Indigo, molecular formula CeightHfiveNOtwo, is an orange red single prism crystal.Easily soluble in hot ethanol, slightly soluble in ether, soluble in hot water, benzene, acetone, soluble in alkali metal oxyhydrogen oxides.
The product is used as an intermediate of dyes and medicine, and is used for the production of drugs such as cinclofen and dye disperse yellow E-3G;In chemical analysis, it is a reagent for determination of cuprous ion, mercaptan, thiophene, and urine blue mother.
Melting point (º C): 203.5 ℃ (partial sublimation)
Solubility: easily soluble in hot ethanol, slightly soluble in ether, soluble in hot water, benzene, acetone, soluble in alkali metal oxyhydrogen oxides.[1]
11. Determine the number of atomic structure centers: 0
12. Number of uncertain atomic structure centers: 0
13. Determine the number of chemical bond structural centers: 0
14. Number of indeterminate chemical bond structure centers: 0
15. Number of covalent bond units: 1[1]
Properties and stability
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Soluble in alkali metalshydroxideIt is purple and turns yellow after being placed.It reacts with amino acids and amines to show various colors.[1]
Storage method
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Store in a cool and sealed place.[2]
synthetic method
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fromIndophenolorindigoIt is prepared by oxidation.Indigo was first developed by French chemistsAuguste LaurentSeparate.In 1878,Adolf von Baeyer Finished indigototal synthesis。In 1880, Bayer developed fromO-nitrocinnamic acidThe method of synthesizing indigo.In 1883, fromO-NitrobenzaldehydeThe method of synthesizing indigo was patented by Bayer.Since then, the method of synthesizing indigo from indigo has gradually replaced the method of extracting indigo from plants and become the main source of indigo.
1 First anilineTrichloroacetaldehydeOxime condensation to oxime groupAcetanilideAnd then cyclization and hydrolysis to obtain indigo red.
2. Put sodium carbonateSodium nitrite, acetic acid, ice and water are mixed and dissolved, and then mixedsulfur dioxideWhen the gas reaches the ph value of 1, the control temperature shall not exceed 10 ℃ during the process.After the reaction, steam is introduced to raise the temperature above 30 ℃.Add trichloroacetaldehyde and anhydrous sodium carbonate into the obtained sodium hydroxysulfamate, fully stir to dissolve, then add aniline, steam, heat to boiling for 2-3 min, stand for 1~1.5h, cool to complete crystallization, filter and dry.The obtained isonitroacetanilide is added into concentrated sulfuric acid at 50 ℃ in batches. At the same time, it is stirred fully and cooled indirectly with cold water to keep the temperature between 60 and 75 ℃. After the addition of isonitroacetanilide, it is heated to 80 ℃. After 10 to 15min, the reaction solution is poured into cold water, left to stand, crystallized completely, filtered, washed and crystallized to neutral, and the obtained product is crude.The crude product is precipitated by acid and alkali, and recrystallized by ethanol to obtain reagent 2,3-dioneindene.
3. Preparation method:
Add 130g (0.5mol) of indigo and 400mL of water into a 2L reaction bottle equipped with a stirrer, a thermometer and a drip funnel, and mix them to form a uniform suspension.joinSodium dichromate175g (0.5mol) is dissolved in 200mL water to form a solution, and then 6.5g nitrobenzene is added.Cool the ice water bath to about 5 ℃, drop 285g of 63% sulfuric acid, control the reaction temperature between 0~10 ℃, and add ① in about 7~8h.It was left overnight and then heated to 65 ℃ for 1.5h.Cool to room temperature and filter.Discard the water layer (green), add the filter cake into 1300mL of water, heat it to 50 ℃, and add sodium hydroxide aqueous solution until it becomes alkaline.Filter and recover 10g of unreacted indigo.The filtrate is decolorized by activated carbon at 80 ℃, acidified with hydrochloric acid to PH3-4, and bright orange crystals are separated.Cool for 24h, filter by suction, wash with water until neutral, dry at 100 ℃, and obtain indigo. ②105g, yield 77% (calculated according to the actual indigo participating in the reaction), mp199-201 ℃.Note: ① In the process of adding sulfuric acid, the reactant changes from blue to dark brown.After adding sulfuric acid, the reaction system is acidic. ②It can also be prepared by oxidizing indigo with dichromate in nitric acid.[1-2]
purpose
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1. The product is used as an intermediate of dyes and medicine, and is used to produce medicine cinchondrin and dye disperse yellow E-3G;In chemical analysis, it is a reagent for determination of cuprous ion, mercaptan, thiophene, and urine blue mother.
2. It is used as a reagent for the determination of amino acids and amines by thin-layer analysis or low chromatography.It is also used to determine cuprous, mercaptan, thiophene, and dye synthesis.[2]
Cut off the ignition source.Wear self-contained breathing apparatus and general fire protection clothing.Leak stoppage under the condition of ensuring safety.Water spray mist can reduce evaporation.Mixed absorption with sand or other incombustible adsorbent.Then it is transported to an open place for burial, evaporation or incineration.In case of a large amount of leakage, the dike shall be used to collect it, and then it shall be collected, transferred, recycled or discarded after harmless treatment.
2、 Protective measures
Respiratory system protection: When the concentration in the air is high, you should wear a gas mask.In case of emergency rescue or evacuation, it is recommended to wear self-contained breathing apparatus.
Eye protection: wear chemical safety goggles.
Body protection: Wear anti-static work clothes.
Hand protection: wear protective gloves.
Others: Smoking is strictly prohibited at the work site.Avoid long-term repeated contact.
3、 First aid measures
Skin contact: Take off the contaminated clothes and wash thoroughly with soap water and clean water.
Eye contact: immediately open the upper and lower eyelids and flush with flowing water for 15 minutes.Get medical attention.
Inhalation: leave the site to fresh air.dyspneaGive oxygen.When breathing stops, perform artificial respiration immediately.Get medical attention.
Ingestion: Rinse the mouth with water, drink enough warm water, induce vomiting, and seek medical advice immediately.[3]
