水可分散体羧甲基纤维素醋酸丁酸酯结构与性能研究

采用大浴比碱化、醚化与半均相酯化的合成方式,制备出纤维素混合醚酯——羧甲基纤维素醋酸丁酸酯（CMCAB）。利用^1H—NMR、FTIR、XRD、TG和DSC等技术对CMCAB结构与热性能进行分析与表征,并对其溶液表面性能、水分散体流变性能进行了研究。结果表明,CMCAB分子链上亲水性羧基分布均匀;CMCAB结晶度低、热...     

微交联聚合物降滤失剂的合成与性能

针对深井、超深井钻井液体系中的降滤失剂受长时间高温、高矿化度作用易降解的问题，以氮丙啶与3-氯丙烯反应制得-N-烯丙基氮丙啶（ALAI）； ALAI与乙二胺反应制得四烯基交联剂单体（EAAD）； EAAD与丙烯酰胺（AM）和2 丙烯酰胺基-2-甲基丙磺酸（AMPS）发生水溶液自由基共聚反应，合成了微交联共聚物降滤失剂(PAAT)，其结构和性能经¹H NMR, IR和TG-DTG表征。结果表明：PAAT可抗220 ℃高温，在高温、高矿化度条件下可维持钻井液的滤失量与流变性能，API滤失量均低于4.0 mL，高温高压滤失量均小于13.0 mL。     

CP/MAS 13C-NMR技术对桉木浆纤维素微观结构的研究

利用交叉极化结合魔角旋转技术13C 核磁共振法(CP/MAS ¹³C NMR)对桉木浆纤维的微观结构进行研究, 为进一步研究木质纤维素材料开发过程中反应障碍特征奠定基础. 通过对NMR光谱C1区(δ 102～108)进行洛仑兹拟合, 得到桉木浆纤维中纤维素Iα的相对含量为26.92%, 纤维素Iβ的相对含量为52.04%, 主要以纤维素Iβ晶体形式为主. 通过计算纤维素C4结晶区(δ 86～92)和非结晶区(δ 80～86)的相对含量得到桉木浆的纤维素结晶度为47%. 通过洛仑兹和高斯函数的混合模型对NMR光谱C4区(δ 80～92)进行拟合得到基原纤尺寸和微原纤横向尺寸分别为4.0与17.9 nm, 并通过计算不同形态的结晶纤维素的相对含量得到纤维素结晶度为51%, 证实了在微原纤内部次晶纤维素的存在.     

高取代度阳离子淀粉的合成及其降滤失性能

高取代度阳离子淀粉的合成及其降滤失性能;环氧丙基三甲基氯化铵;阳离子淀粉;半干法;钻井液;降滤失剂     

2位仲羟基单取代的β-环糊精乙烯酯的结构分析

近年来环糊精因具有疏水性空腔,可应用在药物载体、手性物质的分离和吸附、与有机物和高分子形成稳定复合体、生物工程中酶的保护和酶活性的提高、模拟酶的研究等而受到广泛的关注.含有多个环糊精的线性聚合物,因具有更多的疏水性空腔,从而能增强环糊精的应用范围.乙烯基环糊精单酯是制备线性含有环糊精聚合物的重要单体.因环糊精中几个葡萄糖环中羟基的化学反应性质的相似性,利用一般的化学催化剂制备单取代的环糊精衍生物需要保护和去保护的多步反应.本文用酶做催化剂,在温和、简单易行条件下,制备了3种乙烯基的β-环糊精单酯.利用13C NMR、1H NMR、IR、MS和DSC对产物进行分析.在1H NMR中,酯化上的取代基与糖环上氢的积分面积之比和MS中分子离子峰的值证实是单取代产物;在13C NMR中,被取代的葡萄糖环上C-1的共振吸收峰向高场移动(δ=98.83),相应的C-2的共振吸收峰移向低场(δ=73.78);在1H NMR中,被取代的葡萄糖环上H-1峰出现在低场(δ=5.05).结果表明:3种乙烯基β-环糊精衍生物是单取代的酯并且取代位置发生在2位仲羟基上.     

