Research progress on dissolution and functional modification of cellulose in ionic
liquids 溶出度及功能化改性纖維素在離子液體中的研究進展
AB S T R A C T
Ionic liquids with physico-chemical special characteristics such as the low melting
point, adjustable acidity and good solubility have been used widely as the
environment-friendly solvents; Cellulose are the most abundant natural renewable
resources. Non-derivative cellulose solvents which being one category of ionic
liquids have attracted enormous studies in cellulose recently. This review summarizes
the dissolution and functional modification of cellulose as ionic liquids based on
previous researches.
離子溶液已被廣泛應用於特殊的物理化學特性，如熔點低，酸度可調，並具有
良好的溶解性離子液體可作為良好的環境相融性溶劑，纖維素是相當豐富的天然
可再生資源。例如非衍生性纖維素溶劑，便是其中的一類溶劑。
在最近，纖維素溶液的研究，有相當的吸引力。綜述在離子溶液的溶解性，再
根據以往的研究與纖維素的功能作一修改。
1. Introduction
In recent decades, the development and utilization of natural polymer have been
attracted increasingly because of the consumption and over-exploitation of
non-renewable resources. Cellulose which consists of β-(1→4)-linked glucose
repeating units is the largest renewable biological resources [1–3], it has been widely
used in industrial domains such as fiber, paper, polymer, textile and food industries
[4–6]. However, natural cellulose is high crystalloid, strong inter- and intra-molecular
hydrogen bonding caused by the hydroxyl groups and insoluble in water and common
organic solvents, these properties affect their development and utilization. Therefore,
the research and development of new fiber with green solvent systems, in particular,
which the homogeneous reaction of cellulose derivative can occur in cellulose
solvents, become a hotspot [5–8].
1．簡介
近幾十年來，因為消費需求和非再生資源的過度開採，吸引越來越多開發
和利用天然高分子。其中纖維素由β-（1→4）-葡萄糖的重複單元連接便是
最大的可再生生物資源 [1-3]，它已被廣泛應用於工業領域，如纖維，紙張，
聚合物，紡織品和食品行業[4-6]。然而，天然纖維素高晶體，較強的鍵結與
分子內氫鍵所造成的羥基團體和不溶於水的一般有機溶劑，這些屬性會影響
其開發和利用。因此，研究和開發新型纖維與綠色環保的溶劑系統，特別是，
均相反應的纖維素衍生物可併於在纖維素溶劑中的反應，為一個焦點[5-8]。
Due to their biodegradability [9] and low toxicity [10,11], Ionic liquids are
considered as potential substitute of environmentfriendly green solvent in
sustainable process [12]. Besides, compared with volatile organic solvents, ionic
liquids have optimized the compound characteristics: a broader selection of
anion and cation combinations [13], lower hydrophobicity [14,15], lower
viscosity [16,17], enhanced electrochemical stability [18] and thermal stability
[19], and the higher reaction rates whichmay lead to greater amount of output [20]
and non-flammable property. Consequently, ionic liquids have been employed
with increasing industrial interests [21]. Applications in various fields including
chemical reaction [22,23], electrochemical [24–27], inorganic nanomaterials
[28–31], segregation analysis [32–35] and food industry [36], have been
attracting more extensive attention.
由於其生物降解性[9]和低毒性[10,11]，離子液體被視為潛在的替代型環
保型綠色溶劑中可持續過程 [12]。此外，相比於含有揮發性有機溶劑，離
子液體具有能優化化合物的特點：更廣泛的選擇陰離子和陽離子組合[13]，
低疏水性[14,15]，低粘度[16,17]，增強電化學穩定性 [18]和熱穩定性[19]，
具有較高的反應率，這可能會帶來更大的輸出量輸[20]和不易燃性。因此，
離子液體已隨著工業的利益[21]，應用在各個領域包括化學反應 [22,23]，
電化學[24-27]，無機奈米材料[28-31]，隔離分析[32-35]，食品等行業[36]，
已吸引更廣泛的關注。
In 2002, Rogers et al. [37] found that cellulose could be dissolved in ionic
liquids 1-butyl-3-methyl imidazole chloride ([C4mim]C1), which opened up a
new way for the development of a class of cellulose solvent systems. In recent
years, ionic liquids have began to be used in cellulose materials processing,
studies on the dissolution of cellulose and the homogeneous derivative and
modification of cellulose materials such as paper, fiber have published in
newspapers and other periodicals, but number was relatively rare. This paper
reviews the dissolution and functional modification of cellulose in ionic liquids
in order to promote the research and application of ionic liquids in cellulose
materials.
