyl-5-ethylhept-3-ene (4). Reaction of (1) with potassium-t-butoxide in t-butanol afforded (3) whilst with water/triethylamine (4) was obtained. With ethanethiol and sodium benzylthiolate, respectively, hexamer (1) gave ethyl and benzyl [tricosafluoro-3-ethyl-3-methyl-2-(1-methylpropyl)pent-1-enyl]sulphides (6) and (7). With aqueous potassium cyanide 1-cyanotricosafluoro-3-ethyl-3-methyl-2-(1-methylpropyl)pent-1-ene (8) was obtained.     

Fluorocarbon derivatives of nitrogen. Part I. Some reactions of perfluoro-1-azacyclohexene

Controlled displacement of fluorine from perfluoro-1-azacyclo-hexene (I) by the nucleophilic reagents Me₂NH, Et₂NH, $\text{CH}{}_2\text{CH}{}_2\text{O(CH}{}_2\text{)}{}_2\text{N}$H, C₆Cl₅ONa, and (CF₃)₂NONa provides the derivatives (II) - (IV), respectively. The last of these can also be obtained by treatment of the parent compound (I) with mercury^II bistrifluoromethylnitroxide.     

Reactions involving fluoride ion. Part 21 [1]. Nucleophilic substitution reactions of perfluorocyclobutene oligomers

Reaction of perfluorocyclobutene oligomers, (1) - (4), with some simple nucleophiles gives products arising from S_N2′ displacement [N.B. this term is used here to describe the overall process of addition of a nucleophile to an alkene and elimination of an allylic fluorine and is not meant to imply that the reaction is concerted] or vinylic substitution of fluorine, or a mixture of both processes. The reactivity of the dimers, (1) and (2), is much greater than that of acyclic analogues and this can be attributed to the ring strain present in these compounds.     

Reactions of tetralouroethene oligomers Part 6. Some reactions of 4-diazo-1,1,1,2,2-pentaflouro-3-pentaflouethyl-3-triflouromethylbutane

The isocyanate R_fCH₂NCO (R_f=CF₃(C₂F₅)₂C)reacts under strongly acidic conditions to form the salt R_fCH₂NH₃⁽⁺⁾HSO₄⁽⁻⁾(1) which yields, on treatment with sodium nitrite the diazaoalkane R_fCHN₂ (3). Dissolution of (1) in D.M.S.O. gives, by a remarkable decomposition reaction, the alkane R_fH (2). Reaction of (3) with excess sodium nitrite affords the isocyanate R_fNCO (4) which is stable to water,but which reacts with ammia to give the urea R_fNHCONH₂ (5); this latter was not readily hydrolysed .Photolysis of (3) yields the diazadiene R_fCHNNCH R_f (7). Thermolysis of (3) alone afforded the diazadiene (7), but reaction in the presence of copper (II) perchlorate afforded (7) and the aldehyde R_fCHO (6)     

Reactions involving fluoride ion Part XIII. Reactions of perfluoro-4-vinylpyridine

1-Chloro-1-(2′,3′,5′,6′-tetrafluoropyridyl)tetrafluoroethane, obtained by reaction of chlorotrifluoroethylene with pentafluoropyridine in the presence of caesium fluoride, was dehalogenated over iron at 310°, giving perfluoro-4-vinylpyridine (IV). Reactions of (IV) have been surveyed; nucleophilic attack occurs at both the ring and the difluoromethylene group using MeO^- but with PhO^-, selective attack at the difluoromethylene group occurred. A dimer is produced by reaction of (IV) with CsF and the intermediate carbanion was trapped with tetrafluoropyridazine. Thermal cyclodimerisation of (IV) gave a single isomer whose structure was established by n.m.r. and by defluorination to a cyclobutene. Cyclobutanes were formed in thermal cycloaddition reactions with chlorotrifluoroethylene and with hexafluoropropene. Photochemical reaction of (IV) with hexafluoroacetone gave an oxetane.     

