Schweizer's Reagent Research Articles

Are nonwoven fabrics used in foods made of cellulose or plastic? Cellulose/plastic separation by using Schweizer's reagent and analysis based on a sample of tea bags

Tea ranks high among the most popular drinks worldwide, second only to water. But the term covers a very wide range of products, extending from common black tea to herbal teas containing elements of various plant species, offered in bulk tea as well as tea bag form. Tea bags are a popular option worldwide, given the ease of use they offer. It is often noted that tea bags are made of cellulose, save for some exceptions made completely of nylon or PET plastics (silken, pyramid). The present study is essentially an analysis of tea bags occupying a significant portion of the shelf space in the tea section of supermarkets, which are purportedly made of cellulose. In this context, Schweizer's reagent (SR), a strong solvent of cellulose, was applied within the framework of ATR-FT-IR analyses to see whether any plastics were used in the nonwoven fabric of cellulose tea bags. The analysis of various brands of tea bags purchased from various supermarkets in Turkey revealed that 4 out of 11 tea bags for use in teacups, called cellulose bags, contained plastics (polyester, PE, and PP-PE blends), whereas the figure for the tea bags for use in the teapot was 11 out of 11. Whenever tea bags are used in brewing hot drinks such as tea, often consumed for its enjoyable taste and as a herbal remedy, the bag may contain plastic fibers, posing potential health risks. Furthermore, the use of durable materials such as plastics in tea bags, which are purportedly compostable products, also constitutes a risk in terms of environmental sustainability.

Novel fabrication of cellulose sprinkled crystalline nanocomposites using economical fibrous sources: High performance, compatible catalytic and electrochemical properties

We report an innovative green synthesis of cellulose based copper oxide nanomaterials by simple sol-gel derived solvo-thermal method. The physio-chemical properties of nanocomposite has enhanced by dissolving filter paper, cotton (Gossypium) and kapok cotton (Ceiba pendantra) as natural cellulose materials in cuprammonium hydroxide (Schweizer's reagent). Hybrid of polysaccharide-copper oxide nanocomposite has exhibited versatility. The composites were characterized by XRD, FESEM-EDAX, HRTEM, FT-IR, UV–Vis, CV, GCD and EIS studies. The sharp XRD peaks have confirmed the crystalline monoclinic phase of CuO as well as crystalline cellulosic materials with crystalline size of 55.7 nm. The observed FT-IR peaks at 523.19 and 1118 cm−1 has proved the Cu–O stretching as well as C–O linkage in cellulose material respectively. The UV–Vis study of nanocomposites has confirmed the specific absorption property of synthesized nanomaterials. The redox peaks in CV and GCD curve have confirmed that the synthesized nanocomposites are the very good energy storage material with the specific capacitance value of 120 F g-1 at the current density of 1 A g-1. They have showed an effective antimicrobial activity against gram positive as well as gram negative bacterial strains and also exhibited good catalytic activity as heterogeneous catalyst in esterification of biodiesel production for industrial applications.

Theoretical and experimental study of dissolution mechanism of cellulose

Cellulose is one of the most abundant, sustainable and renewable materials on Earth. Accordingly, its utilization in different forms on different scales is in focus. Cellulose-based nanomaterials are considered to be one of the most exciting nanomaterials. Preparation of cellulose-based materials necessitates formation of cellulose-based solutions using environmentally hazardous solvents, which stems from the chemical nature of cellulose. In this work, an experimental and theoretical study of cellulose dissolution is described. As a model system, dissolution of cellulose in Schweizer's reagent is studied experimentally and theoretically as a model non-derivatizing method, elucidating and describing the physico-chemical aspects of the process. Dissolution of individual fibers pulled off banana woolery and cotton linters is studied experimentally. It is observed that a fiber can begin to swell before dissolution, even though it does not happen always. Then, the cross-sectional fiber size diminishes linearly in time, allowing direct measurement of the rate of cellulose dissolution. The theoretical model developed here links the rate of dissolution with the number of hydrogen bonds associated with hydroxyls on the surface of cellulose molecule required to be broken by chelating copper ions. This number is shown to be within the range of 1.28 × 1010–4.05 × 1010 cm−2, indicating that nanocellulose fibrils of length of 100–1000 nm are chipped off from cellulose during dissolution process. In concert with the dissolution rate, osmotically- driven flow of solvent towards the dissolving cellulose surface was also found.

Facile in situ formation of luminescent cellulose paper using Schweizer's reagent as an inorganic solvent in water

The inorganic solvent Schweizer reagent was attached to the surface of cellulose, followed by an in situ chemical reaction performed directly on the solvent forming a stable and luminescent Cu(i) cluster-functionalized cellulose paper.

Preparation and characterization of a novel spherical cellulose-copper(II) oxide composite particles: as a heterogeneous catalyst for the click reaction.

In this research, the cellulose-copper(II) oxide composite particles were provided by a novel and simple approach using Schweizer's reagent via dialysis method at ambient temperature. The prepared particles are spherical in shape and uniform in size with average diameters of approximately 500nm that have a good dispersion in water. These particles were characterized by means of X-ray diffraction, scanning electron microscopies, transition electron microscopy, energy-dispersive X-ray spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller analysis and inductively coupled plasma optical emission spectrometry. The performance of the particles was illustrated in the click reaction as a heterogeneous catalyst in water.

