isomers

different types of isomers

1. ISOMERS

2. Objectives Isomers Structural isomer Stereoisomer Conformational isomer Configurational isomer Geometrical isomer Optical isomers L and D isomers R and S racemic mixtures The importance of isomers in drug prescription The importance of isomers in biological processes

3. Definition of isomers Isomers is a term which call in two compounds that have the same molecular formula . There are two major classes (types) of isomers, and under these major classes there are further classifications of isomers.

4. Structural Isomer (Constitutional) Definition: Structural isomers are molecules with the same molecular formula, but have different structures or arrangements. *Let's take a look at a molecular formula: C 4 H 10 . While the molecular formula can't tell us how the atoms are arranged, it can help us find some of the possible arrangements. In this case, there are two different arrangements for this molecular formula: butane and isobutane. Butane and isobutane have the same number of carbon (C) atoms and hydrogen (H) atoms, so their molecular formulas are the same. However, each one has a different structural formula, which shows how the atoms are arranged. So, we can say that butane and isobutane are structural isomers.

5. https://rbnenergy.com/you-can-just-iso-my-butane-isobutane-and-isomerization http://www.meritnation.com/ask-answer/question/draw-3-structural-isomers-butane-plzz-help/carbon-and-its-compounds/1828050

6. Types of Structural Isomerism 1 - Chain Isomerism. 2 - Position Isomerism. 3 - Functional Group Isomerism.

7. Chain Isomerism T here are two isomers of butane, C 4 H 10 . In one of them, the carbon atoms lie in a "straight chain" whereas in the other the chain is “branched”.

8. Position Isomerism For example, there are two structural isomers with the molecular formula C 3 H 7 Br . In one of them the bromine atom is on the end of the chain, whereas in the other it's attached in the middle.

9. Functional Group Isomerism In this type, the isomers contain different functional groups. For example, a molecular formula C 3 H 6 O could be either propanal (an aldehyde) or propanone (a ketone).

10. Stereoisomer Stereoisomers : Isomers that have the same connectivity of their atoms but a different orientation of their atoms in space . http://study.com/academy/lesson/stereoisomers-definition-types-examples.html

11. CONFORMATIONAL ISOMERS Conformational isomers are the type of stereoisomerism Stereoisomers have the same functional groups and connectivities, they differ only in the arrangement of atoms and bonds in space The different spatial arrangements that a molecule can adopt due to rotation about carbon-carbon single bonds are known as conformations • Different conformations also are called conformational isomers or conformers

12. NEWMAN PROJECTIONS A convenient way to describe conformation isomers is to look at the molecule along the axis of the bond of interest • A Newman projection is a graphical representation of such a view http://universe.bits-pilani.ac.in/uploads/Dubai/rusalraj/Conformational%20Isomers.pdf

13. Conformations of Alkanes: Rotation About C-C Single Bonds When ethane molecules rotate about the carbon-carbon bond there are two extremes: staggered conformation and eclipsed conformation

14. Configurational isomers Configurational isomers are stereoisomers that cannot be converted at room temperature and can be separated. Types of Configurational isomers: Geometric isomers: differ in the spatial position around a bond with restricted rotation or across a ring system.

15. Configurational Isomers Optical isomers: differ in the 3D relationship of the substituents about one or more atoms. Types: Enantiomers: Optical isomers that image of each other and have the same physical and chemical properties

16. Diastereomers:stereoisomers that is not a mirror image and have different physical and chemical properties.

17. Geometrical isomer Geometric isomerism concerns the type of isomer where the individual atoms are in the same order, but manage to arrange themselves different spatially. The prefixes cis- and trans- are used in chemistry to describe geometric isomerism. Geometric isomers occur when atoms are restricted from rotating around a bond. Divisions of geometrical isomers are: Cis Trans

18. Cis-trans isomers Cis The cis- prefix is from the Latin meaning "on this side". In this case, the chlorine atoms are on the same side of the carbon-carbon double bond. This isomer is called cis-1,2-dichloroethene.

19. Cis-trans isomers Trans The trans- prefix is from the Latin meaning "across". In this case, the chlorine atoms are across the double bond from each other. This isomer is called trans-1,2-dichloroethene.

20. Optical Activity. Solutions of some organic compound have the ability to rotate the plane of polarized light. These compounds are said to be optically active. This property of a compound is called Optical Activity Optical activity in a compound is detected and measured by means of a Polarimeter http://www.polarimeter.eu/

21. · The compound which rotate the plane of polarized light to the right [clockwise] is said to be Dextrorotatory. It is indicated by the sign (+). The compound which rotates the plane of polarized light to the left [anticlockwise] is said to be Laevorotatory. It is indicated by the sign (-) An optically active compound can exist in two isomeric forms that polarize the plane of light on opposite directions. These are called optical isomers and this phenomenon as optical isomerism. Dextrorotatory isomer or (+) isomer Levorotatory isomer or (-) isomer Optical Isomerism.

