13 resultados para Arn

em Chinese Academy of Sciences Institutional Repositories Grid Portal


Relevância:

20.00% 20.00%

Publicador:

Resumo:

本论文对榧属(TorreyI)的研究历史作了回顾.以形态性状为依据,结合叶片的解剖,花粉表面的电镜观察,以及种子蛋白的电泳等,对榧属的系统分类进行了研究。结果表明: l、支持根据种子胚乳深皱与微皱分榧属为两个组的观点. 2、从叶片气孔带乳突的特征及种子蛋白电泳带的类型,似可支持榧属两组的建立. 3、根据各种榧树叶肉组织中石细胞的观察,不支持将石细胞的有无作为分组的特征。 4、云南榧与巴山榧叶的解剖特征有较多相似性,但在石细胞的含量、栅栏组织细胞层数及结晶大小等方面存在差别.考虑到其他性状及地理分布,认为将云南榧改为巴山榧的变种较为自然。 5、本属植物花粉形态较为一致,种问无明显的差别.对组和种的划分无重要参考价值. 6、经研究订正,榧属共6种2变种和11个栽培变种。其中1新变种(九龙山榧),1改级新组合(云南榧),6个新载培变种。 7、结合前人的研究,作者归纳出红豆杉科植物的进化趋势,支持榧属为进化类群的观点。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

稻属(OryzaL.)隶属禾本科(Poaceae)之稻族(OryzeaeDUmort.),广布于全球热带与亚热带地区。目前认为该属约含20个野生种和2个栽培种,中国产4个种。亚洲栽培稻(O. sativaL.)是世界上最重要的粮食作物之一,而在中国则为第一粮食作物。在稻种基因库中,发掘野生稻中丰富的遗传多样性是解决当今人口与粮食矛盾的必由之路。因此,保护野生稻的遗传多样性举世瞩目。针对热带与亚热带地区的环境恶化而导致野生稻居群的大量绝灭与急剧萎缩的状况,制订有效的策略,最大限度地保护野生稻的遗传多样性已迫在眉睫。然而,目前对野生稻种内遗传多样性的知识十分贫乏,缺乏制订保护策略的科学基础。这一问题在中国尤为突出。本文基于1994-1995年对中国三种野生稻濒危状况的调查结果,利用等位酶分析对普通野生稻26个居群,药用野生稻8个居群和疣粒野生稻l7个居群进行了遗传多样性的研究,并重点对目前育种价值最大而濒危程度最高的普通野生稻从五个方面作了进一步的探讨。最后根据遗传多样性的研究结果讨论了它们的濒危原因,并提出了初步的保护策略。主要结果如下: 一.普通野生稻D.rufipogon Griff. 在中国的三种野生稻中,普通野生稻的遗传多样性水平最高(A=1.33,P= 0.227,Ho=0.033和He=_0.068),遗传分化水平较低(Fst=0,310)。广西与广东的居群较其它地区的居群具有较丰富的遗传变异。因此,华南可能是中国普通野生稻的遗传多样性中心;云南现存的所有三个居群的遗传多样性水平偏低(A=1.10.p=0.148,Ho=0.007和He=0.079),与该地区栽培稻丰富的遗传多样性形成鲜明对照,普通野生稻居群间的遗传一致度与地理距离无明显相关。 1.通过14个中央居群与5个边缘居群的对比研究表明了边缘居群的遗传结构明显不同于中央居群:其遗传多样性水平与遗传分化均低予中央居群,杂合子比中央居群更为不足。而且,从中央居群到边缘居群,位点的多态性逐渐丧失,遗传多样性水平递减,一些多态位点的等位基因频率逐渐地发生变化。 2. 通过7个受栽培稻基因渗入的居群与5个隔离较好居群的对比研究表明,被渗入居群虽然在形态上表现出复杂的变异式样,但遗传多样性水平并无相应的增高。栽培稻基因流对野生居群遗传结构的影响可能主要是遗传同化,即阻止其居群内与居群间的遗传分化。 3. 通过对2个低纬度居群与2个北缘居群两个生活史阶段的遗传多样性研究表明繁育系统是影响普通野生稻居群遗传结构的因素之一。在低纬度居群中种子阶段的遗传变异高于植株阶段,在高纬度居群中则相反。 4.通过对北缘居群(江西东乡)1980年,1985年和1994年的居群遗传结构的研究,发现该居群的遗传结构逐渐在发生变化,表现为遗传多样性水平不断下降,居群越来越偏移哈迪一温伯格平衡和杂合子变得越来越缺乏。 5.通过对一个典型的普通野生稻居群(元江居群)的居群内遗传结构的研究,表明遗传变异在3个亚居群间分布不均衡,基因型里聚集分布,使得亚居群间有一定的遗传分化。导致其居群遗传结构的亚划分的主要原因可能是有限的基因流(Nm=0.964Arn.ex Watt. 疣粒野生稻的遗传多样性水平(A=1.Ot5,p—0.0633,Ho- 0.022和He=O.O16)在三种野生稻中最低,但居群遗传分化却很高(FsT=0.859)。海南的遗传多样性水平与云南差别不大。剧烈的遗传分化不仅发生在海南与云南之间,而且还发生在地区内,甚至在很小地区内的居群阍。对每个地区来说,居群间的遗传一致度与地理距离明显相关,符合“隔离一距离”模型。该物种是克隆植物,遗传变异贫乏但居群遗传分化剧烈是这类植物的特征。 四. 对保护中国野生稻遗传资源的启示 中国的三种野生稻是居群水平上而非物种水平上的的濒危。人类的剧烈干拢和生境遭受破塥是导致它们濒危的主要原因。对普通野生稻和药用野生稻来说,人为的干扰导致了它们现存的居群变小且相互隔离,居群间的基因流受阻,遗传漂变的作用在小群体中显得尤为突出,并与严重的近交相交织,导致遗传多样性大量丧失,居群的遗传结构也进一步改变,从而产生真正遗传学上的濒危,甚至灭绝。对于普通野生稻的大多数居群来说,栽培稻频繁的基因流带来的遗传同化,也会直接或间接地引起濒危甚至消亡。 鉴于普通野生稻有69.0%的遗传多样性存在于居群内,收集种质资源时应在遗传变异丰富的居群中,特别在其遗传多样性中心的居群中取较多数量的个体,还应在不同的地理区域选择2~3个遗传变异丰富、彼此遗传差异大的居群作为代表,捕获存在于居群间的遗传变异。原位保护点的设置应优先考虑以下类型的居群:a.与栽培稻基因流隔离好的居群;b.边缘居群;c.严重受威胁的居群;原位保护区应在其遗传多样性中心设立,选择有数个相邻的较大居群。 鉴于药用野生稻有21.2%的遗传多样性存在于居群内,在收集种质资源时原则上应选择较多的居群,而在每个居群中取较少的个体。海南与大陆居群间的遗传差异较大,故两地的居群都必须收集;药用野生稻的居群通常较小,建议设立原位保护点即可。海南与大陆均须设立保护点,而且在每个地区内应保护尽可能多的居群。对地区间或地区内的居群间进行人工移植,促进基因流,对增强各居群的适应能力会有裨益。 鉴于仅有14.1%的遗传变异存在予疣粒野生稻的居群内,取样的原则是在云南和海南均取尽可能多的居群,而对每个居群取少数个体即可;该种的居群有时较大,其居群内往往有一定的遗传分化,故收集遗传资源时应按亚居群取样;建议在云南与海南各设置2~3个原位保护区,其中可优先考虑我国分布面积最大的云南思茅地区的居群。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

