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FUNCTIONAL GROUPS

FUNCTIONAL GROUPS. ORGANIC HALIDES. Properties. Halogen makes the molecule more polar, increasing strength of the intermolecular forces Higher boiling points than their corresponding hydrocarbons More soluble in polar solvents Molecules with more halogens are more polar.

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FUNCTIONAL GROUPS

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  1. FUNCTIONAL GROUPS

  2. ORGANIC HALIDES Properties • Halogen makes the molecule more polar, increasing strength of the intermolecular forces • Higher boiling points than their corresponding hydrocarbons • More soluble in polar solvents • Molecules with more halogens are more polar

  3. Preparing Organic Halides Recall:Substitution reaction produce halides in alkanes and aromatic hydrocarbons

  4. Preparing Organic Halides Recall: alkyl halides are produced in halogenation reactions (addition) with alkenes/alkynes

  5. Elimination Reactions • Preparing alkenes from alkyl halides • Most common method of preparing alkenes • Alkyl halides can eliminate a hydrogen and a halide ion from adjacent carbon atoms forming a double bond. • Presence of a hydroxide ion is required

  6. ALCOHOLS • Organic compounds containing a hydroxyl group -OH • E.g. ethanol, cholesterol, retinol (vitamin A) Naming: • -ol suffix e.g. methane + OH = methanol

  7. Polyalcohols • Alcohols containing more than one -OH group • -diol, -triol suffix • Or hydroxy prefix 1,2-dihydroxyethane 1,2,3-trihydroxypropane

  8. Properties of Alcohols • More polar and can hydrogen bond • Higher boiling points • More soluble in polar solvents • Long-chain alcohols are nonpolar (hydrocarbon portion) and polar (-OH) • Ideal solvents in organic reactions because they will dissolve both polar and nonpolar compounds

  9. REACTIONS INVOLVING ALCOHOLS Hydration Reactions (Addition) (Formation of Alcohol) • Alkene + water --> alcohol • Follows Markovnikov’s rule Combustion of Alcohols

  10. Elimination Reactions Dehydration (Condensation) Reactions: • Under certain conditions alcohols can decompose to produce alkenes and water • A catalyst (sulfuric acid) removes a hydrogen atom and a hydroxyl group from neighbouring carbons • Resulting in C=C and H2O

  11. ETHERS • Molecules with C-O-C group • More polar than hydrocarbons • But, unlike alcohols, ethers cannot hydrogen bond • Naming: • Add oxy to the prefix of the smaller hydrocarbon group and join it to the alkane name of the larger hydrocarbon group • E.g. CH3-O-C2H5 is methoxyethane

  12. Condensation Reactions (Formation of Ethers) • When two alcohols combine, an ether and water are formed

  13. ALDEHYDES AND KETONES Ketone: Molecule with a carbonyl group (C=O) between two carbon atoms. Alkane name with -one suffix Aldehyde: Molecule with a carbonyl group (C=O) on a terminal carbon. Alkane name with -al suffix

  14. Properties of Aldehydes and Ketones • Polar but no Hydrogen Bonding • Lower boiling point and less soluble in water than alcohols (no -OH) • More polar than hydrocarbons (higher boiling points and more soluble) • Good solvents (both polar and nonpolar)

  15. Oxidation Reactions • Alcohol + an oxidizing agent (removes electrons) to form an aldehyde or ketone and water • The oxidizing agent removes two H-atoms (one from the -OH group and one from the adjacent carbon) resulting in C=O and H2O

  16. No available H-atom Oxidizing agent

  17. Hydrogenation Reactions • The C=O double bond can undergo an addition reaction with hydrogen to form an -OH group. • Aldehydes always produce 1˚ alcohols • Ketones always produce 2˚ alcohols

  18. CARBOXYLIC ACIDS • Molecules with a carboxyl group -COOH • E.g. lactic acid, citric acid • NAMING: • Alkane name with -oicacid • E.g. methanoic acid

  19. Properties of Carboxylic Acids • Polar • Can hydrogen bond • Similar properties to alcohols (smaller members are soluble in water, larger members are insoluble) • pH < 7 (H-atom in -OH group)

  20. Oxidation Reactions Recall: A 1˚ alcohol can be oxidized to form an aldehyde. An aldehyde can be further oxidized to form a carboxylic acid A ketone cannot be oxidized because there is no free H-atom

  21. Oxidation Reaction

  22. ESTERS • NAMING: • 1st name is the part single bonded to only 1 Oxygen (the part that was originally the alcohol)  it gets named like a side chain with the ending ‘-yl’ • 2nd name is the part double bonded to the Oxygen  it is named with the ending ‘-oate’

  23. EXAMPLES

  24. Esterfication(Formation of Esters) Recall: acid + base --> salt + water (neutralization reaction) Carboxylic acid + alcohol --> ester + water Properties of Esters • Similar to carboxylic acids, but lacking -OH group • Esters are less polar (less soluble in water), lower boiling points (no H-bonds) • Not acidic • Many have characteristic scents

  25. AMINES • An ammonia molecule in which one or more H-atoms are substituted by alkyl or aromatic groups Naming: • Amino + alkane name OR • Alkyl group + amine

  26. Naming 2˚ and 3˚ Amines • N- prefix used for the substituted groups on the nitrogen atom • Alkyl groups are listed alphabetically N,N-dimethyl-2-aminopropane

  27. Properties of Amines • N-C, and N-H polar bonds • H-bonding occurs but N-H is less polar than O-H

  28. Alkyl halide + 1˚ amine --> 2˚ amine + HX • Alkyl halide + 2˚ amine --> 3˚ amine + HX Synthesizing Amines from Alkyl Halides • Alkyl halide + ammonia --> 1˚ amine + HX

  29. Synthesizing Amines from Alkyl Halides

  30. AMIDES • Similar to esters, except N instead of O Recall: Carboxylic acids + alcohols --> esters + water Carboxylic acids + ammonia/1˚/2˚ amines--> amides + water

  31. Naming Amides • 1st part is the name is from the amine • 2nd part is the ending of the acid name changed from -oic to -amide • Alphabetical order with N- groups N-ethyl propanamide

  32. Summary

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