group nine organic chemistry presentation

This ppt answers qtns in organic compounds

1. GROUP 9 ORGANIC CHEMISTRY 2.1 1.NAKIMULI OLIVIA VU-BPC-2307-0506-DAY 2.NKALUBO ISAAC VU-BPC-2307-0873-DAY 3.AINEMBABAZI BELIEVE VU-BPC-2307-0919-DAY 4.ADIKIN AIDAH ELDRINE VU-BPC-2307-0460-DAY

2. 1. disscus why iodoform does not exhibit sterioisomerism despite having heavy atoms(iodine) attached to a carbon. what creteria must be met for a compound to be achiral. Why Iodoform Does Not Exhibit Stereoisomerism The central carbon atom in iodoform (C) is bonded to three iodine atoms (I) and one hydrogen atom (H). Since three of the groups (the iodine atoms) are identical, the central carbon atom is not chiral. A carbon atom with three identical groups (I) does not meet the conditions to have non-superimposable mirror images, so iodoform is achiral and cannot exhibit stereoisomerism. Open structure of iodoform

3. Criteria for a Compound to Be Achiral Symmetry: The molecule has a plane of symmetry or a center of symmetry, meaning that one half of the molecule is a mirror image of the other. This symmetry ensures that the molecule can be superimposed on its mirror image. No Chiral Center: The molecule lacks a carbon atom (or other atom) attached to four different groups. If all the substituents on the central atom are not unique, the molecule is achiral. Identical Substituents: If a carbon atom is bonded to two or more identical groups, the molecule cannot have chiral isomers because it does not have a unique, asymmetric arrangement of substituents.

4. Qtn 3. How does the presence of the chloro group affect the overall stereochemical behavior of 2,4-dinitrochlorobenzene? Electron withdrawing effect The chloro group is electron withdrawing meaning it pulls electron density away from the benzene ring. This effect is enhanced by the two nitro groups (NO2), making the ring more electrophilic. Steric hindrance The chloro group occupies a position on the ring, influencing the approach of reactants and the orientation of substituents. Directing effects In electrophilic aromatic substitution reactions, the chloro group directs incoming electrophiles to the ortho para(2, 4) positions, due to its electron-withdrawing nature.

5. Reactivity The chloro group makes the molecule more reactive towards nucleophilic aromatic substitution reactions. Conformational effects The chloro group's presence may influence the molecule's conformation, particularly in relation to the nitro groups.

6. QTN 4 How does the ratio of nitric acid to sulfuric acid influence the stereochemistry of the product(2,4 dinitrochlorobenzene) The nitration reaction involves the formation of the nitronium ion (NO2+), which attacks the aromatic ring. Acid ratio effects: Nitric acid excess: High HNO3 concentration favors the formation of 2,4 dinitrochlorobenzene, as it increases the availability of NO2+ ions. Sulfuric acid excess: High H2SO4 concentration enhances the formation of the nitronium ion, but excessive H2SO4 can lead to sulfonation side reactions, reducing the yield.

7. cont... Stereochemical Impact The acid ratio influences the stereochemistry by: Controlling the reaction rate: A higher H2SO4 concentration accelerates the reaction, reducing the likelihood of rearrangements or side reactions. Directing effects: The nitronium ion's direction of attack is influenced by the electron-withdrawing chloro group, favoring ortho-para substitution. Product distribution: The ratio affects the relative yields of 2,4-dinitrochlorobenzene and other isomers ( e.g 2,6-dinitrochlorobenzene).

8. By optimizing the HNO3:H2SO4 ratio, we can control the reaction's selectivity, yield, and stereochemical outcome, ensuring the desired product, 2,4-dinitrochlorobenzene, is formed predominantly.

9. QTN2 . 3-nitrophathalic acid has a nitro group attached to the third position of the phathalic acid ring.disscus wether this molecule can exhibit charility. what is the impact of the nitro group’s position on the molecule’s symmetry,and how does this influence the potential for sterioisomerism. Symmetry: 3-nitrophthalic acid has a plane of symmetry due to the arrangement of the two carboxyl groups at positions 1 and 2 on the benzene ring. The molecule is symmetric along the axis that bisects the ring between the carboxyl groups. No Chiral Center: The structure lacks a carbon atom or other atom attached to four distinct groups. The nitro group at position 3 does not create an asymmetric environment that could result in a non-superimposable mirror image.

10. Impact of the Nitro Group’s Position on Symmetry: The nitro group at the 3rd position is attached to the ring symmetrically relative to the carboxyl groups, reinforcing the molecule’s overall symmetry. If the nitro group were attached to a different position, such as the 4th position (para to the carboxyl groups), this could break the symmetry to some extent but would still not create a chiral center, as the molecule remains planar and does not have four distinct groups attached to any single carbon. structure of 3-nitrophathalic acid

11. Influence on Potential for Stereoisomerism: The position of the nitro group in the 3rd position does not introduce any form of asymmetry that could give rise to stereoisomers (such as enantiomers or diastereomers). Stereoisomerism arises when there is either a chiral center (like in alkenes or cyclic compounds) leading to isomers that are not superimposable on each other. However, in 3-nitrophthalic acid, there is no such stereocenter, nor does the nitro group’s position induce restricted rotation.

12. Why is Glycine not a chiral amino acid? This is because its alpha carbon atom is attached to two hydrogen atoms making it impossible for it to have four different substituents .