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ALKANES, KETONES, CARBOHYDRATES, First step: Carbonyl protonation, Second…

- - - - carbonyl group
      - aldehyde
      - ketone
    - - named as aldehyde
      - ketone named as "oxo" substituent
    - - cyclic : cyclo- -one
      - diketones : suffixe -dione
  - - - with PCC (Pyridinium chlorochromate)
      - with DMP (Dess‑Martin Periodinane)
    - - Hydride reduction of ester
      - Hybride reduction of acid halide
      - Hybride reduction of a nitrile
    - - e.g. terminal alkyne with disiamylborane followed by oxidation with hydrogen peroxide and hydroxide
  - - - more resistant to oxidation than aldehydes : no H atom attached to the carboxyl
      - Baeyer-Villiger Oxidation
        
        oxidation of ketone to ester
        
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        Intramolecular proton transfer
        
        Nucleophilic attack on the carbonyl
  - - - 1st step: nucleophilic attack,
        2nd step: protonation
    - - 1st step: Nucleophilic attack to form a tetrahedral alkoxide intermediate
      - 2nd step: protonation to form an alcohol
    - - step 1: Nucleophilic addition,
        step 2: proton transfer,
        step 3: protonation,
        step 4: elimination of water,
        step 5: deprotonation
    - - 1st step: The acid catalyst protonates the carbonyl oxygen,
        2de step; An alcohol undergoes nucleophilic addition to the carbonyl
        3rd step: Water acts as base to cause a deprotonation
        4th step: The OH group of the hemiacetal is protonated
        5th step: Lone pair electrons on the ether oxygen reforms the C=O bond
        6th step: A second alcohol undergoes nucleophilic additon to oxonium ion
        7th step: Water acts as a base and causes a deprotonation
    - - 1st step: Nucleophilic attack on the carbonyl double bond
        2nd step: Formation of the 4-membered oxaphosphetane ring.
        3rd step: Intramolecular elimination
    - - Basic conditions
      - Acidic conditions
    - - The carbon is electrophil : good cible for a nucleophil
    - - 1st step: bond formed between the nucleophile and the electrophilic Carbon atom
      - 2nd step : alkoxide intermediate is protonated byt addition of an acid to form an alcohol
    - - aldehyde more reactive : 1°carbocation less stable than 2°carbocation of a ketone
      - reactivity of a carbonyl toward nucleophilic addition decrease with increase of the bulkiness of carbonyl substituents
- - - - 2) Nucleophilic attack by the enolate
        
        The enolate adds to the electrophilic carbonyl group on a second molecule.
      - 3) Protonation
        
        Protonation of the alkoxide forms the neutral aldol product and regenerates the base.
      - 1) Enolate formation
        
        A base removing an alpha hydrogen to form a nucleophilic enolate.
    - - This reaction is a dimerization of an aldehyde/ ketone to form a beta-hydroxy aldehyde/ ketone
      - It is an equilibrium reaction and is reversible
      - Weaker bases can be used to perform this reaction
  - - - A catalytic amount of base is used to generate only a small amount of the the enolate ion
        
        The base catalyst is regenerated which can then produce more enolate ion and continue the cycle.
        
        All steps are reversible
    - - The enolate ion intermediate is generated all at once with a full equivalent of strong base at low temperature
        
        The reactive enolate intermediate then is quickly quenched by rapid addition of the electrophile to complete the substitution reaction
  - - - 1) Form an enolate
        
        The base removing an alpha-hydrogen to form an enolate ion.
      - 2) Form the enone
        
        The alkoxide reforming the carbonyl C=O bond promotes the elimination of alcohol OH as a leaving group which reforms the base catalyst
    - - 1) Protonation
        
        Two step tautomerization process to form an enol.
      - 2) Form an enol
        
        Creation of the enol
      - 3) Protonation
        
        Protonation of the alcohol OH increases its ability to act as a leaving group.
      - 4) Elimination
        
        Lone pair electrons from the enol reform the carbonyl C=O bond and promoted the elimination of water as a leaving group.
      - 5) Deprotonation
        
        Deprotonation by water in the final step create the neutral enone product and regenerates the acid catalyst.
- - - - Tautomerism is the transformation of one functional group into another, most often by the concomitant displacement of a hydrogen atom and a π bond
      - Tautomers
        
