Notes, summaries, assignments, exams, and problems for Chemistry

Organic Synthesis and Reaction Mechanisms

Malonic Ester Synthesis and Carbonyl Reactivity

Electrophiles (e+) for Malonic Ester Synthesis include epoxides, primary haloalkanes, and conjugated ketones. Esters react with 2 equivalents of irreversible nucleophiles, such as LiAlH4 and RMgBr, to yield an alcohol product. Acyl halides undergo fast hydrolysis and do not require a catalyst because the acyl halide is a better electrophile compared to carboxylic acids, and Cl- is a better leaving group than OH-.

Carbohydrate Chemistry

• Reducing sugars contain hemiacetals at the anomeric carbon.
• Alpha 1,4-linked polyglucans are known as amylose, used for energy storage in plants (digestible by humans).
• Oligosaccharides consist of 3-10 units.
• Reduction of monosaccharides

Aryl halide to diphenyl

Aryl halide reacts with sodium metal in the presence of dry ether to form diphenyl.

Name: Fittig reaction

Equations for SN1 step: tert‑butyl bromide to tert‑butyl alcohol

Equations for the step in SN1 of the conversion of tert‑butyl bromide into tert‑butyl alcohol.

IUPAC name for product from 2‑bromopentane with alcoholic KOH

IUPAC name for the major product obtained when 2‑bromopentane is heated with alcoholic KOH. Equation and name:

ANS: pent-2-ene

CH3-CH2-CH-CH3 ------> CH3-CH2-CH=CH-CH3

                     I

                   Br

NAME: elimination reaction

Why aryl halides are less reactive toward nucleophilic substitution

Aryl halides are less reactive towards nucleophilic... Continue reading "Key Organic Reactions: Fittig, Wurtz, Swarts, Kolbe‑Schmitt, Williamson" »

Hydrocarbon Classification and Properties

Chemical Categories

• Aliphatic: Chains/rings (Alkanes, Alkenes, Alkynes).
• Aromatic: Contains benzene ring.
• Derivatives: Organic. Atoms like O, N, halogens replace H.
• Inorganic: Oxides (CO₂, CO), Carbonates (CaCO₃, NaHCO₃), Carbides (CaC₂, SiC), Cyanides (NaCN).

Functional Groups

• Carboxylic Acid (-oic acid)

5. Describe what is electrodeposition, describe the different Experimental methods. Give examples. Advantages and disadvantages. It is the process of production a coating, usually Metallic, on a surface by the action of an electric current._Experimental Methods::-Electroplating: It is a plating process in which metal ions in a Solution are moved by an electric field to coat an electrode. Metallic cations From a solution are reduced on a conductive object (to form a thin layer).-Electrophoretic Deposition:Colloidal particles suspended in a liquid migrate under the Influence of an electric field (electrophoresis) and are deposited onto an Electrode._Advantages: uniform coating thicknen,easy control,high speed of Coating and high pucity._Disadvantages:

Challenges of Hydrogen Fuel Cells

The main issue with hydrogen fuel cells is that hydrogen is rarely found as a free element; it is usually found chemically combined with other elements, making it difficult to obtain.

• High cost: Due to this issue, producing, storing, and transporting hydrogen is expensive, and fuel-cell vehicles themselves cost more to make.
• Difficult storage: Hydrogen is very light and reactive, so it must be stored in strong tanks at very high pressures or extremely low temperatures, which is costly and complex. Its high reactivity means it can ignite easily, posing fire and explosion risks.
• Limited infrastructure: There are very few hydrogen refueling stations compared to gasoline or EV charging stations.
• Energy inefficiency:

Gas Chromatography Instrumentation and Analysis

1. Draw a block diagram of a GC instrument, labeling all the important components.

The components of a Gas Chromatography (GC) system follow this sequence:

• Mobile Phase Reservoir: Pressurized Helium (He) cylinder
• Sample Injector: Micro-syringe (located inside the oven)
• Stationary Phase: Column (located inside the oven)
• Detector: Thermal Conductivity Detector (TCD) or Flame Ionization Detector (FID)
• Readout: Computer system

2. What quantities are plotted on the x- and y-axes of (a) a chromatogram and (b) a calibration curve?

• a. Chromatogram: The x-axis represents time, and the y-axis represents the detector signal.
• b. Calibration Curve: The x-axis represents concentration, and the y-axis represents the peak

Fundamentals of Electrolysis

Electrolysis is the decomposition of a compound, in solution or in the molten state, brought about by the passage of electric current through it.

Definitions and Components

• An electrolyte is a substance in the molten state or as a solution in water, which allows the passage of electricity.
• A non-electrolyte is a substance in a solution that does not conduct electric current.
• A conductor is a substance which conducts or allows the passage of electricity.
• An insulator is a solid substance which does not conduct electricity.

Electrolysis Laws and Quantities

The amount of substance deposited or liberated is directly proportional to the quantity of electricity (Q) passed through the solution during electrolysis.

The moles of... Continue reading "Fundamentals of Electrolysis and Electrochemical Cells" »

Required Practical 1: Making Soluble Salts

Aim

To prepare a pure, dry sample of a soluble salt from an insoluble base, for example, making copper(II) sulfate from copper(II) oxide.

Method

1. Add excess copper(II) oxide to warm sulfuric acid and stir.
2. Filter the solution to remove the excess, unreacted base.
3. Gently evaporate the water from the filtrate to crystallize the salt.
4. Leave the solution to cool and then dry the resulting crystals.

Key Points to Remember

• Ensure excess base is used to neutralize all the acid.
• Avoid boiling the solution; use gentle heating to prevent it from spitting.
• Filter carefully to remove all unreacted solid for a pure salt solution.

Required Practical 2: Neutralization by Titration

Aim

To determine the concentration of an acid or... Continue reading "Essential Chemistry Practicals: Salts, Titration & Electrolysis" »

Atomic Structure and Electron Configuration

• Atomic number = number of protons
• Mass number = protons + neutrons
• Isotopes differ by the number of neutrons

Quantum Mechanics and Orbital Rules

• Orbitals: s (1 orbital), p (3), d (5), f (7)
• Aufbau Principle: Electrons fill the lowest energy orbitals first.
• Hund’s Rule: Electrons spread out before pairing up in orbitals.
• Pauli Exclusion Principle: No two electrons can have the same set of quantum numbers.

Photoelectron Spectroscopy (PES) Basics

• X-axis: Binding energy (values increase to the left).
• Peak height: Corresponds to the number of electrons.
• Position: Peaks farther to the left are closer to the nucleus.

Chemical

1. Emulsions: Preparation and Stability

Definition: An emulsion is a biphasic liquid dosage form in which one immiscible liquid is dispersed as fine droplets in another liquid with the aid of an emulsifying agent.

Types: Oil-in-water (O/W) and water-in-oil (W/O).

Methods of Preparation

• Dry gum method: Oil, gum, and water are generally used in a 4:2:1 ratio. Gum is triturated with oil, followed by rapid addition of water to form the primary emulsion.
• Wet gum method: Gum is first triturated with water to form mucilage; oil is then added gradually with continuous trituration.
• Bottle method: Suitable mainly for volatile or low-viscosity oils. Ingredients are placed in a bottle and shaken thoroughly.

Identification and Stability

Identification tests: Dilution... Continue reading "Pharmaceutical Formulations and Indian Pharmacopoeia Standards" »