Comparison of “on water” and solventless procedures in the rhodium-catalyzed hydroformylation of diolefins, alkynes, and unsaturated alcohols

Article abstract of DOI:10.1016/j.molcata.2016.06.003

Catalytic systems containing Rh(acac)(CO)₂ or Rh/PAA (PAA?=?polyacrylic acid) and hydrophobic phosphine (PPh₃) were used in the hydroformylation of diolefins, alkynes, and unsaturated alcohols under solventless and “on water” conditions. The total yield of dialdehydes obtained from 1,5-hexadiene and 1,7-octadiene reached 99%, and regioselectivity towards linear dialdehydes was higher in the “on water” system. The tandem hydroformylation-hydrogenation of phenylacetylene led to the formation of saturated aldehydes (3-phenylpropanal and 2-phenylpropanal) at 98% conversion with a good regioselectivity towards the linear aldehyde in the “on water” reaction. In contrast, solventless conditions appeared better in the hydroformylation of 1-propen-3-ol. 4-Hydroxybutanal, formed in this reaction with an excellent selectivity, was next transformed to tetrahydrofuran-2-ol via a ring-closure process. Cyclic products were also obtained in hydroformylation of 1-buten-3-ol. In reaction of undec-1-ol and 2-allylphenol linear aldehydes were formed with the yield 69–87%. The hydroformylation of 3-buten-1-ol performed under “on water” conditions showed very good regioselectivity towards a linear aldehyde, 5-hydroxypentanal. Further cyclization of the aldehyde to tetrahydropyran-2-ol was observed.

Full text of DOI:10.1016/j.molcata.2016.06.003

Accepted Manuscript
Title: Comparison of “on water” and solventless procedures in
the rhodium-catalyzed hydroformylation of diolefins, alkynes,
and unsaturated alcohols
Author: W. Alsalahi A.M. Trzeciak
PII:
S1381-1169(16)30216-3
DOI:
Reference:
http://dx.doi.org/doi:10.1016/j.molcata.2016.06.003
MOLCAA 9909
To appear in:
Journal of Molecular Catalysis A: Chemical
Received date:
Revised date:
Accepted date:
3-3-2016
26-5-2016
1-6-2016
Please cite this article as: W.Alsalahi, A.M.Trzeciak, Comparison of “on water”
and solventless procedures in the rhodium-catalyzed hydroformylation of diolefins,
alkynes, and unsaturated alcohols, Journal of Molecular Catalysis A: Chemical
http://dx.doi.org/10.1016/j.molcata.2016.06.003
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Comparison of “on water” and solventless procedures in the rhodium-
catalyzed hydroformylation of diolefins, alkynes, and unsaturated alcohols
W. Alsalahi and A.M. Trzeciak*
Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie St., 50-383 Wrocław, Poland
E-mail: anna.trzeciak@chem.uni.wroc.pl

Graphical abstract
CHO
CHO
Rh/PPh3
H2O
+ CO + H2
+

Highlights
1. Highly efficient hydroformylation was performed under solventless conditions.
2. Dialdehydes were formed selectively in “on water” hydroformylation of dienes.
3. Linear aldehyde was obtained from phenylacetylene in “on water” conditions.
4. Solventless conditions facilitated formation of linear aldehydes from alcohols.

Abstract
Catalytic systems containing Rh(acac)(CO)2 or Rh/PAA (PAA = polyacrylic acid) and
hydrophobic phosphine (PPh3) were used in the hydroformylation of diolefins, alkynes, and
unsaturated alcohols under solventless and “on water” conditions. The total yield of dialdehydes
obtained from 1,5-hexadiene and 1,7-octadiene reached 99%, and regioselectivity towards linear
dialdehydes was higher in the “on water” system. The tandem hydroformylation-hydrogenation
of phenylacetylene led to the formation of saturated aldehydes (3-phenylpropanal and 2-
phenylpropanal) at 98% conversion with a good regioselectivity towards the linear aldehyde in
the “on water” reaction. In contrast, solventless conditions appeared better in the
hydroformylation of 1-propen-3-ol. 4-Hydroxybutanal, formed in this reaction with an excellent
selectivity, was next transformed to tetrahydrofuran-2-ol via a ring-closure process. Cyclic
products were also obtained in hydroformylation of 1-buten-3-ol. In reaction of undec-1-ol and
2-allylphenol linear aldehydes were formed with the yield 69-87%. The hydroformylation of 3-
buten-1-ol performed under “on water” conditions showed very good regioselectivity towards a
linear aldehyde, 5-hydroxypentanal. Further cyclization of the aldehyde to tetrahydropyran-2-ol
was observed.
Keywords: hydroformylation; on water; rhodium; solventless

