Functional methacryloyoxy acetals: II. Electophilic addition of alcohols to vinyloxyalkyl methacrylates

Article abstract of DOI:10.1023/A:1013905514252

Alcohols of various structures, in particular, ethylene, acetylene, fluorocontaining alcohols, add regio-and chemoselectively to the vinyloxy group of vinyloxyalkyl methacrylates at 20-40°C in the presence of catalytic quantities of trifluoroacetic acid a

Full text of DOI:10.1023/A:1013905514252

Russian Journal of Organic Chemistry, Vol. 37, No. 12, 2001, pp. 1683 1687. Translated from Zhurnal Organicheskoi Khimii, Vol. 37, No. 12, 2001,
pp. 1763 1768.
Original Russian Text Copyright
2001 by Gorelova, Oparina, Parshina, Gusarova, Trofimov.
Dedicated to Academician M.G.Voronkov on occasion of his 80th birthday
Functional Methacryloyoxy Acetals: II. Electophilic Addition
of Alcohols to Vinyloxyalkyl Methacrylates
O. V. Gorelova, L. A. Oparina, L. N. Parshina, N. K. Gusarova,
and B. A. Trofimov
Faworsky Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, 664033 Russia
Received March 25, 2001
Abstract Alcohols of various structures, in particular, ethylene, acetylene, fluorocontaining alcohols, add
regio- and chemoselectively to the vinyloxy group of vinyloxyalkyl methacrylates at 20 40 C in the presence
of catalytic quantities of trifluoroacetic acid affording functional acetalmethacrylates in high yield.
Vinyloxyalkyl methacrylates are highly active
bifunctional monomers containing reactive
amounts of reagents under catalysis with trifluoro-
acetic acid (1 2 wt%).
a
( anchor ) vinyloxy group that can easily undergo
addition to various hydroxy, thiol, and carboxy func-
tions. Yet this approach to methacrylates synthesis is
not developed up till now although the electrophilic
addition of alcohols to the other vinyl ethers is
studied intensively [2 13]. As a rule the vinyl ethers
in the presence of acidic catalysts readily take up
alcohols to furnish the corresponding acetals in high
yield [5 10]. It should be noted that acids can also
catalyze the nucleophilic addition of alcohols to the
double bond of methacrylates (due to electrophilic
assistance through the carboxy group) [14]. Therefore
the possible result of the reaction between vinyloxy-
alkyl methacrylates with alcohols is not unambiguous.
Scheme 1.
R = (CH2)2 (I, IV XII), (CH2)2O(CH2)2 (II, XIII),
CH(Me)(CH2)2 (III, XIV, XV); R
= Me (IV,
We report here for the first time on results of
research on the reaction between vinyloxyalkyl
methacrylates with alcohols aimed at the synthesis of
XIII), Et (V, XIV), i-Pr (VII), t-Bu (VIII, XV),
CHF2CF2CH2 (IX), CH2=CHCH2 (X), CH C(CH2)2
(XI), MeO(CH2)2 (XII).
new
polyfunctional
methacrylates,
promising
synthons and monomers for preparation of new types
of methacrylate polymers.
The addition is accompanied with slight heat
evolution (2 7 C with vinyl ethers I and III and
15 20 C with ether II). The reaction progress was
We found conditions of the reaction providing
regio- and chemoselective addition of alcohols with
different structures (alkanols, 2,2,3,3,-tetrafluoro-
propan-1-ol, 2-propen-1-ol, 3-butyn-1-ol, 2-methoxy-
ethanol) to vinyloxyalkyl methacrylates only across
the vinyloxy group furnishing the products IV XV
in high yield (Scheme 1).
1
monitored by IR and H NMR spectroscopy. In the
course of reaction gradually disappear the char-
acteristic absorption bands of the vinyloxy group
1
(830 850, 963 965, 1205, 1367, 1620, 3060 cm )
1
and the hydroxy group (3375 cm ) and changes the
set of bands in the absorption region of C O C
1
moiety (1050 1205 cm ). At the same time the
The reaction occurs under mild conditions (20
40 C, 0.5 2 h, under argon) at stirring equivalent
absorption bands corresponding to stretching vibra-
tions of the fragments in the methacrylate moiety
1
*
C=C C=O (1640, 1720 cm ) and CH2=
For communication I see [1].
