Halogenoalkanes

• Factors that affect the rate of nucleophilic substitution reactions include temperature, concentration, solvent polarity, and steric hindrance.
• Fluorine is the most electronegative element and has the highest electron affinity.
• The halogens are group VIIA (17) on the periodic table, which includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I).
• Halogenoalkanes react with reducing agents such as zinc metal or sodium because the halogen atoms act as electron acceptors.
• Halogenoalkanes undergo nucleophilic substitution reactions more readily than alkanes due to the increased electrophilicity of the carbon atoms adjacent to halogen atoms.
• Halogenoalkanes have higher melting and boiling points than alkanes of the same molecular mass due to increased intermolecular attractions.
• Chlorine is the most commonly used halogen due to its abundance and ease of use.
• Halogens are highly reactive non-metals that form compounds with other elements.
• The reaction between an alkyl halide and water is called hydrolysis.
• Acid-catalyzed hydrolysis involves protonation of the halide ion to form a more reactive species.
• Hydrolysis can be catalyzed by acids or bases.
• Alkenes can be converted into halogenoalkanes by reaction with hydrogen halides (HX) in the presence of peroxide catalysts.
• Nucleophiles can attack either side of the C-X bond in halogenoalkanes, resulting in two possible products.
• Zn + H2SO4 → ZnSO4 + H2
• In the case of halogenoalkanes, reduction removes the halogen atom to produce hydrocarbons.
• Halogens have seven valence electrons and can form one covalent bond with another atom to complete their octet.
• Halogens have high electronegativities and can form ionic compounds with metals or other elements.
• Halogens are highly reactive nonmetals with low melting points and boiling points.
• The reactivity of halogens decreases as their atomic number increases due to an increase in size and decrease in nuclear charge.
• Iodine is rarely used in organic chemistry due to its low volatility and high toxicity.
• Addition polymerization occurs when monomers containing double bonds add together to form long chains called polymers.
• The general formula for alkyl halides is R-X, where X represents a halogen atom.
• Retention occurs when nucleophilic substitution takes place at carbon atoms with trigonal planar geometry.
• In addition reactions, both atoms from the reacting molecule become part of the product.
• Fe + HNO3 → Fe(NO3)3 + NO2 + H2O
• Substitution reactions occur when there is only one carbon attached to the functional group being replaced.
• Cu + HCl → CuCl + H2
• Addition reactions involve adding two molecules together, while substitution reactions replace one atom/group with another.
• In the presence of dilute acid, the reaction proceeds via the protonated carbocation intermediate.
• Alcohols react with halogens to produce haloalcohols through substitution reactions.
• In this process, the base removes the proton from the OH group, making it a stronger nucleophile and allowing it to attack the carbon atom.
• Chlorofluorocarbons (CFCs) were once widely used as refrigerants but have been banned because they contribute to ozone depletion.
• Alkyl halides contain carbon-halogen (C-X) bonds that are polar covalent bonds.
• Chlorine gas was first prepared by Humphry Davy through electrolysis of molten sodium chloride.
• Chlorine has a lower reactivity than fluorine but still reacts vigorously with many substances.
• Chlorination reactions involve adding Cl atoms to an organic compound using chlorine gas (Cl2) or hydrochloric acid (HCl).
• Fluorine is the most reactive element known and forms only fluorides.
• Polytetrafluoroethylene (PTFE) is also known by the brand name Teflon® and has excellent heat resistance and chemical stability.
• Fluorine has a strong affinity for oxygen and forms fluorides such as CaF2 (fluorspar) and Na3AlF6 (aluminum fluoride).
• Fluorine is the most reactive element known and readily forms fluorides with all other elements except helium and neon.