氟烯的结构-特性关系——Ⅵ.烷氧负离子对偏氟乙烯的亲核加成反应

一般烯烃容易发生亲电加成反应,而全氟或多氟(卤)型烯烃容易发生亲核加成反应~([3])但介于典型烯烃(如乙烯)及典型全氟烯烃(如四氟乙烯)之间的偏氟乙烯是否能进行亲核加成,至今尚无答案。偏氟乙烯分子一端的两个氟原子的吸电子诱导效应,使双键的电子密度下降,而且两个氟原子的p电子对与双键的π电子间的p-π排斥作用使该双键发生极化,在CF_2一端的碳上出现δ~(+[4,5]),因此我们认为偏氟乙烯应该可以发生亲核加成,且在CF_2一端接受亲核进攻。为此,我们选用了最典型的亲核试剂t-C_4H_9O~-、i-C_3H_7O~-、n-C_3H_7O~-、C_2H_5O~-及CH_3O~-     

偏氟乙烯和四氟乙烯共聚反应

本文用过氧化二碳酸二异丙酯为引发剂,丙酮为分子量调节剂,对偏氟乙烯-四氟乙烯共聚反应进行了研究,并制得了不同组成,不同分子量的样品,用色谱分析方法分析在共聚反应过程中单体组成的变化,方便地确定了偏氟乙烯-四氟乙烯共聚反应中的“恒比”组成范围,并能控制共聚物组成的均匀性,丙酮有效地调节了共聚物的分子量,对共聚物的性能测定表明,它们有很好的机械性能和热稳定性,在“恒比”组成范围的共聚物的热电系数有一个极大值,它对应于熔点的极小值。     

在烷氧自由基的β-断裂中形成·CF_3和·CH_3的相对难易度研究

形成全氟烷基与碳氢烷基的相对难易度的直接比较问题,是一个根本性问题,但至今未获解决。我们用改进的方法成功地合成了新的次氯酸醋CF_3C(CH_3)_2OCl和CCl_3C(CH_3)_2OCl;又参照Kinillov方法,合成了新的二烷基过二碳酸酯(CF_3C(CH_3)_2OCO_2?_2,并对上述化合物在CCl_4溶液中的热分解反应进行了详细的研究。通过测定相应的烷氧自由基的β-断裂产物的方法,第一次可靠地给出了在烷氧自由基的β-断裂中,·CH_3与·CF_3,·CCl_3与·CH_3形成的相对难易度。     

偏氟乙烯与全卤代烷烃的调聚反应及其产物的研究

偏氟乙烯能够分别与四氯化碳和全氟叔丁基碘进行自由基的调聚反应,得到新型的调聚物CCl₃(CH₂CF₂)_nCl(n=1～6)和(CF₃)₃C(CH₂CF₂)_nI(n=1,2).调聚物的结构由核磁共振谱、红外光谱、元素分析和化学转化所证实.反应中亲电自由基·CCl₃与·C(CF₃)₃主要进攻偏氟乙烯上无氟碳原子,亦即在偏氟乙烯的自由基加成中,极性因素对加成方向起决定性作用.     

四氟乙烯-乙烯共聚物的链结构及其对热稳定性的影响

四氟乙烯和乙烯共聚反应,由于它们的竟聚率接近零,且γ_1·γ_2也远小于1,故容易得到交替倾向很大的共聚物。其电性能与聚四氟乙烯和四氟乙烯-六氟丙烯共聚物几乎相同,但有更佳的机械性能和抗辐射性。同时能用一般热塑性塑料的加工方法成型。七十年代,四氟乙烯-乙烯共聚物(简称F-40)已发展成一种通用产品,广泛地用作原子能工业中的抗辐射材料,电子计算机中的薄壁导线材料,化学工业中防腐蚀涂层衬里以及日常生活中的各种器皿。共聚物的性能往往决定于单体的性质、共聚物组成和它们的链结构等因素。本文研究了     

