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Lecture 25

Lecture 25. Amine nomenclature Basicity of amines Synthesis of amines (on board). Nomenclature of Aldehydes & Ketones: IUPAC Rules. Functional Group Suffix if highest priority group As a substituent CO 2 H carboxylic acid -oic acid -carboxy-

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Lecture 25

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  1. Lecture 25 • Amine nomenclature • Basicity of amines • Synthesis of amines (on board)

  2. Nomenclature of Aldehydes & Ketones: IUPAC Rules Functional Group Suffix if highest priority group As a substituent CO2H carboxylic acid -oic acid -carboxy- CO2R ester -oate -alkoxycarbonyl- CO2NR2 amide -amide -carbamoyl- CHO aldehyde -al -oxo- CRO ketone -one -oxo- OH alcohol -ol -hydroxy- NR2 amine -amine -amino- SH thiol -thiol -mercapto-

  3. Nomenclature of Primary Amines: IUPAC Primary Amines 1. Find the longest chain to contain the -NH2 group; this is the parent chain. 2. This parent chain’s name ends in ‘amine’ - the suffix. E.g., take alkane and convert to alkanamine. 3. Number the parent chain such that the carbon bearing the -NH2 has the lowest number possible. Give location of -NH2 group in name. 4. Give name; be sure to list substituents alphabetically and to give their location; these are the prefixes. Remember that sec-, tert-, o-, m-, p-, di-, tri-, tetra- are not considered when alphabetizing, but iso is. Name the following:

  4. Nomenclature of Primary Amines: Common Name Primary Amines If the primary amine is a simple structure, that is the carbon group is simple, then the common name is easy to determine. In the common name, the amine’s name is “alkyl amine”; two words. Name the following:

  5. Nomenclature of 2° & 3° Amines: IUPAC B. 2° & 3° Amines 1. Find the longest R group chain to contain the -NR2/-NHR group; this is the parent chain. The carbon of the parent chain that’s bound to the N gets the #1 designation. 2. This parent chain’s name ends in ‘amine’ - the suffix. E.g., take alkane and convert to alkanamine. 3. The other R groups are listed first (as the first word) and alphabetically with an “N-” in front of them to designate that the R group is bound to the nitrogen. (Similar to 2° and 3° amide nomenclature.) 4. Give name; be sure to list the parent chain substituents alphabetically and to give their location; these are the prefixes. Remember that sec-, tert-, o-, m-, p-, di-, tri-, tetra- are not considered when alphabetizing, but iso is. Name the following:

  6. Nomenclature of 2° & 3° Amines: Common Name B. 2° & 3° Amines 1. Identify the R groups bound to nitrogen. 2. List the alkyl groups alphabetically. Remember not to alphabetize di-, tri-, sec-, or -tert. 3. End the name with the word “amine”. Name the following:

  7. Nomenclature: Heterocyclic Amines Parent names of some heterocyclic amines: Name the following:

  8. Basicity of Amines • Basicity of amines dominates its chemistry. • Measure of basicity is pKb:

  9. Basicity of Amines • The lower the pKb value, the more basic the amine. • pKb values are related to the pKa values of the conjugate acids: • pKa + pKb = 14 • Example: NH3 has a pKb = 4.74, so the pKa of its conjugate • acid, NH4+ is 9.26. • It is common to find the pKa for the ammonium salt; then need • to convert to pKb. • Unlike carboxylic acids, the effect of the R substituents on the • nitrogen’s basicity is minimal except for aniline derivatives.

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