Cellulose esters reactivity

Cellulose esters of aromatic acids, aUphatic acids containing more than four carbon atoms and aUphatic diacids are difficult and expensive to prepare because of the poor reactivity of the corresponding anhydrides with cellulose Httle commercial interest has been shown in these esters. Of notable exception, however, is the recent interest in the mixed esters of cellulose succinates, prepared by the sodium acetate catalyzed reaction of cellulose with succinic anhydride. The additional expense incurred in manufacturing succinate esters is compensated by the improved film properties observed in waterborne coatings (5). 

Production of cellulose esters from aromatic acids has not been commercialized because of unfavorable economics. These esters are usually prepared from highly reactive regenerated cellulose, and their physical properties do not differ markedly from cellulose esters prepared from the more readily available aHphatic acids. Benzoate esters have been prepared from regenerated cellulose with benzoyl chloride in pyridine—nitrobenzene (27) or benzene (28). These benzoate esters are soluble in common organic solvents such as acetone or chloroform. Benzoate esters, as well as the nitrochloro-, and methoxy-substituted benzoates, have been prepared from cellulose with the appropriate aromatic acid and chloroacetic anhydride as the impelling agent and magnesium perchlorate as the catalyst (29). 

First, the acid anhydride is produced by the reaction of the free acid with DCC. NucleophiUc attack by 4-pyrroUdinonepyridine on the anhydride results in the corresponding, highly reactive acylpyridinium carboxylate this leads to the formation of cellulose ester, plus a carboxylate anion. The latter imdergoes a DCC-mediated condensation with a fresh molecule of acid to produce another molecule of anhydride. N,N-carbonyldiimidazole (CDl) may substitute DCC for acid activation, the intermediate being N-acyhmidazol,... 

No systematic studies of the principles governing the synthesis of cellulose esters by the trans-esterification reaction had been available in the literature until the present authom published work permitting one to ascertain the relation between the reactivity cf low-mol ular-weight esters and their structure, and the direction trf the reactions involved. 

It has been demonstrated that wood cellulose can also be employed for the commercial manufacture of cellulose esters. Several descriptions of suitable purification processes have appeared in the technical literature. - The material has now attained large industrial use and when properly purified approaches the quality of cotton cellulose. Important considerations in the preparation of wood pulp for acetylation are the proper removal of impurities to yield a product of high alpha cellulose content without severe loss of viscosity, and with retention of uniform reactivity of the cellulose toward acetylation. Color and haze in the acetylated product are difficult to eliminate to the degree possible with cotton linters. 

Propargylcellulose containing reactive ethynyl groupings was used to prepare new types erf cellulose esters acetonylcellulose (1), 2-methoxy-propen-l-ylcellulose (II), 2-diethylaminopropen-1 -ylcellulose (III) ... 

When used as an additive in a converting system, the cellulose ester does not have to be a high-performance film former but can be very low viscosity and still perform the function expected of it. Upon application, the presence of CAB in the coating gives it certain lacquer like properties including rapid dry-to-touch time. During conversion, the cellulose ester performs as a polyol and converts with the balance of the reactive film former. 

NFPA Health 1, Flammability 3, Reactivity 0 Storage Store in tightly closed containers in cool, well-ventilated area separate from work place limit quantities in use Uses Solvent for natural and syn. resins, cellulose esters and ethers, paints, printing inks, waxes, veg. oils, pharmaceuticals organic synthesis chemical intermediate in polishes brake fluids degreasing solvent antiseptic antifoam, solvent in cosmetics synthetic flavoring agent in foods and pharmaceuticals in food-pkg. adhesives in cellophane for food pkg. 

Properties Colorless liq. plum-like odor misc. with oils, hydrocarbons, alcohols, ether, ketones si. sol. in water m.w. 116.16 dens. 0.880-0.885 m.p. -73.5 C b.p. 123.5 C flash pt. 26.6 C Toxicology LD50 (oral, rat) > 5 g/kg, (skin, rabbit) > 5 g/kg toxic by inh. and ing. mod. irritant by skin contact TSCA listed Precaution Flamm. dangerous fire risk reacts vigorously with heat, flame, oxidizing materials NFPA Health 1, Flammability 3, Reactivity 0 Uses Solvent for cellulose esters, resins films... 

