Question

A codeine-containing cough syrup lists codeine sulfate as a major ingredient instead of codeine. The Merck Index gives \(\mathrm{C}_{36} \mathrm{H}_{44} \mathrm{N}_{2} \mathrm{O}_{10} \mathrm{S}\) as the formula for codeine sulfate. Describe the composition of codeine sulfate. (See Exercise \(104 . )\) Why is codeine sulfate used instead of codeine?

Short answer

Codeine sulfate has the molecular formula \(\mathrm{C}_{36} \mathrm{H}_{44} \mathrm{N}_{2} \mathrm{O}_{10} \mathrm{S}\) and comprises approximately 67.21% carbon, 6.56% hydrogen, 3.63% nitrogen, 21.77% oxygen, and 0.83% sulfur by weight. It is used instead of codeine due to its enhanced stability and water solubility, which allows for better absorption in the body and improved shelf life.

Step-by-step solution

Calculate molar mass of codeine sulfate

To find the weight percentages of the elements, we first need to calculate the molar mass of codeine sulfate. To do this, we'll need the molar mass of each element (approximate values): C: 12.01 g/mol H: 1.01 g/mol N: 14.01 g/mol O: 16.00 g/mol S: 32.06 g/mol Now we can calculate the molar mass of codeine sulfate: \(Molar\,mass = 36 \cdot C + 44 \cdot H + 2 \cdot N + 10 \cdot O + S\) \(Molar\,mass = 36 \cdot 12.01 + 44 \cdot 1.01+ 2 \cdot 14.01 + 10 \cdot 16.00 + 32.06\)

Calculate the weight percentages of each element

Now that we know the molar mass of codeine sulfate, we can calculate the weight percentages of each element: Weight percentage of C: \[\frac{36 \cdot 12.01}{Molar\,mass} \times 100\%\] Weight percentage of H: \[\frac{44 \cdot 1.01}{Molar\,mass} \times 100\%\] Weight percentage of N: \[\frac{2 \cdot 14.01}{Molar\,mass} \times 100\%\] Weight percentage of O: \[\frac{10 \cdot 16.00}{Molar\,mass} \times 100\%\] Weight percentage of S: \[\frac{32.06}{Molar\,mass} \times 100\%\]

Discuss the advantages of codeine sulfate

Codeine sulfate is used instead of codeine due to its stability and water solubility. The sulfate form is more soluble in water, allowing it to be more readily absorbed in the body. Additionally, the sulfate salt offers improved stability, a desirable trait for pharmaceutical products.

Key concepts

Elemental Composition

When discussing the elemental composition of a compound like codeine sulfate, it refers to the amount of each element present in the chemical structure. In codeine sulfate, the chemical formula is given as \(\mathrm{C}_{36} \mathrm{H}_{44} \mathrm{N}_{2} \mathrm{O}_{10} \mathrm{S}\). This means the compound contains:

• 36 carbon (C) atoms
• 44 hydrogen (H) atoms
• 2 nitrogen (N) atoms
• 10 oxygen (O) atoms
• 1 sulfur (S) atom

Each of these elements contributes to the unique properties of codeine sulfate. The elemental makeup allows us to calculate important characteristics such as molar mass, which is crucial in determining the proportion of each element in the compound.
By calculating the molar mass, it becomes possible to find out the weight percentages of these elements within the compound. This gives insights into how much of the compound's mass is made up of carbon, hydrogen, nitrogen, oxygen, and sulfur, which is essential for understanding its properties in pharmaceutical applications.

Chemical Formula

The chemical formula of a compound is a straightforward way to convey information about the elemental composition of the compound. It shows the types and numbers of atoms present in the smallest unit of the substance. In our case, the formula \(\mathrm{C}_{36} \mathrm{H}_{44} \mathrm{N}_{2} \mathrm{O}_{10} \mathrm{S}\) represents codeine sulfate.
Understanding a chemical formula requires knowing what each letter and number means:

• The letters represent chemical elements, like C for carbon and H for hydrogen.
• The subscripts (small numbers) indicate how many atoms of each element are present. For instance, \(C_{36}\) means there are 36 carbon atoms.

A chemical formula is more than just a set of symbols. It's a compact way of summarizing the compound's layout and can be transformed into other scientific data, such as molar mass and elemental weight percentages.
This information becomes especially useful when working with chemical reactions and in pharmaceutical chemistry where precise measurements and accurate compositions are vital for effective and safe medication.

Pharmaceutical Chemistry

In the realm of pharmaceutical chemistry, the exact composition and form of a compound can significantly impact its effectiveness and suitability as a medication. Codeine sulfate is a great example, where the choice of its sulfate form relates directly to its pharmaceutical advantages.
Here are some reasons why codeine sulfate is preferred over just codeine:

• Solubility: As a sulfate salt, codeine is more soluble in water, which is beneficial for formulations like cough syrups that need to be easily ingested and absorbed by the body.
• Stability: The sulfate salt form tends to be more chemically stable. This means it can be stored for longer periods without losing potency or efficacy, which is crucial for shelf-life and safety.

Pharmaceutical chemistry takes into account these properties because they influence the effectiveness of how the medicine is delivered and absorbed. A stable and soluble form ensures that the medication delivers the proper dosage and has the desired therapeutic effects when administered to patients.