Chapter 25: Functonal Groups and Organic Reactions

Intro: 1. Hydrocarbon skeletons of molecules are chemically inert. Chemistry of alkanes is limited. 2. Most organic chemistry involves substituents

25.1 Functional Groups 1. Substituents contain oxygen, nitrogen, sulfur, or phosporus. 2. A functional group is a specific arrangement of atoms in an organic compound that is capable of characteristic chemical reactions. 3. "functional group chemistry"

4. Symbol R is used to represent any carbon chains or rings attached to functional group. 5. Double and triple bonds of alkenes and alkynes are chemically reactive and are considered functional groups.

25.2 Halocarbons 1. Halocarbons are a class of organic compounds containing convalently bonded flourine, chlorine, bromine, or iodine. 2. Not usually found in nature, but easily prepared. 3. Anesthetics and insecticides. 4. Name using IUPAC rules based on parent hydrocarbon.

5. Names are in 2 parts. 1st part is hydrocarbon as an alkyl group. 2nd part is halogen with -ide. Examples:

6. Halocarbons with aliphatic chain are called alkyl halides. 7. Halocarbon with arene ring are aryl halides.

8. Important: see Table 25.2 (click), page 713.Table 25.2 Iso- methyl group on carbon is second from unsubstituted end. Secondary- carbon joining alkyl group to another group is bonded to 2 other carbons. Tertiary- carbon joining alkyl group is bonded to 3 carbons. Vinyl- ethene with 1 substituent instead of H. Phenyl- benzene

9. See Table 25.3 for examples. See Table 25.4 for mass vs bp.Table Molecules held together by weak van der Waals forces called dispersion forces. Increase in halogen substitution increases mass and bp.

25.3 Substitution Reactions 1. Organic reactions are slower due to breaking of strong covalent bonds. 2. Substitution reaction is the replacement of an atom or group of atoms by another atom or group. 3. Halogen replaces hydrogen on alkane to make halocarbon: R-H + X 2 ---> R-X + HX

4. Sunlight or uv radiation is catalyst: CH 4 + Cl 2 ---> CH 3 Cl + HCl 5. Iron compounds are catalyst:

6. Halogen is replaced by hydroxide to produce alcohol and salt: R-X(halocarbon) + OH - (hydroxide) ---->R-OH(alcohol) + X - (halide ion) 7. Chemists use aqueous sodium or potassium hydroxide to produce OH ions:

25.4 Alcohols 1. Alcohols are organic compounds with an -OH group.

2. The -OH functional group in alcohols is called a hydroxyl group or hydroxy function. It is not a hydroxide ion because the oxygen is covalently bonded to carbon

3. Aliphatic alcohols can be arranged in structural categories according to number of R groups.

4. IUPAC and common names used. With continuous chains (IUPAC), drop -e and add -ol. 5. The parent alkane is longest chain that includes C attached to OH. 6. Give OH lowest possible number.

7. 2, 3, and 4 OH's are diols, triols, tetrols. 8. Compounds with more than one OH are glycols. Examples of aliphatic hydrocarbons from page 719..

9. Phenols have hydroxyl attached to aromatic ring like benzene. 10. Phenol (one OH) is parent. 11. Cresol is name for o, m, and p isomers of methylphenol.

Examples of phenol and isomers of methylphenol, page 719.

25.5 Properties of Alcohols