过氧化二苯甲酰为引发剂用于液态聚硅烷合成聚碳硅烷

以聚二甲基硅烷裂解制备的液态聚硅烷为原料,添加引发剂过氧化二苯甲酰合成聚碳硅烷,使液态聚硅烷合成聚碳硅烷的产率提高了20%~25%.利用FTIR和GPC对反应过程进行跟踪分析,利用元素分析,1H-NMR,13C-NMR,TG-DTA和XRD对产物的组成结构和性能进行了表征,提出了过氧化二苯甲酰对液态聚硅烷合成聚碳硅烷的促进反应机理.结果表明,过氧化二苯甲酰受热分解形成自由基,促进了液态聚硅烷中的Si—Si键断裂重排,同时也引发了小分子硅碳烷中的Si—H和Si—CH3键断裂生成Si—CH2—Si结构,使聚碳硅烷分子量长大,产率提高.同时过氧化二苯甲酰分解产生的苯基和苯甲酰氧基会作为端基或侧基引入到聚碳硅烷分子中,引起产物C、O含量的少许增加.但对聚碳硅烷高温烧结后的陶瓷收率没有显著影响.     

不同温度下聚铝碳硅烷的合成与表征

为了研究合成温度对聚铝碳硅烷(PACS)结构的影响, 采用具有Si—C骨架结构的低分子量液态聚碳硅烷(LPCS)与乙酰丙酮铝[Al(AcAc)3]为原料, 在300, 360和420 ℃下分别合成了固态PACS, 并对合成的PACS样品进行元素组成及结构表征. 表征结果显示, 合成温度明显影响样品的Al, O含量及Si—H键数量. 合成温度升高, Al含量与O含量增大, 但PACS中的Si—H键数量急剧减少, 在360 ℃下合成的样品具有理论Al含量, 而在300和420 ℃下合成的样品的Al含量分别小于和大于理论Al含量. 27Al MAS NMR结果显示, Al与O形成AlO4, AlO5和AlO6 三种配位形式. 反应过程中消耗Si—H键形成Si—O—Al交联结构是PACS数均分子量及多分散系数增加的主要原因.     

Synthesis and Characterization of Organosilyl Derivatives of Keggin Polyoxometalates [XW11O40（SiR）2]n- CX=CoIII, P; R=CH=CH2, OH）

以CoIIIW11和有机硅烷为原料,在pH=1,乙醇-水（体积比=2∶1）的混合溶剂中,首次合成了Keggin型有机硅取代的钨钴酸盐[CoIIIW11O40（SiR）2]5-（CoIIIW11（SiR）2,R=CH=CH2,OH）.这里,乙醇作为共溶剂增加硅烷在溶液中的溶解度,使CoIIIW11在转化为饱和结构之前能够快速与硅烷相遇并反应.产物的组成和结构用IR,UV-Vis,NMR,TG-DTA,元素分析等技术进行了全面表征.结果显示,两个SiR基团进入了CoIIIW11的空位,并形成Si—O—Si桥,得到与先前报道的硅取代钨硅酸盐和钨磷酸盐相似的结构.还运用此条件成功合成了以往需要在固-液相转移条件下合成的[PW11O40（SiR）2]3-[PW11（SiR）2,R=CH=CH2,OH],进一步证明了此方法在合成有机硅取代的多金属氧酸盐方面的可行性和通用性.     

Keggin型有机硅取代的多金属氧酸盐衍生物[XW11O40（SiR）2]n-(X=CoIII,P;R=CH=CH2,OH)的合成和表征

以CoIIIW11和有机硅烷为原料,在pH=1,乙醇-水(体积比=2∶1)的混合溶剂中,首次合成了Keggin型有机硅取代的钨钴酸盐[CoIIIW11O40(SiR)2]5-(CoIIIW11(SiR)2,R=CH=CH2,OH).这里,乙醇作为共溶剂增加硅烷在溶液中的溶解度,使CoIIIW11在转化为饱和结构之前能够快速与硅烷相遇并反应.产物的组成和结构用IR,UV-Vis,NMR,TG-DTA,元素分析等技术进行了全面表征.结果显示,两个SiR基团进入了CoIIIW11的空位,并形成Si—O—Si桥,得到与先前报道的硅取代钨硅酸盐和钨磷酸盐相似的结构.还运用此条件成功合成了以往需要在固-液相转移条件下合成的[PW11O40(SiR)2]3-[PW11(SiR)2,R=CH=CH2,OH],进一步证明了此方法在合成有机硅取代的多金属氧酸盐方面的可行性和通用性.     