钮子瓜(Zehneria maysorensis Arn.)是一种常用的中草药,其性味苦、凉,主要功效为清热利湿、散风止痛,主治膀胱炎、头痛。体外活性筛选实验表明,袋花忍冬(Lonicera saccata Rehd.)95%乙醇提取物的乙酸乙酯部分对血管紧张素转化酶显示较强的抑制活性。为明确钮子瓜的药用物质基础和袋花忍冬中具有ACE抑制活性的成分,首次对两个植物的成分进行了研究。 1. 从钮子瓜95%乙醇提取物中主要通过色谱方法首次分离了14个化合物,通过波谱方法鉴定为(2S,3S,4R,10E)-2-[(2R)-2-羟基二十四烷酰基氨基]-10-十八烷-1,3,4-三醇(1)、(2S,3S,4R)-2-二十四烷酰基氨基-十八烷-1,3,4-三醇 (2)、胡萝卜苷(3)、swertish (4)、苯甲酸(5)、水杨酸(6)、loliolide (7)、胸腺嘧啶(8)、尿嘧啶(9)、(23Z)-9,19-环阿尔廷-23-烯-3β,25-二醇(10)、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇(11)、十六烷酸 1-甘油酯(12)、大豆脑苷Ⅰ(13)和(22E,24S)-24-甲基-5α-胆甾-7,22-二烯-3β,5α,6β-三醇(14)。其中化合物4为一黄酮碳苷,具有旋转异构现象,有止痛作用;化合物6具有抗炎、镇痛、减热的活性,它们可能是钮子瓜药用物质基础的一部分。 2. 从袋花忍冬95%乙醇提取物中首次分离并鉴定了16个已知化合物:胡萝卜苷(3)、(20S,22E,24R)-5α,8α-表二氧-麦角甾-6,22-二烯-3β-醇(11)、十六烷酸 1-甘油酯(12)、E-p-coumaryl behenate (15)、谷甾醇(16)、2,6-dihydroxyhumula-3(12), 7(13),9(E)-triene (17)、环阿尔廷-25-烯-3β,24ξ-二醇 (18)、二十四烷酸 (19)、2,4-二羟基-3,6-二甲基苯甲酸甲酯 (20)、乌苏酸 (21)、柚皮素 (22)、木犀草素 (23)、柏双黄酮(24)咖啡酸 (25)、洋芹素(26)和木犀草素-7-O-β-D-葡萄糖苷 (27)。其中木犀草素(23)和咖啡酸(25)含量较高,它们为抑制ACE活性的成分。 3.综述了黄酮碳苷的旋转异构现象。 Zehneria maysorensis is a folk medicine for the treatment of cystitis and headache. The ethyl acetate soluble fraction of the 95% ethanol extract of Lonicera saccata showed obvious ACE inhibitory activity in vitro. To reveal their active constitutents, they were subjected to chemically study. From the 95% ethanol extract of the whole plants of Zehneria maysroensis fourteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were characterized to be (2S,3S,4R,10E)-2-[(2R)-2-hydroxytetracosanoylamino]-10-octadecene-1,3,4-triol (1), (2S,3S,4R)-2-tetracosanoylamino-1,3,4-octadecanetriol (2), daucosterol (3), swertish (4), benzoic acid (5), salicylic acid (6), loliolide (7), thymine (8), uracil (9), (23Z)-9,19-cycloart-23-ene-3β,25-diol (10), (20S,22E,24R)-5α,8α-epidioxy-ergosta- 6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), soya-cerebroside (13) and (22E,24S)-24-methyl-5α-cholesta-7,22-diene-3β,5α,6β-triol (14). Compound 4, a C-glycosylflavone, showed a very interesting rotational isomerism. Compounds 4 and 6 may be the active constituents of Zehneria maysorensis considering their sedative and anti-inflammation activity, respectively. From the whole plants of Lonicera saccata, sixteen compounds were isolated for the first time. On the basis of spectral data and/or by comparison with