Synthesis of cyclic acetals by hydroformylation of oct-1-ene in the presence of polyols

Article abstract of DOI:10.1007/s11172-015-0959-6

Rhodium-catalyzed hydroformylation of oct-1-ene in acid medium in the presence of polyols gives acetals of the initially formed aldehydes. The use of water-soluble trisodium salt of tris(sulfonatophenyl)phosphine as a ligand favors easy separation of the reaction products and enables repeated use of the catalytic system. A minor additive (2 wt.%) of the obtained acetal mixture improves the lubricating properties of diesel fuel by 30% and markedly reduces gum formation during combustion.

Full text of DOI:10.1007/s11172-015-0959-6

Russian Chemical Bulletin, International Edition, Vol. 64, No. 4, pp. 943—947, April, 2015
943
Synthesis of cyclic acetals by hydroformylation of octꢀ1ꢀene
in the presence of polyols
D. N. Gorbunov, S. V. Egazaryants, Yu. S. Kardasheva, A. L. Maksimov, and E. A. Karakhanov
Department of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie gory, 119992 Moscow, Russian Federation.
Eꢀmail: kar@petrol.chem.msu.ru
Rhodiumꢀcatalyzed hydroformylation of octꢀ1ꢀene in acid medium in the presence of
polyols gives acetals of the initially formed aldehydes. The use of waterꢀsoluble trisodium salt of
tris(sulfonatophenyl)phosphine as a ligand favors easy separation of the reaction products and
enables repeated use of the catalytic system. A minor additive (2 wt.%) of the obtained acetal
mixture improves the lubricating properties of diesel fuel by 30% and markedly reduces gum
formation during combustion.
Key words: hydroformylation, homogeneous catalysis, rhodium complexes, acetalizaꢀ
tion, polyols.
Higher olefins serve as the raw materials for numerous
promising syntheses of petrochemicals, for example, for
hydroformylation. This reaction is suitable, in particular,
for performing tandem oneꢀpot reactions involving two or
more chemical transformations within one process flow
chart. According to the flow charts that do not require
changes in the reaction conditions, the intermediates are
not isolated and the starting reactants, materials, and
solvents are fed to the reactor in one operation. The prodꢀ
ucts of oxo synthesis, aldehydes, can be used for the synꢀ
thesis of acetals in the presence of polyols, in particular,
those of plant origin. Acetals are of interest as surfactants,
components of engine fuels and lowꢀtemperature lubriꢀ
cating oils; they can also be used as flavoring agents and
disinfectants.1—3 Despite the broad scope of applicability
of acetals based on polyhydric alcohols, methods for their
synthesis have not been thoroughly elaborated, especially
for acetals of higher aldehydes. Only acetalization taking
place between aliphatic aldehydes and alcohols containꢀ
ing two or three hydroxy groups was described in detail.4,5
Here we attempted to prepare cyclic acetals based on
natural polyols and higher olefins by a hydroformylaꢀ
tion—acetalization tandem process. Octꢀ1ꢀene was taken
as the model olefin.
In the general form, tandem process is a sequence of
two reactions, where the first stage is olefin hydroformylaꢀ
tion, while the second stage is acetalization of the aldeꢀ
hydes formed in the first reaction (Scheme 1).
Scheme 1
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 0943—0947, April, 2015.
1066ꢀ5285/15/6404ꢀ0943 © 2015 Springer Science+Business Media, Inc.

