Quaternary ammonium cationic starch

Quaternary ammonium alkyl ethers are prepared similarly an alkaline starch is reacted with a quaternary ammonium salt containing a 3-chloto-2-hydtoxyptopyl or 2,3-epoxyptopyl radical. Alternatively, such derivatives can be prepared by simple quaternization of tertiary aminoalkyl ethers by reaction with methyl iodide. Sulfonium (107) and phosphonium (108) starch salts have also been prepared and investigated. Further work has explained the synthesis of diethyl aminoethyl starch (109) as well as the production of cationic starches from the reaction of alkaline starch with... 

Cationic Starches. Commercial cationic starches are starch ethers that contain a tertiary amino or quaternary ammonium group, eg, the diethylaminoethyl ether of starch or the 2-hydroxy-3-(trimethylammonio)propyl ether of starch [9063-45-0], sold as its chloride salt [56780-58-6]. 

Etherification. A mixture of ethylene chlorohydrin ia 30% aqueous NaOH may be added to phenol at 100—110°C to give 2-phenoxyethanol [122-99-6] ia 98% yield (39). A cationic starch ether is made by reaction of a chlorohydfin-quaternary ammonium compound such as... 

Quaternary ammonium compounds (quats) are prepared - by moderate heating of the amine and the alkyl halide in a suitable solvent - as the chlorides or the bromides. Subsequently conversion to the hydroxides may be carried out. Major applications of the quat chlorides are as fabric softeners and as starch cationizing agent. Several bio-active compounds (agrochemicals, pharmaceuticals) possess the quat-structure. Important applications of quat bromides are in phase transfer catalysis and in zeolite synthesis. 

Starch is the most widely used dry strength additive and is normally made in a cationic form by introducing a reactive monomeric or polymeric tertiary amine or quaternary ammonium derivative into the molecule. The most commonly used reagent for tertiary amino starch is 2-chloroethyldiethylammonium chloride, and for quaternary starch is 2,3-epoxypropyltrimethylammonium chloride (Figure 7.10). 

Cationization and carboxymethylation of starch in an extruder has been reported.45 17 Cationization of potato starch in a twin-screw extruder had an optimum reaction efficiency of 71%. Further work yielded 80% efficiency and products with 0.03-0.10 DS.44 Additional heat treatment of extruded products (made via reaction with quaternary ammonium reagents) with sodium trimetaphosphate or citric acid has improved reaction efficiencies and/or viscosities.48 Dry cationization in the presence of methanol and isopropanol49 or combined with microwave irradiation has also been done.50... 

Various aminoalkyl and alkylaminoalkyl halides react with starch in alkaline media and are readily available by the reaction of epichlorohydrin with primary, secondary, and tertiary amines and even aqueous ammonia. Prior to the reaction with starch, the quaternary ammonium compounds were either decomposed to free amines, or they reacted as amminium compounds to give cationic aminium starches. Cationic starches were produced by the reaction of starch with arylalky-laminoalkyl epoxides. In the presence of formaldehyde, inorganic ammonium salts provided the source of amino groups.1316... 

Cationic starches are obtained by reaction of starch with reagents containing amino, imino, ammonium, sulfonium groups. The two main types of commercial products are the tertiary amino and quaternary ammoniiun starch ethers (135). 

Addition of several types of days as well as modified (organophiHzed clays) were found to improve mechanical properties and decrease water uptake of starch-based bionanocomposites viz., natural sodium montmoriUonite (MMT) [155], MMT, hectorite, hectorite modified with 2-methyl, 2-hydrogenated taUow quaternary ammonium chloride and kaolinite [150], natural sodium montmoriUonite (Na MMT, Cloisite Na+), and organically modified montmoriUonite (OMMT) with methyl taUow bis-2-hydroxyethyl ammonium cations located in the silicate gallery (Cloisite 30B) [151], MMT (hydrophilic Cloisite Na+ day and hydrophobic Qoisite 30B, lOA, and 15A) [152, 153). 

Carr ME. 1994a. Preparation of cationic starch containing quaternary ammonium substituents by reactive twin-screw extrusion processing. J Appl Polym Sci 54 1855-1861. 

---