单2-O-和单6-O-(2-羟丙基)-β-环糊精结构表征

以β-环糊精和环氧丙烷为原料,分别在1.5%、30%(m/m)NaOH水溶液和β-环糊精与环氧丙烷的摩尔比为1∶7的条件下合成了2-O-(2-羟丙基)-β-环糊精和6-O-(2-羟丙基)-β-环糊精,以异丙醇-水-氨水(6∶3∶1,V/V)为洗脱液,分别经柱色谱分离得到单2-O-(2-羟丙基)-β-环糊精和单6-O-(2-羟丙基)-β-环糊精,并利用DSC,ESI-MS,1HNMR,13C NMR对单2-O-(2-羟丙基)-β-环糊精、单6-O-(2-羟丙基)-β-环糊精的结构进行了系统研究。结果发现,2-O-(2-羟丙基)-β-环糊精的热稳定性要高于6-O-(2-羟丙基)-β-环糊精。13C NMR结果表明,当β-环糊精2-位上引入取代基后,会影响2-位、1-位、3-位碳化学位移的变化,当β-环糊精6-位上引入取代基后,会影响6-位、5-位碳化学位移的变化,因此,可以用13C NMR方法有效地识别2-HP-β-CD取代基的位置。     

N-取代-5-氧代吡咯烷-3-甲酸化合物的合成

本文以衣康酸二甲酯为原料,分别和3种脂环胺发生Michael加成反应,得到3种N-取代-5-氧代吡咯烷-3-甲酸甲酯(2a～2c),再经碱性条件下水解得到3种N-取代-5-氧代吡咯烷-3-甲酸(1a～1c)。目标化合物及中间体结构通过~1H NMR、~(13)C NMR和ESI-MS确证。同时,以衣康酸二甲酯与环丁胺的Michael加成反应为模型,确定该步的优化反应工艺为:物料摩尔比n(环丁胺)∶n(衣康酸二甲酯)=1.3∶1,甲苯作溶剂,110℃反应2h。在该反应条件下,化合物2b收率为91.2%,其结构进一步通过X-射线单晶衍射确证。     

CP/MAS ~(13)C NMR技术对木浆纤维微观结构的研究

利用交叉极化结合魔角旋转技术~(13)C核磁共振法(CP/MAS ~(13)C NMR)对桉木浆纤维的微观结构进行研究,为进一步研究木质纤维素材料开发过程中反应障碍特征奠定基础.通过对NMR光谱C1区(δ 102～108)进行洛仑兹拟合,得到桉木浆纤维中纤维素Iα的相对含量为26.92%,纤维素Iβ的相对含量为52.04%,主要以纤维素Iβ晶体形式为主.通过计算纤维素C4结晶区(δ 86～92)和非结晶区(δ 80～86)的相对含量得到桉木浆的纤维素结晶度为47%.通过洛仑兹和高斯函数的混合模型对NMR光谱C4区(δ 80～92)进行拟合得到基原纤尺寸和微原纤横向尺寸分别为4.0与17.9 nm,并通过计算不同形态的结晶纤维素的相对含量得到纤维素结晶度为51%,证实了在微原纤内部次晶纤维素的存在.     

纤维素苯甲酸酯接枝二乙二醇十六烷基醚的制备及性能

分别以1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)和1-乙基-3-甲基咪唑醋酸盐([Emim]Ac)/N,N-二甲基乙酰胺(DMAc)为溶剂体系,以微晶纤维素(聚合度为220)和苯甲酰氯(BC)为原料制备纤维素苯甲酸酯(CB).探索了溶剂体系、反应温度和投料比对产物取代度、溶解性和熔融性能的影响.结果表明,以[Amim]Cl为溶剂时,随着反应温度的升高(60~80℃)或体系中苯甲酰氯与葡萄糖单元环(AGU)投料量的增加(3∶1~9∶1),产物的溶解性和熔融性能均提高,取代度也随之升高(0.13~2.98);以[Emim]Ac/DMAc为溶剂时,产物中苯甲酰基的接枝度较低,且共聚物中引入乙酰基不适合制备纤维素-g-苯甲酰氯.初步探讨了在[Amim]Cl中合成纤维素苯甲酸酯接枝二乙二醇十六烷基醚(CB-g-E_2C_(16))固-固相变材料的性能,研究结果表明,CB-g-E_2C_(16)相变材料的相变温度为12.7~29.1℃,相变焓为12~24 J/g,在294℃仍能保持热稳定性,为该类纤维素基固-固相变材料的可熔融加工奠定了理论基础.     