        Constitutional isoemers
    - - Keto is largely more found than Enol forms are equilibrium but Enol forms are responsible of the most of reactivity from these compunds
        
        Examples
    - - In each, the mechanism is different
        
        Base catalyzed enol formation
        
        It involves protonation of the carbonyl owygen and then deprotonation of the alpha hydrogen
        
        Acid catalyzed enol formation
        
        It involves deprotonation of the alpha hydrogen and then the formation of a negatively charched enolate which is protonated on oxygen to form an enol
  - - - Only the α position of carbonyl is acidic, so the only α-hydrogen can be removed by a base
  - - - Through Enol intermediate
        
        Which is an alkene with an alcohol function in the vinyl position
      - Trough Enolate intermediate
        
        which is resulting from the irreversible tearing of a proton by a base from an enol
      - Step by step
        
        We start with an enol formed thank tautomerism
        
        Enol are reacting as nucleophile because their double bond are electronrich. So they react with elecrophile
  - - - Hell–Volhard–Zelinskii reaction
  - - - Hydrogen at α position is weakly acidic and can be removed by a strong base. From a carbonyl compound, it will lead to an enolate ion as seen in the Keto-Enol tautomerism
        
        This enolate formation occurs when a α C-H bond is oriented parallel to the p orbitals of the carbonyl group
        The α carbon of enolate ion is sp² hybridized and has p orbital that overlaps the carbonyl p orbitals
        The negative charge is shared by the
        electronegative oxygen atom, and the enolate ion is stabilized by resonance
        
        When a hydrogen is surrounded by 2 carbonyl groups, it's even more acidic
    - - Enols are less useful than enolates because they are less stable. They are present only as an intermediary
      - On the contrary, one can easily obtain enolates in a stable manner with the use of a strong enough base.
      - Thanks their negative charge, enolate are the most reactive as well
    - - Akylation reaction in the alpha position through an SN2 reaction with akyl halides
        
        There are difference of reactivity depending on what is the R and what is the X
      - Malonic ester Synthesis
        
        Malonic synthesis is a set of reactions allowing the synthesis of many primary or secondary carboxylic acids from diethyl malonate
        
        To simplify , Malonic ester is written as:
        
        )
        
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      - In the same kind of reaction as malonic ester synthesis, the synthesis of acetoacetic ester converts an alkyl halide to a methyl
        ketone having three other carbons
- - - - they cannot be converted into simpler sugars (such as glucose)
        
        Among the monosaccharides, we can find aldose and ketose (for example, glucose is aldose and fructose is ketulose)
    - - Disaccharides
        
        Maltose and Cellobiose
        
        Maltose consists of two -D-glucopyranose units connected by 1→4-α-glycosidic bonds
        
        Both maltose and cellobiose are reducing sugars because the anomeric carbon on the right glucopyranose unit has a hemiacetal group and is in equilibrium with the aldehyde form. Although their structures are similar, cellobiose and maltose have very different biological properties
        
        Cellobiose consists of two β-glucopyranose units connected by 1→4-β-glycosidic bonds
        
        Sucrose
        
        Sucrose is a disaccharide that is hydrolyzed to produce 1 equivalent of glucose and 1 equivalent of fructose. It is not a reducing sugar and does not undergo mutarotation. As a result, sucrose has no hemiacetal group.
      - Polisaccharides
        
        Starch and Glycogen
        
        Starch can be divided into two parts: Amylose and amylopectin. Amylose accounts for about 20% by weight Starch is connected by hundreds of glucose molecules 1→4-glycosidic bond, so 80% of the remaining polysaccharide is amylopectin
        
        Glycogen is a polysaccharide with the same energy storage function Starch plays a role in plants in animals. Like amylopectin found in starch, glycogen contains complex branches It has a structure of 1→4 and 1→6 links, but they contain more branches
        
        Cellulose
        
        Consists of thousands of D-glucose units connected by 1→4-β-sugar side bonds.
        
        Nature mainly uses cellulose as a structural material to give strength and stiffness of plants
  - - - Then, an L sugar is the mirror image (enantiomer) of the corresponding D-sugar. It is also important that the D and L systems of the carbohydrate nomenclature only describe the configuration of one chiral center, but do not mention the configuration of other chiral centers that may exist