Preparation of cellulose and pulp carbamates through a reactive dissolution approach

Labafzadeh, Sara R.; Kavakka, Jari; Vyavaharkar, Kashmira; Sievänen, Katja; Kilpeläinen, Ilkka

doi:10.1039/c4ra02316a

Cited by 14 publications

(21 citation statements)

References 36 publications

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“…1 With the increasing consciousness of environmental protection and the dwindling supply of petroleumbased products, natural cellulose-based materials are being actively pursued. [4][5][6] The properties and processability of cellulose can be dramatically modied by the substitution reactions of its hydroxyl groups, and cellulose is the most commercially signicant nature polymer with billions of kilograms of its sales each year for a wide range of applications. It is neither meltable nor soluble in most common solvents because of the strong inter-and intramolecular hydrogen bonding and its high degree of crystallinity in structure.…”

Section: Introductionmentioning

confidence: 99%

Green mechanical activation-assisted solid phase synthesis of cellulose esters using a co-reactant: effect of chain length of fatty acids on reaction efficiency and structure properties of products

Zhang

et al. 2015

RSC Adv.

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Esterification is an important chemical modification for the preparation of natural cellulose-based materials.However, esterification of cellulose is commonly carried out in organic solvents, which reduces the economic and environmental feasibility of the synthetic technologies. Herein we report a novel technology for the production of cellulose esters, which combines mechanical activation (MA) and esterification in a stirring ball mill under solid phase conditions without the use of solvents. With the use of acetic anhydride as co-reactant and fatty acids as long chain esterifying agents, 1 H and 13 C NMR measurements confirmed that both acetyl and long chain fatty acyl groups were successfully grafted on cellulose by the technology of MA-assisted solid phase synthesis (MASPS). The factors which contributed to the successful preparation of cellulose esters were: the formation of highly reactive mixed acetic-long chain fatty acid anhydride, the generation of active hydroxyl groups in cellulose, the weakening of the steric effect of long chain fatty acids, and the improved contact between reagents and cellulose which were first induced by intense milling. It also showed that the reactivity of fatty acids and the degree of substitution (DS) of fatty acyls decreased with the increase in their chain length, and the long chain fatty acylium ions preferred to react with the more reactive hydroxyl group in the anhydro glucose unit of cellulose. Moreover, Fourier transform infrared spectroscopy, X-ray diffractometry, and scanning electron microscopy analyses were used to measure the changes in chemical structure, crystal structure, and surface morphology of the cellulose before and after esterification by MASPS, respectively. The results indicate that this green, simple, and efficient technology is suitable for the direct production of cellulose esters with long chain substituents.

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Section: Introductionmentioning

confidence: 99%

Green mechanical activation-assisted solid phase synthesis of cellulose esters using a co-reactant: effect of chain length of fatty acids on reaction efficiency and structure properties of products

Zhang

et al. 2015

RSC Adv.

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“…To afford these compounds, we were attracted by the mild reaction conditions provided by the carbamoylation of primary and secondary alcohols with isocyanates in the presence of tin-based catalyst. 37–38 In particular, this reaction proceeds under neutral conditions, which was deemed important in view of the relative instability of the PTL scaffold under acidic or basic conditions. Gratifyingly, the desired carbamate-based parthenologs could be successfully prepared starting from 2 or 3 in the presence of the appropriate isocyanate reagent and catalytic amounts of dibutyltin dilaurate (DBTDL) (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%

Anticancer activity profiling of parthenolide analogs generated via P450-mediated chemoenzymatic synthesis