HMIS Health 2, Flammability 1, Reactivity 1 Uses Plasticizer for cellulose esters and ethers antimicrobial, preservative for cosmetics, biological fluids and solutions anesthetic in dentistry antiseptic mild sedative topical analgesic Use Level 0.0001-0.5% (parenterals) 0.2-0.65% (ophthalmics)... 

Hazardous Decomp. Prods. Heated to decomp., emits toxic fumes of NOx NFPA Health 3, Flammability 2, Reactivity 0 Storage Store in a cool, dry, well-ventilated area, out of direct sunlight limit quantities in storage Uses Anticorrosion agent for ferrous metals solvent for oils, resins, some cellulose esters raw material for vulcanization accelerators, lubricant additives, antioxidants flotation reagents dyestuffs... 

Precaution DOT Flamm. liq. dangerous fire hazard exposed to heat, sparks, flame reactive with oxidizers violent reactions possible Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke, irritating fumes Uses Solvent for paints, cellulose esters and ethers, vinyl resins, lacquers, inks ore flotation paint and varnish removers insect repellent mfg. of methyl isobutyl ketone Manuf/Distiib. Allchem Ind. http //www.allchem.com, Ashland http //www.ashchem.com, Atofina SA http //www.atofina.com, Celanese http //www. celanesechemicals. com, http //www.chemvip.com, Corco Coyne http //www.coynechemicai.com. Delta Distributors http //www.deitadist.com, Dow http //www.dow.com, Eastman http //www.eastman.com, Fluka http //www.sigma-aidrich. com G.J. Chem. Harcros... 

Hazardous Decomp. Prods. Heated to decomp., emits acrid smoke and irritating fumes NFPA Health 0, Flammability 2, Reactivity 0 Uses Preservative, skin conditioner in cosmetics fragrance in perfumes dyestuffs intermediate solvent for cellulose esters and ethers, resins, rubber synthetic flavoring agent in foods and pharmaceuticals Features Fruity flavor... 

Two papers point to the use of renewables in the production of interesting polymeric materials based on renewables. The contribution from Kelley describes a model compound study on the reactivity of pyrolysis oils, and how this information can be used in the formulation of new renewables based adhesives. Glasser describes the use of steam explosion technology to facilitate the simultaneous production of lignin and cellulose esters, useful in the production of thermoplastic structural polymers from wood. 

Another strategy for in situ activation, used for the s3uithesis of aliphatic cellulose esters, is the exploitation of DCC in combination with 4-pyrrolidinopyridine (PP) [35]. Among the advantages of this method are the high reactivity of the intermediately formed mixed anhydride with PP and a completely homogeneous reaction in DMA/LiCl up to hexanoic acid. If the reaction is carried out with the anhydrides of carboxylic acids, the carboxylic acid liberated is recycled by forming the mixed anhydride with PP, which is applied only in a catalytic amount. The toxic DCC can be recycled from the reaction mixture (Fig. 16.4). In addition, the method is utilized to obtain unsaturated esters (e.g. methacrylic-, cinnamic-, and vinyl acetic acid esters) and esters of aromatic... 

Isomerized oils n. Oils which have been iso-merized from a molecular rearrangement by several means, such as the catalytic action of alkalis, sulfur dioxide, nickel, etc. Isomerized oils exhibit greater reactivity, more rapid polymerization and greater drying rate than their non-isomerized parent oils. Paint pigment, drying oils, polymers, resins, naval stores, cellulosics esters, and ink vehicles, vol 3. American Society for Testing and Material, Conshohocken, PA, 2001. Shahidi F, Bailey AE (eds) (2005) Bailey s industrial oil and fat products. John Wiley and Sons. 

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