α,α,ω-三氢全氟醇类的化学

四氟乙烯与甲醇在游离基引发剂的作用下发生調节聚合反应,生成一系列的低級調聚产物,即含有奇数碳原子的α,α,ω三氫全氟醇类: nC_2F_4+CH_3OH→H(CF_2—CF_2)_nCH_2OH(n=1—12)这些产物具有多氟化合物特有的稳定性和不燃性,又含有活泼的伯醇基,所以是氟有机化学中的一类重要合成中間体,又是制备某些特殊材料如高溫潤滑剂、介     

α-甲氧羰基二氟乙酰氟及3,3,3-三氯二氟丙酰氟的合成

α-甲氧羰基二氟乙酰氟 FCOCF_2CO_2CH_3(1)及3,3,3-三氯二氟丙酰氟Cd_3CF_2COF(2)是合成含羧酸前体的全氟烯醚的重要原料。全氟烷基乙烯基醚 CF_2=CFOR_f 与四氟乙烯共聚得到的共聚物,具有聚四氟乙烯的化学稳定性,又能克服聚四氟乙烯难以加工的缺点。近二十年来,由于发现在全氟聚合物的主链上引入带功能团的侧链后,可以使其在保持氟碳链优点的同时,又具有某些特殊功能,如化学催化、离子交换与选择透过性、电荷传递等能力,因此合成带各种功能团的全氟烷基乙烯基醚,作为全氟功能高分子的共聚单体,是一个有趣的课题。     

聚氟代单烯烃的~(19)F核磁共振波谱研究

本文研究了聚偏氟乙烯(PVF_2),偏氟乙烯-全氟丙烯(VF_2-HFP)共聚物和偏氟乙烯-四氟乙烯-全氟丙烯(VF_2-TFE-HFP)共聚物的~19F核磁共振谱。由谱线的化学位移和强度归纳出二单元组和三单元组链节的序列分布,并计算出两者的相互比例。     

多氟烯烃和炔烃的钯催化氢化

本文报道Pd/Al_2O_3(1%)催化剂催化氢化CF_3CCl=CClCF_3,CF_3CCI==CHCF_3和CF_3C=CCF_3等多氟烯烃和炔烃的结果。经1~H和(19)~F核磁共振、质谱、红外等分析,证明了用制备色谱分离后的氢化产物主要成份的结构。前二者的氢化产物中主要是CF_3CH_2CH_2CF_3和CF_3CH_2CHClCF_3的混合物,而CF_3C=CCF_3氢化后只生成CF_3CH_2CH_2CF_3。     

形成全氟正丙基与全氟异丙基自由基的相对难易度的动力学研究

形成碳氢系列烷基自由基的相对难易度的动力学研究已有很多报道,但其中主要是测出β-断裂反应相对速度的方法,而有关全氟烷基自由基的β-断裂反应的动力学测定迄今未见报道.显然,这些数据对自由基化学和有机氟化学来说都是很基本的和重要的.专利中也都提到这类反应的相对速度,它在应用方面,如在乙烯、四氟乙烯及全氟(丙基乙烯基)醚共聚反应中对控制分子量起了重要作用.     

Atmospheric chemistry of CF3CF═CH2 and (Z)-CF3CF═CHF: Cl and NO3 rate coefficients, Cl reaction product yields, and thermochemical calculations

