Skip to main content

What is the equation for calculating percentage yield with aspirin made with salicylic acid and pyridine?

Aspirin or acetylsalicylic acid is made by reacting salicylic acid with a base. There are various ways to synthesize aspirin (but the method of calculating the percent yield is the same for any chemical reaction). One way is to react salicylic acid with acetic anhydride, a base, in the presence of pyridine as a catalayst. In brief, pyridine hydrogen bonds with the phenolic hydrogen, thus activating it for acetylation.  The chemical equation for this is as follows:

`2C_7H_6O_3 + C_4H_6O_3 -> 2C_9H_8O_4 + H_2O ` , where the chemical species are salicylic acid, acetic anhydride, aspirin, and water, respectively. Note that pyridine is not in the balanced chemical equation since it only acts as a catalyst and is not consumed in the chemical reaction.


Percent yield is a parameter used to determine efficiency of chemical reactions. It is very important in industrial and pharmaceutical chemical industries - in calculating cost-benefit of a reaction and synthesis of a drug, for instance, or in organic chemistry labs in determining the efficiency of their synthesis route. Percent yield is calculated as follows:


%yield = (actual yield / theoretical yield) x 100.


Actual yield is the amount of product empirically produced after conducting the reaction. Meanwhile, theoretical yield is the yield obtained by stoichiometrically calculating the amount to be produced using the chemical equation using the amount of starting materials provided.


------ An example


For instance, if we start with 100 g of salysilic acid (SA for simplicity, and I'll use A for aspirin) (and enough acetic anhydride), we can calculate the expected amount of aspirin produced using the chemical equation above.


mol aspirin produced = 100g SA / 138.121g/mol SA * 2 mol A / 2 mol SA = 0.76 mol of aspirin produced.


This is equivalent to 0.76 mol * 180.157g/mol = 137 g of aspirin produced theoretically.


If you performed the same reaction in a lab and was able to retrieve 100 g of aspirin, your theoretical yield will be: 100/137 * 100 = 73%.

Comments

Post a Comment

Popular posts from this blog

What are some external and internal conflicts that Montag has in Fahrenheit 451?

 Montag, the protagonist of Fahrenheit 451, faces both external and internal conflicts throughout the novel. Some examples of these conflicts are: External Conflicts: Conflict with the society: Montag lives in a society that prohibits books and critical thinking. He faces opposition from the government and the people who enforce this law. Montag struggles to come to terms with the fact that his society is based on censorship and control. Conflict with his wife: Montag's wife, Mildred, is completely absorbed in the shallow and meaningless entertainment provided by the government. Montag's growing dissatisfaction with his marriage adds to his external conflict. Conflict with the fire captain: Montag's superior, Captain Beatty, is the personification of the oppressive regime that Montag is fighting against. Montag's struggle against Beatty represents his external conflict with the government. Internal Conflicts: Conflict with his own beliefs: Montag, at the beginning of th...
Post a Comment
Read more

In A People's History of the United States, why does Howard Zinn feel that Wilson made a flimsy argument for entering World War I?

"War is the health of the state," the radical writer Randolph Bourne said, in the midst of the First World War. Indeed, as the nations of Europe went to war in 1914, the governments flourished, patriotism bloomed, class struggle was stilled, and young men died in frightful numbers on the battlefields-often for a hundred yards of land, a line of trenches. -- Chapter 14, Page 350, A People's History of the United States Howard Zinn outlines his arguments for why World War I was fought in the opening paragraph of Chapter 14 (referenced above). The nationalism that was created by the Great War benefited the elite political and financial leadership of the various countries involved. Socialism, which was gaining momentum in Europe, as was class struggle, took a backseat to mobilizing for war. Zinn believes that World War I was fought for the gain of the industrial capitalists of Europe in a competition for capital and resources. He states that humanity itself was punished by t...
Post a Comment
Read more

Where did Atticus take the light and extension cord in To Kill a Mockingbird?

Atticus brings the light to the courthouse jail so that he can protect Tom Robinson.  Atticus learns that Tom Robinson, his client, is in danger.  A group of white men want to prevent the trial and lynch Robinson. He is warned by a small group of men that appear at his house.  He refuses to back down.  Atticus knows that the Cunninghams will target his client, so he plans to sit up all night with... Atticus brings the light to the courthouse jail so that he can protect Tom Robinson.  Atticus learns that Tom Robinson, his client, is in danger.  A group of white men want to prevent the trial and lynch Robinson. He is warned by a small group of men that appear at his house.  He refuses to back down.  Atticus knows that the Cunninghams will target his client, so he plans to sit up all night with Jim if that’s what it takes to protect him.  Atticus tells the men that he will make sure his client gets his fair shake at the law.  “Link, that boy might go to the chair, but he’s not going till ...
Post a Comment
Read more