1
(3100 cm ) remain unchanged. In the 1H NMR
1070-4280/01/3712-1683$25.00 2001 MAIK Nauka/Interperiodica

1684
GORELOVA et al.
quantitative, and their ratio is respectively
Scheme 2.
2.9 : 1.4 : 1.0.
The acetals IV XV obtained also undergo dis-
proportionation on storage in the presence of acid
providing the corresponding symmetrical acetals
XVI XVIII and XIX XXX (Scheme 2).
To avoid this process the acid catalyst should be
neutralized just after the completion of the reaction
between the alcohol and the vinyloxyalkyl metha-
crylate.
spectra ( , ppm) of the reaction mixtures was ob-
served only one signal from methine proton (4.6
4.9 q) and one signal of a methyl group ( 1.3 d)
belonging to the acetal fragment evidencing that
(1-organylethoxy)alkyl methacrylates IV XV were
the only reaction products and that they formed in
virtually quantitative yield.
The disproportionation of acetalmethacrylates
IV XV occurs not only under the action of acids but
also at heating (100 160 C) during the fractional
distillation in a vacuum. Therefore the GLC analysis
of the reaction mixtures is not reliable since in the
vaporizer (250 300 C) the acetals synthesized suffer
deep transformation, not only disproportionation, but
also pyrolysis to the initial compounds as show the
The complete conversion of 2-vinyloxyethyl
methacrylate (I) in reactions with ethanol, 2-propanol,
and tert-butanol into the corresponding acetals V, VI,
VIII is attained within 2 h at 20 C whereas with
stronger OH-acids (2,2,3,3-tetrafluoropropan-1-ol,
3-butyn-1-ol, 2-propen-1-ol, methanol, 2-methoxy-
ethanol) [15] the reaction completes already in 1
1.5 h. The rate of the reaction studied was also
affected by the structure of the initial methacrylates
I III; the most active among them turned out to be
2-[(2-vinyloxy)ethoxy]ethyl methacrylate (II).
1
GLC and H NMR data.
Yet such probable side processes as polymerization
of the initial vinyl ethers I III or their reaction with
the forming acetals IV XV usually catalyzed by acids
[2 4] were not observed in the study of the reaction
in question.
The reaction of vinyloxyalkyl methacrylates with
alcohols (Scheme 1) is sensitive to moisture that
hydrolyses the original vinyl ethers I III. The follow-
ing reaction of the acetaldehyde formed both with the
initial and arising from the hydrolysis alcohol
furnishes symmetrical acetals XVI XXX (Scheme 3)
It was confirmed that the trifluoroacetic acid is a
specific, highly selective and mild catalyst of alcohols
addition to the vinyloxy group [6, 7]. The replace-
ment of this acid by a dioxane solution of dry HCl in
reaction of vinyl ether I with methanol resulted in
nearly twice faster process (1 wt% of catalyst, 20 C,
0.5 h) but the target actalmethacrylate IV suffered
disproportionation into acetaldehyde bis(2-methacryl-
oylethyl) acetal (XVI) and acetaldehyde dimethyl-
acetal (XIX): in the 1H NMR spectrum appeared
three quartets of methine protons at 4.85, 4.68, and
4.58 ppm.
1
appearing in the H NMR spectrum as a triple set of
the proton signals from the acetal fragments. Thus the
hydrolysis is another reason (besides the symmetriza-
tion) of formation of acetals mixture in the course of
the reaction under study.
Scheme 3.
The regio and chemoselectivity of the reactions
are not hampered even by the use of excess alcohol
with respect to vinyloxyalkyl methacrylate: In the
latter case still do not form adducts at the double
bond of the methacrylate group. Yet the mixing of
2-vinyloxyethyl methacrylate (I) with a double excess
of methanol afforded alongside the expected acetal-
methacrylate IV also the corresponding symmetrical
acetaldehyde bis(2-methacryloylethyl) acetal (XVI)
and acetaldehyde dimethylacetal (XIX). The overall
yield of acetals IV, XVI, and XIX is virtually
The stability of the acetals obtained to the dis-
proportionation depends also on the structure of the
alcohol radical R . Thus in the presence of acids and
at heating the acetals with electronegative groups
R O IX XI are less prone to disproportionation and
pyrolysis than alkoxyacetals IV VIII, XII XV;
therefore the former are prepared in better preparative
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 12 2001

FUNCTIONAL ACETALMETHACRYLATES: II
Table 1. Yields and characteristics of methacrylates IV XV
1685
Compd. Yield,a
bp,
C
Found, %
Calculated, %
%
(p, mm Hg)
n2D0
Formula
no.
