TYPES OF REACTION…：反应类型….docVIP

TYPES OF REACTIONS1. Addition reaction: an atom (or group) is added across a double/triple bond.2. Substitution reaction: an atom (or group) replaces another atom in a molecule.3. Elimination reaction: something is removed in a molecule to create a multiple bond. (Reverse of addition reactions)4. Oxidation/Reduction: both reaction take place together, anytime one species gets oxidized (loss of electron) then another species has to get reduced (gains electron)a. Oxidation: carbon atoms form more bonds to oxygen (double bond) or less bonds to hydrogen.b. Reduction: carbon atoms form fewer bonds to oxygen (single bond) or more bonds to hydrogen.c. There are specific chemicals that will oxidize or reduce a specific type of functional group.Oxidation-Reduction: A quick overview to be revisited in electrochemistry unit. Symmetrical versus AsymmetricalReacting species:Molecules being added also:Markovnikovs Rule: a halide (F, Cl, Br, I) or OH group in an addition reaction is added to more substituted carbon atom (carbons with highest number of alkyl groups attached to it). However, the products will predominantly follow the rule however a minor amount will not.Preamble to Markovnikovs rule:321For the people that want to know why?ADDITION REACTIONS IN ALKENES AND ALKYNES1. Hydrogenation: Hydrogen is added in the presence of an appropriate catalyst (Pd, Pt or Ni).H2C=CH2 + 1 H2 CH3-CH3HC=CH + 2 H2 CH3-CH3Practical application: Used to convert vegetable oils into margarine and solid cooking fats.2. Hydrohalogenation: Addition of any HX, where X=F, Cl, Br, I.CH3CH=CH2 + HCl 3. Halogenation: Addition of F2, Br2, Cl2 or I2, this reaction is rapid, occurs at room temperature in the absence of light, and without liberation of HCl or HBr gas. (Catalyst needed for example H2O2)4. Hydration: Addition of HOH across an unsaturated bond.(CH3)2C=CH(CH3)5. No Addition reactions in BENZENE of any kind. NOT ALLOWED! Since it will result in a less stable species. SUBSTITUTION REACTIONS6. Alkanes: Substitution of an alkane with a halide is possible in the presence of a catalyst (hv).CH3-CH3 + Br27. Benzene: Benzenes chemical reactivity is comparable to alkanes. For that reason benzene molecules can only undergo substitution.8. Amines: Reaction of an alkylhalide with ammonia in the presence of a base (NaOH).ELIMINATION REACTIONS1. Cracking: used in the petroleum industry (need heat for reaction to proceed)2. Dehydration: removal of water from an alcohol(catalyst: concentrated H2SO4)Thought question of the day: Is it possible for a tertiary alcohol to undergo an elimination reaction?OXIDATION REACTIONS OF ALCOHOL Produce aldehydes or ketones (and carboxylic acids)Recall that there are 3 types of alcohol (primary, secondary, tertiary). It is important to be able to distinguish between the 3 types as it will dictate the type of product. Catalysts used in oxidation reactions include: KmnO4 or K2Cr2O7, in H2SO4.1. Oxidation of primary alcohols: (requires the presence of a catalyst)2. Oxidation of secondary alcohols: (requires catalyst)3. Oxidation of tertiary alcohols: REDUCTION REACTIONS Can be thought of as the opposite of oxidation reaction. Therefore, conversion of aldehydes or ketones or carboxylic acids to alcohol. There are several types of catalysts used in reduction reaction for example: LiAlH4 or NaBH4.1. Reduction of aldehydes to primary alcohols2. Reduction of ketones to secondary alcohols3. Reduction of carboxylic acids to primary alcohols. CONDENSATION REACTIONS Condensation reactions mean removal of a water molecule in the process of joining two molecules together.1. Reaction of alcohols to e