Synthesis and corrosion-protective properties of acetylenic esters of bicyclo[2.2.1]hept-5-ene-2-carboxylic acid

Article abstract of DOI:10.1007/s11167-005-0021-9

A procedure was developed for preparing acetylenic esters of bicyclo[2.2.1]hept-5-ene-2-carboxylic acid. The structures of the compounds were confirmed by IR and ¹H NMR spectroscopy. The Kovats indices of the compounds were determined, and their boiling points were estimated by gas-liquid chromatography. The protective properties of the esters against acid corrosion of steel were studied.

Full text of DOI:10.1007/s11167-005-0021-9

Russian Journal of Applied Chemistry, Vol. 77, No. 8, 2004, pp. 1316 1320. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 8, 2004,
pp. 1331 1335.
Original Russian Text Copyright
2004 by Mamedov.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Synthesis and Corrosion-Protective Properties of Acetylenic
Esters of Bicyclo[2.2.1]hept-5-ene-2-carboxylic Acid
E. G. Mamedov
Institute of Petrochemical Processes, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan
Received March 5, 2004
Abstract A procedure was developed for preparing acetylenic esters1of bicyclo[2.2.1]hept-5-ene-2-car-
boxylic acid. The structures of the compounds were confirmed by IR and H NMR spectroscopy. The Kovats
indices of the compounds were determined, and their boiling points were estimated by gas liquid chro-
matography. The protective properties of the esters against acid corrosion of steel were studied.
Norbornene derivatives exhibit various useful prop-
erties. Thanks to their rigid framework structure, these
compounds with fixed substituents are promising
models for studying structure property relationships
[1]. Some norbornene derivatives exhibit analgetic,
antiseptic, and antiphlogistic properties [2, 3]. Of
particular interest are acetylenic esters of norbornene-
carboxylic acid. On the one hand, they have valuable
properties themselves; on the other hand, they are
promising as synthetic precursors of diverse valuable
compounds owing to the combination of reactive nor-
bornene and acetylenic fragments [4].
The reaction with primary alcohol II occurs at
room temperature with heat liberation and is complete
in 0.5 h. With tertiary alcohols III and IV, the reac-
tion is less facile, and the corresponding esters VI
and VII were obtained by heating at 80 C for 5 h.
The yield of the target products was 90 96%.
The structure of esters V VII was confirmed by
independent synthesis. First, we prepared acetylenic
acrylates IX XI by a reaction of acryloyl chloride
with acetylenic alcohols II IV. This was followed
by the Diels Alder addition of cyclopentadiene VII
to acrylates IX XI to obtain compounds V VII:
The synthesis of propargyl norbornenecarboxylate
by esterification of norbornenecarboxylic acid with
propargyl alcohol in the presence of Brønsted acid cat-
alysts was described in [5]. However, the yield (30%)
and purity (88%) of the target product were poor.
R1
CO2 C C C R2
V VII,
+
(2)
R1
IX XI
VIII
Proceeding with studies concerned with synthe-
sis of acetylenic esters of norbornenecarboxylic acids
[6 8], we developed a convenient synthetic route to
these compounds and examined their protective prop-
erties against acid corrosion of metals. The compounds
were prepared by reactions of bicyclo[2.2.1]hept-5-
ene-2-carboxylic acid chloride I with acetylenic al-
cohols II IV:
where R1 = R2 = H (IX); R1 = Me, R2 = H (X);
R1 = Me, R2 = CH=CH2 (XI).
The constants of compounds IV VII prepared by
both procedures are identical; they are listed in Ta-
ble 1. The compositions and structures of the com-
pounds were also confirmed by elemental analysis and
1
by IR (Table 1) and H NMR spectroscopy.
R1
The IR spectra of V VII contain the stretching
R1
CO2 C C C R2
1
COCl
vibration bands (cm ) of C=O (1730 1740), C O
+ HO C C C R2
R1
(1225 1240) and C C (2160 2165) groups. The band
1
(1) R1
at 3290 cm in the spectrum of V is characteristic of
the C H bond. The stereoisomers of V and VII have
similar IR spectra, with the absorption bands of the
double bond in the norbornene moiety at 1580 1555
I
II IV
V VII
where R1 = R2 = H (II, V); R1 = Me, R2 = H (III, VI);
R1 = Me, R2 = CH=CH2 (IV, VII).