1. Introduction
The hydroformylation of olefins is one of the most important homogeneously catalyzed
industrial processes with about nine million tons of aldehydes produced annually.
Hydroformylation was discovered by Otto Roelen in 1938. However, this reaction is still
extensively studied as a highly attractive process to produce aldehydes and alcohols [1].
“On water” and solventless methods of performing catalytic reactions are gaining significant
attention in green chemistry due to their advantages as environmentally friendly procedures. In
most cases, reactions occur smoothly giving pure products with high selectivity and a high
reaction rate. These procedures are also very attractive from the economic point of view because
they enable the elimination of environmentally harmful, toxic, and flammable organic solvents
[2–7].
The term “on water” means catalytic reactions performed with reactants insoluble in water [5,
36].
It was shown that hydrophobic effect, observed when water was used as a solvent, could enhance
the rate of organic reactions [8-10].
The hydroformylation of diolefins produces a mixture of mono- and dialdehydes, saturated and
unsaturated, linear and branched [11, 12]. Dialdehydes are valuable intermediates for the
production of a range of commercially significant products such as diamines [13], bicarboxylic
acids and their derivatives [14, 15], alicyclic and heterocyclic compounds having different
structures, [16] and cross-linking agents for polymers, such as proteins, polysaccharides, and
other functionalized macromolecular compounds [17–21]. The hydroformylation of diolefins has
been carried out in organic solvents [11, 22–28] and in scCO2 [29]. However, attempts to

hydroformylate diolefins under “on water” or solventless conditions have not been reported till
now.
In contrast to the hydroformylation of alkenes, studies on the hydroformylation of alkynes are
still underdeveloped. [1, 30–33]. The hydroformylation of phenylacetylene, carried out by
Goettmann et al. [31] in an organic solvent with a zirconia-silica catalyst, gave 23% conversion
to enals. The same reaction was reported in a patent [34], Rh(acac)(CO)2 in scCO2 being used as
a catalyst. Here, the reaction products were 3-phenylpropanal (62%), 2-phenylpropanal (18%),
and styrene (20%) at 80% conversion.
4-Hydroxybutanal could be obtained by the hydroformylation of allyl alcohol. It could next be
reduced to 1,4-butanediol, an important component in the synthesis of plastics. Often, 4-
hydroxybutanal undergoes cyclization to substituted 2-hydroxytetrahydrofuran [35–37].
We have recently developed protocols for the hydroformylation of olefins “on water” and under
solventless conditions which give excellent selectivity to aldehydes at a very high activity of Rh
catalyst [38].
In this paper, we would like to report the application of these two protocols to the
hydroformylation of diolefins, alkynes, and unsaturated alcohols. The catalytic systems
contained a water-soluble immobilized catalyst, Rh/PAA, or a water-insoluble complex,
Rh(acac)(CO)2, with an excess of hydrophobic phosphine, PPh3. The substrates, diolefins,
phenylacetylene, and 1-hexyne, are insoluble in water, while allyl alcohols are miscible with
water.

