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M.B. GRAHAM AND J.H.P. TYMAN
(t, Me), 1.30 (m, CH2), 2.35–2.55 (t, 2H, CH2), 3.35–3.45 (m,
CH(OH), 5.0–5.60 (bs, OH, D2O exch.), 6.4–6.8 (m, 4H,
HAr). The experiment was repeated with cardanol (10 g) to
give yields of 73 and 53% for the hydroxylation/formoxyla-
tion and hydrolysis stages, respectively. The chemical shift at
δ 0.90 was due to traces of (15:0)-cardanol.
requires C, 81.55%; H, 10.68%; δH as for 3-octylphenol pre-
pared from ozonization and reductive treatment.
Ozonization of anacardic acid to 6-(8-formylheptyl)-2-hy-
droxybenzoic acid, 8. Anacardic acid (Fig. 1a–d) (1.0 g, 2.91
mmol) in ethyl acetate (25 mL) was ozonized at −78°C for
5.5 h, at which time TLC monitoring indicated that no acid
remained. The mixture was hydrogenated in the presence of
Pd-C (0.12 g), and reduction was considered to be complete
upon absorption of hydrogen (110 mL). Filtration of the mix-
ture and rotary evaporation of the filtrate in vacuo gave a
crude brown oil (0.80 g, 73%); IR, υmax (film/cm−1), 3300
(O–H), 2980 (C–H), 2850 (CH, arom.), 1710 (C=O),
1650–1670 (C=O, H-bonded), 1610 (CH, arom.), 1460, 1240,
The polyol product (0.80 g, 2.20 mmol) in ethanol (60 mL)
was added to potassium periodate (1.50 g) in 1 M sulfuric acid
(75 mL), and the mixture was stirred at 40°C for 20 min, after
which dilution with water, extraction with diethyl ether, drying
(Na2SO4), and recovery by evaporation in vacuo afforded the
crude product as a pale oil (0.61 g, 80.4%, as a mixture of 4 with
heptanal), having strong IR absorption at 1690 cm−1. After rotary
evaporation in vacuo to constant weight to remove heptanal, the
product was spectrally similar to that obtained from ozonolysis.
(ii) Cardanol acetate. Although stability experiments indi-
cated that relatively little attack on the aromatic ring and the
OH group had occurred, it was of interest to examine the use
of cardanol acetate. This was prepared from mixed cardanol
(3.98 g, 13.27 mmol) in pyridine (14 mL) containing acetic
anhydride (7 mL) by warming for 2 h followed by dilution
with iced water, extraction with light petroleum ether, acidic
washing, drying (Na2SO4), and evaporation to afford a pale
brown oil (4.30 g, 95%).
Cardanol acetate (3.07 g, 8.87 mmol) with 98% formic acid
(17.25 mL) was cooled in an ice bath, stirred, and treated
slowly with 30% H2O2 (1.10 g, 32.0 mmol). After TLC moni-
toring and reaction overnight, the mixture was extracted with
light petroleum ether (3 × 100 mL), and the combined extracts
were washed with NaCl solution, dried (Na2SO4), and evapo-
rated to give a crude pale brown oil (2.15 g, 52%; yield calcu-
lated on basis of the percent composition of the unsaturated
constituents of cardanol and formation of the monoformate of
each trans-polyol as the phenolic acetate) with IR absorption
maxima at 1700 and 1750 cm−1 (mono OCHO and OCOMe)
and diminished alkene absorption (2970 cm−1). The formy-
lated acetylated product (1.59 g) was hydrolyzed with 1 M
sodium hydroxide (17 mL) and warmed at 40°C until TLC
monitoring indicated hydrolysis to the trans-polyols was com-
plete. Workup as before afforded a viscous brown oil (1.16 g,
92.0%); IR, υmax (film/cm−1) 3300 cm−1 (OH); 1H NMR, δH
(60 MHz, CCl4, ppm) 0.90 (t, Me), 1.35 (m, 12H, CH2),
2.35–2.60 (t, 2H, CH2Ar), 3.40 [m, 4H, CH(OH)], 3.4–5.0 (bs,