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Gorbunov et al.
Yield (%)
100
Results and Discussion
Optimization of the tandem process conditions. The secꢀ
ond stage performed under homogeneous conditions is
usually catalyzed by mineral acids: pꢀtoluenesulfonic acid
(pꢀTsOH), H2SO4, HCl, or H3PO4. Sulfuric acid proved
to be the optimal choice for our purpose, as HCl is
a catalytic poison, phosphoric acid forms esters with polyꢀ
ols, and the use of pꢀTsOH requires the addition of more
water to the system. In a series of experiments, we found
that the best results are attained with 1M aqueous H2SO4
(the yield of a mixture of acetals was 80%). It was shown
that the process can also be performed without an organic
solvent (Fig. 1). Thus, the system containing a rhodium
catalyst of hydroformylation (soluble in the olefin) and
a 1M solution of sulfuric acid taken in a volume equal to the
polyol volume proved to be optimal for the synthesis of
acetals from olefins. Under these conditions, we carried
out the reactions using pinacol, glycerol, pentaerythritol,
xylitol, and sorbitol as the polyols (Table 1).
80
60
40
20
1
2
Olefins
Aldehydes
Acetals
Fig. 1. Composition of the products of octꢀ1ꢀene hydroformylaꢀ
tion in the presence of ethylene glycol in reaction mixtures conꢀ
taining (1) and not containing (2) toluene as the solvent. Reꢀ
action conditions: synthesis gas (CO—H2 (1 : 1), 4.0 MPa),
Rh(acac)(CO)2, 1 M H2SO4, 70 C, 5 h.
Synthesis and analysis of acetal mixtures. In the first,
hydroformylation, stage, octꢀ1ꢀene is converted to four
isomeric aldehydes. The subsequent reaction with the
polyol affords mixtures of acetals, the number of acetal
isomers increasing as the polyol structure becomes more
complex. In the case of ethylene glycol, isomers 1a—d are
formed (see Table 1, run 1), while pinacol gives rise to
isomers 2a,b (run 2).
In order to make the interpretation of the spectra and
chromatograms of the obtained mixtures easier, authentic
samples of unbranched nꢀnonanal acetals were syntheꢀ
sized. The reaction of nꢀnonanal with ethylene glycol yieldꢀ
ed only one product 1a, whereas the reaction with glycerol
furnished four isomers 3a—d in approximately equal
amounts (their spectra were reported6).
Table 1. Synthesis of cyclic acetals by hydroformylation of octꢀ1ꢀene in the presence of polyols
Run
Polyol
Conditionsа
Products
Total yieldc (%)
«linear»
«branched»
ratiob
1
2
3
4
5
6
7
8
9
Ethylene glycol
Ethylene glycol
Pinacol
Glycerol
Glycerol
Pentaerythritol
Xylitol
A
B
A
A
B
A
A
B
A
1а
1a,b
2a
3a—d
3a—d
4a
5a,b
5a,b
6a—c
1b—d
1c,d
2b
3e—h
3e—h
4b
5c,d
5c,d
6d
2 : 1
—
2 : 1
2 : 1
—
2.5 : 1
3 : 1
—
75
92
75
70
50
55
50
45
50
Xylitol
Sorbitol
3 : 1
a Conditions А: synthesis gas (CO—H2 (1 : 1), 4.0 MPa), Rh(acac)(CO)2, 1 M H2SO4, 70 C, 5 h. Conditions B: synthesis
gas (CO—H2 (1 : 1), 4.0 MPa), Rh(acac)(CO)2, TPPTS, 1 M H2SO4, 70 C, 5 h.
b Ratio of the linear and branched products.
c Isolated product yield.

Cyclic acetals
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
945
The hydroformylation of octꢀ1ꢀene in the presence of
glycerol under optimal conditions results in the formation
of not only isomers 3a—d but also products 3e—h with a
branched alkyl substituent (Fig. 2, Table 1, run 4).
case of nꢀnonanal, one may expect similar products 5a
and 5b. The structure of products was confirmed by comꢀ
parison with published data8 and with the 13C NMR
spectra of acetals 1a and 3a—d.
Apart from products 5a,b, the hydroformylation of octꢀ
1ꢀene in the presence of xylitol and the acid catalyst yields
isomers 5c,d (50% overall yield, see Table 1, run 7). The
13C NMR spectrum of the acetal mixture (Fig. 3) has
a signal at  107.8, characteristic of the acetal carbon
atoms of compounds 5c and 5d and signals at  101.5 and
104.9 characteristic of acetals 5a and 5b with linear
substituents.
The use of pentaerythritol gives rise to two isomers 4a
and 4b (see Table 1, run 6).
1
The H NMR spectrum of a mixture of acetals 5a—d
exhibits a triplet at  0.88 for protons of the terminal meꢀ
thyl groups and proton signals for the ꢀacetal methyl
group shifted downfield by several ppm. The quantitative
ratio of the products was determined from the ratio of the
integrated intensities of these signals.
The reaction of xylitol with acetaldehyde is known to
give acetals with fiveꢀ and sixꢀmembered rings.7 In the
The acetalization of nꢀnonanal in the presence of sorꢀ
bitol yields a mixture of cyclic dialkyl acetals 6a—c.
Yield (%)
30
25
20
15
10
5
3a
3b
3c
3d
3e—h
Fig. 2. Quantitative distribution of products 3a—h obtained
by octꢀ1ꢀene hydroformylation in the presence of glycerol. Reꢀ
action conditions: synthesis gas (CO—H2 (1 : 1), 4.0 MPa),
Rh(acac)(CO)2, 1 M H2SO4, 70 C, 5 h.
105
100
95
90
85
80
75