Alwaseem

Frisch

Fasan

2018

Bioorganic & Medicinal Chemistry

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The plant-derived sesquiterpene lactone parthenolide (PTL) was recently found to possess promising anticancer activity but elaboration of this natural product scaffold for optimization of its pharmacological properties has proven challenging via available chemical methods. In this work, P450-catalyzed C-H hydroxylation of positions C9 and C14 in PTL was coupled to carbamoylation chemistry to yield a panel of novel carbamate-based PTL analogs ('parthenologs'). These compounds, along with a series of other C9- and C14-functionalized parthenologs obtained via O-H acylation, alkylation, and metal-catalyzed carbene insertion, were profiled for their cytotoxicity against a diverse panel of human cancer cell lines. These studies led to the discovery of several parthenologs with significantly improved anticancer activity (2-14-fold) compared to the parent molecule. Most interestingly, two PTL analogs with high cytotoxicity (LC∼1-3μM) against T cell leukemia (Jurkat), mantle cell lymphoma (JeKo-1), and adenocarcinoma (HeLa) cells as well as a carbamate derivative with potent activity (LC=0.6μM) against neuroblastoma cells (SK-N-MC) were obtained. In addition, these analyses resulted in the identification of parthenologs featuring both a broad spectrum and tumor cell-specific anticancer activity profile, thus providing valuable probes for the future investigation of biomolecular targets that can affect cell viability across multiple as well as specific types of human cancers. Altogether, these results highlight the potential of P450-mediated chemoenzymatic C-H functionalization toward tuning and improving the anticancer activity of the natural product parthenolide.

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“…To confirm the successful modification of cellulose, Fourier Transform Infrared Spectroscopy (FTIR) of the original cellulose and CC with different DS were performed, and the results are shown in Figure 2. The obvious absorption peak at 1715 cm −1 for the CC sample was assigned to the stretching vibration of the carbonyl group of the carbamate [32,33]. This indicated that urea had successfully reacted with cellulose to form CC.…”

Section: Confirmation Of Carbamation Of Cellulosementioning

confidence: 94%

Preparation of Microfibrillated Cellulose from Wood Pulp through Carbamate Modification and Colloid Milling

Wei¹,

Zhou

Yao

et al. 2020

Applied Sciences

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This paper studies a new convenient method to prepare microfibrillated cellulose from a bleached eucalyptus kraft pulp. First, the wood pulp was reacted with urea to produce cellulose carbamate (CC), and then the CC was treated with colloid mill in an acidic medium. A feasible preparation process for CC was to soak the pulp with the urea solution, and then the cellulose pulp was dewatered, dried, and reacted with urea at high temperatures above the melting point of urea. The Kjeldahl method, infrared spectroscopy, and solid 13C NMR were used to confirm the effectiveness of the reaction. On the basis of CC with the degree of substitution, DS = 0.123, the aqueous suspension with 2% content of CC at pH values of 1, 3, or 7 was severally ground by a colloid milling. After centrifugation, the nanocellulose carbamate fiber (CCNF) in the supernatant was obtained. X-ray diffraction showed that CC and CCNF had the same crystal form as the cellulose pulp, but the crystallinity decreased successively. The nanometer diameter of the CCNF fiber was observed with scanning electron microscopy. Results showed that when the pH value of the CC suspension decreased during the colloid milling, the crystallinity of the CCNF decreased along with the decrease of fiber diameter, and the zeta potential of the supernatant increased. This indicated that carbamate side groups of CC were protonated at low pHs and the cation repulsion between cellulose molecular chains enhanced the driving force of the pulp separation to CCNF. Interestingly, the thermal stability of CCNF is comparable to that of the original cellulose, and the enhancement effect of CCNF on starch can be clearly observed even at a relatively low loading of CCNF.

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Preparation of cellulose and pulp carbamates through a reactive dissolution approach

Cited by 14 publications

References 36 publications

Green mechanical activation-assisted solid phase synthesis of cellulose esters using a co-reactant: effect of chain length of fatty acids on reaction efficiency and structure properties of products

Green mechanical activation-assisted solid phase synthesis of cellulose esters using a co-reactant: effect of chain length of fatty acids on reaction efficiency and structure properties of products

Anticancer activity profiling of parthenolide analogs generated via P450-mediated chemoenzymatic synthesis

Preparation of Microfibrillated Cellulose from Wood Pulp through Carbamate Modification and Colloid Milling

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