笼型八聚(γ-氯丙基)倍半硅氧烷的合成及表征

以甲醇为溶剂 ,浓盐酸为催化剂 ,γ-氯丙基三乙氧基硅烷在室温下经水解缩合高产率地制备了笼形八聚( γ-氯丙基 )倍半硅氧烷。合成的化合物分别用元素分析 ,1 H,1 3C,2 9Si NMR,FT- IR和 GPC进行了表征。     

氨甲酰基硅烷与酮反应合成α-硅氧基酰胺衍生物

N,N-二甲基氨甲酰基三甲基硅烷与一系列芳基酮、不饱和芳基酮在无水无氧、105℃、甲苯作溶剂的条件下反应,合成了α-三甲基硅氧基酰胺衍生物,收率60%~89%,其结构用元素分析、1H NMR、13C NMR和IR等方法进行了表征.烷基烷基酮、烷基芳基酮、烷基不饱和芳基酮与N,N-二甲基氨甲酰基三甲基硅烷不反应.通过研究反应的影响因素发现,反应底物酮中与羰基相连的芳环上取代基的电子效应是该加成反应的重要影响因素,芳环上取代基的给电子能力越強,反应越慢.     

三甲基硅基取代聚硅烷的合成与性能研究

利用聚甲基硅烷(PMS)的高分子反应合成三甲基硅基取代聚硅烷(SPS),研究其分子组成与结构,热分解性能和导电性能等.FT-IR、1H-NMR、29Si-NMR、UV和GPC分析表明,SPS具有Si—Si相连的主链结构,侧链的部分取代基中含有三甲基硅侧基.SPS可溶于一般常见的有机溶剂,其热分解特性表明,陶瓷产率为44%,可用作SiC陶瓷先驱体.通过热交联反应可以有效提高其分子量,将其与碘掺杂,电导率为10-6S/cm量级,在半导体范围.     

前手性硅甲基的非等时性——卤代烷烃溶剂对化学位移差值的影响

我们曾报道具有手性基团的二甲基二烷氧基砬烷(CH_3)_2Si(OR*)(OR)的前手性硅甲基具有非等时性(anisochronous),即两个硅甲基的~1H NMR化学位移有差别,并研究了分子结构对差值大小的影响。本文将报道卤代院烃溶剂及溶液浓度与化学位移差值的关系,以期深入了解溶剂分子与硅烷分子间的相互作     

耐超高温SiC（A1）纤维先驱体——聚铝碳硅烷纤维的研究

以聚硅碳硅烷（PSCS）与乙酰丙酮铝（A1（AcAc）3）为原料，在常压高温条件下反应制备出聚铝碳硅烷（PACS），经过熔融纺丝制备了PACS纤维．应用GPC、IR、XPS、^29Si．NMR、^29A1，NMR、TG、SEM、元素分析和增重等一系列分析，分别对PACS纤维的微观组成、结构以及性能进行了分析．研究结果表明，以原料质量配比为6：100（AI（AcAc）3：PSCS）合成的PACS化学式为SiQ2.0H7.5O0.13，Al0.018数均分子量为1700左右，最适宜制备PACS纤维；PACS纤维中主要存在SiC4、SiC3H等结构，同时存在si—O—Al键；在氮气气氛中，PACS纤维的陶瓷产率达到52％左右；预氧化处理，PACS纤维中Si—H键与空气中的氧反应形成Si—O—Si交联结构，较聚碳硅烷（PCS）纤维易于氧化，经过预氧化的PACS纤维陶瓷产率达到80％左右，是制备耐超高温SiC（A1）陶瓷纤维的合适纤维；用预氧化PACS纤维制备的SiC（OAl）纤维和SiC（A1）纤维抗拉强度高，耐高温性能好．     