Polyfluoro-1,2-epoxy alkanes and cycloalkanes. Part IV [1]. Thermal reactions of the epoxides of the pentamer and hexamer oligomers of tetrafluoroethene

Oxirans (1) and (2), derived respectively from the pentamer and hexamer oligomers of tetrafluoroethene, were pyrolysed over pyrex glass at 300–500° alone and in the presence of cyclohexene, bromine and toluene. Thus, oxiran (1), pyrolysed alone, afforded perfluoro-2-methylbut-1-ene (3), perfluoro-2,3-dimethylpent-2-ene (4) and (E) and (Z) perfluoro-2,3-hex-3-ene (TFE tetramer) (5a, 5b). Co-pyrolysis of (1) with bromine afforded (E) and (Z) 2-bromoperfluoro-3-methylpent-2-ene (6a, 6b), whilst with toluene, (E) and (Z) 2H-perfluoro-3-methylpent-2-ene (7a, 7b) were obtained: (1) with excess cyclohexene also gave (7a, 7b). The oxiran (2), on pyrolysis alone, gave only (3). In the presence of bromine, (2) gave an equimolar mixture of 1-bromoperfluoro-3-methylpentan-2-one (8) and 3-bromoperfluoro-3-methylpentane (9). Co-pyrolysis of (2) with toluene yielded (3) and 3H-perfluoro-3-methylpentane (10). Pyrolysis of (2) with cyclohexene at 175° gave perfluoro-3-methyl-2-(1-methylpropyl)pent-2-en-1-oylfluoride (11), pentafluoroethylcyclohexane (12) and perfluoro[(1-ethyl-1-methylpropyl) (1-methylpropyl)]ketne (13).     

Reactions of tetrafluoroethylene oligomers. Part 1. Some pyrolytic reactions of the pentamer and hexaher and of the fluorine adducts of the tetramer and pentamer

Pyrolyses of these highly branched fluorocarbons over glass beads caused the preferential thermolyses of CC bonds where there is maximum carbon substitution. Fluorinations of perfluoro-3,4-dimethylhex-3-ene (tetramer) (I) and perfluoro-4-ethyl-3,4-dimethylhex- 2-ehe (pentamer) (II) over cobalt (III) fluoride at 230° and 145° respectively afforded the corresponding saturated fluorocarbons (III) and (IV), though II gave principally the saturated tetramer (III) at 250°. Pyrolysis of III alone at 500—520° gave perfluoro-2-methylbutane (V), whilst pyrolysis of III in the presence of bromine or toluene afforded 2-bromononafluorobutane (VI) and 2H-nonafluorobutane (VII) respectively. Pyrolysis of perfluoro-3-ethyl-3, 4-dimethylhexane (IV) alone gave a mixture of perfluoro-2-methylbutane (V), perfluoro-2-methylbut-1-ene (VIII), perfluoro-3-methylpentane (IX), perfluoro-3,3-dimethylpentane (X), and perfluoro-3,4- dimethylhexane (III). Pyrolysis of IV in the presence of bromine gave (VI) and 3-bromo-3-trifluoromethyl-decafluoropentane (XI): with toluene, pyrolysis gare VlI and 3H-3-trifluoromethyldecafluoropentane (XII). Pyrolysis of II at 500° over glass gave perfluoro-1,2,3-trimethylcyclobutene (XIII) and perfluoro-2,3-dimethylpenta-1,3(E)- and (Z)-diene (XIV) and (XV) respectively. The diene mixture (XIV and XV) was fluorinated with CoF₃ to give perfluoro-2,3-dimethylpentane (XVI) and was cyclised thermally to give the cyclobutene (XIII). Pyrolysis of perfluoro-2- (1′-ethyl-1′-methylpropyl)-3-methylpent-1-ene (XVII) (TFE hexamer major isomer) at 500° gave perfluoro-1-methyl-2-(1′-methylpropyl)cyclobut-1-ene (XVIII) and perfluoro-2-methyl-2-(1′-methylpropyl)buta-1,3-diene (XIX). Fluorination of XVIII over CoF₃ gave perfluoro-1-methyl-2- (1′-methylpropyl)cyclobutane (XX), which on co-pyrolysis with bromine gave VI. XIX on heating gave XVIII. Reaction of XVIII with ammonia in ether gave a mixture of E and Z 1′-trifluoromethyl-2-(1′-trifluoromethyl- pentafluoropropyliden-1′-yl)tetrafluorocyclobutylamine (XXI) which on diazotisation and hydrolysis afforded 2-(2′trifluoromethyl- tetrafluorocyclobut-1-en-1′-yl)-octafluorobutan-2-ol (XXII).     