C
H
C
H
IV
78
83
68
88
78
85
88
87
65
70
70
66
50 (2)
53 (2)
65 (3)
67 (2)
76 (3)
81 (2)
87 (2)
76 (2)
97 (2)
85 (2)
85 (2)
88 (2)
1.4342
1.4308
1.4328
1.4398
1.4350
1.4058
1.4444
1.4566
1.4398
1.4424
1.4360
1.4358
57.55
59.62
61.16
62.76
62.71
45.92
61.48
63.72
56.69
56.94
62.78
65.06
8.62
9.12
9.60
9.80
9.67
5.24
8.50
8.11
8.43
8.55
9.76
10.18
C9H16O4
57.43
59.39
61.09
62.58
62.58
45.83
61.66
63.69
56.88
56.88
62.58
65.08
8.57
V
C10H18O4
C11H20O4
C12H22O4
C12H22O4
C11H16F4O4
C11H18O4
C12H18O4
C11H20O5
C11H20O5
C12H22O4
C14H26O4
8.97
9.32
9.63
9.63
5.59
8.46
8.02
8.67
8.67
9.63
10.14
VI
VII
VIII
IXb
X
XI
XII
XIII
XIV
XV
a
b
Preparative yields are given. Found, %: F 26.32. Calculated, %: F 26.36.
Table 2. Spectral characteristics of methacrylates IV XV
Compd.
1
IR spectrum (cm )
no.
IV
517, 537, 604, 654, 816, 866, 940, 994, 1041, 1059, 1089, 1120, 1136, 1170, 1244, 1297, 1320, 1388, 1454,
1638, 1721, 2830, 2930, 2955, 2989, 3106
V
530, 603, 654, 816, 858, 948, 960, 1007, 1061, 1084, 1101, 1137, 1170, 1244, 1297, 1320, 1340, 1382,
1402, 1453, 1638, 1721, 2882, 2931, 2978, 3106
VI
534, 603, 654, 816, 848, 886, 937, 985, 1007, 1054, 1085, 1135, 1168, 1244, 1297, 1321, 1381, 1454, 1638,
1721, 2876, 2932, 2974, 3106
VII
VIII
IX
519, 603, 655, 739, 760, 815, 853, 878, 937, 1007, 1044, 1078, 1096, 1112, 1138,1169, 1248. 1297, 1320,
1341, 1382, 1404, 1455, 1638, 1721, 2874, 2934, 2959, 2987, 3105
517, 556, 602, 654, 749, 816, 859, 875, 940, 975, 1009, 1056, 1091, 1126, 1170, 1196, 1239, 1260, 1297,
1320, 1366, 1382, 1455, 1638, 1721, 2876, 2934, 2978, 3105
546, 578, 655, 692, 816, 835, 880, 941, 1010, 1044, 1106, 1145, 1169, 1233, 1298, 1321, 1387, 1455, 1638,
1721, 2891, 2955, 2992, 3115
X
518, 602, 655, 815, 881, 938, 990, 1039, 1099, 1137, 1169, 1247, 1297, 1320, 1339, 1388, 1454, 1638,
1721, 2881, 2929, 2957, 2989, 3082, 3102
XI
651, 815, 878, 943, 1003, 1042, 1078, 1101, 1138, 1170, 1246, 1298, 1320, 1384, 1402, 1454, 1637, 1719,
2121, 2884, 2928, 2989, 3107, 3292
XII
XIII
XIV
XV
655, 815, 856, 944, 991, 1043, 1076, 1103, 1140, 1170, 1249, 1297, 1320, 1340, 1387, 1454, 1638, 1720,
2820, 2882, 2932, 2988, 3107
536, 595, 656, 816, 860, 891, 943, 994, 1046, 1095, 1135, 1170, 1249, 1297, 1320, 1342, 1387, 1402, 1453,
1638, 1720, 2830, 2882, 2933, 2988, 3107
657, 815, 845, 862, 891, 938, 989, 1010, 1060, 1084, 1135, 1172, 1296, 1321, 1365, 1380, 1452, 1638,
1718, 2889, 2930, 2979, 3107
655, 815, 848, 939, 976, 1009, 1089, 1118, 1172, 1235, 1260, 1296, 1321 1365, 1380, 1452, 1638, 1718,
2879, 2933, 2978, 3107
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 12 2001

1686
GORELOVA et al.
