Cellulose esterification with fatty acids and acetic anhydride in lithium chloride/N,N-dimethylacetamide medium

Homogeneous esterification of cellulose with saturated fatty acids (n-octanoic to n-octadecanoic) was accomplished with acetic anhydride co-reactant in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) medium. Cellulose mixed triesters (CMT) were obtained after 5 h at 130°C with an average of 2.2 acetyl groups and 0.8 fatty substituents per anhydroglucose unit. A mixed acetic-fatty anhydride, formed in situ, accounts for the grafting of the fatty moiety. The purified products were characterized and compared to the analogous cellulose simple fatty triesters (CST) that were synthesized from fatty acid chlorides in pyridine medium. Dynamic contact angle with water, glass transition, and storage moduli were correlated with the length of the fatty substituents. The CMT proved to be highly hydrophobic and more mechanically resistant than the CST.     

Dispersion and vulcanization characteristics of nitrile rubber reinforced with N,N-dimethylacetamide/lithium chloride treated silica

N,N-Dimethylacetamide/lithium chloride (DMAc/LiCl) treated silica is used as a reinforcing filler in nitrile rubber (NBR). Effect of the treatment on aggregate morphology and dispersion of silica in the matrix is investigated using XPS, SEM, and AFM. Binding energy levels of O1s and Si2p electrons in DMAc/LiCl treated silica have shifted significantly from 532.49 to 530.98 eV and 103.19 to 101.33 eV respectively. SEM observations have revealed a reduction in the agglomerate size of silica-a desirable feature for realizing better processing properties of silica filled rubber compounds. Data from AFM observations have also shown better dispersion of DMAc/LiCl treated silica. Mooney viscosity of masterbatches, measured at 100°C over a period of 7 days, has not exhibited any storage hardening which is an indication of easier processability. At 125°C, Mooney data exhibited a reduction in scorch time as a function of DMAc/LiCl concentration. However, MDR data at 160°C have not shown much changes in the scorch time while NBR with high nitrile content exhibited longer cure times. Higher crosslink density of vulcanizates indicate that DMAc/LiCl treatment of silica could effectively reduce filler-filler interactions and networking in silica filled rubber compounds thereby enabling mixing and processing operations energy efficient.     

Structopendant unsaturated cellulose esters via acylation in homogeneous lithium chloride/N,N-dimethylacetamide solutions

Novel acylation reactions of cellulose were accomplished with a series of unsaturated carboxylic acids or their respective anhydrides including crotonic acid (CRA), methacrylic acid (MAA), vinyl acetic acid (VAA), fumaric acid monoethyl ester (FAME), and cinnamic acid (CINA) in lithium chloride (LiCl)/dimethylacetamide (DMAc) homogeneous solutions. The acylation reactions were conducted at room temperature using dicyclohexylcarbodiimide (DCC) as a condensation agent and 4-dialkyl-aminopyridine (4-[N,N-dimethylamino-] or 4-pyrrolidino-pyridine, DMAP or PP) as a catalyst. A reaction mechanism is proposed based on experimental evidence. The acylated cellulose derivatives obtained from CRA, MAA, or their anhydrides exhibit poor solubility in organic solvents. Side reactions, e.g., the Michael addition, likely occur at the high temperatures required for reaction of these acyl groups. However, acylation of cellulose with VAA, FAME, and CINA is facile with derivatives readily soluble in DMSO. The structures of these derivatized celluloses were characterized with FTIR and ¹H-NMR spectroscopy and degrees of substitution were calculated. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 293–305, 1997     

2-溴-6-氯吡啶的合成研究

介绍了标题化合物的合成方法。以2,6-二氯吡啶为起始原料,经水合肼取代及溴取代两步反应合成了目标化合物,并经MS和1H NMR对其结构进行了表征。本合成路线原料易得、反应条件温和、操作简便,适合于工业化生产。反应总收率59%。     

3-溴-6-甲基哒嗪的合成

以乙酰基丙酸、水合肼为原料,通过3步反应,高产率地合成了标题化合物,其结构经1HNMR和MS-ESI确证.该方法步骤短,收率高,是一种合成3-溴-6-甲基哒嗪的简捷方法.     