偕双硅高烯丙胺的硅基aza-Prins环化反应研究

在三氟甲磺酸三甲基硅酯作用下,偕双硅高烯丙胺与醛发生硅基aza Prins环化反应,合成了9个C4位含环外烯基硅的新型哌啶类化合物,收率47%~96%,其结构经¹H NMR, ¹³C NMR和LC-MS（ESI）表征,Z/E比由产物的¹H NMR分析得到;主要异构体的环外烯基硅构型经¹H, ¹H COSY和NOE确证。醛上取代基的电子效应对所生成的烯基硅的构型有较大影响：芳环取代对应Z-式构型,拉电子酯基取代对应单一的E-式构型产物。     

Structure and solution properties of cyanoethyl celluloses synthesized in LiOH/urea aqueous solution

Cyanoethyl celluloses (CECs) with different degree of substitution (DS) were synthesized by homogeneous reaction of cellulose (cotton linter pulp and absorbent cotton) with acrylonitrile (AN) in LiOH/urea aqueous solutions. The reaction showed quick reactivity and high transfer efficiency of etherification agent. The DS values of CECs were controlled by varying the molar ratio of AN to anhydroglucose unit (AGU) and the cellulose concentration. The DS values of the CEC-1–CEC-10 increased from 0.27 to 1.78 with increasing molar ratio of AN to AGU from 0.5:1 to 9:1. While the CEC-11–CEC-21 with DS values of 0.26–1.81 could be obtained by adjusting the molar ratio from 1:1 to 27:1. The relative reactivity of hydroxyl groups is in the order of C-6 > C-2 > C-3. The DS values of the water-soluble derivatives are in the range of 0.47–1.01. As the DS values increase to 1.37, CEC samples can not be dissolved in water or dilute alkali solution, but have good solubility in organic solvents, such as DMSO, DMF and pyridine. The dilute solution properties and molecular parameters of the CEC samples were studied by static light scattering and dynamic light scattering. The results indicated that the water-soluble samples could form a small number of aggregates spontaneously in 0.9 wt% NaCl aqueous solution, while the water-insoluble samples showed extended stiff chains in 0.5% LiCl–DMAc.     

Synthesis,characterization and properties of novel cellulose derivatives containing phosphorus: cellulose diphenyl phosphate and its mixed esters

Using ionic liquid 1-allyl-3-methylimidazolium chloride as reaction medium, a series of novel cellulose esters containing phosphorus including cellulose diphenyl phosphate (C-Dp) and cellulose acetate (CA)–diphenyl phosphate mixed esters was synthesized homogeneously. The degree of substitution was well controlled by altering reaction conditions, such as the molar ratio of the acylating reagents/anhydroglucose unit and reaction time. The structure and thermal properties of cellulose esters were characterized by FTIR, NMR, wide-angle X-ray powder diffraction and differential scanning calorimetry. All the products possessed excellent solubility in some common organic solvents, and transparent films of cellulose esters were obtained by solution casting. In contrast to C-Dp, CA–diphenyl phosphate mixed esters showed clear glass transitions. More interestingly, these cellulose mixed esters exhibited thermoplastic behavior and could be processed by traditional melt processing methods.     

Synthesis of cellulose benzoates under homogeneous conditions in an ionic liquid

The ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) as a reaction medium was studied for the synthesis of cellulose benzoates by homogeneous acylation of dissolved cellulose with benzoyl chlorides in the absence of any catalysts. Cellulose benzoates with a degree of substitution (DS) in the range from about 1 to 3.0 were accessible under mild conditions. The DS of cellulose derivatives increased with the increase of the molar ratio of benzoyl chloride/anhydroglucose unit (AGU) in cellulose, reaction time, and reaction temperature. Benzoylation of cellulose with some 4-substituted benzoyl chlorides including 4-toluoyl chloride, 4-chlorobenzoyl chloride and 4-nitrobenzoyl chloride was also readily carried out under mild conditions. Furthermore, regioselectively substituted mixed cellulose esters were synthesized in this work. All products were characterized by means of FT-IR, ¹H-NMR, and ¹³C-NMR spectroscopy. In addition, at the end of benzoylation of cellulose, the ionic liquid AmimCl was easily recycled. When the recycled AmimCl was used as the reaction media, the cellulose benzoate with a similar DS was obtained under comparable reaction conditions.     

Novel cellulose esters derived from the levopimaric acid-maleic anhydride adduct: synthesis,characterization, and properties

Synthesis of maleated pimaric acid (MPA) cellulose esters is first reported in this work. Cellulose esterification was performed by reacting microcrystalline cellulose with monoacid chloride of MPA (MPA-Cl) in presence of pyridine as catalyst and reaction medium. The syntheses were started in a heterogeneous solid–liquid reaction medium, but as the reaction advanced, the reaction mass turned into a homogeneous solution. The effects of MPA-Cl/anhydroglucose unit molar ratio, reaction temperature, and reaction duration on the yield and degree of substitution (DS) of cellulose esters (CEs) were investigated. CEs with DS ranging from 2.6 to 2.8 were achieved at molar ratios of 5.5–6.0 after 12–16 h at 118 °C. The purified products were characterized by elemental analysis, IR and ¹³C-NMR spectroscopy, and thermogravimetric analysis. CEs are soluble or partially soluble in usual organic solvents, depending on DS. Transparent films were prepared using CE-cyclohexanone solutions.     