Employing a T-shirt template and variant of Schweizer's reagent for constructing a low-weight, flexible, hierarchically porous and textile-structured copper current collector for dendrite-suppressed Li metal

A low-weight and flexible T-shirt structured porous Cu current collector with superior performance for Li metal anodes was fabricated and could suppress Li dendrite growth.

Photomobility and photohealing of cellulose-based hybrids(a)(a)Contribution to the Focus Issue Self-assemblies of Inorganic and Organic Nanomaterials edited by Marie-Paule Pileni.

In an effort to control the electronic and mechanical interaction between an inorganic surface and a defined polymeric coating, we present a new and easy method of a cellulose-based hybrid formation. We used Schweizer's reagent, a specific copper ammonia hydroxide-based solvent for cotton dissolution and found the optimal concentration for the formation of photosensitive uniform cellulose coating on titania, TiO2-cellulose coating and free-standing hybrid. Photomobility, the material mobility induced by light, of a cellulose layer on a titania surface and of a TiO2-cellulose hybrid on a silicon wafer has been studied. This can be used for photohealing, and the most promising system is the one that can be healed with light due to in situ activation of titania nanoparticles assembled on cellulose fibers in a hydrogel. The interfacial contact between titania particles and fiber is important for local transport of electrons and ions, thus the most promising system was obtained by in situ synthesis of titania nanoparticles on cellulose dispersed in Schweizer's reagent. We propose that cellulose coatings on titania surface and free-standing hybrids can be applicable for a wide range of photochemical devices: films for optics, drug delivery systems, and inks for printing of biologically relevant lab-on-chips.

Przegląd metod badań technologicznych zabytkowych kodeksów na przykładzie Codex Aureus Gnesnensis

In 2012 Codex Aureus Gnesnensis called the „Gold Codex” from the Archdiocesian Archive of Gniezno (item „BK Ms 1a”) was investigated by scientific workers from the Nicolaus Copernicus University in Toruń. The codex was made on parchment, reachly illuminated, block covered with wooden boards and leather, and decorative silver elements were set to the cover. All basic elements and substances of the object were investigated: metal elements, wooden boards, leather, pigments and binders, parchment, paper products, textile materials, materials used for reparation. Attempts were also put on investigation of degradation products of materials and decayed areas. Several methods applied to characterise meterials the object consists of. They were as follows: A). non-invasive methods: observation in ViS light, rentgenography (RTG), reflectography in the UV light, UV induced fluorescence, NIR reflectography, X-ray fluorescence, FTIR spectroscopy, False IR analysis, pH measure of paper products, B). microdestrucive analyses on samples: X-ray fluorescence, observation of morphological features under optical microscopes (VIS, PL, UV), SEM with energy dispersive X-ray spectrometer (EDX), FTIR spectroscopy, False IR analysis, gas chromatography, collagen shrinkage temperature (MHT), fiber identification of paper products and textiles (morphological features, Herzberg stain, Schweizer reagent), lignin detection in paper products (phloroglucin), microchemical identification of organic substances (saponification test, hydroxyroline test, ninhydrin, sudan black, malachite green, amido black). Also the microbiological investigations were performed (nondestructive: ATP, insects identification; microdestructive: observation of sampled microorganisms under optical microscope). Results of investigations allowed dating of parts of the codex as well as realisation of the conservation-restoration project.

Synthesis of 3,4-Disubstituted Pyridines Starting from Baylis-Hillman Adducts Using Schweizer Reaction

Recently, we have reported the facile synthesis of polysubstituted pyridine derivatives from the Baylis-Hillman adducts. As shown in Scheme 1, the Baylis-Hillman adducts of alkyl vinyl ketone 1a could be converted easily into their tosylamide derivatives 2a. Sequential Michael addition of 2a to the appropriate Michael acceptor, aldol type cyclization, dehydration, elimination of p-toluenesulfinic acid, and the final isomerization afforded polysubstituted pyridines. In the reaction, compound 2a served threecarbons and one-nitrogen atom for the final pyridine while the Michael acceptor served two-carbon atoms. In this paper we wish to report the application of another two-carbon unit, vinyltriphenylphosphonium bromide (3a, Schweizer reagent), for the synthesis of 3,4-disubstituted pyridines. Extensive efforts have been devoted to the synthesis of 3,4-disubstituted pyridine derivatives due to their biological importance and the usefulness as synthetic intermediates. As shown in Scheme 2 and in Table 1, the reaction of 2a and 3a in CH3CN in the presence of DBU at 40-50 C for 16 h afforded 5a in 72% yield. Benzylidene derivative 5a must be formed via the successive Michael-Wittig reaction (Schweizer reaction). We could prepare 3-benzyl-4-methylpyridine (6a) from the reaction of 5a under K2CO3/DMF