Fig. 3. 13C NMR spectrum of the mixture of acetals 5a—d.

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Gorbunov et al.
Apart from 6a—c, tandem process affords products with
a
b
branched substituent, the predominant compound among
them being 2,4:3,5ꢀbisꢀOꢀ(2ꢀmethyloctylidene)ꢀD,Lꢀsorꢀ
bitol (6d). The 13C NMR spectrum of this product exhibꢀ
its a characteristic signal at  107.8.
Fig. 4. Gumming products in the diesel fuel (а) and absence of
such products after the addition of 2 wt.% xylitol acetals (b).
(Table 1, run 2), we demonstrated that the aqueous phase
containing the dissolved catalytic complex can be reused,
the catalyst activity remaining at the same level for five
cycles (Table 2). The yield of acetal mixture 1a—d is, on
average, 90%. This method also proved useful for the synꢀ
thesis of other acetals (see Table 1, runs 5, 8).
To conclude, we demonstrated good prospects of using
the hydroformylation—acetalization tandem process for
the preparation of cyclic acetals. The obtained mixture of
xylitol acetals was tested as a possible diesel fuel additive
according to GOST 9490ꢀ75 "Liquid Lubricating and Plasꢀ
tic Materials. Method of Testing for Lubricating Properꢀ
ties on a FourꢀBall Machine". Using this method, it was
shown that the addition of 2 wt.% xylitol acetal mixture to
the diesel fuel reduces the relative friction by 30% and
markedly reduces the gum formation (Fig. 4).
Experimental
Separation of the catalyst from the reaction products.
In all of the aboveꢀdescribed cases, the obtained acetal
mixture is easily separated from the unreacted polyol;
however, it is impossible to separate it from the catalyst.
This problem could be solved by using a waterꢀsoluble
ligand, for example, trisodium salt of tris(sulfonatoꢀ
phenyl)phosphine (TPPTS), which can transfer the cataꢀ
lytic complex into the aqueous phase. In this case, the
reaction would proceed in a twoꢀphase system water—
organic solvent, the reaction products (acetals) would
occur in the organic layer (toluene), while the catalyst and
the remaining polyol would be in the aqueous phase. In
relation to the reaction of octꢀ1ꢀene with ethylene glycol
Commercial octꢀ1ꢀene, nꢀnonanal, ethylene glycol, glycerol,
pinacol, sorbitol, xylitol, and pentaerythritol (Aldrich) were used.
The trisodium salt of tris(sulfonatophenyl)phosphine9 and
Rh(acac)(CO)210 were prepared as described. 1H and 13C NMR
spectra were recorded on a Varian XLꢀ400 instrument operating
at 400 MHz. GC analysis of the mixtures obtained upon the
reaction of ethylene glycol with nꢀnonanal and octꢀ1ꢀene was
carried out on a HewlettꢀPackard chromatograph with a flame
ionization detector and a 30 m capillary column containing the
SEꢀ30 phase, with temperature programming from 60 to 230 C,
using helium as the carrier gas. nꢀNonane served as the internal
standard.
Preparation of cyclic acetals under hydroformylation condiꢀ
tions. The reaction was conducted in a 50 mL steel autoclave
equipped with a magnetic stirrer and a temperature control faꢀ
cility at temperatures of up to 110 C. The autoclave was charged
with Rh(acac)(CO)2 (3 mg, 0.01 mmol), octꢀ1ꢀene (0.6 mL,
3.8 mmol), polyol (9 mmol), and 1M H2SO4 (0.5 mL). The
autoclave was filled with synthesis gas (CO : H2 = 1 : 1) up to
a pressure of 4.0 MPa and heated for 5 h at 70 C with continuꢀ
ous stirring. The products were analyzed by 1H and 13C NMR
spectroscopy.
Table 2. Total yields of acetals 1a—d in five catalytic cycles of
octꢀ1ꢀene hydroformylation in the presence of ethylene glycol*
Catalytic Yield of 1a—d
Catalytic Yield of 1a—d
cycle
(%)
cycle
(%)
Preparation of cyclic acetals under hydroformylation condiꢀ
tions in the presence of TPPTS. The reaction was conducted in
a 50 mL steel autoclave equipped with a magnetic stirrer and
a temperature control facility at temperatures of up to 110 C. The
autoclave was charged with Rh(acac)(CO)2 (3 mg, 0.01 mmol),
TPPTS (34.8 mg, 6 mmol), octꢀ1ꢀene (0.6 mL, 3.8 mmol), polyꢀ
1
2
3
88
92
88
4
5
88
79
* Reaction conditions: synthesis gas (CO—H2 (1 : 1), 4.0 MPa),
Rh(acac)(CO)2, TPPTS, 1 M H2SO4, 70 C, 5 h.

