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What is the experimental and theoretical percent yield of synthesis of methyl orange?

What is the experimental and theoretical percent yield of synthesis of methyl orange?

Chemistry
Chemistry
10th Edition
ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Publisher:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
Chapter1: Chemical Foundations
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What is the experimental and theoretical percent yield of synthesis of methyl orange?

Introduction Methyl orange is an azo dye whose thesis can be accomplished by a diazo coupling reaction between the diazonium salt of sulfanilic acid and N,N-dimethylaniline. Since the coupling reaction is conducted in an acidic solution, the first product to form is the acid form of methyl orange, called helianthin, which is bright red. The addition of a base leads to the conversion of helianthin to its sodium salt, which is methyl orange. H H;C. CH3 OCH3 H3C OAc НОАс H,C ČH3 proton transfer H3C H3C Helianthin (red) NaOH H3C N=N -SO,Na H3C Methyl oran It is necessary to carry out the diazotization reaction in an acidic solution. However, sulfanilic acid is insoluble in acidic solutions. To overcome this problem, the sulfanilic acid is first dissolved in a basic solution: an aqueous solution of sodium carbonate- Sodium nitrite is then added to this basic solution. Finally, the solution is chilled and then acidified with hydrochloric acid. The instant the sulfanilic acid precipitates from the solution, it becomes diazotized, yielding a finely divided white precipitate of the diazonium salt of sulfanilic acid. This diazonium salt is allowed to react immediately with dimethylaniline in the solution in which it was precipitated.
Transcribed Image Text:Introduction Methyl orange is an azo dye whose thesis can be accomplished by a diazo coupling reaction between the diazonium salt of sulfanilic acid and N,N-dimethylaniline. Since the coupling reaction is conducted in an acidic solution, the first product to form is the acid form of methyl orange, called helianthin, which is bright red. The addition of a base leads to the conversion of helianthin to its sodium salt, which is methyl orange. H H;C. CH3 OCH3 H3C OAc НОАс H,C ČH3 proton transfer H3C H3C Helianthin (red) NaOH H3C N=N -SO,Na H3C Methyl oran It is necessary to carry out the diazotization reaction in an acidic solution. However, sulfanilic acid is insoluble in acidic solutions. To overcome this problem, the sulfanilic acid is first dissolved in a basic solution: an aqueous solution of sodium carbonate- Sodium nitrite is then added to this basic solution. Finally, the solution is chilled and then acidified with hydrochloric acid. The instant the sulfanilic acid precipitates from the solution, it becomes diazotized, yielding a finely divided white precipitate of the diazonium salt of sulfanilic acid. This diazonium salt is allowed to react immediately with dimethylaniline in the solution in which it was precipitated.
Running the reaction: 0.065 g of anhydrous sodium carbonate were dissolved in 5 mL water in a 25 mL Erlenmeyer flask 0.202 g of sulfanilic acid were added and the mixture was heated which caused the solids to dissolve After cooling the mixture to room temperature, 0.092 g of sodium nitrite were added while stirring The mixture was placed in an ice bath to cool it to 5 °C before 0.30 mL concentrated hydrochloric acid was added dropwise Slowly, a fine, white precipitate was formed Part 2: Running the reaction: The suspension formed in part 1 was placed in an ice-bath 0.17 mL of N,N-dimethylaniline and 0.12 mL of glacial acetic acid were placed in a 3-mL vial This solution was added dropwise to the suspension obtained in part 1 The mixture was stirred affording a red precipitate After 10 minutes, 1.5 mL of 10 % NaOH were added dropwise The mixture was stirred for 10 minutes and then the pH value was tested (pH=8-9) Product isolation: The suspension was heated to a gentle boil and 0.60 g of solid NaCl was added The solution could cool to room temperature and then be placed in an ice-bath The solid was isolated by filtration on a Buchner funnel The remaining solids were transferred using 5 mL of cold sodium chloride solution The solids and the filter paper were placed in 15 mL of boiling water to dissolve the product The mixture could cool to room temperature before placing in an ice bath (~15 minutes) The solids are isolated by vacuum filtration After allowing to dry, weigh the product Product characterization: 0.185 g of the product
Transcribed Image Text:Running the reaction: 0.065 g of anhydrous sodium carbonate were dissolved in 5 mL water in a 25 mL Erlenmeyer flask 0.202 g of sulfanilic acid were added and the mixture was heated which caused the solids to dissolve After cooling the mixture to room temperature, 0.092 g of sodium nitrite were added while stirring The mixture was placed in an ice bath to cool it to 5 °C before 0.30 mL concentrated hydrochloric acid was added dropwise Slowly, a fine, white precipitate was formed Part 2: Running the reaction: The suspension formed in part 1 was placed in an ice-bath 0.17 mL of N,N-dimethylaniline and 0.12 mL of glacial acetic acid were placed in a 3-mL vial This solution was added dropwise to the suspension obtained in part 1 The mixture was stirred affording a red precipitate After 10 minutes, 1.5 mL of 10 % NaOH were added dropwise The mixture was stirred for 10 minutes and then the pH value was tested (pH=8-9) Product isolation: The suspension was heated to a gentle boil and 0.60 g of solid NaCl was added The solution could cool to room temperature and then be placed in an ice-bath The solid was isolated by filtration on a Buchner funnel The remaining solids were transferred using 5 mL of cold sodium chloride solution The solids and the filter paper were placed in 15 mL of boiling water to dissolve the product The mixture could cool to room temperature before placing in an ice bath (~15 minutes) The solids are isolated by vacuum filtration After allowing to dry, weigh the product Product characterization: 0.185 g of the product
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