2002 年，羅傑斯等人。[37]發現，纖維素可以溶解在離子液體 1 - 丁基
-3 - 甲基咪唑氯化物（[C4mim] C1），開闢了一條新的途徑為發展一類的
纖維素溶劑體系。近年來，離子液體已開始被用在纖維素材料加工，研究
纖維素的溶解和均勻的纖維素衍生物和修改材料，如紙張，纖維已經刊登
在報紙和其他期刊，但數量相對稀少。本文回顧了溶出和功能改性纖維素
在離子液體，以促進研究與應用離子液體在纖維素材料。
2. The dissolution of cellulose in ionic liquids
纖維素在離子液體中的溶出度
Ionic liquids, which are also referred to as room temperature ionic liquids, room
temperature molten salts(RTILs), organic ionic liquids, etc. refer to an ionic system
which takes on a liquid state at the room temperature or slightly warmer. They are
salts composed of organic nitrogen inorganic cations and inorganic anions [38–40]. As
a promising class of new solvents, cation types of ionic liquids which have been
studied (Fig. 1) include: A) alkyl quaternary ammonium cation[NRXH4 − X]+; B)
alkyl quaternary phosphonium cation [PRXH4 − X]+; C) N-alkyl pyridine
cation[RPy]+; and D) N, N-2- alkyl imidazole cation[R1 R3im]+, in which im
represents the imidazole structure, (if substituting group-R is at the 2-position, the
structure would be indicated which is expressed with [R1R2Rim]+). As is shown in
Fig. 1, the cations are usually alkylsubstituted imidazole. Anions such as BF−4, PF− 6,
CF3 SO3 − ,(CF3SO2) 2N−, C3F7CO0−, C4F9SO3 − , CF3COO−, ClO4− can be used in
combination with the above cations to form low melting point liquids [41]. Most of
the cations are 1-alkyl-3-methylimidazolium cations with the chemical structures as
shown in Fig. 2. The dissolution mechanismof cellulose in ionic liquids [42] involves
the oxygen and hydrogen atoms of cellulose-OH in the formation of electron
donor-electron acceptor (EDA) complexes which interact with the ionic liquid (Fig. 3).
For their interaction, the cellulose atoms serve as electron pair donor and hydrogen
atoms act as anelectron acceptor. In corresponding fashion, the cations in ionic liquid
solvents act as the electron acceptor center and anion as electron-donor center. The
two centers must be located close enough in space to permit the interactions and to
permit the EDA complexes to form. Upon interaction of the cellulose-OH and the
ionic liquid, the oxygen and hydrogen atoms from hydroxyl groups are separated,
resulting in opening of the hydrogen bonds between molecular chains of the cellulose
and, finally, the cellulose dissolves.
離子液體，這也被稱為室溫離子液體，室溫熔融鹽（離子液體），有機離子
液體等，是指一個離子系統，在室溫或稍暖下變為液體狀態。它們是由有機鹽類
無機氮和無機陽離子、陰離子組成的鹽[38-40]。為一種有價值的新型溶劑，陽
離子型離子液體已研究（圖 1）包括：A）烷基-銨鹽陽離子 [NRXH4 - X] +; B）
烷基-鏻陽離子 [PRXH4 - X] +; C）N -烷基吡啶陽離子 [RPY] +和 D）N，N - 2 烷基咪唑離子 [R1 R3im] +，其中 IM 代表咪唑結構，
（如果取代基- R 是在 2 位，
結構會表示這是表示[R1R2Rim] +）。正如圖所示。
陽離子通常為磺醯咪唑，而陰離子如 BF - 4，PF - 6，CF3 SO3 -，
（CF3SO2）2N
，C3F7CO0 ，C4F9SO3 ，CF3COO ，ClO4 的，可用於結合上述陽離子形成低熔
點液體 [41]。大部分的陽離子為 1 - 烷基-3 - 甲基咪唑陽離子，化學結構如圖
2。在纖維素溶出在離子液體機裡 [42]涉及氧和氫原子的纖維素- OH 形成的電子
供體 - 電子受體（EDA）配合物與離子液體的相互作用（圖 3）
。對於他們的互
動，纖維素原子作為電子對供體和氫原子扮演一個電子受體。在對應中心離子在
離子液體溶劑做為電子受體中心和陰離子作為電子供體的中心。這兩個中心，必
須要緊靠足夠的空間才能相互作用，並達到 EDA 複合物形成。當纖維素- OH
和離子液體，氧和氫原子的羥基被分離，造成開放性的氫鍵分子鏈之間的纖維
素，最後的反應結果為纖維素達到溶解。
Cellulose could be effectively dissolved in N, N-dimethyl acetamide/lithium chloride
(DMAc/LiC1), dinitrogen tetroxide/dimethyl formamide
(N2O4/DMF),1,3-N-methyl-morpholine-N-oxide (NMMO), dimethyl