authentic samples, they were identified to be daucosterol (3), (20S,22E,24R)-5α,8α-epidioxy- ergosta-6,22-diene-3β-ol (11), 2,3-dihydroxypropyl hexadecoate (12), E-p-coumaryl behenate (15), β-sitosterol (16), 2,6-dihydroxyhumula-3(12),7(13),9(E)-triene (17), cycloart-25-ene-3β,24ξ-diol (18), tetracosanoic acid (19), methyl 2,4-dihydroxy- 3,6-dimethylbenzoate (20), ursolic acid (21), naringenin (22), luteolin (23), cupressuflavone (24), caffeic acid (25), apigenin (26) and luteolin-7-O-β-D- glucopyranoside (27). Luteolin (23) and caffeic acid (25) were the ACE inhibitory active constituents. Rotational isomerism for C-glycosylflavonoid was reviewed.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本学位论文共有5章。第一章报道白芍的化学成分及芍药苷的微生物转化研究成果;第二章报道天山雪莲的化学成分研究;第三章报道两面针的化学成分研究;第四章报道通关藤的化学成分研究成果;第五章概述了花椒属植物中最近十年报道的新化合物及药理研究情况。 在第1章的第一部分报道了白芍(Paeonia lactiflora Pall.)的化学成分。我们采用正、反相硅胶柱层析等各种分离方法,从白芍的干燥根中共分离出14个化合物,其中1个为新化合物,其结构通过波谱分析证实为没食子酰白芍苷,另外还有2个为首次从该植物中分离得到。第二部分报道了芍药苷的微生物转化生产芍药苷代谢素-I的研究,从15株厌氧菌中筛选出10株有转化活性的菌株,其中短乳杆菌Lactobacillus brevis AS1.12的转化活性最好,对其转化条件进行了初步的筛选,确定了相对合理的转化工艺。 在第2章报道了天山雪莲(Saussurea involucrate Kar.et Kir.)全草乙醇提取物化学成分的分离纯化和结构鉴定。通过正、反相硅胶柱层析等分离纯化和MS、NMR等波谱解析,共分离鉴定了28个化合物,结构类型分属于黄酮、倍半萜和木脂素等,其中2个新倍半萜化合物的结构分别表征为6α-羟基云木香酸6-β-D-吡喃葡萄糖苷和11βH-11,13-二氢去氢云木香内酯8α-O-(6′-乙酰)-β-D-吡喃葡萄糖苷。 第3章报道了两面针(Zanthoxylum nitidum (Roxb.)DC.)干燥根的乙醇提取物化学成分的分离纯化和结构鉴定。通过正、反相硅胶柱层析等分离纯化和MS、NMR等波谱解析以及X-射线单晶衍射,共分离鉴定了16个生物碱,结构类型分属于苯并啡啶类、喹啉类和阿朴啡类等,其中2个新苯并啡啶类生物碱的结构分别表征为二聚双氢两面针碱和丙酮基双氢崖定椒碱。 第4章报道了通关藤(Marsdenia tenacissima (Roxb.) Wight et Arn.)水提取物化学成分的分离纯化和结构鉴定。通过正、反相硅胶柱层析等分离纯化和MS、NMR等波谱解析以及X-射线单晶衍射,共分离鉴定了14个化合物,结构类型均属于C21多羟基甾醇,其中4个新化合物tenacigenoside A, tenacigenoside B, tenacigenoside C和tenacigenoside D的结构分别表征为3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-17β-tenacigenin B (62), 3-O-2,6- dideoxy-4-O-methyl-D-lyxo-hexopyranosly-11α-O- methylbutyryl-12β-O-acetyl-tenacigenin B (63), 3-O-6-deoxy-3-O-methyl-β-D- allopyranosyl-(1→4)-β-D-oleandropyranosyl-11α-O-tigloyl-tenacigenin C (64)和3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-11α-O-2- methylbutyryl-tenacigenin C (65)。 第5章概述了花椒属植物的化学成分及药理活性研究进展。 This dissertation consists of 5 chapters. The first chapter elaborate the phytochemical investigation of Paeonia lactiflora Pall., and microbial transformation of paeoniforin. The second, third and four chapters elaborate the phytochemical investigation of Saussurea involucrate Kar.et Kir., Zanthoxylum nitidum (Roxb.) DC. and Marsdenia tenacissima (Roxb.) Wight et Arn., respectively. Chapter 5 is a review on chemical constituents and bioactivities of Zanthoxylum species. The part one of chapter 1 focus on the isolation and identification of