Cloroform

--

Abstract:

This synthesis of cloroform (trichloromethane) is an application of the the haloform reaction. In this haloform reaction, a hypochlorite (OCl-) reacts with a methyl ketone or secondary alcohol to form chlorform.

--

Reagents used:

A hypochlorite; either sodium hypochlorite (NaOCl) or calcium hypochlorite ( Ca(OCl)2 ). OTC sources for these are bleach (~6% NaOCl soln) or an HTH pool chlorinating compound. Be sure, if you get a pool chlorinator, that it is, in fact, calcium hypochlorite and not ____________________.

A methyl ketone or secondary alcohol; the most readily available and simplist to use reagent is acetone, a methyl ketone, because it does not require oxidation.  If you use an alcohol, more hypochlorite will be required in order to oxidise the alcohol to a ketone.  If you wish to use an alcohol, use isopropanol, a secondary alcohol. Special reagents that will work are ethanol and ethanal (acetylaldehyde).  Ethanal, besides being too valuable for this reaction, requires increased pressure due to its low BP, and, therefore, it is not feasable for most home hobbiests.


Table of Physical Constants:

Substance		MM(g/mol)		MP(*C)		BP(*C)		Density(g/cm3)
Acetone
Calcium Hypochlorite
Calcium Chloride
Ethanol
Ethanal
Isopropanol
Sodium Hypochlorite

--

General Reactions:

For a methyl ketone:					For a secondary alcohol:

CH3-CO-R + 3OCl- (aq) --> CCl3-CO-R + 3OH-		CH3-CHOH-R + OCl- (aq) --> CH3-CO-R + Cl- + H2O

CCl3-CO-R + OH- --> HOOC-R + CCl3-			You have now sythesised a methyl ketone. Continue

R-COOH + -CCl3 --> R-COO- + CHCl3			from the reaction for a methyl ketone.


Specific Reactons:

For acetone:						For isopropanol:

CH3-CO-CH3 + 3OCl- (aq) --> CCl3-CO-CH3 + 3OH-		CH3-CHOH-CH3 + OCl- (aq) --> CH3-CO-CH3 + Cl- + H2O

CCl3-CO-CH3 + OH- --> HOOC-CH3 + CCl3-			You have now sythesised acetone. Continue

CH3-COOH + -CCl3 --> CH3-COO- + CHCl3			from the reaction for acetone.


For ethanol:

CH3-CH2-OH + OCl- (aq) --> CH3-Ch2-CHO + Cl-

CH3-CHO + 3OCl- (aq) --> CCl3-CHO + 3OH-

CCl3-CHO - OH- --> CHOOH + CCl3-

COOH + CCl3- --> CHOO- + CHCl3

--

Equipment used:

Simple and fractional distillation apparatus

Separatory funnel

Ice bath




Proceedure:



--