Chemistry 121/122

1. Chemistry 121/122 Functional groups

2. Functional Groups • In the previous chapter, the only organic compounds we looked at were hydrocarbons • There were cases where there was the presence of substituents – added groups being substituted for a hydrogen (ex. methyl (CH3) • These substituents were composed of carbon and hydrogen only • There are other substituents which may be composed of oxygen, nitrogen, sulfur, and/or phosporous

3. What is a functional group? A specific arrangement of atoms in an organic compound that is capable of characteristic chemical reactions More often than not, functional groups exist within organic compounds The symbol “R” can be used to represent the carbon chain or rings attached to the functional group

4. Organic Compounds Classified by Functional Group • Table 23.1, page 726 – it would be beneficial to memorize this… • Halocarbons • Contains a covalently bonded fluorine, chlorine, bromine or iodine (a halogen substituent) • The halogens attached are named as substituents • The name is still based on the parent chain • They can be named using IUPAC rules or given a common name

5. IUPAC Naming The IUPAC name of a halocarbon is defined as: • Identify the parent chain • Identify any substituents accordingly • Ex. CH3Cl • CH3 is methane with a hydrogen removed to accommodate the substituent “Cl” • The parent name is methane • The substituent is chlorine • The IUPAC name is chloromethane

6. Common Names • The parent chain is identified as the hydrocarbon’s alkyl group • Methyl, ethyl, and propyl… • The second part identifies the halogen with the ending of –ide. • Ex. CH3Cl – methyl chloride The names of common alkyl groups are identified in Table 23.2, page 727

8. Naming Carbon A primary carbon is identified as a carbon atom joined to an alkyl halide and one other carbon Secondary carbon is identified as one in which it is attached to an alkyl halide and two carbon atoms Tertiary carbon is that in which it is attached to an alkyl halide and three other carbon atoms

9. The Rules of Naming Alkyl Groups The prefix “iso-” is used when there is a methyl group attached to the second carbon from the unsubstituented end of the longest chain Remember, these are considered alkyl groups so their ending reflects the rule of the suffix changing to “yl” Vinyl has its own unique structure and phenyl is derived from benzene

10. Substitution Reactions • Typically, organic compounds produce slower reactions than inorganic compounds • Relatively strong covalent bonds have to be broken in order for the reaction to proceed • A common type of organic reaction is substitution • In such a reaction, one atom or group of atoms replaces another • A halogen can replace a hydrogen atom on an alkane to produce a halocarbon • Ex. R – H + X2→ R – X + HX • Sunlight or another form of UV light is the catalyst required to produce halocarbons

11. More examples of substitution reactions… Page 729

12. Addition Reactions Alkenes and alkynes can incorporate more atoms into their structure by breaking their multiple bond(s) Ex. ethene + chloride → 1,2-dichloroethane Ex. propene + hydrogen chloride → 2-chloropropane or 1-chloropropane

13. For the remainder of class… Questions 4 – 6, page 729 Section Review 23.1 Chapter 22 Wednesday Extra Help second half of lunch today