02 Organic

Organic
- Substitution and elimination reactions
  - Handwritten notes (17 pg)
  - https://www.youtube.com/watch?v=hz-fSXifP9w&t=286s&ab_channel=TheOrganicChemistryTutor very good video that explains everything in sub elimination nd provides a good table for easy learning
  - https://www.youtube.com/watch?v=qTc2uud7TVU&ab_channel=TheOrganicChemistryTutor test review
- Addition reactions
  
  These reactions are exothermic because the electron density around the carbon atoms becomes polarized, making them more commercially viable.
  - Addition reactions
    - Addition rxn general mechanism
      - Since carbocation is preferred stability is 3>2>1
      - Order of reactivity of Hydrogen halides is HF<<<<HCl<HI where HI is the fastest because its always polarized
        
        F**i**C**kle **B**err**I
      - Constitutional isomers and regioselectivity
        
        Constitutional isomers
      - Markovnikovs rule
        
        Product with more branches is preferred
        
        H goes to Carbon atom with more Hydrogen ( rich becomes richer ) and the product we get is the major product
        
        major requires lower Gibbs free energy
        
        Both back side and front side attack is possible therefore this results in the formation of a racemic mixture of two possible enantiomers, since the addition can occur from either side of the double bond.
      - Stereochemistry of ionic addition to alkene
      - Anti- Markovnikovs rule
        
        Peroxide has no effect on HI and HCl ( R-O-O-R is a peroxide )
        
        Chain initiation and chain propagation ( Formation of free radical and formation of Halo hydrocarbon )
        
        https://www.youtube.com/watch?v=ZMcCvD5dDMU explains this
        
        Basically, Chain initiation happens first where bond is broken and we get roh and Br
        
        and then propogation happens where the Br we got from before attacks to form a stable carbocation which is then attacked by HBR again to provide the hydrogen
    - Addition rxn with H2SO4 to form alcohol
      - Addition of H2SO4 to alkene
        
        It is stereo-specific and follows markonikovs rule
    - Addition rxn with water
      - Acid catalyzed Hydration
        
        Follows Markovnikovs reaction
      Step 2 and 3 are fast follows markovnikovs
    - Le Chatliers principle
      
      The hydration dehydration equilibria is altered towards hydration —> alcohol —> adding dil. acid at low temp towards dehydration —> Alkene —> adding conc. acid at high temp
    - Oxymercuration Hydration
      
      Regiospecific rxn
      
      follows markovnikovs rxn we get Oh , nabh4 removes the HgOAc
    - Hydro Boration Hydration rxn
      
      https://www.youtube.com/watch?v=RBwOfhS6mBM
      
      Boron is less e-ve than hydrogen that's why the oppo happens , concerted rxn
      
      first step u get tri alky bromine 2^nd step u add h202
      
      Anti markovnikovs rxn
      
      remember ch3 in back or front and Oh in front and back they will be oppo of each others positions
      
      (your alcohol and hydrogen should be on the same side)
      
      https://www.youtube.com/watch?v=PFwYIkkOyzA&ab_channel=FrankWong helps alot
      
      https://www.youtube.com/watch?v=I-pmeHcjD8M&ab_channel=Leah4sci
      
      Mechanism
    - Electrophilic addition of Br2/Cl2 to Alkenes
      
      General rxn we get enantiomers
      
      https://www.youtube.com/watch?v=ZfOcYntQmlk&list=RDCMUCEWpbFLzoYGPfuWUMFPSaoA&start_radio=1&rv=ZfOcYntQmlk&t=6
    - Halo hydrin formation
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- **Practice Qs + Tutorial**

    ![Untitled 57](https://github.com/Muqaram0/Muqaram0/assets/130496042/01ffd97b-4ec7-495a-8af0-7cfcdaaa55da)

    ![Untitled 58](https://github.com/Muqaram0/Muqaram0/assets/130496042/5fc7016a-f081-4a6a-988f-279eb2c671c7)

    ![Untitled 59](https://github.com/Muqaram0/Muqaram0/assets/130496042/09629a50-0ef8-4314-882d-bbaea54640a1)

    Fickle Beri :- Cl is more e-ve

    ![Untitled 60](https://github.com/Muqaram0/Muqaram0/assets/130496042/9c39f85e-f3c4-48af-bc6f-538698234290)

