Thermo Scientific
| Reagents, Solvents and Accessories
19
Alkylation and Alkylation Reagents
When used in derivatization for gas chromatography,
alkylation represents the substitution of an active hydrogen
by an aliphatic or aliphatic-aromatic
1
(benzyl) group. This
technique is used to modify those compounds containing
acidic hydrogens, such as carboxylic acids and phenols.
The principal chromatographic use of this reaction is the
conversion of organic acids into esters, which produce
better chromatograms than the free acids.
In addition, alkylation reactions can be used to prepare
ethers, thioethers and thioesters;
N
-aIkylamines; and
amides.
2
As the acidity of the active hydrogen decreases,
the strength of the alkylating reagent must be increased.
As the reagents and conditions become harsher, the
selectivity and applicability of the methods become more
limited.
References
1. Kawahara, F.K. (1968). Microdetermination of derivatives of phenols and
mercaptans by means of electron capture gas chromatography.
Anal. Chem.
40(6)
, 1009.
2. Kananen, G.,
et al.
(1972). Barbiturate analysis – a current assessment.
J. Chrom. Sci.
10
, 283-287.
BF
3
-Methanol
Provides convenient, fast and quantitative esterification of
fatty acids.
BF
3
-Methanol
14% BF
3
MW 67.82
86% CH
3
OH MW 32.04
F B CH
3
F
F
O
H
:
BF
3
-Methanol methylation is one of the most convenient
ways to prepare methyl esters of fatty acids. Supplied in an
easy-to-use septum-sealed Hypo-Vial Sample Storage Vial,
Thermo Scientific BF
3
-Methanol offers convenient syringe
removal of your sample – without exposing the contents.
PROTOCOL 1
For preparing fatty acid methyl esters.
1. Combine 100 mg fatty acid and 3 ml BF
3
-Methanol in a 5.0 ml
Thermo Scientific Reacti-Vial Small Reaction Vial.
2. Cap vial and heat at 60°C for 5-9 minutes.
3. Cool and transfer to separatory funnel with 30 ml hexane.
4. Wash 2 times with saturated NaCI solution.
5. Discard aqueous layers.
6. Dry over sodium sulfate.
7. Evaporate solvent under nitrogen.
8. Analyze by gas chromatography.
PROTOCOL 2
For preparing C8-C17 fatty acids.
1. Combine 500 mg fatty acid and 5 ml BF
3
-Methanol in a 25 ml flask.
2. Heat on a steam bath for 5 minutes.
3. Add saturated NaCI solution until total volume is ~20 ml.
4. Cap flask and invert several times.
5. Allow organic layer to collect at the top, then separate.
6. Dry organic layer over Na
2
SO
4
.
7. Evaporate solvent under nitrogen.
8. Analyze by gas chromatography.
Ordering Information
Product # Description
Pkg. Size
✖
TS-49370
BF
3
-Methanol
100 ml Hypo-Vial
Sample Storage Vial
✖
Additional hazardous handling charge.
Thermo Scientific
Alkylation Reagents
