Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D209/00—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom
  • C07D209/02—Heterocyclic compounds containing five-membered rings, condensed with other rings, with one nitrogen atom as the only ring hetero atom condensed with one carbocyclic ring
  • C07D209/04—Indoles; Hydrogenated indoles
  • C07D209/10—Indoles; Hydrogenated indoles with substituted hydrocarbon radicals attached to carbon atoms of the hetero ring
  • C07D209/18—Radicals substituted by carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals
  • C07D209/20—Radicals substituted by carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals substituted additionally by nitrogen atoms, e.g. tryptophane

Definitions

• the present invention relates to the field of tryptophan purification. STATE OF THE ART
• Tryptophan is an amino acid known to be used widely in both the human and animal food industry.
• the various methods for purifying tryptophan derived from bacterial cultures include chromatographic purification, which involves the use of columns of sizeable dimensions and is very costly on an industrial scale.
• the invention relates to a process for the purification of tryptophan which comprises treating a solution of semi-crude tryptophan with acetic acid in the presence of a base.
• the present invention enables the aforesaid problems to be overcome by means of a process which comprises a passage whereby the solution containing tryptophan is acidified with acetic acid in the presence of a base.
• the culture broth containing the tryptophan is filtered to separate the culture impurities (cells etc.) by means of known systems (centrifugation, microfiltration, filtration with the aid of diatomaceous earth etc.).
• the solution of crude tryptophan thus obtained is treated, again in substantially known manner, with an adsorption medium (generally activated carbon or dicalite, preferably the latter). Said medium is then removed by filtration and washed to recover as much tryptophan as possible.
• an adsorption medium generally activated carbon or dicalite, preferably the latter.
• the semi-crude tryptophan in aqueous solution thus obtained is then suitably diluted in demineralised water in the presence of acetic acid and base at a temperature between 20°C and 80°C and the solution is left to crystallize.
• acetic acid and base at a temperature between 20°C and 80°C and the solution is left to crystallize.
• the addition of a base is necessary to partially neutralize the acetic acid and to enable crystallization of the amino acid.
• the solid is then re-suspended in water, the pH is corrected to the isoelectric point (pH 5.9) by adding base and finally the crystals are collected by filtration and dried.
• the tryptophan thus obtained has a purity above 99% and the yield with respect to the starting product (crude tryptophan) is calculated to be about 55-65%.
• the preferred acid is acetic acid and the base is ammonium hydroxide.
• 80% commercial acetic acid is used in a quantity between 10% by volume and a volume equivalent to the solution containing tryptophan, a 30% ammonium hydroxide solution then being added until the pH stabilizes at around a value of between 3.0 and 5.0.
• ammonium acetate can be used to bring the pH to around a value between 3.0 and 5.0 then diluting the solution with 80% commercial acetic acid in a quantity to bring the total concentration of acetic/acetate within a range between 5% and 40%.
• the wet mass of about 3.2 litres in volume, was re-suspended in 1.6 litres of demineralised water and the pH was brought to pH 5.9 with 280 ml of 30% NH 4 OH.
• the crystalline mass was filtered off with the aid of filter paper and washed with demineralised water.
• the suspension was then filtered and the carbon residue was washed with 500 litres of demineralised water.
• the wet mass of about 90 litres in volume, was re-suspended in 45 litres of demineralised water and the pH was brought to pH 5.9 with 5 litres of 30%
• the solution was brought to pH 5.0 by adding 150 g of ammonium acetate.
• 150 ml of 80% acetic acid, technical grade, and 450 ml of demineralised water were added to the solution and the entirety was brought to 60°C while under agitation.
• the precipitate was filtered off with the aid of filter paper and washed with demineralised water.
• the wet mass of about 100 ml in volume, was re-suspended in 80 ml of demineralised water and the pH was brought to pH 5.9 with 30% NH 4 OH.
• the crystalline mass was filtered off with the aid of filter paper and washed with demineralised water.
• the product obtained was finally oven dried at 70°C for 3 days.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)

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• 2004
  • 2004-03-19 IT ITFI20040063 patent/ITFI20040063A1/it unknown
• 2005
  • 2005-03-18 WO PCT/EP2005/051271 patent/WO2005090306A1/en not_active Application Discontinuation
  • 2005-03-18 EP EP05740139A patent/EP1756055A1/de not_active Withdrawn

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