    ![Untitled 61](https://github.com/Muqaram0/Muqaram0/assets/130496042/dd3ade01-17b2-4b2c-8315-528839d2555e)
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- Aromaticity
  - Conditions to check for aromaticity
    - Acidic strength is proportional to stability
    - https://www.youtube.com/watch?v=qDZIvjcM_Gk&list=PLaySzQJTCO1mdBoL-BLBfKrhgdwRpbOnx helpful video on this
    - It has to be cyclic ( self-explanatory)
    - Planar
      
      Has to have a 2-D structure and not a 3D structure
      
      sp3 - tetrahedral is 3D and wont be aromatic , sp2 - trigonal planar is aromatic because flat
    - Conjugated at the ring
      
      Should be able to follow resonance , in the other two figures it cant follow resonance because the carbon atom is sp3 hybridized and cant accept more ( mainly depends on the availability of the p orbital )
      
      - Should follow huckels rule
      
      4n + 2 = pi electrons where n should be a whole number , if n is not a whole number then it is not aromatic
      
      💡SHORTCUT :- if there are even no. of electron pairs then we will get n as a fraction therefore not aromatic or we can say it does not obey huckels rule , if odd then its aromatic
      
      eg:-
      
      11 pairs :- which is odd and therefore follows huckels rule no need to do lengthy calc
      
      IMPORTANT :- Here it follows huckels rule because we are counting the lone pair from -ve charge also as an e- pair
    - There are 3 classes :- Aromatic , Anti Aromatic and non aromatic
      
      Aromatic and Anti aromatic they both look the same but one follows huckels rule and the other does not
      
      Non aromatic don't follow all 4 properties
    - Heterocyclic aromatic compounds are compounds where not all are carbon atoms
      
      They want to be aromatic which means it wants to resonate
      
      check if the atom is participating in resonance or not , if its participating with a pi bond you don't add the electrons in , if its not participating you use the lone pair
      
      (or) if the atom has a pi bond you dont use the lone pair , if it does not have a pi bond you use the lone pair , if it has 2 lone pairs you use only one
      
      eg:-
      
      we are not using the lone pair , that is why we wont count it in the huckel rule and get it as aromatic and not anti-aromatic
  - Annulenes
    - Nomenclature
      
      Annulenes must have even number of electrons
      
      branches into two , either anti aromatic annulenes or aromatic annulenes (refer to huckels rule)
    - Some examples
      
      due to repulsion or ang. strain
      
      happens with [8] annulene, [10] annulene , [14] annulene and [18] annulene (non aromatic)
  - Practice Qs
    
    notice how there is -ve charge (lone pair) after treating it with strong base
    
    h) is anti atomaticc not aromatic*
    
    order is pyridine>pyrolidene>pyrole not pyridene>pyrole>pyrolidene
    
    depends on basicity which depends on the no. of lp
    
    if we look at pyridine and pyrole , if we dont consider the lp it is less basic then pyrole , but because of the presence of lp it is more basic as it has more donating power now
    
    similarly, if we look at pyrole and pyrolidene pyrolidine will be more basic than pyrole because pyrole has less donating power as its lone pair is being used
- Stereochem
  
  Stereochemistry
  - Identification of chirality or achirality
    
    https://www.youtube.com/watch?v=KztTL3FTcOw helpful video
    
    It needs to have 4 different functional groups attached to the carbon atom for it to be chiral
    
    2^n is the max no. of stereomers you can have , where n is the no. of chiral centers
    
    if we have 2 chiral centers then molecule may or may not be chiral depending on the symmetry
    
    Chiral means active , Achiral means inactive
  - Diff. Types of Isomers
    - Types of isomers
      - Isomerism :- Different compound but same molecular formula
      - Constitutional Isomers :- Atoms have diff connectivity
        
        IMPORTANT :- Numbering diff = constitutional isomer
      - Stereoisomers :- Atoms differ in arrangement of their atoms in space
      - Enantiomers :- Non superimposable mirror images
      - Diastereomers :- Non superimposable non mirror images
      - Cis-trans geometric isomers
    - Some examples
    Achiral can never be enantiomer instead its a meso compound ( have a plane of symmetry )
    