1
[ (C=C)] and 730 710 [ (=C H)] cm . The unusual
1070-4272/04/7708-1316 2004 MAIK Nauka/Interperiodica

SYNTHESIS AND CORROSION-PROTECTIVE PROPERTIES OF ACETYLENIC ESTERS
1317
Table 1. Properties of acetyenic esters V VII of norbornenecarboxylic acid
bp,
P, mm Hg
C
Com-
pound
Found, %
Calculated, %
1
Yield, %
nD20
d420
Formula
IR spectrum, , cm
100
5
74.61
75.0
6.73
6.81
1740 (C=O), 1110 (C C),
1620 (C=C), 3290 ( C H)
V
96
92
90
1.4936 1.0836
1.4810 1.0318
1.5011 1.0269
C11H12O2
C13H16O2
C15H18O2
78
2
75.01
74.45
7.11
7.84
1735 (C=O), 1020 (C C),
1620 (C=C), 2160 (C C)
VI
98
2
77.21
78.26
7.12
7.82
1730 (C=O), 1040 (C C),
1615 (C=C), 2165 (C C)
VII
Table 2. Retention volumes Vr, relative retention volumes Vrrel (menthol as reference), Kovats indices IK, and boiling
points of compounds V VII and reference substances
Vrrel
Vr
log Vr
Compound
IK
bp,
C
(on Apiezon)
PEGS
Apiezon
PEGS
Apiezon
Menthol
exo-V
endo-V
1
1
228
730
880
440
560
810
1000
446
730
780
860
910
2310
2500
60
4.21
4.91
4.15
4.85
5.02
6.92
1.46
1.52
1.45
1.50
2.45
2.65
2.86
2.89
2.93
2.96
3.36
3.40
1.78
1.99
2.23
2.43
2.72
2.95
3.22
3.56
1128
1240
1256
1268
1243
1438
800
221.3
223.9
227
229.3
257.1
259.7
125
157
174
196
216
exo-VI
endo-VI
exo-VII
endo-VII
Octane
Nonane
Decane
Undecane
Dodecane
Tridecane
Tetradecane
Pentadecane
99
900
168
266
528
888
1668
2600
1000
1100
1200
1300
1400
1459
235
253
263.7
position of the first band may be due to the strained
state of the ethylene bond in the bicyclo[2.2.1]heptene
moiety [9]. The position of the (=C H) band depends
on the orientation of the substituent in the carbon
skeleton of V (705 700 and 735 720 cm for exo
and endo isomers, respectively).
In the 1H NMR spectra, the major differences between
stereoisomeric propargyl esters of bicyclo-[2.2.1]hept-
5-ene-2-carboxylic acid consist in the positions of the
signals of the protons at the C2, C5, and C6 atoms.
The olefinic protons (at C5, C6) in the endo iso-
mer of V are nonequivalent because of the steric prox-
imity of the substituent situated in the rear part of
the bicyclic core. Therefore, these protons give rela-
tively widely separated signals: at 6.12 (5-H) and 6.24
(6-H) ppm. The 5-H and 6-H protons in the exo iso-
mer of V, more weakly influenced by the remote sub-
stituent, give closely situated signals. The 2-H proton
in exo-V has an endo orientation and gives a signal
at 2.97 ppm, whereas the 2-H proton in endo-V has
an exo orientation and gives a multiplet at 2.17 ppm.
1
The coupling constants are as follows (Hz): endo-
3
3
3
V, J5, 6 = 5.62, J1, 6 = 3.66, J4, 5 = 3.00; exo-V,
3J5, 6 = 5.60, J1, 6 = J4, 5 = 2.93.