Some reactions of tetrafluoroethylene oligomers

As part of a programme to prepare and evaluate a series of perfluoro- chemicals for use as inert fluids, the fluorinations of some tetrafluoroethylene oligomers over cobalt (III) fluoride have been studied.Fluorination of perfluoro-3,4-dimethylhex-3-ene (tetramer) and perfluoro-4-ethyl-3,4-dimethylhex-2-ene (pentamer) over CoF₃ at 230°C and l45°C respectively afforded the corresponding saturated fluorocarbons however, at 250°C, pentamer gave predominantly the saturated tetramer. The thermal behaviour of these saturated fluorocarbons alone and in the presence of bromine and toluene has been studied.Pyrolysis of pentamer over glass beads at 500°C gave perfluoro-1,2,3- trimethylcyclobutene and isomers of perfluoro-2,3-dimethylpenta-1,3- diene. Under similar conditions perfluoro-2-(1-ethyl-1-methylpropyl). 3-methylpent-1-ene (hexamer) gave perfluoro-1-methyl-2-(1-methyl- propyl)-cyclobut-1-ene and perfluoro-2-methyl-3-(1-methylpropyl)-buta- 1,3-diene.These reactions and the structural elucidation of the products will be discussed.     

Hydride-transfer reactions of [(h5-cyclohexadienyl)(h5-cyclopentadienyl)iron] alkylium ions

In CF₃ CO₂ H solution, (h⁵-cyclohexadienyl)(h⁵-cyclopentadienyl)iron derivatives containing an R¹ R² C(OH) substituent attached either to the cyclopentadienyl ring or to C(1) of the cyclohexadienyl ligand are converted into (h⁶-arene)(h⁵-cyclopentadienyl)iron cations by hydroxyl loss and hydride migration.     

Reactions of coordinated molecules : XXV. The preparation of several bis[(hydroxy)(methyl)]carbenoid complexes of rhenium

When the rhenium(I) complexes, XRe(CO)₅ (where X is Cl, Br or I), are treated with two molar-equivalents of methyllithium, dianionic complexes of the type, fac-(OC)₃(X)Re[C(CH₃)O]₂^–, are formed. The diprotonation of these dianions with HX affords the neutral, bis-carbenoid complexes, fac-(OC)₃(X)Re[C(CH₃)(OH)]₂. When X is methyl, the reaction with methyllithium gives only a monoanion. The iodo, bis-carbenoid complex decomposes in solution with the elimination of acetaldehyde and with the formation of the known dimeric complex, [Re(CO)₄I]₂. The X-ray molecular structure determination of this dimeric complex is reported. The ^13C NMR data of the chloro and bromo biscarbenoid complexes are also presented.     

Reactions of group IV organometallic compounds : XXVII. Some reactions of [(trimethylsilyl)imino]phosphorane

The reaction of [(trimethylsilyl)imino]methyldiphenylphosphorane: Ph₂MePNSiMe₃ (I) with several acid anhydrides or alkyl isocyanates took place by the simple cleavage of silicon-nitrogen bond. In contrast the interaction of (I) with phenyl isocyanate, isothiocyanate or carbon disulphide led to addition-elimination reactions of the Wittig type. Detailed investigation in the case of phenyl isocyanate indicated the usual elimination of Ph₂MePO is suppressed by the strong affinity of the trimethylsilyl group for anionic oxygen atom.     

Reactions of xenon difluoride. Part 6. Some reactions of phosphorus,arsenic and iodine compounds

The reaction of XeF₂ with some organo-phosphorus, -arsenic and-iodine compounds is described. The products were identified by fluorine nmr spectroscopy and the conditions under which fluorine exchange occurs were briefly investigated. Organoiodine (III) difluorides are suitable for the conversion of Ph₂Te to Ph₂TeF₂; the decomposition of RIF₂liberates IF and fluoroalkane.     

