Difference Between Sulfa and Sulfur

The key difference between sulfa and sulfur is that sulfa is an antibiotic drug, whereas sulfur is a chemical element.

Sulfur is the chemical element having the symbol S and atomic number 16. It can form various chemical compounds. Sulfonamide is one such compound, which is mainly used to produce some drugs; the group of drugs produced from sulfonamide are called sulfa drugs.

CONTENTS

1. Overview and Key Difference
2. What is Sulfa 
3. What is Sulfur
4. Side by Side Comparison – Sulfa vs Sulfur in Tabular Form
5. Summary

What is Sulfa?

Sulfa is a name of a group of antibiotic drugs that has the sulfonamide functional group in their structure. These are synthetic drugs. These were the first drugs people used to treat bacterial infections in humans. However, the use of these drugs has diminished since there are other antibiotics which are more safe and effective. Furthermore, they are still in use (for urinary tract infections), but it is prescribed carefully because allergies caused by sulfa drugs is very common.

Figure 01: Structure of a Sulfonamide

Sulfa drugs are distinctive from other sulfur-containing drugs and food additives, i.e. sulfates and sulfites. These are chemically unrelated to the sulfonamide functional group. Moreover, they do not show allergy reactions shown by sulfonamide.

We can prepare sulfa drugs using the reaction of a sulfonyl chloride with ammonia. Sometimes, the sulfonamide is mixed with other antibiotics such as Trimethoprim, in order to act against some enzymes such as dihydrofolate reductase.

What is Sulfur?

Sulfur is a chemical element having the symbol S and atomic number 16. It is a nonmetal that is abundant in nature and under normal conditions, it appears as a bright yellow coloured crystalline solid. And, this solid contains octatomic molecules of sulfur, which has cycles of sulfur atoms with molecular formula S8.

Figure 02: Appearance of Naturally Occurring Sulfur

Since sulfur occurs in nature as mines, we can obtain this element via mining. Moreover, pyrite is another source of sulfur. In recent times, people have extracted elemental sulfur from salt domes. However, we now produce this element as a side product of industrial processes, i.e. oil refining.

R-S-R + 2 H2 → 2 RH + H2S (hydrodesulfurization)

3 O2 + 2 H2S → 2 SO2 + 2 H2O

SO2 + 2 H2S → 3 S + 2 H2O

What is the Difference Between Sulfa and Sulfur?

Sulfa is a name of a group of antibiotic drugs that has a sulfonamide functional group in their structure, while sulfur is a chemical element having the symbol S and atomic number 16. Hence, the key difference between sulfa and sulfur is that sulfa is an antibiotic drug, whereas sulfur is a chemical element. Moreover, sulfur occurs naturally, but sulfa is a synthetic compound, which does not occur naturally.

The below infographic shows more comparisons related to the difference between sulfa and sulfur.

Summary – Sulfa vs Sulfur

Although the terms sulfa and sulfur sounds similar, they are two different terms with several differences between them. The key difference between sulfa and sulfur is that sulfa is an antibiotic drug, whereas sulfur is a chemical element.

Reference:

1. “Sulfa Drug.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 28 June 2017, Available here.

Image Courtesy:

1. “Sulfonamide” By Edgar181 – Own work (Public Domain) via Commons Wikimedia
2. “Sulfur-sample” By Ben Mills – Own work (Public Domain) via Commons Wikimedia

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