烷基取代聚硅烷共聚物的侧基对螺旋构象的影响

以手性化合物n-癸基-(S)-(+)-2-甲基丁基二氯硅烷(Si1)和非手性化合物n-癸基-2-乙基丁基二氯硅烷(Si2)为单体合成了聚硅烷共聚物[P(Si1-co-Si2)].通过改变Si1和Si2的投料比,聚合得到一系列P(Si1-co-Si2).通过核磁表征P(Si1-co-Si2)为无规共聚物.利用圆二色谱(CD)和紫外吸收光谱研究系列共聚物的手性传递行为.研究发现,Si2的均聚物在其对应的紫外吸收带324 nm处没有CD信号.当加入Si1共聚后,产生CD信号,随着Si1含量的增加,共聚物的CD信号迅速增强,当Si1摩尔分数为2%时可诱导共聚物形成单手螺旋优势构象.当Si1含量达到70%时,信号强度最大.在P(Si1-co-Si2)中Si1含量增加的过程中,共聚物的紫外吸收带同时发生蓝移.当Si1含量达到50%时,分子量较低的样品具有较强的光学活性,并且随着分子量的增大,紫外吸收红移.研究结果初步表明,聚硅烷共聚物的螺旋结构由手性侧基决定,但非手性侧基的奇偶性却没有体现.     

1,3-Migration of Trimethylsilyl Group from Carbon to Oxygen in Highly Sterically Hindered Silanol of the Type (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeOH and Reaction of the Related Iodide with Iodine Monochloride and Iodine Monobromide

The silanol (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeOH has been shown to isomerize to (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) when it was kept at room temperature for 10 h in 0.2 M NaOMe/MeOH. Corresponding isomerizations of the above silanol (to give (Me 3 Si) 2 CHSi(C 6 H 4 Me- p ) (Me)(OSiMe 3 )) are complete after 26 h under reflux in pyridine. The reaction involve 1,3-migration from carbon to oxygen within a silanolate ion to give a carbanion, which rapidly acquires a proton from the solvent. Treatment of (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeOH with MeLi in Et 2 O/THF give, by the same rearrangement, the organolithium reagent (Me 3 Si) 2 CLiSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) which on treatment with Me 2 SiHCl gives (Me 3 Si) 2 C(SiMe 2 H)Si(C 6 H 4 Me- p )(Me)(OSiMe 3 ) and (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). When the experiment was repeated, but with Me 3 SiCl in place of Me 2 SiHCl, it gives exclusively (Me 3 Si) 2 CHSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). Treatment of the organolithium reagent (Me 3 Si) 2 CLiSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ) with Mel gives exclusively (Me 3 Si) 2 CMeSi(C 6 H 4 Me- p )(Me)(OSiMe 3 ). The related iodide (Me 3 Si) 3 CSi(C 6 H 4 Me- p )Mel reacts with ICI and IBr to give rearranged (Me 3 Si) 2 C(SiMe 2 X)Si(C 6 H 4 Me- p )Me 2 and unrearranged products (Me 3 Si) 3 CSi(C 6 H 4 Me- p )MeX, (X = Cl, Br) respectively. The rearranged bromide (Me 3 Si) 2 C(SiMe 2 Br)Si(C 6 H 4 Me- p )Me 2 reacts with a range of silver [I] salts AgY (Y = OOCCH 3 , SO 4 2 m ) and Mercury [II] salt HgY 2 (Y = OOCCH 3 , SO 4 2 m ) in glacial CH 3 COOH to give the corresponding species (Me 3 Si) 2 C(SiMe 2 OOCCH 3 )Si(C 6 H 4 Me- p )Me 2 . The reaction of the bromide with AgBF 4 in MeOH or i -PrOH give the corresponding rearranged products (Me 3 Si) 2 C(SiMe 2 Y)Si(C 6 H 4 Me- p )Me 2 (Y = --OMe, --OPr i ).     