sulfoxide/tetrabutylammonium fluoride (DMSO/TBAF), and molten salt hydrates
(such as LiC104–3H2O, LiSCN·2H2O) [43,44]. However, these solvents suffer from
more or less some drawbacks such as toxicity, difficulty in recycling, high cost, and
instability in the process for use. Swatloski et al. [37] took the lead in research on the
uses of ionic liquids used as cellulose solvents, and they reported that ionic liquid
1-butyl-3-methyl imidazole chloride ([C4mim] C1) could be used as cellulose solvent
in 2002, the effects of ionic liquids with varying structures of cations and anions on
the dissolution properties of cellulose were explored. Swatloski and colleagues
studied subsequently to find that ionic liquids only wet cellulose fibers at room
temperature, but cannot dissolve them. However, with heating to 100–110 °C,
cellulose could be dissolved slowly in ionic liquids which contained some anions C1−,
Br−, SCN−, etc. and a series of cellulose solution could be obtained.
纖維素可以有效地溶解在 N，(N -二甲基乙醯胺/氯化鋰 DMAc/LiCl），四氧化
二氮/二甲醯胺（N2O4/DMF）
，1,3- N -甲基嗎啉- N -氧化物（NMMO）二甲基亞
砜/四丁基氟化（DMSO/ TBAF）
，和熔鹽水合物（如 LiCl04-3H2O，LiSCN· 2H2O）
[43,44]。
然而，這些溶劑或多或少患有一些缺點如毒性，回收困難，成本高，而且使用
過程中很不穩定。 Swatloski 等， [37]率先在研究上使用離子液體作為纖維素
溶劑，他們報告說，離子液體 1 - 丁基-3 - 甲基咪唑氯化物（[C4mim] C1）可
以作為纖維素溶劑，而後在 2002 年，探索不同結構的陽離子和陰離子的溶出特
性對離子液體纖維素的影響。 Swatloski 和同事研究了隨後地發現，離子液體只
有濕性纖維素纖可維持在室溫溫度，但不溶於其中。然而，隨著加熱至 100-110
° C，纖維素可以慢慢溶解在離子液體，其中包含了一些陰離子 C1 -，BR -，
SCN -等，這一系列纖維素從而知曉解決提升溶解性的方法。
After Swatloski first publicly reported that cellulose could be dissolved in ionic
liquids, the behavior and changes of cellulose in the dissolution process was more
extensively studied. Ren et al. [45,46] found that ionic liquid
1-allyl-3-methylimidazole chloride ([Amim]C1) had good properties for cellulose
dissolution. They added cellulose activated with alkali (DP=640) to [Amim]C1,
placed it on a magnetic stirring plate in oil bath at 80 °C, and obtained 5%
solution of cellulosewhich resisted degradation. Heinze et al. [47,48], using the three
kinds of ionic liquids [C4mim]C1, 3-methyl-1-butyl-N pyridine chloride([C4mpy]C1)
and dimethyl benzyl ammonium chloride 14 alkyl (BDTAC) as solvents, discussed on
the change in the degree of polymerization of cellulose (DP=290–1200) in the process
of dissolution, and found that all three ionic liquids were all direct cellulose solvents.
Side reactions forming cellulose derivatives did not occur in the process of dissolution,
and the solubility of cellulose lowered with increase of degree of polymerization. The
results are shown in Tables 1 and 2. Zhai et al. [49] found that the cellulose with
different degrees of polymerization might be dissolved directly in ionic liquids
[bmim]Cl without other derivative reaction occurring under certain conditions. After
cellulose which had been dissolved in ionic liquids [bmim]C1, was regenerated by
treatment with water, and cellulose I was changed into cellulose II, although the
degree of crystallinity and the thermal stability more decreased than original cellulose.
But these changes did not affect the application value of their materials, and moreover
ionic liquidscould be recycled.