Table 2. (Contd.)
Compd.
no.
1H NMR spectrum (CDCl3), , ppm (J, Hz)
OCHOq Me, d
= CH2 (2J, 4J)
Me C= ,
R (3J)
R
(3J)
(3J)
d.d (4J)
IV
V
4.69
(5.2)
1.30 5.56 d.q (trans, 1.94 (0.8, 3.70 m, 3.77 m (each 1H, 3.30 s (3H, Me)
(5.2) 1.5, 1.6), 6.12 m 1.6)
OCH2), 4.30
OCH2, 5.5)
t
(2H,
(cis)
3
4.75
(5.4)
1.30 5.56 d.q (trans, 1.94 (0.8, 3.71 m, 3.78 m (each 1H, 1.18 t (3H, Me, J 7.1),
(5.4) 1.6, 1.6), 6.12 m 1.6)
OCH2), 4.28 t (2H, OCH2, 3.42 d.q, 3.57 d.q (each
5.7)
(cis)
1H, OCH2, 3J 7.1, 2J
11.8)
VI
4.81
(5.2)
1.29 5.55 d.q (trans, 1.94 (1.0, 3.70 m, 3.75 m (each 1H, 1.15 two d (each 3H, Me,
(5.2) 1.6, 1.6), 6.11 m 1.6)
OCH2), 4.28 t (2H, OCH2, 3J 6.2), 3.89 d.q (1H,
(cis)
5.7)
CH, 3J 6.2)
3
VII
4.69
(5.4)
1.28 5.54 d.q (trans, 1.93 (0.9, 3.66 m, 3.75 m (each 1H, 0.91 t (3H, Me, J 7.3),
(5.4) 1.5, 1.6), 6.09 m 1.6)
OCH2), 4.25 t (2H, OCH2, 1.36 m, 1.52 m (each 2H,
(cis)
5.4)
CH2), 3.38 d.t, 3.55 d.t
3
(each 1H, OCH2, J 6.6,
2J 9.3)
VIII
IX
4.98
(5.3)
1.28 5.55 d.q (trans, 1.94 (1.0, 3.69 t (2H, OCH2, 5.1), 1.23 s (9H, Me)
(5.3) 1.6, 1.6), 6.11 m 1.6)
4.27 t (2H, OCH2, 5.8)
(cis)
4.86
(5.4)
1.32 5.58 d.q (trans, 1.93 (1.0, 3.68 m, 3.80 m (each 1H, 3.86
(5.4) 1.5, 1.6), 6.11 m 1.6)
m
(2H, OCH2),
OCH2), 4.29 t (2H, OCH2, 5.90 t.t (1H, CHF, 3J
5.8)
5.1, 2J 53.2)
(cis)
2
X
4.80
(5.2)
1.32 5.55 d.q (trans, 1.94 (0.9, 3.71 m, 3.77 m (each 1H, 4.00 d.d (3J 5.3, J 12.8),
(5.2) 1.6, 1.6), 6.11 m 1.6)
OCH2), 4.28 t (2H, OCH2, 4.12 d.d (3J 5.7, 2J
(cis)
5.6)
12.8), (each 1H, OCH2),
3.15 d.d, 3.25 d.d (each
1H, CH2= , 3J 10.4, 3J
17.2, 4J 1.5), 5.88 q.t
(1H, CH= , 3J 10.4, 3J
17.2)
XI
4.80
(5.4)
1.31 5.56 d.q (trans, 1.94 (0.8, 3.59 m, 3.69 m (each 1H, 1.97 s (1H, CH ), 2.44 t
3
(5.4) 1.6, 1.6), 6.12 m 1.6)
OCH2), 4.28 t (2H, OCH2, (2H, CH2, J 6.8), 3.60 t
3
(cis)
5.6)
(2H, OCH2, J 6.8)
XII
4.78
(5.2)
1.30 5.54 d.q (trans, 1.93 (1.2, 3.67 m, 3.76 m (each 1H, 3.34 s (3H, Me), 3.46 t
(5.2) 1.5, 1.6), 6.09 m 1.6)
OCH2), 4.26 t (2H, OCH2, (2H, OCH2, 3J 4.8),
(cis)
5.8)
3.55 m, 3.67 m (each 1H,
OCH2)
XIII
XIV
XV
4.67
(5.2)
1.28 5.55 d.q (trans, 1.93 (1.2, 3.58 m, 3.67 m (each 1H, 3.30 s (3H, Me)
(5.2) 1.6, 1.6), 6.11 m 1.6)
OCH2), 3.65 t, 3.74 t
(4H, OCH2, 5.2), 4.29 t
(2H, OCH2, 5.1)
(cis)
4.65
(5.4)
1.26 5.52 d.q (trans, 1.92 br.s 1.28 (3H, Me, 6.2), 1.83 1.17 t (3H, Me, 3J 7.0),
(5.4) 1.5, 1.5), 6.07 m
1.89 m (2H, CH2), 3.46 m, 3.46 m, 3.59 m (each 1H,
3.59 m (each 1H, OCH2), OCH2)
5.09 m (1H, OCH)
(cis)
4.84
(5.3)
1.24 5.48 br.s (trans), 1.89 br.s 1.19 (3H, Me, 6.0), 1.76 1.18 s (9H, Me)
(5.3) 6.03 m (cis)
1.84 m (2H, CH2), 3.44 m,
3.52 m (each 1H, OCH2),
5.04 m (1H, OCH)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 12 2001

FUNCTIONAL ACETALMETHACRYLATES: II
1687
yield (Table 1). Such effect of substituents on the