Allylsilane‐Modified Amino Acids from the Claisen Rearrangement

The Claisen rearrangement of the N‐protected, silylated allyl glycinates 11 and 12 led to the formation of allyl/silyl‐functionalized amino acids 13 and 14 in yields up to 80%. The diastereoisomer ratio varied from 2 : 1 to 29 : 1 for 11mb , and from 2 : 1 to 46 : 1 (syn/anti) for 12mb , depending on reaction conditions, as shown by X‐ray crystallographic analysis of 14mb . The relationship between the size of the alkyl groups on the chlorosilane reagent (Me₂R″SiCl, R″=Cl, Me, t‐Bu, Ph) used as an enolate trap and the observed stereoselectivity was investigated in the case of the Ireland–Claisen variant. Me₃SiCl gave the best results. However, the size of the alkyl groups on the silylated ester (Me₂R″Si, R=Me, t‐Bu, Ph, i‐Pr) did not exert a significant effect on the diastereoselectivity or yield of the rearrangement.     

聚硅氮烷在氨气中的裂解研究

聚硅氮烷在氨气中的裂解研究胡海峰陈朝辉冯春祥张长瑞宋永才（国防科技大学五系长沙４１００７３）关键词聚硅氮烷，氨气气氛，裂解机理先驱体转化法是制备陶瓷的一种独特方法，但裂解产物往往偏离化学稳定相组成，尤其是硅氮烷裂解后氮含量不足影响了材料的高温性能．...     

Silylation products of cyclic tri-aminal carbanions and their lithiation

The structure of 1,3,5-trimethyl-1,3,5-triaza-cyclohexane (TMTAC) was determined by single crystal X-ray diffraction and compared with earlier gas-phase data. It shows a preference for an aee-conformation in all phases. Lithiated TMTAC, [(RLi)(2)·(RH)] (1) (R = 2,4,6-trimethyl-2,4,6-triaza-cyclohex-1-yl), was reacted with Et(3)SiCl, Ph(3)SiCl and PhMe(2)SiCl to afford the substituted silanes Et(3)SiR (1), Ph(3)SiR (2) and PhMe(2)SiR (3) in moderate yields. They were characterised by NMR spectroscopy ((1)H, (13)C, (29)Si). 1 reacts with Me(2)SiCl(2) and Ph(2)SiCl(2) to give Me(2)SiR(2) (5) and Ph(2)SiR(2) (6) which were characterised by NMR spectroscopy. 5 was also identified by crystal structure determination. Analogous triple substitution could not be observed by employing trichlorosilanes. Quantumchemical calculations explain this by sterical overcrowding of the silicon atom. The reaction of 1 with SiCl(4) did not yield fourfold substitution but a formal insertion product of SiCl(2) into a C-N bond of the TMTAC ring (2,4,6-trimethyl-2,4,6-triaza-1,1-dichloro-1-sila-cycloheptane, 7) in very small quantities. It was identified by X-ray crystallography and shows an intramolecular Si···N dative bond. The reactions of (3) and (5) with n-butyl lithium afforded lithiation of the silicon bound methyl groups in both cases. The products, 8 and 9, were characterised by NMR spectroscopy ((1)H, (13)C, (29)Si), 8 was also characterised by X-ray crystallography.     

