Relative kinetics of the homolytic addition of 2-phenyl-1,3-dioxolane to unsaturated compounds

The CH₂ = CHX olefins form a series relative to their reactivity in reactions with 2-phenyl-1,3-dioxolan-2-yl radicals, which qualitatively correlates with the electron-withdrawing capacity of substituent X: CN CO₂Me >> SiMe₃ C₄H₉. This behavior indicates that the dioxolanyl radical is nucleophilic.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 7, pp. 1663–1666, July, 1992.     

Radical telomerization of 3,3,3-trifluoropropene with diethyl hydrogen phosphonate: Characterization of the first telomeric adducts and assessment of the transfer constants

The radical telomerization of 3,3,3-trifluoropropene (TFP) with diethyl phosphate (or diethyl hydrogen phosphonate, DEHP) was investigated to synthesize fluorinated telomers bearing a phosphonate end-group, as H(TFP)_nP(O)(OEt)₂. Di-tert-butyl peroxide was the most efficient radical initiator. A careful structural study of typical TFP/DEHP telomers was performed by ¹H, ¹⁹F, and ³¹P nuclear magnetic resonance spectroscopies. These analytical methods allowed us to prove the selective addition of the phosphonyl radical onto the hydrogenated side of TFP, while the telomers containing more than two TFP units were composed of TFP isomers containing normal and reversed adducts. The kinetics of telomerization led to the assessment of the first four order transfer constants giving an infinite transfer constant of 0.75 at 140 °C for DEHP.     

Radical reactions of vinyltrimethylsilane with 2-methyl-1,3-dioxolane

Conclusions Vinyltrimethylsilane in radical reactions with a cyclic acetal gives 2- and 4-substituted 1,3-dioxolanes together with telomers of linear structure. Increasing the concentration of the monomer and reducing the reaction temperature favors an increase in the proportion of cyclic telomers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1616–1620, July, 1986.     

Radical reaction of ethyl orthoacetate with 3,3,3-trifluoropropene

Summary The reaction of 3,3,3-trifluoropropene with ethyl orthoacetate leads to the formation of an acetate CH₃C(O)OCH(CH₃)CH₂CH₂CF₃ and a ketone CH₃C(O)CH₂CH(CF₃)CH₂CH₂CF₃. A reaction mechanism is proposed which involves rearrangement of the radicals CR₃C(OC₂H₅)₂OCH(CH₃) (CH₂CHCF₃) _n ^. with 1,7- and 1,5-migration of an H atom and stabilization by fragmentation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1583–1586, July, 1986.     

Radical reactions of ethyl orthoformate with 3,3,3-trifluoropropene

Conclusions The radical reaction of 3,3,3-trifluoropropene with ethyl orthoformate largely leads to the formation of the adduct, EtOC(O)OCH(Me)CH₂CH₂CF₃ due to rearrangement of the intermediate radicals with 1,5 hydrogen atom migration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp.1418–1420, June, 1985.     

Radical telomerization of 1,3‐butadiene with perfluoroalkyl iodides in the presence of potassium carbonate

The radical telomerization of 1,3‐butadiene with perfluoroalkyl iodides (C₆F₁₃I or merely C₈F₁₇I) initiated by di‐tert‐butyl peroxide was studied in the presence of various amounts of potassium carbonate at 145 °C in acetonitrile. The influence of this salt on both the kinetics and the telomer characteristics (color, molar mass, and functionality) was established. First, the determination of the chain‐transfer constant of C₈F₁₇I led to a value (2.52) similar to that obtained under the same conditions without any K₂CO₃ (2.59). Second, 1,3‐butadiene conversion was much faster, and the molar mass/time profiles were also quite different, revealing the formation of high molar mass polymers at the end of conversion, which was not observed in previous studies without any K₂CO₃. Moreover, great improvements in the functionality of the fluorinated telomers were achieved (closer to unity). The products were also not as colored as before (black in the absence of K₂CO₃), and this allowed valuable application tests. With electronic microscopy, K₂CO₃ was shown to neutralize hydrogen iodide (HI) produced in the course of the reaction, which caused major drawbacks (e.g., low functionality and dark color). © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3743–3756, 2002     

Radical telomerization of 3,3,3-trifluoro-1-propene with carbon tetrachloride

Telomerization of 3,3,3-trifluoropropene with CCl₄ was carried out in the presence of Fe(CO)₅ in combination with dimethylformamide (DMF) or hexamethylphoshoric triamide (HMPA) with formation of the telomers CCl₃(CH₂CHCF₃)_nCl, n=1–3, as the main products. Chromatography-mass spectrometry showed the presence of CCl₃CH₂CH(CCL₃)CF₃, a product of recombination of the adduct radical and CCl₃, in the reaction mixture, which confirms the radical nature of the process. The structure of all the reaction products was confirmed by¹³C NMR and (or) mass spectrometry.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1807–1811, August, 1990.     