Rate coefficients, k, for the gas-phase reactions of Cl atoms and NO(3) radicals with 2,3,3,3-tetrafluoropropene, CF(3)CF═CH(2) (HFO-1234yf), and 1,2,3,3,3-pentafluoropropene, (Z)-CF(3)CF═CHF (HFO-1225ye), are reported. Cl-atom rate coefficients were measured in the fall-off region as a function of temperature (220-380 K) and pressure (50-630 Torr; N(2), O(2), and synthetic air) using a relative rate method. The measured rate coefficients are well represented by the fall-off parameters k(0)(T) = 6.5 × 10(-28) (T/300)(-6.9) cm(6) molecule(-2) s(-1) and k(∞)(T) = 7.7 × 10(-11) (T/300)(-0.65) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and k(0)(T) = 3 × 10(-27) (T/300)(-6.5) cm(6) molecule(-2) s(-1) and k(∞)(T) = 4.15 × 10(-11) (T/300)(-0.5) cm(3) molecule(-1) s(-1) for (Z)-CF(3)C═CHF with F(c) = 0.6. Reaction product yields were measured in the presence of O(2) to be (98 ± 7)% for CF(3)C(O)F and (61 ± 4)% for HC(O)Cl in the CF(3)CF═CH(2) reaction and (108 ± 8)% for CF(3)C(O)F and (112 ± 8)% for HC(O)F in the (Z)-CF(3)CF═CHF reaction, where the quoted uncertainties are 2σ (95% confidence level) and include estimated systematic errors. NO(3) reaction rate coefficients were determined using absolute and relative rate methods. Absolute measurements yielded upper limits for both reactions between 233 and 353 K, while the relative rate measurements yielded k(3)(295 K) = (2.6 ± 0.25) × 10(-17) cm(3) molecule(-1) s(-1) and k(4)(295 K) = (4.2 ± 0.5) × 10(-18) cm(3) molecule(-1) s(-1) for CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF, respectively. The Cl-atom reaction with CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF leads to decreases in their atmospheric lifetimes and global warming potentials and formation of a chlorine-containing product, HC(O)Cl, for CF(3)CF═CH(2). The NO(3) reaction has been shown to have a negligible impact on the atmospheric lifetimes of CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF. The energetics for the reaction of Cl, NO(3), and OH with CF(3)CF═CH(2) and (Z)-CF(3)CF═CHF in the presence of O(2) were investigated using density functional theory (DFT).     

Quaternary salts containing the pentafluorosulfanyl (SF5) group

The first quaternary salts of pyridine (2), N-methyl imidazole (3), N-propyl triazole (4), and pyridazine (5) that contain the pentafluorosulfanyl (SF(5)) group were prepared and characterized. Neat reactions of the aromatic nitrogen compounds with SF(5)(CF(2))(n)(CH(2))(m)I (n = 2 or 4, m = 2 or 4) gave quaternary iodides 6a-c, 7a-c, 8a, and 9a,b, which were metathesized with LiN(SO(2)CF(3))(2) to form the bis(trifluoromethylsulfonyl)amides 10a-c, 11a-c, 12a, and 13a,b, in high yields. With the exception of the pyridine bis(trifluoromethylsulfonyl)amide salts, the compounds melted or exhibited a T(g) at <0 degrees C. The methylimidazolium, pyridinium, and pyridazinium salts exhibited densities of approximately 2 g/cm(3). Particularly striking was the density of CF(3)(CF(2))(5)(CH(2))(2)-pyridazinium N(CF(3)SO(2))(2) measured at 2.13 g/cm(3); however, an atypically high density for the 1-CF(3)(CF(2))(5)(CH(2))(2)-3-methyl imidazolium amide (14) was also observed at 1.77 g/cm(3). All quaternary salts were characterized via IR, (19)F, (1)H, and (13)C NMR spectra and elemental analyses.     

