Introduction to Para-Aminobenzoic Acid
Para aminobenzoic acid is also known as aminobenzoic acid or 4-aminobenzoic acid. It is considered a growth factor in several microorganisms. For example, it is used in the synthesis of folic acid in bacteria. Folic acid is important in the synthesis of bacteria. Therefore, the drug sulfanilamide is generally administered during bacterial infection since it targets the process of bacterial utilization of Para aminobenzoic acid during folic acid synthesis in these organisms.
However, vertebrates do not synthesize their own folic acid and rather take it as a nutritional supplement. Therefore, PABA benzoic acid is not used for DNA synthesis in vertebrates. However, it has other applications for vertebrates. For example, it is an essential component in Brewer’s yeast, used to make beer. Moreover, it is an active ingredient in different sunscreen lotions as it can act as a screen against harmful ultraviolet radiation.
Chemical Properties of Para Aminobenzoic Acid
Para aminobenzoic acid is also known as 4-aminobenzoic acid. It is so called since the functional group is attached to the fourth carbon in the benzene ring. Since this carbon is present in the para position, it is also called para aminobenzoic acid. Because of the benzene ring, Para aminobenzoic acid is considered an organic compound.
The formula for Para aminobenzoic acid is H2NC6H4CO2H. It is a white solid compound. However, you might find that the commercially available Para aminobenzoic acid is grey in color. The organic compound is slightly soluble in water. It has carboxyl and amino groups attached to the benzene ring.
Chemical Synthesis of Para Aminobenzoic Acid
In industries, Para aminobenzoic acid is prepared by two routes. In one of the processes, terephthalic acid is used. Monoamide is produced from terephthalic acid. Hoffman degradation of this monoamide results in the formation of Para aminobenzoic acid.
In another process, 4-nitrobenzoic acid is reduced to form Para aminobenzoic acid. This reaction takes place in a controlled manner. Para aminobenzoic acid can also be obtained from different food sources like Brewer’s yeast, liver, unfiltered beer, molasses, mushrooms, whole grains, and animal kidneys.
Use of Para Aminobenzoic Acid in DNA Synthesis
Para aminobenzoic acid is one of the chief constituents in the process of DNA synthesis in different organisms like bacteria, fungi, and plants. Even E.coli, the bacteria found in the human intestine, can produce Para aminobenzoic acid. The process of DNA synthesis using Para aminobenzoic acid is given below.
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Tetrahydrofolate synthesis pathway
Plants can produce PABA and folic acid in their chloroplast. However, humans cannot produce Para aminobenzoic acid in their cells. They lack the enzyme required for folic acid synthesis. Therefore, they require Para aminobenzoic acid as a food supplement, like green leafy vegetables.
Para aminobenzoic acid was once considered a vitamin for humans. It was termed Vitamin Bx. However, it is no longer considered a vitamin since the microbiome in the human intestine can produce Para aminobenzoic acid.
Para Aminobenzoic Acid Uses in the Medical Field
Since Para aminobenzoic acid is an essential component in the process of DNA synthesis in several bacteria, targeting this process can be an essential step in preventing bacterial growth following infection. Sulfanilamide drugs are designed to target this process so that the bacteria cannot synthesize their DNA.
The potassium salt of this drug is also used against several fibrotic skin disorders like Peyronie’s disease. The commercial name of this compound is called Potaba. If any patient suffers from irritable bowel syndrome, Para aminobenzoic acid can also be used to treat gastrointestinal symptoms. It is also used for determining urinary nitrogen, potassium, and sodium levels. These are some of the prominent para aminobenzoic acid uses.
PABA Supplements For Nutritional Purposes
Till now, there are no known problems associated with Para aminobenzoic acid deficiency in humans. However, people who lack colonic bacteria can get affected by such a deficiency, requiring a PABA supplement. These PABA supplements can help them in the growth of new bacterial colonies in their intestine.
Many companies have claimed that Para benzoic acid has several nutritional values. It can be used as a supplement to treat depression, fatigue, weeping eczema, irritability, scleroderma, pigment loss from the skin in patches, and premature grey hair. Moreover, as stated earlier, it can block ultraviolet radiations and be used as an essential component of different sunscreen lotions. You can search for more Para aminobenzoic acid using keywords like ‘Para aminobenzoic acid Adalah.’
