why alcohols are not prepared from alkanes
Answers
Answer: ans here
Explanation: Generally alkyl halides can be prepared from alcohols via:
R-OH+HX→ R-X + H2O
Alkyl fluoride cannot be prepared via this reaction because:
H-F is a weak acid, does not ionise to give ample F- ions for the reaction.
Alcohol has OH- ion, a poor leaving group. HCl, HBr and HI are stronger acids. They increase the tendency of the OH- ion to depart from the R component. However since HF is a very weak acid, it cannot obtain the above tendency.
Talking about the other methods:
Alcohols cannot be reacted with PF5 to yield RF ( unlike PCl5 to get RCl) because:
a. Fluorine atoms in PF5 are poor leaving groups (possibility of back-bonding from fluorine atoms to the P centre).
b. Thus PCl5 is more reactive than PF5 and the reaction mechanism will not be initiated in case of PF5, i.e. the first step will not occur; forget the whole reaction!
Source of image: Chemistry Stack Exchange
2. SOF2 is again more stable than SOCl2 (due to higher S-O bond order for SOF2), thus retarding the first step itself!
Explanation:
alcohols are not prepared from alkanes as alkanes cannot combine with OH to form alcohol, while Alkyl groups can combine with OH to form Alcohols