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Sunday 31 August 2014

Synthesis of erythro-9,10-dihydroxystearic acid, ارثرو-10،9-ثنائي هيدروحامض الستيارك, erythro-9,10-Διυδροστεατικό οξ

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Erythro-9,10-Dihydroxystearic acid [3639-32-5]



Name erythro-9,10-Dihydroxystearic acid
Synonyms (9R,10S)-rel-9,10-Dihydroxyoctadecanoic acid
Name in Chemical Abstracts Octadecanoic acid, 9,10-dihydroxy-, (9R,10S)-rel-
CAS No 3639-32-5
EINECS No
Molecular formula C18H34O4
Molecular mass 330.51








Oleic acid
KMnO4/NaOH
reacts to
erythro-9,10-Dihydroxystearic acid


Literature
A. Lapworth und E. N. Mottram, J. Chem. Soc., 1925,1628-31


Reaction type:addition to alkenes, oxidation, cis-hydroxylation
Substance classes:alkene, alcohol, natural product
Techniques:stirring with magnetic stir bar, filtering, recrystallizing, extracting
Instruction (batch scale 10 mmol) 
Equipment 
5 L beaker or Erlenmeyer flask, heatable magnetic stirrer, magnetic stir bar, suction flask, 
Buechner funnel, mortar, desiccator 
Substances 
oleic acid (techn. 90%) 3.14 g (equivalent to 10.0 mmol pure oleic acid) 
(oleic acid, pure: mp 16 °C, 
bp 193 °C/1.6 hPa) 
potassium permanganate 2.50 g (15.8 mmol) 
sodium hydroxid 3.14 g (78.5 mmol) 
hydrochloric acid (conc., 36%) 94 mL 
sodium sulfite or sodium disulfite 
petroleum ether (bp 60-80 °C) about 200 mL 
ethanol (bp 78 °C) for recrystallizing 
Reaction 
3.14 g (10.0 mmol) oleic acid (techn. 90%) are added to a solution of 3.14 g (78.5 mmol) 
NaOH in 320 mL water in a 5 L beaker with a magnetic stir bar. The mixture is heated under
stirring until a clear solution is formed. After the addition of 2.5 L ice-cold water, 250 mL 1% 
potassium permanganate solution are added within 1 minute under stirring at a temperature of 
10 °C. After 5 minutes so much solid sodium sulfite oder sodium disulfite is added, that the 
excess of potassium permanganate is reduced. Afterwards the solution is acidified with 94 mL 
conc. hydrochloric acid. The solution becomes colourless, and a colourless fluffy precipitation 
is formed. 
Work up 
The precipitation is sucked off and dried. Crude yield: 3.01 g, mp 81-88 °C 
The crude product is washed with 50 mL petroleum ether (60-80 °C) and dried under reduced 
pressure. The dried product is powdered in a mortar and digested with 100-150 mL petroleum 
ether in a beaker. Thus the sturated carboxylic acids contained in the oleic acid as impurities 
are removed. The dihydroxystearic acid is insoluble in petroleum ether. It is sucked off and 
recrystallized from ethanol. 
Yield: 2.74 g (8.70 mmol, 87%); mp 132 °C; colourless powder 
Yield71%Target product mass0.26gSum of input masses290gMass efficiency0.89mg/gMass index1100g input / g productE factor1100g waste / g product

Equipment

Batch scale:0.0011 mol


beaker 500 mLbeaker 500 mLheatable magnetic stirrer with magnetic stir barheatable magnetic stirrer with magnetic stir bar
suction flasksuction flasksuction filtersuction filter
mortarmortarexsiccator with drying agentexsiccator with drying agent






Operating scheme





crude product chromatogram


TLC: crude product
TLC layerMerck silica gel 60 F254
mobile phaseEtOAc
detectionimmerse into solution of 2.7 g KMnO4, 18 g K2CO3, 216 mg NaOH in 274 mL H2O, heating with air dryer
Rf (educt)0.87
Rf (product)0.67



1H NMR


1H-NMR: erythro-9,10-Dihydroxystearic acid
250 MHz, DMSO-d6
delta [ppm]mult.atomsassignment
0.86t (3J = 6.4 Hz)3 HCH3
1.2-1.6m26 Hother CH2
2.18t (3J = 7.3 Hz)2 H2-CH2
3.25m2 H9-CH-OH, 10-CH-OH
2.45s6 HDMSO


13C NMR


13C-NMR: erythro-9,10-Dihydroxystearic acid
62.5 MHz, DMSO-d6, 373°K
delta [ppm]assignment
13.0C18 (CH3)
21.2C17 (CH2
23.9CH2
24.8CH2
27.9CH2
28.0CH2
28.3CH2
28.4CH2
28.6CH2
30.6CH2
31.8CH2
33.2C2
73.4C9, C10 (CH-OH)
173.4C1 (COOH)
38.5-40.5DMSO-d6
IR


IR: erythro-9,10-Dihydroxystearic acid
[KBr, T%, cm-1]
[cm-1]assignment
3500-2500O-H valence, superimposed on C-H valence
1716C=O valence, carboxylic acid





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