chemical constituents from P. lactiflora. Fourteen compounds were isolated from the roots of P. lactiflora by repeat column chromatography over normal and reversed phase silica gel. Among them, one is a new compound and the structure was suggested as galloyl-albiflorin by spectral evidence. In addition, two compounds were firstly reported in this plant. The part 2 is about microbial transformation of paeoniforin. Chapters 2, 3 and 4 were isolations and identifications of chemical constituents from S. involucrate, Z. nitidum and M. tenacissima, respectively. From the aerial parts of S. involucrate, 28 compounds including 7 flavonoids and 13 sesquiterpenoids were isolated and identified. Among them, 2 new compounds were characterized as 6α-hydroxycostic acid 6-β-D-glucoside and 11βH-11,13-dihydrodehydro- costuslactone 8α-O-(6'-acetyl)-β-D-glucoside, respectively, by means of spectroscopic analysis. Otherwise, 11 ones were firstly reported from this plant. The third chapter is about the phytochemical investigation of Z. nitidum. Sixteen compounds were isolated and identified. Among them, 2 new benzophenanthridine alkaloids were characterized as 8-acetonyldihydrofagaridine and 1,3-bis(8-dihydronitidinyl)-acetone by spectroscopic analysis. The fourth chapter is about the phytochemical investigation of M. tenacissima. Fourteen compounds were isolated and identified. Among them, 4 new compounds, tenacigenosides A~D, were characterized as 3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-17β- tenacigenin B, 3-O-2,6-dideoxy-4-O-methyl-D-lyxo-hexopyranosly-11α-O-methyl butyryl-12β-O-acetyl-tenacigenin B, 3-O-6-deoxy-3-O-methyl-β-D-allopyranosyl- (1→4)-β-D-oleandropyranosyl-11α-O-tigloyl-tenacigenin C, and 3-O-6-deoxy-3-O- methyl-β-D-allopyranosyl-(1→4)-β-D-oleandropyranosyl-11α-O-2-methylbutyryl- tenacigenin C. Chapter 5 is a review on recent progress in bioactive constituents from plants of Zanthoxylum species.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Herpetineurontoccoae(Sull.et.Lesq.)Card.〕、(ThuidiumkanedaeSak.)、〔Claopodiumpellucinerve(Mitt.)Best.〕、〔Anomodonrugelii(C.Mll.)Keissl.〕、Haplohymeniumtriste(Ces.)Kindb.〕〔Lescuraeapatens(Lindb.)Arn.etJens〕、(LeskeapolycarpaEhrh.exHedw.)、〔Bryohaplocladiummicrophyllum(Hedw.)R.WatanabeetIwats〕、(FauriellatenerrimaBroth.)Bryohaplocladiumangustifolium(HampeetC.M櫣ll.)R.WatanabeetIwats.〕HaplohymeniumDoz.etMolk.)、(AnomodonHook.etTayl.)、属〔Herpetineuron(C.M櫣ll.)Card.〕(Anomodontaceae)是合理的;小羽藓属(BryohaplocladiumR.WatanabeetIwats.)Claopodium(Lesq.etJam.)RenetCard.〕Leskeaceae)。