3
3
The stereoisomers of V were separated by prepara-
tive gas liquid chromatography. The isomeric compo-
sition of esters V VII was determined by GLC anal-
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 77 No. 8 2004

1318
MAMEDOV
Table 3. Inhibiting effect of acetylenic esters V VII of bicyclo[2.2.1]hept-5-ene-2-carboxylic acid in HCl solutions*
25 C
Z, %
60 C
80 C
Z, %
Inhibitor
cHCl
N
,
cinh,
mM
K,
K,
K,
Z, %
1
1
1
g m 2 h
g m 2 h
g m 2 h
No inhibitor
V
1
1
1
1
3
3
3
3
5
5
5
5
1
1
1
3
3
3
5
5
5
1
1
1
3
3
3
5
5
5
3
1.64
0.28
0.27
0.36
2.67
0.3
0.22
0.22
8.27
1.23
0.67
0.23
0.31
0.29
0.28
0.4
94.3
2.4
1.3
1.5
141
1.9
0.97
0.79
287
18.0
8.4
474
14.2
7.3
3
6
12
82.9
83.5
78
5.7
6.1
4.4
97.6
98.6
98.4
39.3
72.5
63
36.8
96.3
98.8
33.4
64.8
91.2
5.2
No inhibitor
V
776
35.1
21.7
3.4
1334
255
109
25
3
6
12
89.8
91.8
91.8
8.9
12.1
12.1
98.7
99.3
99.4
74.2
145.4
178.5
95.5
97.2
99.6 228.2
22.1
35.8
No inhibitor
V
3
6
12
3
6
12
3
6
12
3
6
12
3
6
12
3
6
12
3
6
12
30
85.1
91.9
97.2
80.1
81.2
82.9
79.8
81.9
81.8
83.1
91.1
94.2
91.8
93.8
93.1
86.2
93.1
96.2
89.9
91.3
90.8
87.26
6.7
12.4
35
4.3
5.7
5.9
7.9
11.1
11.02
5.9
11.3
13.3
5.9
6.3
4.7
9.1
98.7
97.1
98.6
94.4
94.2
94.1
96.7
97.3
97.4
97.8
96.1
92.2
98.8
99.5
99.6
99.8
99.7
99.9
96.5
97.2
99.1
90.56
15.9
34.2
73.6
34.3
66.4
57
71.2
139.4
165.3
165.4
34.2
69.6
41.3
74.5
65
76.2
147.4
180.5
171.5
34.2
75.6
10.56**
80.9
91.8
98.1
34.7
93.5
95.4
92.5
94.2
5.2
12.2
53.5
31.2
60.0
81.02
21.1
34.8
3.9
2.8
1.6
1.4
VI
13.21
7.1
4.9
2.8
34.1
20.7
13.4
25.4
106.5
21.7
12.2
5.3
0.3
1.42
1.44
1.93
1.89
1.97
2.1
0.94
0.71
1.4
0.91
0.71
1.71
8.2
0.39
1.27
0.69
0.39
0.21
0.20
0.19
0.27
0.24
0.23
1.1
96.5 210.1
78.8
90.1
92.1
38.8
99.3
99.8
97.5
99.3
81.9
93.6
99.8
98.9
51.0
12.1
51.5
35.4
66.8
93.2
24.1
37.7
7.2
VII
4.2
33.1
19.7
2.4
2.51
104.5
23
12.7
12.8
19.1
13.1
4.9
13.1
53.5
53.7
0.57
0.18
1.36
3.7
21.0
Prop-2-ynyl
benzoate
7.9**
No data
(reference)
*
(K) Corrosion rate, (Z) degree of protection, and ( ) inhibition coefficient.
**
Calculated from data for the reference.
ysis. It was found that the isomeric composition fully
dure from [11]) of the compounds were determined
(Table 2).
coincided with that of the starting acid chloride I.
The fraction of the exo isomer in adducts V VII
is 10%.
Compounds V VII were tested as inhibitors of
the acid corrosion of steel. The inhibiting activity was
studied in relation to the structure of the alcoholic
moiety; the temperature was varied within 25 80 C;
the HCl concentration was 1, 3, and 5 N; and the in-
hibitor concentration was 3, 6, and 12 mM. The re-
sults are listed in Table 3.
The compounds synthesized were studied chroma-
tographically on two stationary liquid phases: polar
[5% polyethylene glycol succinate (PEGS) in Dino-
khrom P] and nonpolar (5% Apiezon N on Dino-
khrom P). The polar PEGS phase appeared to be the
best for separation of the endo and exo isomers
of V VII. The retention parameters, Kovats indices
(procedure from [10]), and boiling points (proce-
As can be seen from Table 3, all the compounds
V VII are effective inhibitors of the acid corrosion
of steel. They surpass in inhibiting power the known
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SYNTHESIS AND CORROSION-PROTECTIVE PROPERTIES OF ACETYLENIC ESTERS
1319
structurally related inhibitor, propargyl benzoate. This
fact suggests that the certain contribution to the in-
hibiting effect of V VII is made by the norbornene
moiety, along with the acetylenic fragment.
the filtrate was evaporated, and the residue was dis-
tilled in a vacuum to give 20 g of V; bp 100 C (5 mm
Hg), nD20 = 1.4936, d420 = 1.0836. Published data
[2]: bp 72 80 C (0.7 mm Hg).
