Alcohols and Epoxides Flashcards
Alcohols
- Polar sp3-hybridised oxygen atom
- Creates a permanent dipole
- soluble in water and can form hydrogen bonds
Synthesis of alcohols
- Nucleophilic substitution on an alkyl halide
- Via Sn2 mechanism compete with elimination
- Markovnikov product more carbon cations (oxymercuration)
- Acid catalysed hydration with H+
Acetylide ion reacting with formalderhyde
Formation of primary alcohol
Reagent in Markovnikov
Boron
Reagent in AntiMarkovnikov
Mercuary
Organometallic compound
- Covalent bonds between carbon atoms and metal ions
- Has nucleophilic carbon atoms strong nucleophile
Grignard Reagents
- Groups are not acidic enough to be deprotonated by NaNH2
- When ketone or alderhyde is converted to alohol with another group
- Alkyl halide with magnesium metal in a anhydrous ether solution
Oxidation
- Loose H2 or adding oxidising agent
Reduction
- Loose O, O2 or X2 or adding reducing agent
Oxidation of primary alcohol reagent
- NaOCl or chromic acid H2CrO4
- Forms alderhyde
Oxidation of primary alcohol to alderhyde
- Dess–Martin periodinane
- NaOCl
- Forms carboxylic acid
Oxidation of alcohol in body Ethanol
- Ethanol reacts with the reagent NAD in the liver
- The alcohol dehydrogenase forms acetalderhyde
- then acetalderhyde reacts with NAD again and is oxidsed to acetic acid - not toxic
Markovnikov product
Acid-catalysed hydration with H2O
Oxymercuration–demercuration
Hg(OAc)2 followed by NaBH4
Chemical agents
- Disinfection on inanimate objects and antiseptic for human tissue
- Only few chemicalsagen achieve sterility
Factors that influence efficacy
- Kind of organism
- Degree of contamination
- Time of exposure
- Nature of the material treated
- Concentration of disinfectant
Synthesis of Alcohols from Alkenes
- Dihydroxylation synthesis add potassium manganite and hydroxyl ion
- Alkene turns to peroxyacid then to epoxide then carboxylic acid to alcohol
Organolithium Reagent
- Lithum reacts with halide to for organolithium reagent
- Strong nucleophiles and bases
Alcohol synthesis with Grignard reagent
- Formation of grignard where magnesium reacts with an alkyl halide in an anhydrous ether
- Grignard reagent attacks a carbonyl compound to form alkoxide salt
- After first reaction is complete water is added to protonate the alkoxide and give alcohol
- Alcohol with new Carbon-Carbon bond formed
Epoxide with organometallic reagent
- Nucleophilic displacement of epoxide forming a primary alcohol
Organometallic reagent with acid chloride and ester
- Both form tertiary alcohol
- Formation of unstable intermediate
- Formation of Ketone then alkoxide finally tertiary alcohol
Reduction of C=O synthesis of primary and secondary alcohol
- Hydride reagent add hydride ion reducing C=O to alkoxide ion
- Sodium Borohydride transfers a hydride ion to form carbon forming alkoxide
- Alcohol solvent protonates the alkoxide
Reduction of C=O using LiAlH4
- LAH transfers hydride ions to hydride ions forming an alkoxide ion
- After first reaction is complete water or diluted acid is added to protonate alkoxide
- Stronger than NaBH4 easily reducing ketones and alderhydes
- Reduces carbonyl groups and esters