Polyfluorocycloalkenes. Part XVI [1]. Some addition reactions of 1-trifluoromethylnonafluorocyclohex-1-ene

Reactions with alcohols and base replaced the vinylic fluorine of 1-trifluoromethylnonafluorocyclohex-1-ene(I) by methoxy and ethoxy groups. Fluorination with cobaltic fluoride gave, from the former, a number of saturated polyfluoro-ethers. Oxidation of the alkoxy-cycloalkenes gave hexafluoroglutaric acid. Cycloalkene I gave which ammonia an imino-enamine, which was hydrolysed by dilute acid to a keto-enamine. I was defluorinated by heated iron to octafluorotoluene.     

Reactions of cyclic oxalyl compounds,Part 30: Some reactions with N-amino-pyrimidine derivatives

Summary 1-Amino-5-benzoyl-4-phenyl-1H-pyrimidine derivatives1 add arylisocyanates2 to give the N,N-disubsituted ureas3 which can be cyclized by use of oxalyl dichloride to the imidazolyl-pyrimidinones(thiones)4. In addition,1 is transferred into the desaminated pyrimidines6 either by diazotation reaction or by thermolysis of the parental functionalized pyrimidine derivatives7.Dedicated to o. Univ. Prof. Dr. F. Sauter on the occasion of his 60th birthday     

Fluorocarbon derivatives of nitrogen. Part VII [1]. Reaction of N-iminopyridinium ylide with perfluoro-1-azacyclohexene,perfluoro-2-azapropene,and perfluoroacetonitrile

The novel ylides (II) and (III) have been obtained $\text{via}$ treatment of perfluoro-1-azacyclohexene and perfluoro-2-azapropene, respectively, with $\text{N}$-iminopyridinium ylide (I) generated $\text{in}$$\text{situ}$ from $\text{N}$-aminopyridinium iodide and anhydrous potassium carbonate in methylene chloride. A mixture of the $\text{s}$-triazolo[1,5-$\text{a}$]pyridine (IV) and a compound thought to be its dihydro-analogue (V) were isolated following attack on perfluoroacetonitrile by the parent ylide (I); the former product was also prepared by heating 1,2-diamino-pyridinium iodide with trifluoroacetic anhydride.     

Reactions involving fluoride ion. Part 33 [1]. Perfluoroaza-alkylation of fluorinated heteroaromatics with perfluoro-1-methyl-1,3-diazacyclopent-2-and -3-ene

The nitrogen anion (1), generated by reaction of fluoride ion with (2), can be trapped by fluorinated heteroaromatics. Reaction of (1) with pentafluoropyridine gives a mono-substituted product. Mono- and di-substituted products are obtained with tetrafluoro-pyridazine and -pyrimidine, and fluoride ion catalysed isomerisation is observed. The mechanistic consequences of this are discussed. Reaction of (1) with trifluoro-1,3,5- triazine gives a tri-substituted product.     

Sulfenyl halides in the synthesis of heterocycles. 3. Interaction of perfluoro-1-ethyl-2-methyl-1-propenyl-iminochloromethanesulfenyl chloride with 1-allyl-2-methoxybenzene

Reaction of perfluoro-1-ethyl-2-methyl-1-propenyliminochloromethanesulfenyl chloride with 1-allyl-2-methoxybenzene in methylene chloride and nitromethane gives as the main products β-and β-chloro sulfides plus derivative of 2,3-dihydrobenzofuran. The reaction in nitromethane in the presence of lithium perchlorate gave a product of addition of sulfur-containing electrophiles to the double bond-a derivative of 1,3-thiazolidin-2-one-in preference to the cycloaddition product. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, 1558–1564, October, 2006.     

Thermal,photochemical and mass spectral reactions of 2-ethyl-5-methyl-1-pyrroline

Pyrolysis of 2-ethyl-5-methylpyrroline ( 1 ) results in formation of 2,5-dimethylpyrrole, 2-ethyl-5-methylpyrrole, 2-ethylpyrrole and other minor products. Loss of a hydrogen atom or methyl radicals is suggested as the first step in these reactions. Support for the former comes from hydrogen atom abstraction by photo-excited benzophenone. The mass spectral reactions of 1 are briefly considered.