Cellulose Solutions in Water Containing Metal Complexes

Aqueous solutions of a number of metal complexes have been found to dissolve cellulose. Recently, a number of new metal complexes have been developed that completely dissolve cellulose by deprotonating and coordinative binding the hydroxyl groups in the C2 and C3 position of the anhydro glucose. A detailed comparative light scattering study is given for cellulose in Schweizer's reagent (cuoxam), Ni-tren, and Cd-tren. Cuoxam is the well-known solution of cupric hydroxide in aqueous ammonia, and the abbreviation tren stands for tris(2-aminoethyl)amine. Cuoxam and Ni-tren are deep blue solvents. The light scattering measurements were carried out with the blue line of an argon ion laser at wavelength λ0 = 457.9 nm, and the data from these solvents required an absorption correction according to the Lambert−Beer law. Cd-tren is almost colorless, and the data could be used without correction. Because of traces of colloid particles, possibly originating from the metal hydroxides, a special treatment for optical clarification became necessary. A large number of samples, cotton linters, various pulp celluloses, and bacterial celluloses, were studied. All three solvents exhibited good solution properties, but only Cd-tren was capable of dissolving also the highest degrees of polymerization of cotton linters and bacterial cellulose (DPw = 9700). The limits for the two other solvents were DPw < 6300 for Ni-tren and DPw < 5300 for cuoxam. A fairly high chain stiffness was found with Kuhn segment lengths of lK = 15.8 ± 1.4 nm for Cd-tren, lK = 10.2 ± 0.8 nm for Ni-tren, and lK = 13.1 ± 1.2 nm for cuoxam, corresponding to characteristic ratios of C∝ = 24.6, 15.4, and 19.4, respectively. The problem of preferential adsorption is discussed.

Investigating the Cuprammonium Rayon Process in a High School Laboratory

We have found the cuprammonium rayon process to be an excellent system for high school independent study. Meeting twice a week provided time for the student-teacher investigation to result in a productive year of study. One can study the shift of the equilibrium to the complex ion, tetraamminecopper(II) hydroxide, and then return to copper(II) hydroxide by adding saturated copper(II) sulfate. The pH dependence of this equilibrium shift is studied as well as the pH dependence of Schweizer's reagent used to dissolve a-cellulose. The methods for rayon fiber formation and rayon disks are described. The fibers in a cuprammonium rayon membrane for a kidney dialysis machine are pictured.

Cellulose in Schweizer's Reagent: A Stable, Polymeric Metal Complex with High Chain Stiffness

Cellulose in Schweizer's Reagent: A Stable, Polymeric Metal Complex with High Chain Stiffness

Changes in glucan synthetase activity and plasma membrane proteins during encystment of the cellular slime mold Polysphondylium pallidum

The activity of glucan synthetase increased dramatically during encystment of Polysphondylium pallidum cells. The majority of activity was present in purified plasma membranes. Activity, measured as glucose incorporation from UDPG into NaOH-insoluble glucan, increased 30-40 fold in the membranes. Increases in activity within the cells preceded plasma membrane increases and the enzyme appeared to be rapidly transported to the plasma membrane. Intracellular activity was relatively low. When cells were incubated with UDPG and when phloretin was included to inhibit glucose uptake, no NaOH-insoluble glucan was synthesized. Hence, the UDPG-binding site was not exposed at the cell-surface. When the NaOH-insoluble glucan was digested with endo-β-1,4-glucanase the products were cellobiose and glucose. The glucan could also be precipitated from Schweizer's reagent with acetic acid. These results suggest that the glucan contained predominantly β-1,4-linkages and may be cellulose. Experiments with cycloheximide confirmed that protein synthesis was required for encystment. Labeling of cells with [1-(14)C]-acetate showed that the synthesis of certain plasma membrane proteins was developmentally regulated. A number of proteins (e.g., myosin heavy chains and actin) were synthesized during the lag phase and their synthesis was subsequently reduced or ceased altogether. Immediately prior to the commencement of cyst wall formation seven new plasma membrane proteins were synthesized. These proteins were not detected intracellularly, indicating rapid transfer to the plasma membrane. The possible relationship between the seven developmentally regulated proteins and a postulated "multi-enzyme-complex" involved in cellulose synthesis is discussed. Their synthesis may be related to the increase in particles in the outer leaflet of the plasma membrane observed during encystment with freeze-etching (G.W. Erdos and H.R. Hohl, 1980, Cytobios, 29, 7-16).

Addition compounds and complexes with polymers and models

Abstract

Cellulosic wall component produced by the golgi apparatus of Pleurochrysis scherffelii.

The Golgi apparatus of a marine chrysophycean alga Pleurochrysis scherffelii Pringsheim produces wall fragments (circular-to-ellipsoidal "scales") which are released to the periphery by an exocytotic process involving the fusion of cisternae and the plasma membrane. The cellulosic component of the scales is a complex network of fibrils (10 to 25 angstroms in diameter) that resist treatment with strong alkali. Untreated washed scales yield galactose, ribose, arabinose, and traces of glucose; alkali-purified scales yield much more glucose. The fibrillar scale constituent shows a positive iodine dichroism of the intact wall, a positive zinc chloride-iodine reaction, breakage sites characteristic of highly crystalline cellulose, and solubility in Schweizer's reagent.