Side reactions of phenylisocyanate in N,N-dimethylacetamide

Side reactions of isocyanate groups in N,N-dimethylacetamide (DMAC) were studied. Although 4,4′-diphenylmethane diisocyanate (MDI) in DMAC was stable and no changes occurred at 3°C, the isocyanate content decreased and a gel was finally formed at 40°C. Using phenyl isocyanate (PI) as a model compound of MDI, the identification of PI side-reaction products in DMAC were studied. From these experiments, the following five products were identified; (1) 1,3-diphenylurea (DPU), (2) 1,3-diphenyl-5-phenylcarbamyl-6-dimethylaminouracil (PUR), (3) 1,3,5-triphenylbiuret (TPB), (4) triphenyl-s-triazine-2,4,6-trione (TTT), and (5) 1,1-dimethyl-3-phenylurea (DMPU). Among these identified products, the novel side reaction product PUR, which was formed between PI and DMAC as solvent, was found along with TPB and TTT, which were already known to cause three-dimensional network formation.     

N,N-二甲基乙酰胺的合成反应动力学

为了给N,N-二甲基乙酰胺的工业生产提供动力学支持,文章研究了二甲胺和冰醋酸直接缩合反应生成N,N-二甲基乙酰胺的本征动力学。在消除外扩散的影响下,考察了质量分数40%二甲胺与醋酸的摩尔比和反应温度对缩合反应的影响。测定和分析了在389.15,397.15,403.15,407.15,418.15 K下的动力学实验数据,利用数据处理软件进行拟合,得到N,N-二甲基乙酰胺的合成反应动力学方程,并通过了实验验证,为反应精馏的优化模拟提供了重要的基础数据。     

反应条件对N-炔丙基-4-溴-1,8-萘酰亚胺与水合肼反应产物的影响

水合肼作为转移氢化试剂可选择性还原C=C双键和C≡C三键,亦可作为肼解试剂与邻苯二甲酰亚胺通过Gabriel反应制备伯胺;此外,由于水合肼是富电子基团,可对卤化物进行亲核取代反应.本文通过单因素实验研究了反应时间、反应温度、水合肼用量、溶剂、气体环境等因素对N-炔丙基-4-溴-1,8-萘酰亚胺与水合肼反应产物的影响.结...     

1-溴-6-氰基-2-萘酚的合成

以2-萘酚(Ⅱ)为原料,经一锅两步反应制备6-溴-2-萘酚(Ⅳ),收率为89.0%;然后经氰化反应制备6-氰基-2-萘酚(Ⅴ),投料比n(CuCN)∶n(Ⅳ)=1.5∶1时收率为91.2%;最后分别用溴素和N-溴代丁二酰亚胺(NBS)两种不同的溴化试剂制备了1-溴-6-氰基-2-萘酚(Ⅰ)。以溴素为溴化试剂,乙酸为溶剂,n(Br2)∶n(Ⅴ)=1∶1,Ⅰ的收率为89.8%;该法成本较低,适合工业上大规模生产。以NBS为溴化试剂,乙腈为溶剂,n(NBS)∶n(Ⅴ)=1.00∶1.03,收率几乎定量(99.2%);该法条件温和,简单高效,可避免溴素易挥发和吸入毒性大的缺点,更适合实验室小规模合成。     

Reaction of amines with conjugated olefins using lithium naphthalenide in non-ethereal solvents

It was found that lithium naphthalenide can be prepared from metallic lithium cuttings and naphthalene in non-ethereal solvents, such as benzene–N,N,N′,N′-tetramethylethylenediamine (TMEDA) or benzene-N,N,N′,N′-tetramethyldiaminopropane (TMDAP), under ultrasonic irradiation. Secondary amines reacted with conjugated olefins, such as isoprene or myrcene, using lithium naphthalenide in such non-ethereal solvents to give allylic amines. The yields of products were higher than in the reaction using lithium naphthalenide in tetrahydrofuran. From diethylamine (I) and isoprene (II), a mixture of N,N-diethyl-3-methyl-2-butenylamine (IV) and N,N-diethyl-2-methyl-2-butenylamine (V) (IV:V = 79:21) was obtained in 77% yield, and from diethylamine (I) and myrcene (III), N,N-diethylgeranylamine (VI) and N,N-diethylnerylamine (VII) (VI:VII = 88:12) were produced in 72% yield. These terpenic amines, VI and VII, are used as starting compounds for the preparation of perfumery materials.     

4-溴-6-氯吲唑的合成

以邻氟苯胺为原料,NCS(N-氯代丁二酰亚胺)氯化得到2-氟-4-氯苯胺,收率80％;2-氟-4-氯苯胺用NBS(N-溴代丁二酰亚胺)溴化得到2-氟-4-氯-6-溴苯胺,收率90％;2-氟-4-氯-6-溴苯胺重氮化反应,将得到的重氮盐与甲醛肟反应得到2-氟-4-氯-6-溴苯甲醛,收率45％.2-氟-4-氯-6-溴苯甲醛与80％水合肼反应得到目标产物,收率90％.4步总收率29.2％.     

