Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
  • C08B31/00—Preparation of derivatives of starch
  • C08B31/08—Ethers
  • C08B31/12—Ethers having alkyl or cycloalkyl radicals substituted by heteroatoms, e.g. hydroxyalkyl or carboxyalkyl starch
  • C08B31/125—Ethers having alkyl or cycloalkyl radicals substituted by heteroatoms, e.g. hydroxyalkyl or carboxyalkyl starch having a substituent containing at least one nitrogen atom, e.g. cationic starch

Definitions

• the preparation of cationic starch is a well known commercial process.
• the basic water-slurry process for the quaternization of starch employing the reaction product of epichlorohydrin and an amine is taught in U.S. patent 2,876,217.
• an alkali metal salt e.g. NaCl or Na 2 S0 4 should be used to inhibit gelatinization.
• the starch is usually slurried in water at a dry weight (d.b.) of from about 10 to about 42 percent. Reaction times are generally from 12 to 20 hours, the slurry is maintained at a pH between 11 and 12 and the- temperature must be low to prevent gelatinization during the process, generally from room temperature up to 50°C.
• cationic starch products can be made in the absence of alkali and-at temperatures much higher than normal, up to just under 200°C, which is the browning temperature of the polysaccharide.
• This invention is directed to a process for preparing cationic starch by reacting in an aqueous medium said starch with a halohydrin quaternary amine in the presence of an alkaline catalyst characterized by (1) initiating said reaction with an alkali metal oxide or hydroxide and (2) thereafter adding an alkaline earth metal oxide or hydroxide to complete the reaction.
• the catalyst of the present invention is a combination of an alkali metal oxide or hydroxde and an alkaline earth metal oxide or hydroxide employed in sequence, the latter being added after the reaction has been initiated by the former.
• the alkali metal oxide or hydroxide catalyst is employed at a concentration of from 0.35 to 1.2 percent by weight and preferably from 0.6 to 1.0 percent; while the alkaline earth metal oxide or hydroxide is employed at a concentration of from 0.15 to 0.8 percent by weight, preferably from 0.3 to 0.6 percent.
• the use of less than the indicated amount of either catalyst will give low yields and, in the case of adding insufficient lime, gelation can occur.
• the alkali metal is sodium or potassium and the alkaline earth metal is calcium or barium.
• the halohydrin quaternary amine has the formula
• X is chlorine or bromine
• R 1 , R 2 and R 3 are independently selected from the group of ⁇ -0 4 straight or branched alkyl radicals with the proviso that the total number of carbon atoms in R 1 , R 2 , and R 3 does not exceed 8, and n is 1-3.
• starch is reacted with 3-chloro-2-hydroxypropyltrimethylammonium chloride according to the method of the present invention by employing an aqueous starch slurry of 40 to 46 percent by weight of dry starch with from 2 to 4 percent by weight of 3-chloro-2-hydroxypropyltrimethylammonium chloride in the presence of 0.5 to 2.0 percent by weight of a gelatinization inhibitor, all based on total reaction mixture.
• the time of reaction is from 4 to 14 hours, depending upon the temperature, and preferably from 7 to 10 hours. Temperatures in the range of from 35° to 60°C are employed and preferably from 45° to 55°C.
• the yields of the process of the present invention are from 70 to 85 percent. This compares to yields in the range of 55 percent to 60 percent known and practiced in the prior art. In addition to the yield advantage, shorter reaction times and reduction in waste effluents are achieved.
• corn starch is exemplified in the following experiments, wheat, rice, potato and (waxy) maize starches can also be employed in the present process.
• Suitable gelatinization inhibitors include, for example, Na 2 S0 4 , NaCl, KC1, K 2 S0 4 , Na 2 C0 3 and
• the resultant cationic starch is ordinarily neutralized with an acid, such as, for example, hydrochloric, citric, nitric, phosphoric, or adipic, to a pH of neutral or below, usually about 6.
• an acid such as, for example, hydrochloric, citric, nitric, phosphoric, or adipic
• the product is usually filtered and washed.
• the product obtained normally is dried before use.
• Example 1 a 500 ml round bottom flask, equipped with stirrer and placed in a 50°C constant temperature bath. To the flask was added 15.4 g of a 50 percent solution of 3-chloro-2-hydroxypropyltrimethyl- ammonium chloride plus a caustic solution made of 2 g NaOH diluted with 97 g of water. The contents was stirred and after formation of the epoxide which was determined by a drop of the pH from 13.2 to 12.3 (approximately 2 minutes), 121.74 g of corn starch mixed with 2.7 g of Na 2 S0 4 was fed into the pot at a rate insuring uniform dispersion (10-15 minutes).
• the temperature at which the reactions were conducted were: Examples 2-6 and Comparative Run D (45°C); Examples 7-12 and Comparative Runs A through C (50°C). The times of reaction were all 8 hours.
• catalysts (a) NaOH and (b) CaO are given for each example and comparative run as are the amounts of quaternary salt (quat), water, starch and inhibitor salt (Na 2 S0 4 ).
• Example 11 CaO added 30 minutes after starch; Comparative Runs A and B had no CaO added;

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• Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Biochemistry (AREA)
• Materials Engineering (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Polysaccharides And Polysaccharide Derivatives (AREA)
• Epoxy Compounds (AREA)

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Applications Claiming Priority (1)

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Citations (6)

• 1984
  • 1984-08-02 BR BR8407276A patent/BR8407276A/pt unknown
  • 1984-08-02 JP JP59503019A patent/JPS60502211A/ja active Granted
  • 1984-08-02 WO PCT/US1984/001222 patent/WO1985003710A1/en active IP Right Grant
• 1985
  • 1985-09-23 DK DK430985A patent/DK430985D0/da not_active Application Discontinuation
  • 1985-09-24 FI FI853659A patent/FI73227C/fi not_active IP Right Cessation
  • 1985-10-01 NO NO85853874A patent/NO161502C/no unknown

Patent Citations (6)

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