經過 Swatloski首次公開報導，纖維素可以溶解在離子液體中，並更廣泛的研
究纖維素在溶解過程中的變化和行為。[45,46]研究發現，離子液體 1 - 烯丙基-3
- 甲基咪唑氯化物（[Amim] C1）具有良好的溶解纖維素性能。他們補充纖維素
激活鹼（DP=640）為 [Amim] C1，把它放置在磁力攪拌器並在80 °C油浴，獲
得5％纖維素，並且能抵制降解反應。海因策等人。 [47,48]，採用三種離子液
體[C4mim] C1，3 - 甲基-1 - 丁基- N吡啶氯化物（[C4mpy] C1）和二甲基芐基
氯化銨-14-烷基（BDTAC）作為溶劑，討論在溶解過程中纖維素聚合度的變化
（DP=290-1200），發現這三個離子液體都是屬於直接纖維素溶劑 (化學結構為
直鏈型)
溶解的過程中，並沒有出現副反應形成纖維素衍生物，溶解度降低，纖維素的
聚合度增加。結果顯示在表1和2。 [49]發現，纖維素與於不同程度的聚合可能
會直接溶解在離子液體[BMIMCl]，這是已知在一定條件下發生，沒有其他衍生
的反應。纖維素被溶解在離子液體[BMIMCl]，是藉由在分散相(水)的處裡，由纖
維素I相變為纖維素 II，結果雖然是結晶度和熱穩定性比原來的纖維素I減少更
多。但這些變化並沒有影響到他們的材料的應用價值，而且離子液體可循環使用。
Hence, previous research on the dissolution of cellulose in ionic liquids has
provided some information with the following phenomena:
因此，先前對纖維素於離子液體中的溶出度的研究，提供了一些資訊與現象：
a) In linear chain alkyl imidazole chlorine ionic liquids including [C4mim]C1,
[C6mim]C1, [C8mim]C1 [37], etc. The solubility of cellulose decreased as the
length of the solvent carbon chain increased. The solubility of cellulose in the
three aforementioned ionic liquids was 10%, 5% and micro-solution at 100 °C,
respectively.
a）在直鏈烷基咪唑氯離子液體，包括三種[C4mim] C1，[C6mim] C1，[C8mim]
C1[37]等的可溶性纖維素的分子鏈長度減少，添加的溶劑中的碳鏈要彌補
分子鏈長較短的不足。纖維素的溶解度測試，在100°C分別的加入溶劑為，
10％的離子溶液，5％和微溶液上述三個離子溶液。
b) The solubility of cellulose with different degrees of polymerization differed in ionic
liquid [47]. The solubilities of microcrystalline cellulose (DP≈286), wood-pulp rice
dregs (DP≈593) and velveteen (DP≈1198) in [C4mim] at 83 °C, were l8%, 13% and
10% in the sametime, respectively.
程度不同的聚合度與纖維素的溶解性在不同的離子液體 [47] 中的溶解狀
態。有溶解度的微晶纖維素 （DP≈286）
，木材紙漿米渣 (DP≈593) 和絨 (DP≈1198)
在 [C4mim] 83 ° c，分別是商標法 %、 13%及是不是，10%。
在不同的離子液體中 [47]，纖維素的溶解度與不同程度的聚合。微晶纖維素的
溶解度（DP≈286），木漿米渣（DP≈593）和棉絨（DP≈1198）在[C4mim]在83
°C同一時間分別，是18％，13％和10％。
c)Microwave heating can significantly improve the solubility of cellulose when using
ionic liquids. The solubility of cellulose (DP≈1000) in [C4mim]Cl increases to 25%
with microwave heating, while at comparable conditions. However, only 10% of
cellulose (DP≈1000) can be dissolved in [C4mim]Cl [37] with the general heating.
This is because microwave heating is different from conventional heating methods,
microwave heating belongs to the internal heating of materials, traditional heating
belongs to conduction of heat. The microwave heating of materials is closely related
to the process of polarization of materials. The absorption of microwave radiation by
polar solvents is strong and warming occurs rapidly, but non-polar solvents absorb
little or no radiation in the microwave spectrum, resulting in no heating. Thus, ionic
liquids with high polarity, which have good absorption of microwave radiation are
appropriate microwave heating media. But its shortcomings are that, microwave
heating conditions can harsh and must be carefully controlled to avoid the pyrolysis of
cellulose.