Palladium-based telomerization of 1,3-butadiene with glycerol using methoxy-functionalized triphenylphosphine ligands

Glycerol is considered a potential renewable building block for the synthesis of existing as well as new chemicals. A promising route is the telomerization of 1,3-butadiene with glycerol leading to C8 chain ethers of glycerol with applications in, for example, surfactant chemistry. Recently, we reported a new set of palladium-based homogeneous catalytic systems for the telomerization of 1,3-butadiene with glycerol and found that palladium complexes bearing methoxy-functionalized triphenylphosphine ligands are highly active catalysts capable of converting crude glycerol without any significant loss of activity. Herein, we present a detailed account of these investigations by reporting on the influence of the butadiene/glycerol ratio, temperature, and reaction time on product selectivity and activity allowing further optimization of catalyst performance. Maximum activity and yield were reached for high 1,3-butadiene/glycerol ratios at a temperature of 90 degrees C, whereas the selectivity for mono- and diethers of glycerol could be optimized by combining high reaction temperatures and short reaction times with low butadiene/glycerol ratios. Variation of the PdII metal precursors and the metal/ligand ratio showed that palladium precursors with halogen ligands gave unsatisfying results, in contrast to precursors with weakly coordinated ligands such as [Pd(OAc)2] and [Pd(acac)2]. [Pd(dba)2], the only Pd0 precursor tested, gave the best results in terms of activity, which illustrates the importance of the ability to form a Pd0 species in the catalytic cycle. Finally, base addition resulted in a shortening of the reaction time and most likely facilitates the formation of a Pd0 species. Based on these results, we were able to realize the first attempts towards a rational ligand design aimed at a high selectivity for mono- and diether formation.     

Palladium-catalyzed cross-coupling of benzylzinc reagents with 2-bromo-3,3,3-trifluoropropene

α-Trifluoromethyl alkenes can be used as peptide isosteres, moreover, the pre-installed vinyl group make it possible that transformation to diverse fluorine-containing unities. However, the cross-coupling of benzyl group with α-trifluoromethyl alkenes has yet to be developed. In this report, we describe a general method for the cross-coupling of benzylzinc reagents with 2-bromo-3,3,3-trifluoropropene (BTP) to afford diverse α-trifluoromethylalkene derivatives by using Pd(TFA)₂ as catalyst. This method takes advantage of cheap industrial available fluorine building blocks and easily prepared benzylzinc reagents to generate α-trifluoromethylalkene derivatives, which features with mild reaction conditions, wide substrate scope and feasibility of product transformations.     

Radical addition of 2-trichloromethyl-1,3-dioxolane to vinyltrimethylsilane

Conclusion The addition of 2-trichloromethyl-l,3-dioxolane to vinyltrimethylsilane upon initiation by a system consisting of Fe(CO)₅ and a nucleophilic cocatalyst proceeds to cleavage of a C-Cl bond in the trichloromethyl group with the formation of an adduct containing the dioxolanyl ring.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2351–2353, October, 1986.     

Some transformations of 2-methyl-2-allyl-4-methylol-1,3-dioxolane

Conclusions A study was made of the reaction of 2-methyl-2-allyl-4-methylol-1,3-dioxolane with mercaptans, alcohols, halogens and hydrogen halides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1541–1542, July, 1971.     

Synthesis of fluorinated telomers. Part 1. Telomerization of vinylidene fluoride with perfluoroalkyl iodides

Thermal and redox-induced telomerizations of vinylidene fluoride (VDF) with linear (n-C₄F₉I) or branched (i-C₃F₇I) perfluoroalkyl iodides have been performed. In both cases, thermal telomerizations led to telomeric-type distributions of the first five (from linear telogen) or the first three (from branched telogen) adducts produced, with better yields at higher temperatures. The redox-initiated telomerization was more selective since it led to the first two adducts only. For both reactions, mono- and di-adducts were isolated and characterized by ¹H and ¹⁹F NMR spectroscopy. Interestingly, both the diadducts were composed of two isomers (i.e. the expected telomer and R_FCH₂CF₂CF₂CH₂I). Two mechanisms are proposed and it is assumed that the products may be obtained either by chain propagation or by stepwise telomerization. In addition, attack of the electrophilic radical on the nucleophilic side of VDF is discussed.     

FeCl_3/磷酸三丁酯催化四氯化碳与氯乙烯的调聚反应:结构与活性

以四氯化碳与氯乙烯的调聚反应为目标反应,研究了Fe Cl3/磷酸三丁酯(TBP)配合物在反应体系中的结构,并关联了其结构与催化活性.采用摩尔电导、红外光谱和紫外吸收光谱对配合物的结构进行表征,结果表明Fe Cl3/TBP配合物在四氯化碳溶剂中为加合物Fe Cl3(TBP)n(n=1,2和3),配位数n由TBP与Fe Cl3的化学计量数决定.通过表观动力学实验研究了该配合物的催化反应活性,实验结果表明反应表观速率常数(kobs)随着TBP与Fe Cl3的摩尔比(r)的增大而增大,反应引发期(t0)随着r的增大而减小.假定反应遵循链式氧化还原机理,推导了kobs和t0的表达式,表达式和实验结果一致,均表明kobs只与配合物Fe Cl3(TBP)n的配位数和浓度有关.     

Calorimetric investigation of palladium-catalysed telomerization of isoprene in solution

Telomerization of isoprene is characterized by intense thermal effects. The reaction system di-μ-chlorobis(η³-allyl)-dipalladium(II): tri-n-butylphosphine: sodium methylate: isoprene=1∶2∶3∶200 in a solvent-mixture of methanol∶benzene=1∶3 is used as a model. It is concluded that reaction of the catalyst combined with reduction of Pd(II) is followed by the telomerization reaction. There is a marked influence of Pd and phosphine concentration in the catalyst as well as concentration of isoprene. Results are available to optimize technical applications.