reactivity of acetals was already described before [8].
ether I (IR spectroscopy). The reaction mixture was
neutralized with 5% water solution of NaHCO3, the
organic layer was separated, and the water layer was
extracted with ethyl ether (5 3 ml). The extracts and
organic layer were combined, washed with water,
dried with Na2SO4, the solvent was distilled off, and
the residue was subjected to fractional distillation in
a vacuum in the presence of hydroquinone (1 wt%).
Yield 1.46 g (78%). Methacrylates V XV were
obtained in a similar way. The symmetrical acetals
XVI XVIII and XX XXX arising in the course of
the reaction and during distillation were identified
The synthesized acetalmethacrylates IV XV were
isolated from the reaction mixtures after the catalyst
neutralization by vacuum distillation in the presence
of inhibitors of the radical polymerization (hydro-
quinone, ionol, argon). At it in the case of acetals
IV VIII, XII XV was observed partial dispropor-
tionation resulting in a mixture of the initial asym-
metrical and two symmetrical acetals. The expected
elimination of alcohols from acetals IV XV to give
vinyl ethers I III in no case was observed during the
distillation. Acetalmethacrylates IV XV are colorless
liquids soluble in most organic solvents, easily
polymerizable by radical mechanism. Their constants
are given in Table 1, and spectral characteristics in
Table 2.
1
with the help of H NMR spectroscopy or by GLC
using the comparison with the authentic compounds.
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IR spectra were recorded on spectrometer Bruker
1
JFS-25 from samples as microfilms. H NMR spectra
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1-Vinyloxy-3-methylpropyl methacrylate (III).
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1
film, cm ): 654, 815, 895, 945, 963, 993, 1010,
1059, 1108, 1144, 1175, 1202, 1296, 1322, 1355,
1380, 1452, 1617, 1637, 1719, 2881, 2930, 2979,
3050, 3080, 3118. 1H NMR spectrum (CDCl3,
,
ppm): 6.39 d.d (1 H, CH=), 4.11 d.d, 3.95 d.d (each
3
3
1 H, CH2= , Jtrans 14.4, Jcis 6.8, 2J 2.0 Hz),
2
4
6.06 d.q, 5.51 d.q (each 1H, CH2= , J 1.6, J 0.9,
4J 1.6 Hz), 1.93 d.d (3 H, Me, J 0.9, J 1.6 Hz),
5.08 m (1 H, OCH), 3.69 t (2H, OCH2, J 6.4 Hz),
1.96 1.89 m (2H, CH2), 1.29 d (3H, Me, J ‘6.4 Hz).
4
4
3
3
2-(1-Methoxyethoxy)ethyl methacrylate (IV). To
a mixture of 1.56 g (0.01 mol) of vinyl ether I and
0.32 g (0.01 mol) of methanol was added 0,02 g of
trifluoroacetic acid (1 wt%). The mixture was stirred
for 1 h at 20 C till complete disappearance of vinyl
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Peake, E.G., J. Org. Chem., 1971, vol. 36, no. 9,
pp. 1205 1209.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 37 No. 12 2001