2-(1,1-Dimethylprop-2-ynyloxycarbonyl)bicyclo-
[2.2.1]hept-5-ene VI. To a stirred solution of 8.4 g
(0.1 mol) of 1,1-dimethylprop-2-yn-1-ol III and 10.1 g
(0.1 mol) of triethylamine in 30 ml of absolute ben-
zene, we addded dropwise 15.5 g (0.1 mol) of chlo-
ride I. The mixture was refluxed with stirring for 5 h.
The salt precipitate was filtered off, the solvent was
evaporated, and the residue was distilled in a vacuum
to give 18.76 g of VI. The physicochemical character-
istics of VI are listed in Table 1.
Table 3 shows that all the three compounds V
VII show a better performance than the reference,
propargyl benzoate, when added in lower concentra-
tions (3, 6, and 12 mM, against 30 mM for the ref-
erence).
The best performance is shown by V. This may be
due to the steric hindrance produced by two geminal
methyl groups in the position adjacent to the triple
bond in VI and VII.
2-(1,1-Dimethylpent-2-yn-4-enyloxycarbonyl)bi-
cyclo[2.2.1]hept-5-ene VII. To a solution of 11 g
(0.1 mol) of 1,1-dimethylpent-2-yn-4-en-1-ol IV and
10.1 g (0.1 mol) of triethylamine in 30 ml of absolute
benzene, we added dropwise with stirring 15.5 g
(0.1 mol) of chloride I. The mixture was refluxed with
stirring for 5 h and worked up as described above.
Yield of VII 20.7 g; for constants, see Table 1.
EXPERIMENTAL
The IR spectra were recorded on a UR-20 spectro-
1
photometer (4000 400 cm , thin films or KBr pel-
1
lets), and the H NMR spectra, on a Tesla BS-487C
spectrometer (80 MHz, CCl4, internal references
HMDS and TMS). The preparative separation was per-
formed on a Varian-Aerograph chromatograph [900
0.8-cm column, 5% polyethylene glycol adipate on
porous support (Porovina), vaporizer temperature
250 C, column temperature 175 C, carrier gas nitro-
CONCLUSIONS
1
gen (flow rate 200 cm3 min ), sample volume 100 l,
(1) Acetylenic esters of norbornenecarboxylic acid
of high purity were prepared in good yields by reac-
tions of primary and tertiary acetylenic alcohols with
norbornenecarboxylic acid chloride in the presence of
tertiary amines (pyridine, triethylamine). The primary
alcohol reacts with the chloride at room temperature,
whereas in the case of tertiary alcohols, elevated tem-
peratures (80 C) and longer reaction times (5 h against
0.5 h) are required.
flame ionization detector]. The chromatographic anal-
ysis of the compounds, with determination of their
purity, was performed on an LKhM-8MD chromato-
graph [thermal conductivity detector, 300 0.3-cm
columns, 5% Apiezon or PEGS on Dinokhrom P, car-
1
rier gas helium (40 cm3 min , column temperature
150 C, vaporizer temperature 250 C).
The compounds were tested as corrosion inhibitors
in HCl solutions with 50 20 3-mm St.3 steel
plates; the test time was 2 h. The HCl concentration
was 1, 3, or 5 N, and the temperature was varied with-
in 25 80 C. The corrosion rate and the degree of pro-
tection, Z, were determined as described in [12].
(2) Chromatographic procedures were developed
for separation and analysis of acetylenic esters of
norbornenecarboxylic acid; their Kovats indices and
boiling points were determined. The esters are mainly
endo isomers; the content of the exo isomer is 10%.
(3) Acetylenic esters of norbornenecarboxylic acid
were tested as inhibitors of metal corrosion and
showed a good protective performance.
Acryloyl chloride was prepared by refluxing ben-
zoyl chloride with acrylic acid [13] in a 2 : 1 ratio;
bp 75 76 C. Bicyclo[2.2.1]hept-5-ene-2-carboxylic
acid chloride I was prepared by condensation of acryl-
oyl chloride with freshly distilled cyclopentadiene.
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(0.1 mol) of triethylamine in 30 ml of absolute diethyl
ether, we added dropwise 15.5 g of chloride I. The
reaction was exothermic. The precipitate of triethyl-
ammonium chloride was filtered off. The ether from
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MAMEDOV
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