If the excess acetic anhydride is not removed in the reaction vessel an unwanted reaction will occur. The acetic anhydride will react causing esterification.
http://www.cerlabs.com/experiments/1053497774X.pdf follow this link to a pdf file this gives the whole information of synthesis of paracetamol from 4-aminophenol and acetic anhydride.
Adding a small amount of acetic anhydride helps to facilitate the acetylation reaction with aniline, leading to the formation of acetanilide. The acetic anhydride serves as an acetylating agent that transfers an acetyl group to the amine group of aniline, resulting in the desired product. The use of an excess of acetic anhydride is avoided to prevent side reactions and to optimize the yield of acetanilide.
Excess acetic acid can be removed from the reaction mixture prior to distillation in Fischer Esterification by neutralization with a base such as sodium carbonate. The sodium acetate formed is water soluble and can be removed by washing with water, leaving behind the ester product.
Esterification of an acetic acid with isopentyl alcohol can can be used to prepare isopentyl acetate because the equilibria would not favor the formation of the ester, so equilibira will shift to the right IF we use excess amount of one of the reagents (acetic acid). We used large amounts of acetic acid because it's less expensive and it's easier to remove from a reaction mixture than isopropyl alcohol.
Trichloroacetic acid (TCA) can be obtained by reacting acetic acid with chlorine in the presence of a catalyst such as sulfuric acid or phosphorus pentachloride. The reaction involves substitution of three chlorine atoms for three hydrogen atoms on the acetic acid molecule. The reaction is typically conducted under controlled conditions due to the corrosive nature of TCA.
The reaction is: (CH3CO)2O + H2O = 2 CH3COOH
http://www.cerlabs.com/experiments/1053497774X.pdf follow this link to a pdf file this gives the whole information of synthesis of paracetamol from 4-aminophenol and acetic anhydride.
Adding a small amount of acetic anhydride helps to facilitate the acetylation reaction with aniline, leading to the formation of acetanilide. The acetic anhydride serves as an acetylating agent that transfers an acetyl group to the amine group of aniline, resulting in the desired product. The use of an excess of acetic anhydride is avoided to prevent side reactions and to optimize the yield of acetanilide.
Excess acetic acid can be removed from the reaction mixture prior to distillation in Fischer Esterification by neutralization with a base such as sodium carbonate. The sodium acetate formed is water soluble and can be removed by washing with water, leaving behind the ester product.
Esterification of an acetic acid with isopentyl alcohol can can be used to prepare isopentyl acetate because the equilibria would not favor the formation of the ester, so equilibira will shift to the right IF we use excess amount of one of the reagents (acetic acid). We used large amounts of acetic acid because it's less expensive and it's easier to remove from a reaction mixture than isopropyl alcohol.
Trichloroacetic acid (TCA) can be obtained by reacting acetic acid with chlorine in the presence of a catalyst such as sulfuric acid or phosphorus pentachloride. The reaction involves substitution of three chlorine atoms for three hydrogen atoms on the acetic acid molecule. The reaction is typically conducted under controlled conditions due to the corrosive nature of TCA.
This reaction will not proceed, as the equilibrium is far to the left. In order to synthesize acetylsalicylic acid, one must use acetic anhydrate, and the reaction forms acetic acid instead of water.
Since salicylic acid is being reacted with excess acetic anhydride, salicylic acid is the limiting reactant of the reaction. The balanced equation of the reaction of salicylic acid and acetic anhydride indicates that their is a 1:1:1:1 ratio between every reactant and product. Based on this, it can be concluded that the moles of salicylic acid, if reacted entirely, will yield an equivalent amount of moles of aspirin. To find the theoretical yield, you must know the molecular weight of aspirin and salicylic acid. First, the amount of moles of salicylic acid must be calculated by dividing the gram amount of salicylic acid, which is 85 grams, and dividing it by its molecular weight, which is 138.12 grams per mole.85.0/138.12= 0.615 moles of salicylic acidThis is the mole amount of salicylic acid as well as the theoretical mole amount of aspirin. To convert the mole amount of aspirin into grams, this figure be multiplied by the molecular weight of aspirin, which is 180.15980.615 x 180.1598 = 111 grams of aspirin (when rounded to 3 significant figures)
When sodium hydroxide is added to acetic acid, a neutralization reaction occurs, resulting in the formation of sodium acetate and water. This reaction also releases heat. Additionally, the resulting solution will be basic due to the presence of excess hydroxide ions.
With 1,5 g of salicylic acid you can obtain theoretically 1,96 g aspirin (acetylsalicylic acid); but in the laboratory (or industry) I remember that the true yield of reaction is a little more than 90 %.
An acid-base reaction that leaves no excess H+ or OH-
An acid-base reaction that leaves no excess H+ or OH-