用微波加熱離子液體時，可以顯著的提高纖維素的溶解度。在類似條件下，
微波加熱到25％，纖維素的溶解度（DP≈1000）[C4mim] Cl上升。然而，只有
10％的纖維素（DP≈1000）可溶於一般加熱的Cl [C4mim] [37]。這是因為微波
加熱與傳統加熱方式不同，微波加熱屬於內部加熱材料，傳統的加熱屬於熱傳
導。微波加熱的材料與偏振態材料的過程密切相關。吸收微波輻射強極性溶劑和
使加熱迅速發生，但非極性溶劑中吸收很少或根本沒有在微波輻射光譜，從而導
致不加熱。因此，離子液體具有高極性，有良好的微波輻射吸收以及適合微波加
熱的介質。但其缺點是，微波加熱條件苛刻，必須嚴格控制，以避免熱裂解纖維
素。
By means of the adjustment of the anion and the cation of ionic liquids, ionic liquids
with specific function are obtained. Their functionalization by introducing functional
groups on anion or cation of ionic liquids is realized [50].
Task-specific ionic liquids(TSILs) were produced by introducing functional groups at
imidazole cation which made ionic liquids effectively dissolve cellulose. For example,
Ren et al. [45] synthesized [Amim]C1 ionic liquids by appending the
allyl(–CH2–CHfCH2) moiety on the imidazole cation. For dissolving cellulose,
TSILs with more double bond than traditional [C4mim] C1 are effective, the strong
polar of the double bond is essential for dissolution of cellulose in [Amim]C1.
Superiority over straight-chain alkyl imidazole chloride ionic liquids is illustrated by
their ability to dissolve 3% of their amount (w/w) of cellulose using [Amim]C1 ionic
liquids at 70 °C takes in only 1 h, [C4mim]C1 needed 24 h [51].
調整改變陰離子、 陽離子於離子液體中含量或基團的方式，獲取具有特定
功能性基團的離子液體。其功能透過引入官能基團對陰離子或離子液體中的陽離
子化加以實現[50]。
特定基團的離子液體（TSILs）的反應方式是透過引入官能團，在咪唑陽離子反
應下，解出有效溶解纖維素的離子液體。例如，任等人。 [45]合成[Amim] C1離
子液體藉由附加烯丙基（- CH2 - CHfCH2）基團在咪唑陽離子。TSILs具有更多
的雙鍵比傳統[C4mim] C1有效，有較強極性的雙鍵是纖維素在 [Amim] C1 中的
溶出度的必要條件。直鏈烷基咪唑氯化物離子液體強調說明了他們能夠在70° C
使用[Amim] C1離子液體，溶解3％量（W / W）的纖維素，需要僅1小時，但[C4mim]
C1需要24小時[51]。
Moreover, Luo et al. [52] introducing hydroxyl groups on the imidazole cation and
synthesized the hydroxyl-containing cation TSILs 1-(2-hydroxyethyl)-3-methyl
imidazolium chloride([Hemim]C1). Their ionic liquids have better capacity to
dissolve cellulose. The solubility of microcrystalline cellulose reaches 6.8% at 70 °C.
According to the EDA mechanism, the cation imidazole and chloride anion of the
ionic liquids act as the electron acceptor and electron pair donor, respectively, and
promotes the dissolution of cellulose in this ionic liquids [Hemim]C1. The hydroxyl
on the cation side chain and the hydroxyl on cellulose molecules form hydrogen
bonds, which further weakens the inter- and intra-molecular hydrogen bonding,
causing cellulose to be dissolved. The dissolution of cellulose can be achieved by
introducing acetate on anions, anions-functionalized ionic liquids
1-ethyl-3-methylimidazole acetate [C2mim] CH3COO was prepared[51]. In this
solvent, two kinds of ions that are [C2mim] +and CH3COO− are in a free state in
solution. Both ions interact with hydroxyl of cellulose and generate complex
[C2mim]-Cell-Ac, resulting in the formation of both inter- and intra-molecular
hydrogen bonding. The bonds of the cellulose become weakened, and, finally,
cellulose can be dissolved.
