Nomenclature of Organic Compounds – PST05106 Pharmaceutical Organic Chemistry
NTA Level 5 • Semester 1 • PST05106 Nomenclature of Organic Compounds Pharmaceutical Organic Chemistry • Source Session/Topic 4 Full source-text version: all educational wording from the extracted learning source is retained; only presenter/tutor metadata and web-layout noise are removed, while formatting is improved for readability. Session 4: Nomenclature of Organic Compounds. Total Session Time: 120 minutes Prerequisites • None Learning Tasks By the end of this session students are expected to be able to: • Define nomenclature of organic compounds • Explain nomenclature of organic compounds Resources Needed: • Flip charts, marker pens, and masking tape. • Black/white board and chalk/whiteboard markers. SESSION OVERVIEW |Step |Time |Activity/ |Content | | | |Method | | |1 |05 minutes |Presentation |Introduction, Learning Tasks | |2 |10 minutes |Buzzing |Definition of Nomenclature of | | | |Presentation |Organic Compounds | |3 |85 minutes |Group |Nomenclature of organic compounds | | | |discussion | | | | |Presentation | | |4 |10 minutes |Presentation |Key Points | | 5 |10 minutes |Presentation |Evaluation | SESSION CONTENTS STEP 1: Presentation of Session Title and Learning Tasks (5 minutes) READ or ASK students to read the learning tasks and clarify. ASK students if they have any questions before continuing. STEP 2: Definition of Nomenclature of Organic Compounds (10 Minutes). |Activity: Buzzing (5 minutes) | | | |Ask students to brainstorm on the following question: | | | |What is nomenclature of organic compounds? | | | |ALLOW few students to respond | | | |WRITE their responses on the flip chart/ board | | | |CLARIFY and SUMMARISE by using the content below | • Nomenclature is the act or a system of naming. • IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC). STEP 3: Nomenclature of organic compounds (85 minutes). |Activity: Small Group Discussion (20 minutes). | | | |DIVIDE students into small manageable groups. | | | |ASK students to discuss on the following question | |What are the rules for naming organic compounds? | | | |ALLOW students to discuss for 15 minutes. | | | |ALLOW few groups to present and the rest to add points not mentioned. | | | |CLARIFY and SUMMARIZE by using the contents below. | The following are the rules that are followed in naming organic compounds 1. Identification of the parent chain. This chain must obey the following rules, in order of precedence: i. It should have the maximum number of substituents of the suffix functional group. By suffix, it is meant that the parent functional group should have a suffix, unlike halogen substituents. If more than one functional group is present, the one with highest precedence should be used. ii. It should have the maximum number of multiple bonds. iii. It should have the maximum number of single bonds. iv. It should have the maximum length. 2. Identification of the parent functional group, if any, with the highest order of precedence. 3. Identification of the side-chains. Side chains are the carbon chains that are not in the parent chain but are branched off from it. 4. Identification of the remaining functional groups, if any, and naming them by their ionic prefixes (such as hydroxy for -OH, oxy for =O, oxyalkane for O-R, etc.). Different side-chains and functional groups will be grouped together in alphabetical order. (The prefixes di-, tri-, etc. are not taken into consideration for grouping alphabetically. For example, ethyl comes before dihydroxy or dimethyl, as the "e" in "ethyl" precedes the "h" in "dihydroxy" and the "m" in "dimethyl" alphabetically. The "di" is not considered in either case). When both side chains and secondary functional groups are present, they should be written mixed together in one group rather than in two separate groups. 5. Identification of double/triple bonds. 6. Numbering of the chain. This is done by first numbering the chain in both directions (left to right and right to left), and then choosing the numbering which follows these rules, in order of precedence i. Has the lowest-numbered locant (or locants) for the suffix functional group. Locants are the numbers on the carbons to which the substituent is directly attached. ii. Has the lowest-numbered locants for multiple bonds (The locant of a multiple bond is the number of the adjacent carbon with a lower number). iii. Has the lowest-numbered locants for prefixes. 7. Numbering of the various substituents and bonds with their locants. If there is more than one of the same type of substituent/double bond, a prefix is added showing how many there are ( di – 2 tri – 3 tetra – 4 then as for the number of carbons below with 'a' added) • The numbers for that type of side chain will be grouped in ascending order and written before the name of the side-chain. If there are two side-chains with the same alpha carbon, the number will be written twice. Example: 2,2,3-trimethyl- . If there are both double bonds and triple bonds, "en" (double bond) is written before "yne" (triple bond). • When the main functional group is a terminal functional group (a group which can exist only at the end of a chain, like formyl and carboxyl groups), there is no need to number it. 1. Arrangement in this form: Group of side chains and secondary functional groups with numbers made in step 3 + prefix of parent hydrocarbon chain (eth, meth) + double/triple bonds with numbers (or "ane") + primary functional group suffix with numbers. Wherever it says "with numbers", it is understood that between the word and the numbers, the prefix(di-, tri-) is used. 2. Adding of punctuation: i. Commas are put between numbers (2 5 5 becomes 2,5,5) ii. Hyphens are put between a number and a letter (2 5 5 trimethylheptane becomes 2,5,5-trimethylheptane) iii. Successive words are merged into one word (trimethyl heptane becomes trimethylheptane) Note: IUPAC uses one-word names throughout. This is
