AlcoholEtThioChMedl.ppt Flashcards
Are the alcohols homologous?
yepp
Where are alcohol derived from?
Alcohols are derived from alkanes by substituting an -OH group for an -H atom.
When can we get isomeric compounds possible?
For alcohols containing more than two C atoms, isomeric compounds are possible
Polyhydric alcohols
Alcohols with more than one -OH group
Phenols
-OH group directly attached to a benzene ring
Physical properties of alcohol:
- polar
- forms hydrogen bonds
What happens with alcohol in strongly acidic solutions?
In strongly acidic solutions alcohols undergo substitution readily because a protonated alcohol contains very weakly basic leaving group-water
Elimination reaction of alcohol:
When heated with the strong acid, an alcohol with β-hydrogen can undergo dehydration (loss of water) to yield an alkene.
What happens with alcohol when it reacts with carboxylic ester?
reaction of alcohol with carboxylic acid yields carboxylic ester, called simply ester.
What are ethers derived from?
Ethers are derived from alkanes by substituting an alkoxy group (-OR) for an H-atom
Physical properties of ethers:
- slightly polar
- dont form hydrogen bonds
- slightly soluble in water
- mixes well with other nonpolar molecules such as alkanes
- the boiling point is similar to that of the alkane with corresponding relative molecular mass
- the lower ethers are very volatile and dangerously flammable
Thiol
- is an organosulfur compound that contains a sulfur-hydrogen bond (S-H).
- sulfur analogue of an alcohol
Mercaptans
sometimes thiols are referred to as mercaptans
how is the bonding between the thiol groups?
In the solid or molten liquids, the hydrogen-bonding is weak, the main cohesive force being van der Waals interactions between the highly polarizable divalent sulfur centers.
Physical properties of thiols:
- strong odorous resembling that of garlic
- strong and repulsive odorous, particularly those of low molecular weight (e.g. skunk spray)
- low boiling point
- less soluble in water and other polar solvents tan alcohols of similar molecular weight
- thiols are more acidic than alcohols
What can thiols form in proteins?
The thiols group in proteins can be oxidized to disulfide groups. The -S-S- bridge bonds two proteins molecules and hold them in their necessary shapes.
Phenols
compounds that have -OH group directly bound to benzene ring are called phenols.
Phenols are derived from ………
hydroxybenzene
Naphtols and phenathrols
compunds that have -OH group attached to polycyclic benzoid ring. chemically similar to phenol
The methyl phenols are commonly called
cresols.
1,4-benzenediol
hydroquinon
1,3-benzenediol
resorcinol
1,2-benzenediol
catechol
female sex hormone
estradiol
antibiotics
tetracyclines
Phenols compared to alcohols
phenols are stronger acids than alcohol
How can we form esters using phenols?
Phenols react with carboxylic acids anhydrides and acyl chlorides to form esters
Williamsons synthesis
Phenols can be converted to ethers through Williamson synthesis
Cleavage of alkyl aryl esters
when alkyl aryl esters react with strong acids as HI or HBr, the reaction produces an alkyl halide and phenol
