Paracetamol Synthesis & Solar Energy PDF

# Paracetamol Paracetamol, also known as acetaminophen, is a medication used to treat fever and mild to moderate pain. At a standard dose, paracetamol only slightly decreases body temperature. Paracetamol belongs to a group of medicines known as analgesics, or painkillers. It is used to relieve mil...

# Paracetamol Paracetamol, also known as acetaminophen, is a medication used to treat fever and mild to moderate pain. At a standard dose, paracetamol only slightly decreases body temperature. Paracetamol belongs to a group of medicines known as analgesics, or painkillers. It is used to relieve mild to moderate pain. ## Conventional Synthesis of Paracetamol: In the laboratory, paracetamol is easily prepared by nitrating phenol with sodium nitrate, separating the desired p-nitrophenol from the ortho-byproduct and reducing the nitro group with Sodium boro hydride. The resultant p-aminophenol is then acetylated with acetic anhydride in the presence of 3-4 drops of concentrated sulphuric acid as a catalyst. Replacement of active hydrogen present in phenols or amine by acetyl group. ## Green Synthesis of Paracetamol: To begin the synthesis, an electrophilic aromatic substitution on phenol with nitric acid was completed to create p-nitrophenol. P-nitrophenol was then hydrogenated using an iron catalyst to produce p-aminophenol. ## Solar Energy ### Photovoltaic cells: The device which converts solar energy into electrical energy is called photovoltaic cell, and the phenomenon is called the photovoltaic effect. ### Construction and Working of Photovoltaic cell: * **Principle:** The principle involved is the ejection of electrons from the metal surface by striking with photons of solar radiation. * **Construction:** The device consists of a p-n junction diode coated with an anti-reflective layer (TiO2). Two electrical contacts are provided, one in the form of a metallic grid at the top of the junction, and the other is a layer of silver on the bottom of the cell. The antireflective layer coated in between the metallic grids allows light to fall on the semiconductor. ### Working: The photons of solar radiations enter the n-type semiconductor, break the barrier potential, and move to the p-type semiconductor where photons knock the electrons in the p-type to form an electron hole pair. The free electrons formed will travel through the circuit from the n-type, and recombine with the holes again in the p-region. The movement of electrons from the n-type to the p-type generates electric current. The electrical energy produced from the solar cell is used for various applications. ### Advantages of PV cells: * Eco friendly * No moving parts in PV cell, hence no wear and tear * Energy conversion devices * Do not undergo corrode * Low operating cost (no fuel) * No recharging ### Disadvantages of PV cells: * Installation cost is high * Produced only during the day time * Generates only DC current * Sun light is a diffuse, i.e. it is relatively low density energy. **Diagram:** The document includes a chemical diagram illustrating the steps in the synthesis of paracetamol from phenol. It depicts the following stages: 1. Nitration of phenol to produce a mixture of ortho- and para-nitrophenol. 2. Reduction of the nitro group to form p-aminophenol. 3. Acetylation of the amino group to produce paracetamol. The diagram also includes labels for each step and the key chemical reagents involved, e.g. HNO3, NaBH4, and acetic anhydride. **Another diagram:** The document contains another diagram illustrating the working of a photovoltaic cell. The diagram labels the following components: * Anti-reflective coating * N-type Silicon * P-type Silicon * Nickel plating * Load * Electron & hole, and direction of movement The diagram clearly shows how light energy is converted to electrical energy within the photovoltaic cell through the movement of electrons from the n-type silicon to the p-type silicon, generating an electric current.