此外，羅等人。 [52]以引入羥基的咪唑陽離子和合成了羥基含陽離子 TSILs1
- （2 - 羥乙基）-3 - 甲基咪唑氯化物（[Hemim] C1）
。有較好的離子液體可溶解
纖維素的能力。在70°C，微晶纖維素的溶解度達到6.8％。
根據 EDA機制，陽離子咪唑和氯離子的離子液體分別作為電子受體(Donor)
和電子對供體(Acceptor)，促進此離子液體 [Hemim] C1在纖維素的溶解。在陽離
子側鏈羥基和纖維素分子上的羥基形成氫鍵，進一步削弱了分子間和分子內氫
鍵，使纖維素被溶解。其他纖維素的溶出度可以透過一些引入醋酸離子、 陰離
子官能基性的離子液體 1-乙基-3-甲基咪唑醋酸 [C2mim] CH3COO [51]進行試
驗。
3. The functional modification of cellulose in ionic liquids
纖維素在離子液體中的功能化改性
Solution which are formed by dissolving Cellulose in unmodified solvents change the
functional modification reaction of cellulose from a non-homogeneous into a
homogeneous reaction, not only improving reaction rate but the degree of substitution
of derivatives (DS) as well as the distribution of functional groups were better
controlled. At present, only a few cellulose solvent systems have been applied to the
homogeneous reactions of cellulose, and solvent systems such as LiC1/DMAc,
PF/DMSO (Paraformaldehyde/dimethyl sulfoxide), and N2O4/DMF have achieved
the reactions of homogeneous esterification and of etherformation well. The
development of new ionic liquids used as solvents for synthesizing homogeneous
derivatives of cellulose is of great significance for the preparation of high quality
cellulose derivative products.
由纖維素溶解在未改質的溶劑中形成的解決方案將纖維素的功能化改性反
應從非均質變成均相反應、 以及功能組的分佈不只提高反應速率的替代的衍生
物 (DS)，但有更好的控制。目前情況下，只有幾個纖維素溶劑系統已應用於的
纖維素和 PF/二甲基亞碸 (多聚甲醛/二甲基亞碸)，如LiC1/DMAc 溶劑系統均相
反應和 N2O4/DMF和醚類在均相酯化便有很好的反應。
新型離子液體用作合成纖維素溶劑，其次衍生物的發展具有重要的意義，對於能
夠生產高品質的合成纖維素溶液有相當的成因。
Heinze et al. [47,48] and Wu et al. [53] studied on the activity of homogeneous
chemical reactions which occurred in several ionic liquids with different dissolution
properties, respectively. In the carboxymethylation reaction of cellulose, it can be
found that cellulose without activation could undergo the acetylation reaction. The
activity of the acetylation reaction of cellulose in ionic liquid solvent was higher than
that of the acetylation reaction in DMAc/LiC1 solvent. No by-products were formed,
furthermore, ionic liquids could be reused repeatedly. The factors that influenced the
carboxymethylation reaction of cellulose conducted in [C4mim]C1 have been
examined, and it was determined that when the amount of the carboxymethylating
reagent changes, the degree of substitution does not vary, the causes for this
phenomenon are still under study.
海因策 et al.[47,48] 和 [53] et al.研究均相化學反應中，分別指出具有不同溶
出性能的幾個離子液體中所發生的反應。像是羧甲基纖維素的反應，可以發現如
果纖維素溶在其中可進行乙醯化反應，依離子溶液的不同亦有差異。
纖維素在離子液體溶劑中的乙醯化反應的活性明顯高於 DMAc/LiC1 溶劑中
的乙醯化反應。且沒有副產物形成，此外，可反覆使用離子液體。已研究影響纖
維素進行中 [C4mim] C1 羧甲基化反應的因素，並以此羧甲基試劑量發生變化，
取代度不變，這種現象的原因是還在研究之中。
The acylation of cellulose in different ionic liquids in the absence of catalysts using
acetyl chloride produced acetate fibers with the different degrees of substitution. This
one-step reaction afforded products with a controllable degree of substitution and with
the distribution of substituents [46,53]. These studies also revealed that under the
same conditions, the degree of substitution of products using acetic anhydride as
acylating reagent farther was far below the degree of substitution of products attained
using acetyl chloride. Adding an equimolar ratio of pyridine in acetic anhydride can
improve the degree of substitution of products. We think that adding pyridine in acetyl
chloride can make acylation reactions milder. However, the degree of substitution of
products declines, it is probably because that the acetyl chloride reacts with pyridine
to generate a salt, of which activity is less than the activity of acetyl chloride.
