CS237258B1 - Method for analytical determination of o-nitroaniline - Google Patents
Method for analytical determination of o-nitroaniline Download PDFInfo
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- CS237258B1 CS237258B1 CS547982A CS547982A CS237258B1 CS 237258 B1 CS237258 B1 CS 237258B1 CS 547982 A CS547982 A CS 547982A CS 547982 A CS547982 A CS 547982A CS 237258 B1 CS237258 B1 CS 237258B1
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Abstract
Vynález se týká způeobu analytického stanoveni o-nitroanilinu v technickém henzofurazan-N-oxLdu, ze kterého se benzofurazan-N-oxid připravuje. Podstatou vynálezu je odmšrné bromometrické stanovení o-nitroanilinu, spočívající v reakci o-nitroanilinu s bromem za vzniku dibromderivátu o-nitroanilinu a v analytickém stanovení přebytečného bromu reakcí s jodidem draselným a v titraci odmčrným roztokem thiosulfátu sodného.The invention relates to a method for the analytical determination of o-nitroaniline in technical benzofurazan-N-oxide, from which benzofurazan-N-oxide is prepared. The essence of the invention is the volumetric bromometric determination of o-nitroaniline, consisting in the reaction of o-nitroaniline with bromine to form a dibromo derivative of o-nitroaniline and in the analytical determination of excess bromine by reaction with potassium iodide and titration with a volumetric solution of sodium thiosulfate.
Description
Vynález se týká způsobu analytického stanovení o-nitroanilinu v technickém benzofurazan-N-oxidu. o-Ritroanilin slouží k přípravě benzofurazan-N-oxidu a po reakci je přítomen jako nečistota. Benzofurazan-N-oxid je důležitým meziproduktem substituovaných chinoxalin-1,4-dioxidů, z nichž některé patří do skupiny biologicky aktivních látek, které významně stimulují růst hospodářských zvířat. Analytické hodnocení benzof urazan-N-oxidu^ s ohledem na množství nezreagovaného o-nitroanilinu v něm obsaženého, je tedy významné a hlediska průběhu syntézy benzofurazan-N-oxidu.The invention relates to a method for the analytical determination of o-nitroaniline in industrial benzofurazan N-oxide. o-Ritroaniline is used to prepare benzofurazan N-oxide and is present as an impurity after the reaction. Benzofurazan N-oxide is an important intermediate of substituted quinoxaline-1,4-dioxides, some of which belong to the group of biologically active substances that significantly stimulate the growth of livestock. Thus, the analytical evaluation of benzofurazan N-oxide with respect to the amount of unreacted o-nitroaniline contained therein is significant and in terms of the synthesis of benzofurazan N-oxide.
o-#itroanilin lze stanovit např. polarograficky, titanometricky nebo bromometričky.The o-itroaniline can be determined, for example, by polarography, titanometry or bromometry.
Způsob stanovení o-nitroanilinu podle vynálezu spočívá v reak ci o-nitroanilinu s bromem za vzniku dibromderivátu o-nitroanilinu a v analytickém stanovení přebytku bromu reakcí s jodidem draselným a titraci odměrným roztokem thiosulfátem. Za uvedených podmínek podle vynálezu nereaguje s bromem benzofurazan-N-oxid, takže je možno stanovit o-nitroanilin ve směsi s benzofurazan-N-oxidem prakticky v libovolném poměru. Stanovení o-nitroanilinu podle vynálezu umožňuje sledovat průběh syntézy benzofurazan-N-oxidu a optimalizaci procesu tak, aby obsah zbytkového o-nitroanilinu zůstával v únosných mezích.The method for the determination of o-nitroaniline according to the invention consists in reacting o-nitroaniline with bromine to form the dibromo derivative of o-nitroaniline, and in analytical determination of excess bromine by reaction with potassium iodide and titration with volumetric thiosulfate solution. Under these conditions, the benzofurazan N-oxide does not react with bromine, so that the o-nitroaniline can be determined in a mixture with the benzofurazan N-oxide in virtually any ratio. The determination of o-nitroaniline according to the invention makes it possible to monitor the progress of the synthesis of benzofurazan N-oxide and to optimize the process so that the residual o-nitroaniline content remains within acceptable limits.
Následující příklad provedení způsob podle vynálezu dokládá, ale nikterak neomezuje.The following exemplary embodiment illustrates the method of the invention but does not limit it in any way.
g vzorku technického benzofurazan-N-oxidu se v 250 ml jodometrické baňce rozpustí ve 20 ml octové kyseliny, přidá se 5 ml 20/ó chlorovodíkové kyseliny, 5 ml 2C% bromidu draselného a 10,00 ml odměrného roztoku bromičnanu draselného KBrO^ (c = 0,0166 mol/ /1)· Baňka se zazátkuje a ponechá 30 min. v temnu. Poté se přidá 1 g jodidu draselného, rozpuštěného asi v 5 ml vody, směs se ponechá 5 min,v temnu, potom ee přidá asi 100 ml vody a titruje od237 258 měrným roztokem thiosulfátu sodného Na^,^ (c = 0,1 mol/l) ke konci na škrob jako indikátor (spotřeba b). Stejným způsobem se provede slepý pokus (spotřeba a). Rozdíl (a - b) odpovídá množství o-nitroanilinu.a sample of technical benzofurazan N-oxide in a 250 ml iodometric flask is dissolved in 20 ml of acetic acid, 5 ml of 20% hydrochloric acid, 5 ml of 2% potassium bromide and 10.00 ml of standard potassium bromate solution KBrO4 (c) are added. = 0.0166 mol / l) Stopper the flask and leave for 30 min. in the dark. Thereafter, 1 g of potassium iodide dissolved in about 5 ml of water is added, the mixture is left in the dark for 5 min, then about 100 ml of water are added and titrated from a solution of sodium 258 thiosulfate with Na2SO4 (c = 0.1 mol). / l) end to starch as an indicator (consumption b). Carry out a blank test (consumption a) in the same manner. The difference (a - b) corresponds to the amount of o-nitroaniline.
ml odměrného roztoku thiosulfátu sodného Na2S20^ (c = =0,1 mol/l) odpovídá 3,453 mg o-nitroanilinu.ml of a standard solution of sodium thiosulphate Na 2 S 2 O 2 (c = 0.1 mol / l) corresponds to 3.453 mg o-nitroaniline.
Výsledek se popřípadě přepočte na bezvodou sloučeninu, přičemž vodu je možno stanovit metodou K. Fischera. Při obsahu o-nit roanilinu 0,1 t# 1,0 %<íwdnota směrodatné standardní odchylky ( & max. 0,023.If necessary, the result is converted to the anhydrous compound, the water being determined by the K. Fischer method. With a 0.1% Roaniline O-nit content of 1.0% < standard deviation (& max. 0.023.
Claims (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CS547982A CS237258B1 (en) | 1981-08-04 | 1981-08-04 | Method for analytical determination of o-nitroaniline |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CS547982A CS237258B1 (en) | 1981-08-04 | 1981-08-04 | Method for analytical determination of o-nitroaniline |
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| Publication Number | Publication Date |
|---|---|
| CS237258B1 true CS237258B1 (en) | 1985-07-16 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
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| CS547982A CS237258B1 (en) | 1981-08-04 | 1981-08-04 | Method for analytical determination of o-nitroaniline |
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| CS (1) | CS237258B1 (en) |
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1981
- 1981-08-04 CS CS547982A patent/CS237258B1/en unknown
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