Exceptionally strong Bragg diffraction from a mesoporous silica film pretreated with chlorotrimethylsilane toward application in X-ray optics

Exceptionally strong Bragg diffraction from a mesoporous silica film is achieved by exposing the as-deposited film to vapor of chlorotrimethylsilane (Me(3)SiCl) before extracting the surfactant. The intensity of the X-ray diffraction peak increased 7 times after the surfactant removal and it approached 30% reflectivity. This large increase of diffraction intensity cannot be explained simply by the improved contrast of the electron density, and rearrangement of the pore wall during the Me(3)SiCl vapor treatment is suggested. It is shown by infrared spectroscopy that Me(3)SiCl with a high grafting reactivity effectively caps the silanol groups and prevents the following condensation, which causes the structural degradation. The substitution of the hydrogen atom of hydroxyl groups with trimethylsilyl groups should help the improvement of the structural regularity by reducing the hydrogen bonds in the pore wall. The achieved strong diffraction opens the gate for the application of these regular mesoporous films prepared by a self-assembly process to optical elements in the X-ray region.     

Linear and cyclic polysilanes containing the bis(trimethylsilyl)amino group: synthesis,reactions, and spectroscopic characterization

The reaction of linear (Si(n)Cl(2)(n)(+2); n = 3-5) and cyclic (Si(5)Cl(10)) perchloropolysilanes with 1 or 2 equiv of LiN(SiMe(3))(2) results in the formation of the bis(trimethylsilyl)amino derivatives (Me(3)Si)(2)NSi(3)Cl(7) (1), (Me(3)Si)(2)NSi(4)Cl(9) (2), (Me(3)Si)(2)N(SiCl(2))(n)N(SiMe(3))(2) (n = 3, 4; n = 4, 5; n = 5, 6), cyclo-(Me(3)Si)(2)NSi(5)Cl(9) (7), and cyclo-[(Me(3)Si)(2)N](2)Si(5)Cl(8) (8). 1-8 easily can be hydrogenated with LiAlH(4) to give the corresponding amino and diamino polysilanyl hydrides. The monosubstituted and cyclic compounds 1, 2, 7, and 8 additionally afford Si-Si bond scission products, which cannot be separated in all cases. Chloro- and dichloro derivatives of Si(3)H(8), n-Si(4)H(10), and n-Si(5)H(12) are obtained from the corresponding aminosilanes and dry HCl. All compounds were characterized by standard spectroscopic techniques. For Si-H derivatives the coupled (29)Si NMR spectra were analyzed to obtain an unequivocal structural proof.     

Neutral pentacoordinate silicon fluorides derived from amidinate, guanidinate, and triazapentadienate ligands and base-induced disproportionation of Si2Cl6 to stable silylenes

Pentacoordinate silicon fluorides L(1)SiF(3) (2a), L(2)SiF(3) (2b), and (L(3)SiF(2))(2) (2c)(2) based on amidinate (L(1) = PhC(N(t)Bu)(2)), guanidinate (L(2) = 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidinate), and triazapentadienate (L(3) = NC(NMe(2))NC(NMe(2))NAr; Ar = 2,6-(i)Pr(2)C(6)H(3)) ligands were prepared by fluorination of the corresponding chlorosilanes L(1)SiCl(3) (1a), L(2)SiCl(3) (1b), and L(3)SiCl(2) (1c) with Me(3)SnF at ambient temperature. Compounds 1b, 1c, 2a, 2b, and (2c)(2) were characterized by (1)H, (13)C, (19)F, and (29)Si NMR spectroscopic studies. Molecular structures of 1b, 1c, 2a, and (2c)(2) were determined by single crystal X-ray structural analysis. Invariom refinement involving non-spherical scattering factors of the Hansen-Coppens multipole model was performed for 1b. Compound L(3)SiF(2) (2c) is dimeric both in the solid state and in solution, whereas its chloro-analogue 1c is monomeric. The attempted synthesis of diamidinatotetrachlorodisilane by reaction of lithium amidinate with Si(2)Cl(6) led to the formation of the silane (1a) and the silylene L(1)SiCl (3). Reaction of Si(2)Cl(6) with N-heterocyclic carbenes (NHC) afforded NHC adducts of dichlorosilylene and SiCl(4). A one pot method for the preparation of base-stabilized silylenes from Si(2)Cl(6) is discussed.     