Structural and thermal characterization of sugarcane bagasse cellulose succinates prepared in ionic liquid

The chemical modification of SCB cellulose with succinic anhydride using 1-butyl-3-methylimidazolium chloride ionic liquid/DMSO system as reaction medium was studied. The parameters including the molar ratio of succinic anhydride/anhydroglucose units in cellulose from 1:1 to 12:1, reaction time 5-120 min, and reaction temperature 85-105 °C were investigated. The results showed that the degree substitution of succinylated cellulosic preparations ranged from 0.037 to 0.53. It was found that the treatment of the native cellulose in the ionic liquid/DMSO system under the conditions given significantly degraded the cellulose and completely destroyed the cellulose crystals. FT-IR and solid-state CP/MAS ¹³C NMR spectra produced evidence for succinoylation reaction and the results showed that succinoylation occurred at positions C-6, C-2 and C-3. The thermal stability of the succinylated cellulose decreased upon chemical modification.     

活性炭担载的铂催化剂在碱性条件下选择性氧化甘油制备乳酸

生物柴油是一种环境友好的燃料,随着其生产及应用的快速增长,其生产过程中重要的副产物甘油将会大量过剩.因此,将甘油转化为高附加值的化学品对于提高生物柴油整体竞争力具有重大意义.乳酸是重要的化工原料,可用于制备生物兼容和可降解的聚乳酸塑料,广泛应用于食品和医药等领域.近年来,由甘油制乳酸的研究受到格外关注,相对于水热反应和氢解反应等,催化选择氧化反应因温和的反应条件而更具竞争力.
　　目前,甘油催化选择氧化制乳酸一般需加入较高比例的NaOH,而碱的类型对反应性能的影响鲜有报道.另外,催化剂常采用TiO2和CeO2等氧化物载体,而炭载体具有比表面积较大、在酸碱溶液中稳定及贵金属易于回收等优点,在催化领域有着广泛应用.因此,本文研究了活性炭(AC)担载的Pt催化剂在甘油催化选择氧化制乳酸反应中的催化性能.
　　首先研究了Pt/AC催化剂和碱在甘油催化选择氧化制乳酸过程中的催化作用.实验发现, Pt/AC和碱协同作用才能得到乳酸. Pt/AC催化剂在甘油脱氢生成中间产物(甘油醛和二羟基丙酮)的过程中起主导作用,碱的存在能够促进甘油羟基脱氢;中间产物实验证实,中间产物生成乳酸过程中碱起主导作用,它促进甘油醛和二羟基丙酮脱水反应和坎尼扎罗重排反应获得乳酸.进一步研究发现,中间产物二羟基丙酮比甘油醛更有利于乳酸生成,而Pt/AC催化剂有利于中间产物氧化为甘油酸.
　　进一步研究了不同类型的碱对反应性能的影响.结果表明,碱金属氢氧化物(LiOH, NaOH, KOH)比碱土金属氢氧化物(Ba(OH)2)更有利于提高甘油转化率和乳酸选择性.在加入碱金属氢氧化物条件下,甘油转化率与其离子半径呈正相关,而乳酸选择性则呈相反趋势.在LiOH存在下,乳酸选择性明显高于NaOH和KOH条件.当LiOH：甘油摩尔比为1.5时,甘油转化率和乳酸选择性均最高.在较低的LiOH与甘油摩尔比时,随着反应的消耗,溶液中的OH–减少,其促进甘油脱氢的作用变弱,并且不利于中间产物进行坎尼扎罗反应,故反应活性和乳酸选择性较差;而当LiOH比例过高时,会导致溶解氧浓度迅速降低,从而使甘油转化率和乳酸选择性下降,同时副产物甘油酸的选择性有所提高.这可能是因为较高比例的碱会促进中间产物甘油醛生成,该中间产物在Pt/AC催化作用下发生进一步氧化反应生成甘油酸.
　　研究了反应时间对催化性能的影响.结果表明,反应6 h后,甘油已经完全转化,乳酸选择性最高,达到69.3%;进一步延长反应时间,乳酸选择性有所下降,而副产物乙酸选择性略有增加,这可能是部分乳酸分解所致. Pt/AC催化剂经5次循环使用后仍保持了较高的甘油转化率和乳酸选择性.     

