BIOCHEMISTRY 13TH NOV lect 4.pptxiiiiioi

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1. BIOCHEMISTRY 21TH FEBRAUARY 1

2. Acids and Bases

3. WHAT ARE ISOMERS ISO…..MEANS SAME,MERS….PARTS MEANS MOLECULES HAVING SAME MOLECULAR FORMULA BUT DIFFER IN THEIR STRUCTURAL FORMULA AND PROPERTIES.ARE SAID TO BE ISOMERS AND PHENOMENA IS CALLED ISOMERISM Basically are of two types Structural isomerism Sterio isomerism 10

4. Structural isomerism The chain isomerism (differ in carbon chain) Example(n pentane , iso pentane,neo pentane) Position isomerism(differ in the position of same functional group) Example(1-chloropropane,2-chloropropane…..1-butene,2-bute ne) Functional group isomerism( differ in functional group) Example(di methyl ether,ethyl alcohol…..glucose and fructose) Metamerism Type of isomerism arises due to unequal distribution of carbon atoms 11

5. CONTI……. On either side of the functional group Example(Ethyl ether and Methyl n propyl ether) Tautomerism (due to shifting of proton from one atom to other within same molecule) Example(in amino acid one proton from COOH move to NH2 to make it…NH3) Cis Trans(Geometric Isomerism) 2-butene can exist in the form of cis and trans isomers 12

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11. Rules for Naming Alkanes The parent name, longest chain. If two chains have same length, chain with max substituents. number from the end nearest substituent . If same from both ends, number from the end nearest the next substituent. for more substituent, Use di- for two, tri- for three, tetra- for four, etc. and use the number assigned to the carbon to indicate the position of each substituent. 18

12. Branched Alkanes Branched substituents are numbered starting from the carbon of the substituent attached to the parent chain. From this carbon, count the number of carbons in the longest chain of the substituent. The substituent is named as an alkyl group based on the number of carbons in this chain. Numbering of the substituent chain starts from the carbon attached to the parent chain. The entire name of the branched substituent is placed in parentheses, preceded by a number indicating which parent-chain carbon it joins. Substituents are listed in alphabetical order. To alphabetize, ignore numerical (di-, tri-, tetra-) prefixes (e.g., ethyl would come before dimethyl ) 19

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15. Cyclic Alkanes The parent name=number of carbons in the largest ring (e.g., cycloalkane such as cyclohexane). if ring is attached to a chain, the ring is substituent on the chain. When two rings are attached to each other, the larger ring is the parent and the smaller is a cycloalkyl substituent. The carbons of the ring are numbered such that the substituents are given the lowest possible numbers. 22

16. Nomenclature of Alkenes a . - ene . The parent structure is the longest chain containing both carbon atoms of the double bond.   b . Give the double bond the lowest possible numbers regardless of substituent placement.   · Try to name the following compound...   c . Common names that you should know are... vinyl substituent H 2 C=CH- allyl substituent H 2 C=CH-CH 2 - allene molecule H 2 C=C=CH 2   23

17. CONTI………….. . end ocyclic double bonds have both carbons in the ring and exocyclic double bonds have only one carbon as part of the ring. Cyclo pentene is an example of an endO cyclic double bond. Methylene cylopentane is an example of an exO cyclic double bond. e. Double bonds can exist as geometric isomers and these isomers are designated by using either the cis / trans designation or the modern E / Z designation. cis ...The two largest groups are on the same side of the double bond. trans ...The two largest groups are on opposite sides of the double bond.  E/Z nomenclature E = ("trans") Z = (" cis ") 24

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29. Naming Alkynes Rule 1. Find the longest carbon chain that includes both carbons of the triple bond. Rule 2 Number the longest chain starting at the end closest to the triple bond. A 1-alkyne is referred to as a terminal alkyne and alkynes at any other position are called internal alkynes. For example: 4-chloro-6-diiodo-7-methyl-2-nonyne Rule 3 After numbering the longest chain with the lowest number assigned to the alkyne, label each of the substituents at its corresponding carbon. While writing out the name of the molecule, arrange the substituents in alphabetical order. If there are more than one of the same substituent use the prefixes di, tri, and tetra for two, three, and four substituents respectively. These prefixes are not taken into account in the alphabetical order. For example: 1-triiodo-4-dimethyl-2-nonyne 36

30. Conti……… RULES FOR NAMING HYDROCARBONS ACCORDINGLY FUNCTIONAL GROUP 37

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34. The steps to naming an organic compound are: Identify the parent hydrocarbon chain. This chain must follow the following rules, in order of precedence: It should have maximum 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, use the one with highest precedence. It should have maximum number of multiple bonds It should have maximum number of double bonds. It should have the maximum length. 41

35. RULES FOR ALKENE AND ALKYNES Identify double/triple bonds. Number the chain. To number the chain, first number in both directions (left to right and right to left), and then choose the numbering which follows these rules, in order of precedence: Has the lowest locant (or locants ) for the suffix functional group. Locants are the numbers on the carbons to which the substituent is directly attached. Has the lowest locants for multiple bonds (The locant of a multiple bond is the number of the adjacent carbon with a lower number). Has the lowest locants for double bonds Has the lowest locants for prefixes 42

36. 43 Di methyl ether Di ethyl ether

37. methanol

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41. HOME ASSIGNMENT DO THE PRACTICE OF NOMENCLATURE OF HYDROCARBON 48

42. THANKS 49