Oxygen Containing Reactions Flashcards
Nucleophile
Donates e- , lewis base, low electronegativity
RhH2C > RHN- > RO-
ex. -OH and -NH to attack carbonyl
Leaving grp
Portion of molecule that leaves when carbonyl attacked
Good leaving groups: atoms in higher periods, gases, weak nucleophile/weak base
Leaving Grp vs. Nucleophilicity
Leaving grp quality ————————————>
CH3- NH2- OR- OH- NH3 RCOO- H2O
Alcohols
Name ends in -ol, name takes precedence unless carbonyl present, increases BP
Rxns of Alcohols
As nucleophiles: (O donates e-)
As acids: (strongest) methyl> 1° > 2° >3° (weakest)
As leaving grp: Nucleophilic Substitution, -OH as nucleophile (ex. Tosylates and Mesylates for -OH protection)
Alcohol -> Alkyl halide
CH3-CH-OH + H-Cl ->Cl- + CH3-CH-OH2+ ->Cl-CH2-CH3 + H20
O donates e- and take H from H-Cl
H2O leaves and Cl- takes its place
Synthesis of Toslate and Mesylate
H-OR acts as nucleophile and causes Cl- to leave to become H-Cl
Ether Rxns
Common solvent (relatively non-reactive), participates in substitution rxn or cleavage if a reactant
Cleavage of Ether
R-O-R’ + H-Br -> R-OH + R-Br
Nitrogen Rxns
Better nucleophile/worse leaving grp than O
Nitrogen as Nucleophile
Lone pair e- attacks + charge
Nucleophilic Additon: Amine + Aldehyde/ketone
Nucleophilic substitution: Amine + carboxylic acid
Nitrogen as Base
N takes on 4th bond becoming + charged
Ammonia/amines donate e- (acts as base)
Electrophiles and Rxns
Most have carbonyls, planar chemistry aids in decreasing steric hindrance, C with δ+
w/ leaving group: nucleophilic substitution rxn (acyl chlorides, esters, amides)
w/o leaving group: nucleophilic addition rxn (ketones, aldehydes)
Reactivity of Carbonyls
Least -> Amide - Carboxylic acid - Acid Anhdride/Ester - Ketone/Aldehyde - Acid Halide -> Most reactive
Carboxylic Acid Rxns
Via Substitution rxns (either acts as acid and gives up H or has H20 as leaving group)
Carb. acids w/ 4 or fewer C are soluble in H20 (10+ not)
Common Carboxylic Acid Derivatives
O
|| Carboxylic Acid
R-C-OH
O
|| Formic Acid H-C-OH
O
|| Acetic Acid 3HC-C-OH
O
|| Benzoic Acid Ar-C-OH
Reactiity of Carboxylic Acid Derivatives
Least -> Amide - Ester - Carb. Acid - Anhydride - Acid Halide -> Most
Esterification
Carboxylic acid + Alcohol -> H+ -> Ester + H20
Alcohol acts as nucleophile
Transesterification
Ester + Alcohol -> H+ -> New Ester + New Alcohol
Lactone Formation
Intramolecular esterification
Ketone/Aldehyde Rxns
Via addition rxns
Very reactive because -H or -C don’t donate e- density
1. Nucleophile attacks carbonyl carbon
2.Carbon releases pi-bond e- to O
Acidic Conditions: O e- take H+ from acid, then Nuc attacks
Basic Condiions: Nuc attacks, O e- take H+ from H20
Keto-enol tautomers
H hops to neighbor C, =O protonated
H O H OH H
| || | | |
R-C-C-C-H -> R-C=C-C-H
| | | |
H H H H
Kinetic Enolate
Ketone in basic conditions, less substituted double bond, kinetically favored, less stable product
Thermodynamic Enolate
Ketone in basic conditions, more substituted double bond, increases AE, more stable product
Imine
Original amine has 0-1 R groups, C=N
Enamine
Original amine has 2 R groups, C=C
Grignard Synthesis of Alcohol
R-MgX + R-C=O -> R-3-C-O - + MgX -> R-3-C-OH + XMgOH
Reduction Synthesis of Alcohol
H- + Ketone -> R-2-CH-O - -> R-2-CH-OH
Oxidation
Increases bonds to O, loss of C-H bonds, decrease e- density
Reduction
Increases bonds to H or R, decreases bonds to O, increase e- density
Common Oxidizing Agents
K2Cr2O7 - 1° alcohol or aldehyde -> Carb. Acid
K2MnO4 - 1° alcohol or aldehyde -> Carb. Acid
H2CrO4 -1° alcohol or aldehyde -> Carb. Acid
O2
PCC - 1° alcohol -> aldehyde; 2° alcohol -> ketone
Common Reducing Agents
LiAlH4: Carb. Acid or aldehyde -> 1° Alcohol
NaBH4: Aldehyde -> 1° Alcohol, Ketone -> 2° Alcohol
H2 + Pressure
Decarboxylation
Carb. Acid -> CO2 (g), exothermic, hard to do
Aldol Condensation
Carbonyl + Carbonyl
Carbohydrates
C chain w/ alcohol on each carbon except for 1 w/ aldehyde or ketone (aldose/ketose)
Carbohydrate Classification: Linear and Cyclic
D: highest -OH in Fischer projection on right
L: highest -OH in Fischer projection on left
α: -OH points opposite side of methoxy grp while cyclic
β: -OH points same side as methoxy grp while cyclic
5 member ring=furanose; 6 member ring=pyranose
Di/polysaccharide fromation
Via dehydration (acetal formation)
Common disaccharides
Sucrose: Glucose + Fructose, 1,2’ linkage
Maltose: Glucose + Glucose, α-1,4’ linkage
Lactose: Glucose + Lactose, β-1,4’ linkage
Cellulose: Chain of glucose, β-1,4’ linkage
Amylose: Chain of glucose, α-1,4 linkage
Amylopectin: branched glucose chain, α-1,4’ linkage w/ α-1,6’ branching
Glycogen: Branched glucose chain, α-1,4’ linkage w/ α-1,6’ branching
Amino Acids
Contain amine and carboxylic acid
O=C-OH
|
H-C-R
|
NH2
Gabriel Synth
Amino acids synth de novo
Strecher Synth
Amino acid from aldehyde + potassium cyanide + ammonium chloride
Fatty Acids and Triglycerides
even numbered carbon chains w/ carboxylic acid at one end + glycerol + 3 fatty acid tails
Lipogenesis
Fatty acids added on to glycerol to make triglyceride
Lipolysis/Saponification
Removal of fatty acids from glycerol
Saturated vs Unsaturated fatty acids
Saturated: no double bonds
Unsaturated: contains 1+ double bonds, decreased MP
Nucleic Acids
P=O behaves like C=O
-OH on one nucleic acid creates anhydride with phosphate group of another (phosphodiester bond)
Formation of Phosphodiester bond
Nucleophilic substitution rxn
-OH on nucleic acid attacks P of the other prod H20
Hydrolysis of Phosphodiester bond
H2O added and -O attacks P releasing e- back to O of neighboring phosphate