4H, OH, D2O exch.), 6.60–7.2 (m, 4H, HAr). [The peak at δ
0.90 is due to traces of (15:0)-cardanol.] The polyol product
(0.28 g, 0.77 mmol), in ethanol (20 mL), was added to potas-
sium periodate (0.50 g) in 1 M sulfuric acid (25 mL), and the
mixture was warmed to 40°C and stirred for 20 min. After
monitoring by TLC, the cooled mixture was diluted with
water, neutralized with 1 M NaOH solution, and extracted
with light petroleum ether. The combined extracts were dried
(Na2SO4) and rotary evaporated in vacuo to give a crude pale
oil (0.22 g, 92.4%) consisting of 4 (plus heptanal); IR, υmax
(film/cm−1), 1700 cm−1 (C=O); 1H NMR, δH (60 MHz, CCl4,
ppm), 1.30 (s, 12H CH2), 2.20 (t, 2H, CH2CO), 2.80 (t, 2H,
CH2Ar), 6.45–6.80 (m, 4H, HAr), 9.1 (s, 1H, CHO), 9.60 (s,
1H, OH, D2O exch.). After removal of heptanal by evapora-
1
1140, 920, 830 cm−1; H NMR, δH (60 MHz, CCl4, ppm),
0.90 (t, Me), 1.30 (m, 10H, CH2), 2.20 (t, 2H, CH2CHO), 2.80
(t, 2H, CH2Ar), 6.80 (m, 3H, HAr), 8.50 (bs, 2H, OH, HO2C,
D2O exch.), 9.80 (s, 1H, CHO). The small peak at δ 0.90 was
due to some heptanal; m/z (M+ 264, C15H20O4 requires 264),
108 (C7H8O, base peak by loss of CO2).
Ozonization of cardol to 5-(8-formylheptyl)-1,3-benzene-
diol, 9. Cardol (Fig. 1a–d) (0.36 g, 1.14 mmol) in ethyl ace-
tate (75 mL) was treated at −78°C with ozonized air, and the
reaction, which was monitored (TLC), was complete after 4.5
h. The mixture was then hydrogenated with the addition of
Pd-C (0.25 g). After the uptake of hydrogen (53 mL), the mix-
ture was filtered and the filtrate evaporated in vacuo to give a
crude brown oil; IR, υmax (film/cm−1) 3300 (s, C–H), 1695 (s,
C=O) cm-1; m/z (M+ 236, C14H20O3 requires 236). Before ex-
amination of the 1H NMR spectrum, the product had semi-
polymerized although faint chemical shifts were present for
CHO, HAr, and CH2 groups.
Hydroxylation of cardanol and of cardanol acetate with
performic acid and cleavage of the product with periodic acid
to give 8-(3-hydroxyphenyl)octanal, 4. (i) Cardanol. Initially,
the stabilities of the aromatic ring in (15:0)-cardanol toward
performic acid and of cardanol (Fig. 1) to periodic acid were
examined. More than 80% of slightly discolored material was
recovered in each case.
Cardanol (Fig. 1) (2.69 g, 8.97 mmol) added to 98% formic
acid (17.25 mL) was cooled to 0°C, the suspension was slowly
treated with 30% H2O2 (1.1 g, 32.0 mmol), and the suspension
was left for 1 wk. After diluting with water, the reaction mix-
ture was extracted with diethyl ether; the combined extracts
were washed with NaCl solution (100 mL), dried, and evapo-
rated to give a crude pale brown oil (2.85 g, 76.3%) compris-
ing a mixture of vicinal monoformates (from the 8,9-diol, the
8,9,11,12-tetraol, and the 8,9,11,12,14,15-hexaol) having an
Rf value below that of cardanol and an IR spectrum with an
absorption peak at 1720 cm−1 (formate). The product was hy-
drolyzed with 1 M NaOH solution (30 mL) by warming for 3
h (with TLC monitoring). The cooled mixture was acidified
with dilute hydrochloric acid, extracted with diethyl ether (2 ×
100 mL), and the combined extracts were dried (Na2SO4) and
evaporated to give a crude brown viscous liquid (1.39 g,
56.1%) consisting of the trans-polyols having a low Rf value
with strong IR absorption at 3300 cm−1 (OH) and absence of
C=O absorption; in the 1H NMR, δH (60 MHz, CCl4, ppm) 0.9
JAOCS, Vol. 79, no. 7 (2002)