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A series of salicylaldimine-based neutral Ni(II) complexes (3a-j) [ArN = CH(C6H40)]Ni(PPh3)Ph [3a,Ar = C6H5; 3b,Ar = C6H4F(o); 3c, Ar = C6H4F(m); 3d, Ar = C6H4F(p); 3e, Ar = C6H3F2(2,4); 3f, Ar = C6H3F2(2,5); 3g, Ar = C6H3F2(2,6); 3h, Ar = C6H3F2(3,5); 3i, Ar = C6H2F3(3,4,5); 3j, Ar = C6H5] have been synthesized in good yield, and the structures of complexes 3a and 3i have been confirmed by X-ray crystallographic analysis. Using modified methylaluminoxane as a cocatalyst, these neutral Ni(II) complexes exhibited high catalytic activities for the vinylic polymerization of norbornene.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A series of (alpha-diimine)nickel(II) complexes [ArN = C(Nap)C = NAr]NiBr2 (Nap = 1,8-naphthdiyl, Ar = 2,6-Me2C6H3, 3a; Ar = 2,4,6-Me3C6H2 3b; Ar = 2,6-Me-2-4-tBuC(6)H(2), 3c; Ar 2,6-Me-2-4-BrC6H2, 3d; Ar = 2,6-Me-2-4-ClC6H2, 3e; Ar 2,6-iPr(2)C(6)H(3), 3f; Ar = 2,4,6-iPr(3)C(6)H(2), 3g; Ar = 2,6-iPr-4-BrC6H2, 3h) have been synthesized, characterized, and investigated as precatalysts for ethylene polymerization in the presence of modified methylaluminoxane (MMAO).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

alpha-Diimine nickel catalyst hearing two allyl groups [ArN=C](2)C10H6NiBr2 (Ar = 4-allyl-2,6-(i-Pr)(2)C6H2)] (Cat-I) has been synthesized and characterized. The corresponding polymer-incorporated nickel catalysts PC and the SiO2-supported shell-core structure catalyst SC-1 were obtained by the co-polymerization of the olefin groups of Cat-1 with styrene in the presence of a radical initiator. Radical co-polymerizations with styrene in Solution were investigated in detail, and the compositions and molecular weight of the copolymers were determined. All three types of catalysts (Cat-1, PC and SC-1) have been investigated for ethylene polymerization. These catalysts were found to exhibit high activity in the presence of modified methylaluminoxane (MMAO) as a co-catalyst. Among them, the polymer-incorporated PC and SiO2 shell-core catalyst SC-1 displayed very high activity (similar to2.62 and similar to1.11 kg (mmol Ni)(-1) h(-1), respectively) with product molecular weights (M,) in the range 26 x 10(4) to 47 x 10(4) under 0.1 MPa ethylene pressure. The particle morphology of polyethylene produced by the shell-core structure catalyst SC-1 was improved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Self-immobilized nickel and iron diimine catalysts bearing one or two allyl groups of [ArN=C](2)(C10H6)NiBr2 [Ar = 4-allyl-2,6-(i-Pr)(2)C6H2] (1), [ArN=C(Me)[Ar'N=C(Me)]C5H3NFeCl2 [Ar = Ar' = 4-allyl-2,6-(i-Pr)(2)C6H3, Ar = 2,6-(i-Pr)(2)C6H3, and Ar' = 4-allyl-2,6-(i-Pr)(2)C6H3] were synthesized and characterized. All three