Therefore, the degree of substitution of products increases with increasing the activity
of acylation, and the degree of substitution of products can be controlled by changing
the activity of the acylating reagent. With acetyl chloride as acylating reagent in the
ionic liquid [Amim] C1, the degree of substitution at the C6-position is the highest,
and the degree of substitution of C2-position and the C3-position have no significant
difference. In contrast, but using acetic anhydride and pyridine as acylating agents
[Amim]C1 gives products with the highest the degree of substitution at the
C6-position, but the degree of substitution at the C2-position is greater than that the
degree of substitution at the C3-position. Thus, the distribution of substituents of
products can be changed by changing acetylation reaction conditions. We hold that the
stereoselectivity of the reactions achieved in ionic liquids is related to characteristics
of the ionic liquids themselves. Table 3 shows the comparison of cellulose acetate
samples homogeneously prepared in different reaction media.
乙醯基化催化劑若使用乙醯氯在不同離子液體中的纖維素，據此了解生產醋
酸酯纖維結構的不同程度的取代基。這一步反應所提供的產品具有可控制取代度
和取代基分佈。[46,53]。
這些研究還發現在相同的條件下使用乙酸酐乙醯化試劑遠低於使用乙醯氯生成
產物的取代基。添加吡啶以等莫耳比於乙酸酐中可以提高產物取代度。我們認為
加入乙醯氯吡啶可以使乙醯基化反應較為和緩。但是，產物取代基下降的程度，
可能是因為乙醯氯反應生成鹽類，因此反應速率是小於活性氯乙醯氯吡啶的。
產物取代基增加越多，乙醯化反應及產物取代基可透過控制改變乙醯化試劑的
劑量。乙醯氯乙醯化試劑在離子液體 [Amim] C1，C6 位置的取代基程度最高，
和位置 C2 和 C3 位置的取代基有無顯著差異，相比之下，使用醋酸酐和吡啶
為醯化劑 [Amim] C1 使產物的的取代基位置於 C6，但在 C2 位置的取代基大於
C3 位置的取代基。因此，必須以改變乙醯化反應條件進一步更改產物取代基分
佈。我們認為離子液體結構上的立體選擇性取得的反應，關於離子液體本身的特
性。表 3 顯示不同均勻反應介質製備醋酸纖維樣本的比較。
Furthermore, Barthel and Heinze [48] discovered that homogeneous acetylation
reaction efficiency in homogeneous acetylation reaction (3.0 mol per mol AGU) of
cellulose dissolved in ionic liquids increased with the following order: [C4mim]C1 is
smaller than [Adumim]Br, [Adumim]Br is smaller than [C4dmim]C1, [C4dmim]C1 is
smaller than [C2mim]C1. Cellulose in [C2mim]C1, [C4dmim]C1 and [Adumim]Br,
reacted with acetic anhydride, but did not react with acetyl chloride, which differs
from the result with [C4mim]C1. They also studied the homogeneous reaction which
took place between cellulose in ionic liquid and lauroyl chloride (which is shown in
Table 4), but the product, cellulose decanoic acid lipid, precipitated during the process
of reaction.
此外，巴氏和海因策[48]發現，在均質乙醯化反應下，均質乙醯化反應效率（3.0
mol per mol AGU）的纖維素溶解力，離子液體增加順序如下：
[Adumim 的]Br < [C4dmim] C1，[C4dmim] C1 < [C2mim] C1。纖維素在[C2mim]
C1，[C4dmim] C1 和[Adumim]-Br，，纖維素與乙酸酐的反應，但並無與乙醯氯
反應，它有別於 [C4mim] C1 的結果。他們還研究均相反應發生之間纖維素在離
子液體和月桂醯氯 （其中表 4 所示）產物纖維素癸酸脂的沉澱反應過程。
Additional research revealed that polymeric derivatives of the imidazolium-type ionic
liquids, so-called polymeric ionic liquids, were compatible with cellulose and were
applied to the synthesis of cellulose composites. Murakami et al. [1] reported that
cellulose polymerized ionic liquid composite were prepared by an in situ
polymerization method using two kinds of ionic liquids, one of which dissolved the
cellulose and the other bearing a polymerizable acrylate group. Kadokawa et al. [54]
synthesized composites composed of cellulose and a polystyrene-type polymeric ionic
liquid. By using an imidazolium-type polymerizable ionic liquid having two
polymerizable groups in situ polymerization was achieved with the pre-treated
mixture in the presence of 2, 2-azo-bis-iso-butyronitrile(AIBN).