    All chiral centers change in enantiomers
    
    They are the same because of achirality
    
    Constitutional isomers ^
    
    https://www.youtube.com/watch?v=KztTL3FTcOw helpful vid
    - Chirality
      - Diff functional group on Carbon
      - Absence of Planar ( Internal Symmetry —> condition for chirality )
    - Chirality Center
      - Asymmetric Carbon atom
      - Stereocenter :- when the interchange of 2 groups gives stereoisomers ( Asymmetric carbons and cis-trans isomers )
      - Achirality :- When the images can be superimposed and has a plane of symmetry
  - Cahn Ingold Prelog priority system + R and S configuration
    
    Fancy name for what reason
    
    https://www.youtube.com/watch?v=yzfcrwJ37kI helpful video
    
    3 chiral centers therefore using 2^n there will be 8 possible stereomers
    
    Chiral carbon will have 4 different functional groups , to assign it a R or S order we rank the Functional groups using the priority system
    
    Priority is based on atomic no.
    
    I>Br>Cl>S>F>O>N>13C>12C>2H1>1H1
    
    assign numbers to each atom and count from 1 to 4 , 4^th group should be in the back
    
    if anti- clockwise we assign it S config and if clock wise we give it R config R:-rolling—> clockwise
    
    atomic no:- of carbon is 6
    
    switch the configuration from R to S or S to R if the last hydrogen atom is not in the Back (hatched wedge)
    
    Nomenclature
    
    for double and triple bonds you open them up
    
    here it was not shown if H is in the front or the back , so we do the double flip ( interchange oppo groups ) to get the position of H
    
    - Fischer's Projection
    
    groups on the horizontal edge are in the front and groups on vertical ends are in the back
  - Optical Activity and Specific Rotation
    
    Enantiomers rotate the plane polarised light in oppo. direction, but same no. of degrees
    
    Clockwise :- Dextro rotatory (+)
    
    Anti-Clockwise :- Levo rotatory (-) levo-left
    
    S makes light go right , R makes light go left
    - Specific rotation
      
      alpha = observed rotation
      
      l = path length
      
      C = concentration
      
      )
      
      Q. When one of the enantiomers of 2-butanol is placed in a polarimeter, the observed rotation is 4.05 degrees anti-clockwise . The soln. was made by diluting 6g of 2-butanol to a total of 40ml , and the solution was placed into 200mm polarimeter tube for measurement . Determine the specific rotation for this enantiomer of 2-Butanol.
  - Racemic mixtures
    
    will not rotate polarized light because equal amounts of left polarizing and right polarizing light is there in the mixture
  - E/Z system
    
    https://www.youtube.com/watch?v=frtnEDTSzi8 helpful video
    
    when highest priority group is on same side we get Z isomer (Zame) (Zusammen)
    
    when highest priority group is on oppo. sides we get E isomer (OppositE) (Entgegen)
  - Practice Qs + Tutorial
- Conformational Analysis
  - Basic
    
    Conformations:- Different Spatial arrangements that a molecule can adapt due to rotation about the internal bonds
    
    Conformers:- Structurers that differ based on rotation
    
    Conformational analysis :- Study of energy changes that occur during rotations
  - Newmanns Projection
  - Energy
    
    • Torsional strain is an increase in energy caused by electron-electron repulsions between the eclipsing C-H bonds
    
    Why is staggered more stable than eclipse?
    
    The chair conformation is very stable because it eliminates angle strain and torsional strain (all hydrogens on adjacent C atoms are staggered)
    
    Axial is less stable than Equatorial pos because it minimizes steric repulsion
    
    Axial becomes Equatorial and vice versa numbering changes
    
    up stays up and down stays down they dont change
    
    if we go from form A to B the numbering shifts to the next carbon clockwise
    
    if vice versa then numbering shifts back and anti clockwise
    
    The bigger arrow shows that the equilibrium favors the more stable product
  - Problems
    
    bulky group on equatorial thats why more stable than bulky group on axial
  - Tutorial
    
    https://apps.dso.iastate.edu/si/documentdb/spring_2016/CHEM_331_Kraus_ihazlett_331_Worksheet_Week_4_Key_2_.pdf very useful worksheet
    
    https://www.garybreton.com/CHM_223HF/ewExternalFiles/4_6 KEY.pdf Very useful worksheet

Last Updated: 2023-06-01 ; Contributors: Muqaram0

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