Cyclic acetals
Russ.Chem.Bull., Int.Ed., Vol. 64, No. 4, April, 2015
947
ol (10 mmol), 1M H2SO4 (0.6 mL), and toluene (1 mL). The
autoclave was filled with synthesis gas (CO : H2 = 1 : 1) up to
a pressure of 4.0 MPa, heated for 5 h at 70 C with continuous
stirring, and cooled to room temperature. The products were
analyzed by GC and 1H and 13C NMR spectroscopy. For GC
analysis of the products formed from octꢀ1ꢀene and ethylene
glycol, nꢀnonane (internal standard, 0.6 mL, 3.8 mmol) was
added to the cooled reaction mixture.
2,4:3,5ꢀDiꢀOꢀoctylideneꢀDꢀxylitol (5a) and 2,3:4,5ꢀdiꢀОꢀocꢀ
tylideneꢀDꢀxylitol (5b) (mixture). 1H NMR (CDCl3), : 0.88
(t, 12H, CH3), 1.15—1.75 (m, 40 H, CH3(CH2)5CH2); 1.53—1.77
(m, 8 H, CH3(CH2)5CH2); 3.30—4.30 (m, CH2OH, C(2)H,
C(3)H, C(4)H, C(5)H2); 4.3—5.0 (m, 2 H, CHC8H17).
13C NMR (CDCl3), : 13.7 (CH2CH3), 22.2 (CH2CH3); 24.2
(CH2(CH2)5CH3); 28.8 (CH2(CH2)2CH3); 29.1 (CH2(CH2)3CH3);
31.4 (CH2(CH2)4CH3); 33.4 (CH2(CH2)6CH3); 61.1 (C(1) (5a)),
62.1 (C(1) (5b)), 65.4—69.5 (C(2), C(3), C(4), C(5) (5a));
75.4—77.9 (C(2), C(3), C(4), C(5) (5b)); 101.4 (C(6), C(7) (5a));
104.9 (C(6), C(7) (5b)).
Alternative synthesis of cyclic acetals of nꢀnonanal. Nonanal
(0.5 mL, 3.0 mmol), polyol (9.0 mmol), and 1 M H2SO4 (0.5 mL)
were loaded into a reactor kept in a thermostat and equipped
with a magnetic stirrer and reflux condenser. The mixture was
stirred for 5 h at 70 C. The product was extracted into chloroꢀ
form (2×5 mL), washed with aqueous solution of K2CO3 and
water to neutral pH, and dried with calcined calcium chloride.
The solvent was removed on a rotary evaporator.
the Priority Areas of Development of the Science and
Technology Complex of Russia for 2014—2020", event
1.3, Funding Agreement No. 14.607.21.0083).
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This work was financially supported by the Ministry of
Education and Science of the Russian Federation (the
Federal Target Program "Research and Development in
Received February 16, 2015
in revised form March 6, 2015