Swatloskl et al. [55] also reported research on cellulose functional materials in ionic
liquids. Homogeneous magnetic materials and cellulose were fully suspended and
dispersed in an ionic liquid system, and when this mixture was regenerated from
water, various forms of magnetic cellulose materials were obtained, it can be
indicated from X-ray diffraction data that the magnetic materials were wrapped into
the 25 nm particles and their chemical properties were not changed.
進一步的研究顯示，聚合體衍生物的咪唑型離子液體，即所謂的離子液體聚合
物，為符合纖維素合成纖維素複合材料的應用。纖維素聚合離子液體複合物製備
上使用兩種離子液體，其中之一溶解纖維素和其他可聚合丙烯酸酯組的原位聚合
法。合成複合材料組成的纖維素和聚苯乙烯型離子液體聚合物。透過使用具有兩
個可聚合與預先處理混合 2,2-azo-bis-iso-butyronitrile(AIBN)，在進行聚合反應
的情況下實現了原位聚合的咪唑類類型可聚合型離子液體
2,2-azo-bis-iso-butyronitrile(AIBN)。Swatloskl 等。 說明在離子液體中的纖維素
功能材料研究。均質磁性材料和纖維素是一種懸浮行為，分散在離子液體系統，
而當這種混合物是從水再生，獲得各種形式的磁性纖維材料，它可以從 X-射線
數據表示，磁性材料包覆成 25 奈米粒子及其化學性質都沒有改變。
From investigations conducted to data, cellulose functional reactions conducted with
ionic liquids, showed high uniformity in the reaction process, in no need of catalyst,
the reaction time is relatively shorter, yielded cellulose derivatives which are
controllable, and afforded a highly uniform degree of substitution with the absence of
formation of by-product, the ease of separation and purification of products, and the
convenient recovery of solvent, the advantages of ionic liquids are obvious.
從調查數據中，纖維素進行功能性反應與離子液體，呈高均勻性，在反應過程
中，不需要催化劑，反應時間相對較短，產生纖維素衍生物是可控制的，及給予
高均勻取代度的情況下所形成的副產物，易於分離純化產品，方便回收溶劑，離
子液體的優點是顯而易見的。
4. Facing problems and prospect 面臨的問題及發展前景
Ionic liquids, particularly the functionalization derivative of these solvents, bring the
advantages of green chemistry to the process of dissolution of cellulose. The excellent
physical and chemical properties of TSILs make them effective and rapid cellulose
solvents, a process that holds great promise for industrialization. Derivatives reaction
of cellulose occurs readily in ionic liquids. Substituents on derivative products of
cellulose prepared were evenly distributed and the yield of product was high.
離子液體，特別是這些溶劑的功能化衍生物帶來綠色化學的纖維素溶解過程的
優勢。TSILs 具有優良的物理和化學性能使其有效及快速纖維素溶劑，這一過程
帶來了巨大希望的產業化。纖維素衍生物反應很容易發生在離子液體中。取代基
對纖維素製備衍生產品均勻度和產品的產量很高。
Investigation of ionic liquids as new cellulose solvents hold great promise. At present,
the main problems still to be addresses include:
1) The need for additional improvements in salvation performation for the ionic
liquids used with cellulose, [C4mim]C1 and [Amim]C1.
2) The need for additional research to produce new industrial materials using ionic
liquids as cellulose solvent starts soon.
3) Optimization of reaction conditions and methods of acetylation and
carboxymethylation of cellulose in order that more types of cellulose derivatization
reactions can be studied in detail.
研究離子液體作為新型纖維素溶劑抱持很大的希望。目前，存在的主要問題還
有待解決，包括:
1） 離子液體用於纖維素，[C4mim] C1 和[Amim] C1，在官能基與取代基上需要
更多的改進。
2） 需要更多的研究，使離子液體用作纖維素溶劑的新型工業材料能更快進入工
業化程序。
3） 反應條件及乙醯化方式和羧甲基纖維素在順序可以詳細研究更多類型的纖
維素衍生化反應中的優化。
We believe that with the development of technology, the improved preparation of
TSILs will be achieved. Our understanding of the mechanism of dissolution and
derivatization of cellulose will be clarified, and the use of environmentally benign
solvents for cellulose will open broad prospects for the development of new high
quality cellulose materials.
我們相信隨著技術的發展，將實現 TSILs 的製備工藝改進。將會解釋溶出的
機制和纖維素衍生的進一步方法，以及纖維素無毒溶劑的使用將會打開新的優質
纖維素材料，發展前景廣闊。