catalysts were investigated for olefin polymerization. As a result, these catalysts not only showed high activities as the catalyst free from the allyl group, such as [ArN=C](2)C10H6,NiBr2 (Ar = 2,6-(i-Pr)(2)C6H2)], but also greatly improved the morphology of polymer particles to afford micron-granula polyolefin. The self-immobilization of catalysts, the formation mechanism of microspherical. polymer, and the influence on the size of the particles are discussed. The molecular structure of self-immobilized nickel catalyst 1 was also characterized by crystallographic analysis.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A series of 2,6-bis(imino)pyridyl iron and cobalt complexes bearing p-substituent [2,6-(ArN=CMe)(2)C5H3N]-MCl2 (Ar=2,6-Me2C6H3, 2,4,6-Me3C6H2, 2,6-Me-2-4-BrC6H2, 2,6-Me-2-4-ClC6H2, 2,4-Me-2-6-BrC6H2, 2,4-Me-(2)-6-ClC6H2, while M=Fe, Co) have been synthesized and investigated as catalysts for ethylene polymerization in the presence of modified methylaluminoxane as a cocatalyst. The electron effect and positions of the substitueni of pyridinebisimine ligands were observed to affect considerably catalyst activity and polymer property.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The unsymmetrical allyl containing post-metallocene complex [ArN = C( Me)] [(ArN)-N-' = C(Me)]C5H3NFeCl2 [Ar = 2,6(i- Pr)(2)C6H3, Ar' = 4-allyl-2,6-(i-Pr)(2)C6H3] (3) has been prepared and characterized. Complex (3) can be co-polymerized with styrene in the presence of radical initiator to produce polymerized post-metallocene catalyst which exhibits high activity for ethylene polymerization (2.5 x 10(6) g PE/mol Fe.h).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

合成了含烯丙基不对称型的“茂后”催化剂[ArN=C(Me)][Ar’N=C(Me)]C5H3NFeCl2[Ar=2,6-(i-Pr)2C6H3,Ar’=4-烯丙基-2,6-(i-Pr)2C6H3],通过IR,1H NMR,EI-MS,EA对化合物进行表征.利用这个催化剂上的烯烃基团在自由基引发下与苯乙烯共聚,制备出高分子化的“茂后”催化剂.研究了高分子化前后催化剂催化乙烯聚合行为,高分子化的催化剂在常压13℃下催化乙烯聚合时,活性最高达到2.5×106g PE/mol Fe·h,高于未高分子化之前催化剂的活性.证明了高分子化是“茂后”催化剂理想的固载化方式.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Tridentate ligand[(2,6-ArN=C(Me))(2)C5H3N](Ar=4-allyl-2,6-(i-Pr)(2)C6H3)(4)which contains allyl groups on each aryl ring was ready prepared and reacted with FeCl2. 4H(2)O to give the precatalyst [(2,6-ArN=C(CH3))(2)C5H3N]. FeCl2 (5). Compounds 2-5 were characterized by H-1 NMR, EI-MS,and IR. The complex 5 which was actived by methylaluminoxane(MAO) exhibits high activity for ethylene polymerization [1.9 x 10(6) g pE.(mol Fe . h)(-1) at 0 degreesC]. It was showed that the activity was decreased with increasing temperature and the polymer product was highly linear PE with (M) over bar (eta) varying from 50000 to 260000.