22. Optical Isomerism of Tartaric Acid Tartaric acid (2,3-Dihydroxybutanedioic acid) contains two asymmetrical carbon atoms. Four forms of tartaric acid are known. Two are optically active and two optically inactive. The optically active forms are enantiomers. (+) Tartaric acid (-) Tartaric acid (±) Tartaric acid, racemic or equimolar mixture of (+) and (-) isomeric forms. Meso-tartaric acid

23. http://encyclopedia2.thefreedictionary.com/isomer

24. Specific rotation The specific rotation is the number of degrees of rotation caused by a solution of 1.0 g of the compound per mL of solution in a sample tube 1.0 dm long at a specified temperature and wavelength. http://www.organicchem.org/oc1web/exp/polarimetry/polarimetrydes.html

25. Diastereomers Diastereomers are stereoisomers that are not mirror images of one another and are non-superimposable on one another. Stereoisomers with two or more stereocenters can be diastereomers. For example, consider the following molecules. These molecules are not mirror images of one another. Additionally, these molecules are non-superimposable because if one of these molecules is flipped 180 degrees the stereochemistry is different at one carbon (the alcohols) and the same at another carbon (the methyls). Therefore, these molecules are diastereomers .

26. Uses Of Diastereomers Glucose and galactose, two of the most common monosaccharides found in the body, are diastereomers of each other: Lactose, which is found in milk, is formed by a condensation reaction between glucose and galactose. Retinal is a molecule found in the photoreceptor cells of eyes that normally exists in the cis form. When it absorbs light, it undergoes diasteromers.

27. Enantiomers Enantiomers have identical chemical and physical properties except for their ability to rotate plane-polarized light (+/-) by equal amounts but in opposite directions. Enantiomers interact differently with other chiral molecules i.e. biologically active molecules as amino acids, sugars, steroids etc. This means that some molecules have, for example, different odours. Limonene is just such a case. https://projects.cmab.es/resolve/what-is-an-enantiomer.html

28. Properties of enantiomers Not every pair of molecules can be enantiomers. They have to have specific properties. What are these properties? A pair of enantiomers must be a chiral compound, which means it has a chiral carbon. A chiral carbon , or a chiral center, is a carbon that has four different groups attached to it.

29. D and L Isomers[enantiomers] A special type of isomerism is found in the pairs of structures that are mirror image of each other. These mirror images are called enantiomers. https://image.slidesharecdn.com/carbohydratestructure-130906085559-/95/carbohydrate-structure-26-638.jpg?cb=1378457767

30. D and L Isomers[enantiomers] D and L isomers enantiomers The two members of the pair are designated as a D- and an L- sugar. In the D isomeric form, the OH group on the asymmetric carbon (a carbon linked to four different atoms or groups) , while in the L-isomer it is on the left. http://player.slideplayer.com/10/2752124/data/images/img7.jpg

31. IMPORTANCE OF ISOMERS IN DRUG PRODUCTION Stereoisomerism is the term applied to isomers that have the same structural formula but different arrangements of atoms in space. The level of priority groups refers to the molecular mass of a group attached to the parent chain or central atom/ion; highest priority groups have the highest molecular mass. An isomer will be deemed as ‘Cis’ if the highest priority groups are on the same side of the molecule, an isomer would be deemed as ‘Trans’ if the highest priority groups are on different sides of the molecule. An example of cis – trans isomerism is shown above. The structure and position of the groups is highly important to chemistry and the manufacture of pharmaceuticals. http://www.sciencenutshell.com/pharmaceuticals-the-importance-of-stereoisomerism /

32. THE IMPORTANCE OF ISOMERS IN BIOLOGICAL PROCESSES Isomers are important because our entire biology, and that of every organism on the planet, is built on them. First , virtually every biologically important molecule has one or more isomers. This is due, in part, to the necessary complexity of those molecules, which require numerous different types of atoms (a minimum of carbon, oxygen, hydrogen and often nitrogen, phosphorus and others) and will commonly contain a mixture of single and double bonds. Second , evolution, in almost all cases, has favoured the use of one isomer for a given purpose over the use of the others that exist.

33. REFERENCES http://site.iugaza.edu.ps/rmorjan/files/2010/02/Stereochemistry.pd f http://study.com/academy/lesson/structural-isomers-definition-examples.html http://www.chemguide.co.uk/basicorg/isomerism/structural.html http://study.com/academy/lesson/stereoisomers-definition-types-examples.html https://projects.icmab.es/resolve/what-is-an-enantiomer.html study.com/academy/lesson/enantiomers-definition-properties-examples.html http://www.chemeddl.org/resources/stereochem/definitions17.htm https://chemistry.stackexchange.com/questions/43466/examples-from-everyday-life-for-diastereoisomers http://www.iitg.ac.in/ckjana/ckjana/Teaching_files/Organic%20Chemistry-%20Lesson%202.pdf

34. Thank you