CF3CF=CH2 and (Z)-CF3CF=CHF: temperature dependent OH rate coefficients and global warming potentials

Rate coefficients over the temperature range 206-380 K are reported for the gas-phase reaction of OH radicals with 2,3,3,3-tetrafluoropropene (CF(3)CF=CH(2)), k(1)(T), and 1,2,3,3,3-pentafluoropropene ((Z)-CF(3)CF=CHF), k(2)(T), which are major components in proposed substitutes for HFC-134a (CF(3)CFH(2)) in mobile air-conditioning units. Rate coefficients were measured under pseudo-first-order conditions in OH using pulsed-laser photolysis to produce OH and laser-induced fluorescence to detect it. Rate coefficients were found to be independent of pressure between 25 and 600 Torr (He, N(2)). For CF(3)CF=CH(2), the rate coefficients, within the measurement uncertainty, are given by the Arrhenius expression k(1)(T)=(1.26+/-0.11) x 10(-12) exp[(-35+/-10)/T] cm(3) molecule(-1) s(-1) where k(1)(296 K)=(1.12+/-0.09) x 10(-12) cm(3) molecule(-1) s(-1). For (Z)-CF(3)CF=CHF, the rate coefficients are given by the non-Arrhenius expression k(2)(T)=(1.6+/-0.2) x 10(-18)T(2) exp[(655+/-50)/T] cm(3) molecule(-1) s(-1) where k(2)(296 K)=(1.29+/-0.06) x 10(-12) cm(3) molecule(-1) s(-1). Over the temperature range most relevant to the atmosphere, 200-300 K, the Arrhenius expression k(2)(T)=(7.30+/-0.7) x 10(-13) exp[(165+/-20)/T] cm(3) molecule(-1) s(-1) reproduces the measured rate coefficients very well and can be used in atmospheric model calculations. The quoted uncertainties in the rate coefficients are 2sigma (95% confidence interval) and include estimated systematic errors. The global warming potentials for CF(3)CF=CH(2) and (Z)-CF(3)CF=CHF were calculated to be <4.4 and <3.6, respectively, for the 100 year time horizon using infrared absorption cross sections measured in this work, and atmospheric lifetimes of 12 and 10 days that are based solely on OH reactive loss.     

Small scorpionate ligands: silver(I)-organophosphane complexes of 5-CF(3)-substituted scorpionate ligand combining a B-H...Ag coordination motif

The first 5-substituted trihydro(azolyl)borate system, the sodium trihydro(5-CF3-pyrazol-1-yl)borate, Na[H3B(5-(CF3)pz)], has been synthesized by the reaction of 3-trifuoromethyl-pyrazole with NaBH4 in high yield. Na[H3B(5-(CF3)pz)] reacts with AgNO3 in the presence of monodentate tertiary phosphanes PR3 (PR3=P(C6H5)3, P(p-C6H4CH3)3, P(m-C6H4CH3)3, P(o-C6H4CH3)3, or PCH3(C6H5)2) to afford silver(I) bis(phosphane) adducts. These compounds have been characterized by elemental analyses, FTIR, ESI-MS, and multinuclear (1H, 19F, and 31P) NMR spectroscopy. Solid-state structures of {[H3B(5-(CF3)pz)]Ag[P(C6H5)3]2} and {[H3B(5-(CF3)pz)]Ag[P(p-C6H4CH3)3]2} are also reported. They feature kappa2-N,H-bonded trihydro(pyrazolyl)borate ligands and pseudo-tetrahedral silver atoms.     

四氟乙烯与异丙醇的调节聚合研究

采用气相色谱法,研究了反应温度、引发剂浓度、四氟乙烯单体压力对四氟乙烯与异丙醇调聚反应产物重量分布的影响。实验结果表明,随温度升高,n=1的产物含量增加,n>1的各产物含量下降;单体压力的影响则相反;引发剂浓度的影响不明显。反应初期n=1产物生成速率较快,反应中、后期有利于m≥3产物的生成。     

Synthesis and structural characterization of group 6 transition metal complexes with terminal fluoromethylidyne (CF) ligands; a DFT/NBO/NRT comparison of bonding characteristics of terminal NO, CF and CH ligands