N，N-二甲基乙酰胺的合成进展与市场分析

N，N-二甲基乙酰胺是一种重要的精细化工中间体，其用途广泛。文章介绍了国内外N，N-二甲基乙酰胺的研究进展和生产方法，并展望了N，N-二甲基乙酰胺的市场应用领域和市场前景，从而针对性提出国内N，N-二甲基乙酰胺项目的发展前景和投资方向。     

Reaction mechanisms of tridymite iron phosphate with lithium ions in the low-voltage range

The electrochemical reaction mechanisms of tridymite FePO₄ with Li ions were studied in the voltage range of 2.4-0 V. The lithiation/delithiation of FePO₄ was found to be similar to that of binary 3d-metal oxides, which involve the formation and decomposition of Li₂O along with the reduction and oxidation of nanoscale 3d-metal nanoparticles. In the first discharge, FePO₄ was reduced to metallic Fe nanoparticles dispersed in a lithium compound matrix consisting of Li₃PO₄ and Li₂O. In the subsequent charge, these metallic Fe nanoparticles were partially oxidized to FeO by the decomposition of Li₂O. The Li₃PO₄ matrix was inactive during the change of potential from 0 to 2.4 V. It is notable that the re-oxidation of metallic Fe occurred only in the case of small nanoparticles, and the large Fe particles remained electrochemically inert during the reversible reaction.     

1-溴-6-苯基己烷的合成研究

以己二酸单乙酯酰氯为起始原料合成了1-溴-6-苯基己烷。与几种国外已报道的合成方法比较,该方法步骤简单,副产物少,成本较低,环境污染小。     

纤维素LiCl/DMAc体系的溶液特征

本文研究了纤维素LiCl／DMAc体系的溶液特征。实验结果证明该体系具有良好的时间稳定性和热稳定性，能在常温下近30天内没有明显的粘度降低；在100℃高温下，4h不降解。同时测定了溶液的特性粘数和Huggins常数，Huggins常数在0．4～0．6之间，对比纤维素的铜乙二胺（Cuen）溶液，发现特性粘数[η]LICI/DMAc＞[η]Cuen，无扰尺寸ALiCi／DMAc＞ACuen，可见在LiCl／DMAc体系中，溶剂与纤维素分子表现出更强的相互作用力，分子链充分伸展。该体系的特性粘数、粘度常数不仅与温度、溶剂有关，而且是LiCl浓度的函数，具有与聚电解质溶液相类似的性质。这可能是因为纤维素分子链上的H质子和溶液中的Cl-离子相互作用，而使纤维素分子带上部分电荷，相互排斥而引起的。因此利用M－H方程测分子量，粘度常数的确立必须考虑诸多因素的影响，否则会导致分子量的高估。     

Reaction of lithium naphthalene with carboxylic acids containing the dichlorocyclopropane ring system

Carboxylic acids containing the dichlorocyclopropane ring system react with lithium naphthalene to give dechlorinated products. For example, from the reaction of 9,10-dichloromethylene octadecanoic acid and lithium naphthalene, a mixture of 9,10-nonadecadienoic acid as a main product and unidentified minor products were obtained.     

1-苄基-6-溴吲哚-3-甲醛的合成

以6-溴吲哚(2)为原料,通过Vilsmeier-Haack反应、 N-苄基保护,两步反应合成得到1-苄基-6-溴吲哚-3-甲醛(1)。对反应工艺进行了优化,确定合成6-溴-1H-吲哚-3-甲醛(3)的反应温度为25℃,反应时间为5 h;合成1的优化反应条件为:n(3)∶n(BnBr)=1.0∶1.3, n(3)∶n(KOH)=1.0∶1.5,反应温度25℃,反应时间3 h。在优化条件下,两步反应总收率86.5%。产物结构经1H NMR和ESI-MS确证。     

Pd(PPh3)4催化Suzuki偶联反应合成4-溴-2-氟-联苯

以苯硼酸和2-氟-4-溴碘苯为起始原料,经Suzuki偶联反应合成了色谱纯度99.5%以上的医药和液晶中间体4-溴-2-氟-联苯,目标化合物进行了1HNMR、IR和GC-MS表征。结果表明,反应体系中氧气的存在是导致硼酸自偶副产物产生的主要原因;Pd(PPh3)4催化剂及过量的苯硼酸均会导致三联苯副产物的产生。