FAQs on Para-Aminobenzoic Acid
1. What is Para-Aminobenzoic Acid (PABA) and what does its chemical structure signify?
Para-Aminobenzoic Acid, commonly known as PABA or 4-aminobenzoic acid, is an organic compound with the chemical formula H₂NC₆H₄CO₂H. Its structure consists of a benzene ring with two functional groups attached at opposite ends: an amino group (-NH₂) and a carboxylic acid group (-COOH). The term 'para' indicates that these groups are in the 1 and 4 positions on the ring, which is a key feature of its chemical identity.
2. What is the primary biological importance of PABA in microorganisms?
The primary biological role of PABA in organisms like bacteria, fungi, and plants is its function as a crucial intermediate in the synthesis of folic acid (Vitamin B9). These organisms use PABA to produce dihydrofolic acid, a precursor to tetrahydrofolate, which is essential for synthesising the building blocks of DNA and RNA (purines and pyrimidines). This pathway is vital for their growth and reproduction.
3. What are the main industrial methods for synthesising Para-Aminobenzoic Acid?
In industrial settings, Para-Aminobenzoic Acid is primarily manufactured through two main chemical routes:
- Reduction of 4-nitrobenzoic acid: The nitro group (-NO₂) on 4-nitrobenzoic acid is reduced to an amino group (-NH₂) using reagents like tin and hydrochloric acid (Sn/HCl) or through catalytic hydrogenation.
- Hofmann degradation: This process starts with terephthalic acid, which is converted to its monoamide. The subsequent Hofmann degradation of this amide yields PABA.
4. What are some key applications of PABA in medicine and commercial products?
Para-Aminobenzoic Acid has several important applications, including:
- Antibacterial Drug Action: It is central to understanding how sulfa drugs work, as they block PABA utilisation in bacteria.
- Medical Treatments: The potassium salt of PABA, known as Potaba, is used as a prescription drug to treat fibrotic skin disorders like Peyronie's disease.
- Sunscreen: Historically, it was a major ingredient in sunscreens for its ability to absorb UV-B radiation, though its use has declined.
- Dietary Supplements: It is sometimes included in supplements claiming to support skin and hair health, such as preventing premature grey hair.
5. How do sulfa drugs like sulfanilamide use the PABA pathway to stop bacterial infections?
Sulfa drugs function as competitive inhibitors in bacteria. Their molecular structure is very similar to PABA, allowing them to bind to the active site of the bacterial enzyme (dihydropteroate synthetase) responsible for converting PABA into folic acid. By blocking this enzyme, they halt the production of essential folic acid, which in turn stops bacterial DNA synthesis and prevents the bacteria from multiplying. This mechanism is effective because humans are unaffected, as we obtain folic acid from our diet and do not use this pathway.
6. Why is Para-Aminobenzoic Acid no longer classified as an essential vitamin for humans?
PABA was once referred to as Vitamin Bx, but it is no longer considered a true vitamin for humans. An essential vitamin is a compound that the body cannot produce in sufficient quantities and must be obtained from the diet. Humans do not need to consume PABA because the beneficial bacteria (microbiome) living in our intestines are capable of synthesising it. Therefore, it does not meet the criteria of an essential nutrient for humans.
7. Why is PABA not commonly used in modern sunscreen formulations anymore?
Although PABA is an effective UV-B absorber, its use in sunscreens has significantly decreased primarily because it was found to cause a high rate of allergic reactions and skin photosensitivity in a notable percentage of users. To improve product safety and reduce the risk of skin irritation, cosmetic companies have largely replaced PABA with newer, more stable, and less allergenic UV-filtering compounds in modern sunscreen formulations.
8. As per the CBSE syllabus, how can Para-Aminobenzoic Acid be prepared from 4-nitrobenzoic acid?
The preparation of Para-Aminobenzoic Acid from 4-nitrobenzoic acid is a classic example of the reduction of a nitro compound, a key reaction in the Amines chapter of the NCERT syllabus. The nitro group (-NO₂) is converted into an amino group (-NH₂) by using a reducing agent such as tin in the presence of concentrated hydrochloric acid (Sn/HCl) or iron filings and HCl (Fe/HCl). The overall reaction is: HOC₆H₄NO₂ + 6[H] → H₂NC₆H₄CO₂H + 2H₂O.