A family of group 6 transition metal complexes M(C(5)R(5))(CO)(2)(CF) [M = Cr, Mo, W; R = H, Me] with terminal fluoromethylidyne ligands have been synthesized through the reduction of the corresponding trifluoromethyl precursors with potassium graphite or magnesium graphite. They have been characterized spectroscopically and in some cases crystallographically, although the structures show disorder between the CO and CF ligands. The M[triple bond]CF subunit reacts as a triple bond to form cluster complexes containing μ(3)-CF ligands on reaction with Co(2)(CO)(8). Computational (DFT/NBO/NRT) studies on M(C(5)H(5))(CO)(2)(CF) [M = Cr, Mo, W] and the corresponding cationic fragments M(CO)(2)(XY)(+) illustrate significant differences in the metal-ligand bonding between CF and its isoelectronic analogue NO, as well as with its hydrocarbon analogue CH.     

Kinetic study of the reactions of Cl atoms with CF3CH2CH2OH, CF3CF2CH2OH, CHF2CF2CH2OH, and CF3CHFCF2CH2OH

The reaction kinetics of chlorine atoms with a series of partially fluorinated straight-chain alcohols, CF(3)CH(2)CH(2)OH (1), CF(3)CF(2)CH(2)OH (2), CHF(2)CF(2)CH(2)OH (3), and CF(3)CHFCF(2)CH(2)OH (4), were studied in the gas phase over the temperature range of 273-363 K by using very low-pressure reactor mass spectrometry. The absolute rate coefficients were given by the expressions (in cm(3) molecule(-1) s(-1)): k(1) = (4.42 +/- 0.48) x 10(-11) exp(-255 +/- 20/T); k(1)(303) = (1.90 +/- 0.17) x 10(-11), k(2) = (2.23 +/- 0.31) x 10(-11) exp(-1065 +/- 106/ T); k(2)(303) = (6.78 +/- 0.63) x 10(-13), k(3) = (8.51 +/- 0.62) x 10(-12) exp(-681 +/- 72/T); k(3)(303) = (9.00 +/- 0.82) x 10(-13) and k(4) = (6.18 +/- 0.84) x 10(-12) exp(-736 +/- 42/T); k(4)(303) = (5.36 +/- 0.51) x 10(-13). The quoted 2sigma uncertainties include the systematic errors. All title reactions proceed via a hydrogen atom metathesis mechanism leading to HCl. Moreover, the oxidation of the primarily produced radicals was investigated, and the end products were the corresponding aldehydes (R(F)-CHO; R(F) = -CH(2)CF(3), -CF(2)CF(3), -CF(2)CHF(2), and -CF(2)CHFCF(3)), providing a strong experimental indication that the primary reactions proceed mainly via the abstraction of a methylenic hydrogen adjacent to a hydroxyl group. Finally, the bond strengths and ionization potentials for the title compounds were determined by density functional theory calculations, which also suggest that the alpha-methylenic hydrogen is mainly under abstraction by Cl atoms. The correlation of room-temperature rate coefficients with ionization potentials for a set of 27 molecules, comprising fluorinated C2-C5 ethers and C2-C4 alcohols, is good with an average deviation of a factor of 2, and is given by the expression log(k) (in cm(3) molecule(-1) s(-1)) = (5.8 +/- 1.4) - (1.56 +/- 0.13) x (ionization potential (in eV)).     

STUDIES ON THE CHAIN STRUCTURAL EFFECT OF PVDF AND VDF (52)/TrFE(48) COPOLYMER BY MEANS OF THE METHOD OF DIELECTRIC RELAXATION

Through improvements on a fully commercial and automatic system measuring frequency andtemperature spectra of the complex elastic, dielectric, and piezoelectric constants of polymerfilms, the precision for measuring complex dielectric constants achieved 2‰ from original 1%.The complex dielectric constants of PVDF, VDF (95 )/VF (5), VDF (52)/TrFE (48) and VDF(47. 5)/TrFE(47. 5)/HeFP (5) over a range of-120-140℃, 10-2-10~4Hz were measured bythe described system. The diminution of chain regularity due to 5mol% vinyl fluoride in the chainof PVDF led to disappearing of α-relaxation and increase in T_g (3℃) of VDF (95)/VF (5).Because of the spatial impediment of 5mol% HeFP in copolymer chain, the Curie point of VDF(52)/TrFE(48) decreased by 30℃ and T_g by 3℃. The behavior of dielectric relaxation indicatedthat 5mol% vinyl fluoride and HeFP made the relaxation strength of noncrystalline regionreduced, the activation energy of local relaxation increased and the relaxation time prolonged respectively.     