Studies on the synthesis of 2,3-o-hydroxyalkyl ethers of cellulose

Novel 2,3-O-hydroxyethyl- and 2,3-O-hydroxypropyl cellulose products were synthesized by heterogeneous etherification of 6-O-(4-monomethoxytrityl) cellulose (MMTC). Due to the very hydrophobic character of MMTC, the reaction was successful in the presence of anionic and non-ionic detergent in the reaction mixture yielding the 2,3-O-cellulose ethers with a molar degree of substitution (MS) varying between 0.25 and 2.00 after detritylation. The products were characterized by means of (1)H and (13)C NMR spectroscopy including two-dimensional methods. The 2,3-O-hydroxypropyl cellulose samples are soluble in water at a MS as low as 0.8. The spectroscopic studies showed that the unusual solubility results from a preferred substitution of hydroxy groups of the anhydroglucose unit while the newly formed hydroxy moieties are included in the reaction to a minor extent only. In contrast, conventionally synthesized hydroxypropyl cellulose is soluble in water starting at a MS of about 4.0 because of the formation of oxyethylene side chains. (13)C DEPT 135 NMR spectrum of 2,3-O-hydroxypropyl cellulose.     

NMR spectroscopic studies on the mechanism of cellulose dissolution in alkali solutions

It was considered that the dissolution of cellulose in alkali solutions is mainly due to the breakage of hydrogen bonds. As an alkali hydroxide, KOH can provide OH^? just like LiOH and NaOH; but it is well known that LiOH and NaOH can dissolve cellulose, whereas KOH can only swell cellulose. The inability of KOH to dissolve cellulose was investigated and the mechanism of cellulose dissolving in alkali solutions was proposed. The dissolution behavior of cellulose and cellobiose in LiOH, NaOH and KOH were studied by means of ¹H and ¹³C NMR as well as longitudinal relaxation times. The structure and properties of the three alkali solutions were compared. The results show that alkali share the same interaction mode with cellobiose and with the magnitude of LiOH > NaOH > KOH; the alkalis influence the structure of water also in the same order LiOH > NaOH > KOH. The different behavior of the three alkalis lies in the different structure of the cation hydration ions. Li⁺ and Na⁺ can form two hydration shells, while K⁺ can only form loose first hydration shell. The key to the alkali solution can or cannot dissolve cellulose is whether the cation hydration ions can form stable complex with cellulose or not. K⁺ cannot form stable complex with cellulose result in the KOH solution can only swell cellulose.     

Synthesis of O‐(2,3‐dihydroxypropyl) cellulose in NaOH/urea aqueous solution: As a precursor for introducing “necklace‐like” structure

O‐(2,3‐dihydroxypropyl) cellulose (DHPC) samples were synthesized by etherification of cellulose with glycidol (GLY) in a NaOH/urea aqueous solution system under different reaction conditions, so that they had different degrees of ether substitution (DS) in both the overall and regional distributions. The characterization was made by NMR spectroscopy in order to clarify the effects of the molar ratio of in‐fed GLY to anhydroglucose unit and of the reaction temperature not only on the total and regional DSs but also on the molar substitution (MS_dhp) for the multireactive dihydroxypropyl group. The evaluation of MS_dhp was performed after complete propionylation of each DHPC sample. Determination of molecular weights was also conducted on the propionylated DHPCs by GPC analysis. As a preliminary extension, butyralization of DHPC was undertaken in aqueous solution by using p‐toluenesulfonic acid as catalyst together with butyraldehyde (BuA). Two‐dimensional NMR (¹H–¹³C gHSQC) spectra measurements revealed that the products contained butyral groups, owing to dehydration‐cyclization between the BuA‐carbonyl and the duplicate hydroxyls in the side chain of DHPC. Such butyral derivatives of cellulose are expected to be a promising functional material parallel or superior to poly(vinyl butyral) available for safety glass interlayers, etc. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3590–3597     

Homogenous synthesis of 3-allyloxy-2-hydroxypropyl-cellulose in NaOH/urea aqueous system

3-Allyloxy-2-hydroxypropylcelluloses (AHP-celluloses), reactive unsaturated cellulose derivatives, were homogeneously synthesized by the reaction of cellulose with allyl glycidyl ether (AGE) in NaOH/urea aqueous solution. Water-soluble AHP-celluloses with DS_NMR = 0.32–0.67 were prepared from microcrystalline cellulose. The degree of substitution (DS) of AHP-celluloses could be controlled by varying the molar ratio of AGE and NaOH to AGU and the reaction conditions. The structure of AHP-cellulose samples were characterized by means of FT-IR, NMR spectroscopy and size exclusion chromatography. The cellulose ether shows thermoreversible flocculation. Bromination reactions were carried out as subsequent functionalization both to illustrate the reactivity of the allyl function and to determine the DS values.