(四甲基二硅撑)二(3-三甲硅基环戊二烯基)四羰基二铁及其相关化合物的合成及结构

1,2-二(三甲硅基环戊二烯基)四甲基二硅烷与Fe(CO)5在二甲苯中于105～110℃反应除分离到少量标题化合物(Me2SiSiMe2)[η-(3-Me3SiC5H3Fe(CO)]2(μ-CO)2(5)外,主要是生成了脱Me3Si基的产物(Me2SiSiMe2)[η-C5H4Fe(CO)]2(μ-CO)2(1)及1的热重排异构体[Me2SiC5H4-Fe(CO)2]2(2).将5的二甲苯溶液加热回流18h,则转化为其异构体[Me2Si(Me3SiC5H3)Fe(CO)2]2(6).脱硅基发生在由相应反应物制备5的过程中。且脱硅基是与反应物中(Me2SiSiMe2)桥的存在有关。5的晶体结构经X射线衍射测定属单斜晶系,P21/m空间群,晶体学数据:a=0.6780(1)nm,b=2.2303(9)nm,c=0.9988(1)nn,;β=98.96(1)°,V=1.4960nm3.Z=2,Dc=1.36g/cm3.     

Theoretical investigation of the mechanisms and stereoselectivities of reductions of acyclic phosphine oxides and sulfides by chlorosilanes

Computational studies were performed to explain the highly varied stereoselectivities obtained in the reductions of acyclic phosphine oxides and sulfides by different chlorosilanes. The reductions of phosphine oxides by HSiCl(3), HSiCl(3)/Et(3)N, and Si(2)Cl(6) and the reductions of phosphine sulfides by Si(2)Cl(6) (all in benzene) were explored by means of B3LYP, B3LYP-D, and SCS-MP2 calculations. For the reductions of phosphine oxides by HSiCl(3), the calculations support the mechanism proposed by Horner in which a hydride is transferred from silicon to phosphorus through a four-centered, frontside transition state. This mechanism leads to retention of stereochemistry at phosphorus. For the other three reductions, two classes of mechanisms were explored. Phosphorane-based mechanisms that were previously proposed by Mislow and involve SiCl(3)(-) were compared with novel alternative mechanisms that involve nonionic rearrangement processes. In one of these, donor-stabilized SiCl(2) is formed as an intermediate. The calculations support a phosphorane-based mechanism for the reductions of phosphine oxides by HSiCl(3)/Et(3)N and Si(2)Cl(6) (which proceed with inversion) but favor the rearrangement pathways for the reductions of phosphine sulfides by Si(2)Cl(6) (which proceed with retention).     

Untersuchungen zur Umsetzung von [Lithium(trimethylsilyl)amido]-methyl-trimethylsilylamino-silan Me(Me3SiNLi)(Me3SiNH)SiH mit verschiedenen Elektrophilen

Investigations of the Reaction between the [Lithium(trimethylsilyl)amido]-methyl-trimethyl-silylamino-silane Me(Me₃SiNLi)(Me₃SiNH)SiH and different Electrophiles The lithium silylamide Me(Me₃SiNLi)(Me₃SiNH)SiH 1 reacts with chlorotrimethylsilan in the nonpolar solvent n-hexane to the N-substitution product Me[(Me₃Si)₂N](Me₃SiNH)SiH 2 and to the cyclodisilazane [Me(Me₃SiNH)Si—N(SiMe₃)]₂ 3 nearly in same amounts. The reaction of 1 with chlorotrimethylstannane gives besides small amounts of the cyclodisilazane 3 the N-substitution product Me[(Me₃Si)(Me₃Sn)N](Me₃SiNH)SiH 4 . By the reaction of 1 with trimethylsilyltriflate the cyclodisilazane 3 is obtained as the main product. Furthermore 2 and the cyclodisilazane 5 are formed. Ethylbromide shows no reaction with 1 under the same conditions. These results indicate the existence of an equilibrium of the lithium silylamide 1 , the silanimine Me(Me₃SiNH)Si?N(SiMe₃) and lithium hydride.