Methyl Tin(IV) derivatives of HOTeF(5) and HN(SO(2)CF(3))(2): a solution multinuclear NMR study and the X-ray crystal structures of (CH(3))(2)SnCl(OTeF(5)) and [(CH(3))(3)Sn(H(2)O)(2)][N(SO(2)CF(3))(2)

The new tin(IV) species (CH(3))(2)SnCl(OTeF(5)) was prepared via either the solvolysis of (CH(3))(3)SnCl in HOTeF(5) or the reaction of (CH(3))(3)SnCl with ClOTeF(5). It was characterized by NMR and vibrational spectroscopy, mass spectrometry, and single crystal X-ray diffraction. (CH(3))(2)SnCl(OTeF(5)) crystallizes in the monoclinic space group P2(1)/n (a = 5.8204(8) A, b =10.782(1) A, c =15.493(2) A, beta = 91.958(2) degrees, V = 971.7(2) A(3), Z = 4). NMR spectroscopy of (CH(3))(3)SnX, prepared from excess Sn(CH(3))(4) and HX (X = OTeF(5) or N(SO(2)CF(3))(2)), revealed a tetracoordinate tin environment using (CH(3))(3)SnX as a neat liquid or in dichloromethane-d(2) (CD(2)Cl(2)) solutions. In acetone-d(6) and acetonitrile-d(3) (CD(3)CN) solutions, the tin atom in (CH(3))(3)SnOTeF(5) was found to extend its coordination number to five by adding one solvent molecule. In the strong donor solvent DMSO, the Sn-OTeF(5) bond is broken and the (CH(3))(3)Sn(O=S(CH(3))(2))(2)(+) cation and the OTeF(5)(-) anion are formed. (CH(3))(3)SnOTeF(5) and (CH(3))(3)SnN(SO(2)CF(3))(2) react differently with water. While the Te-F bonds in the OTeF(5) group of (CH(3))(3)SnOTeF(5) undergo complete hydrolysis that results in the formation of [(CH(3))(3)Sn(H(2)O)(2)](2)SiF(6), (CH(3))(3)SnN(SO(2)CF(3))(2) forms the stable hydrate salt [(CH(3))(3)Sn(H(2)O)(2)][N(SO(2)CF(3))(2)]. This salt crystallizes in the monoclinic space group P2(1)/c (a = 7.3072(1) A, b =13.4649(2) A, c =16.821(2) A, beta = 98.705(1) degrees, V = 1636.00(3) A(3), Z = 4) and was also characterized by NMR and vibrational spectroscopy.     

全氟甲基乙烯基醚和其它含氟单体乳液共聚合的竞聚率测定

分别通过气相色谱法测定了全氟甲基乙烯基醚 (PMVE)与偏氟乙烯 (VDF)以及PMVE与四氟乙烯(TFE)二元乳液共聚反应中的气相单体组成和共聚物组成 ,然后用非线性回归法 (RREVM )计算得TFE PMVE及VDF PMVE乳液共聚合反应的表观竞聚率分别为γTFE =3 89和γPMVE =0 0 5以及γVDF =1 0 6和γPMVE =0 11.结合已经测定的TFE VDF二元乳液共聚的表观竞聚率 ,计算了由VDF TFE PMVE三元乳液共聚合反应合成的共聚物组成 ,后者与由1 9F NMR实测的共聚物组成吻合