2. Experiment section
2.1. The general procedure of hydroformylation
Hydroformylation experiments were carried out in 100 mL (or 50 mL) stainless steel autoclaves
provided with a manometer, a thermostat, a magnetic stirrer, and a gas inlet/outlet system. The
catalyst, Rh(acac)(CO)2 or Rh/PAA, and PPh3 were placed in the autoclave. Then, 1.5 mL of
substrate were introduced into the autoclave under a nitrogen atmosphere. In the case of
experiments carried out on water, 1.5 mL of twice distilled water was added. The autoclave was
closed, flushed with hydrogen (5 bar) three times, and thereafter pressurized with a synthesis gas
(H2: CO =1:1) to 10 bar (or 14 bar) and heated to 80 oC (or 60oC). After the reaction was
finished, the autoclave was cooled to room temperature and the residual gases depressurized. The
product mixture was immediately analyzed by NMR spectra, the catalyst was removed by
StratospheresTM Spe, and the obtained products were identified by means GC and GC-MS.
Selected reaction mixtures were analyzed additionally using 1H and 13C NMR.
b
b
a
a
Fig. 1. 1H NMR and 13C NMR spectra (C6D6) of a) 1,7-octadiene and b) post-reaction mixture after the
hydroformylation of 1,7-octadiene under solventless conditions

b
b
a
a
Fig. 2. 1H NMR and 13C NMR spectra (C6D6) of a) phenylacetylene and b) solution obtained after the
hydroformylation of phenylacetylene under solventless conditions.
b
a
b
a
Fig. 3. 1H NMR and 13C NMR spectra (C6D6) of a) allyl alcohol and b) products after the
hydroformylation of allyl alcohol under solventless condition at substrate to rhodium ratio 600.
3. Results and discussion
3.1. Hydroformylation of 1,7-octadiene
The hydroformylation of 1,7-octadiene was carried out in “on water” and solventless conditions,
using rhodium precursors, Rh(acac)(CO)2 (water-insoluble) and Rh/PAA (water-soluble), as

catalysts, with a 13-fold excess of hydrophobic phosphine (PPh3). The possible reaction products
are shown in Scheme 1 and the results are given in Table 1. In all experiments, the conversion of
1,7-octadiene was 100%. The main products were dialdehydes (1,10-decanedial 4 and 2-
methylnonanedial 3). Smaller amounts of 2,7-dimethyloctanedial 2 and 6-nonenal 1
(monoaldehyde isomerization product) were also formed. Interestingly, iso-dienes, possible
isomerization products, were not formed under the hydroformylation reaction conditions.
The reaction under solventless conditions, performed by applying the catalytic system
Rh(acac)(CO)2/PPh3, exhibited good selectivity to form dialdehydes.
CHO
+
CHO
[Rh]
CHO
H2 / CO
2
CHO
CHO
CHO
1
+
3
CHO
CHO
OHC
4
Scheme 1: Hydroformylation of 1,7-octadiene
In the same reaction carried out under “on water” conditions, an increase in the 4/(2+3) ratio to
1.69 was noted (Table 1, entry 2). The “on water” hydroformylation of 1,7-octadiene, catalyzed
by water-soluble Rh/PAA, showed even higher 4/(2+3) ratio, equal 3.28 (Table 1, entry 4).
Thus, the catalyst Rh/PAA used in a water medium promoted regioselectivity towards the linear
dialdehyde. It should be underlined here that the reaction with a Rh/PAA catalyst was slower and
it took about 3 h, whereas already 1.5 h was enough to get a total conversion of 1,7-octadiene
using Rh(acac)(CO)2. The difference in the reaction rate can be related to the hydrophobic effect

expressed stronger when the catalyst is insoluble in water [8-10]. On the other hand application
of the soluble catalyst resulted in the increase of the selectivity to the linear aldehyde.
The analysis of solventless, “on water” and in toluene reactions performed with a
Rh(acac)(CO)2/PPh3 system (Table 1, entries 1, 2 and 3) led to the conclusion that there is not
much difference in the three system, the results were very similar. In all cases the selectivity
expressed as the (4/(2+3) ratio was significantly lower than with Rh/PAA as the catalyst (Table
1, entry 4).
Table 1. Hydroformylation of 1,7-octadiene “on water”, under solventless conditions and in toluene.
Entry Solvent Conversion
%
1(E and
2 %
3 %
4 %
4/(2+3)
Z) %
1
2
-
100
100
100
100
1
3
5
4
4
6
36
32
31
15
58
61
60
69
1.41
1.69
1.71
3.28
Water
Toluene
Water
3
4a
5
10
Reaction conditions:1,7-octadiene 1.5 mL (0.01 mol),water 1.5 mL or toluene 1.5 mL as solvent,
Rh(acac)(CO)2 (1.27 . 10-5 mol), PPh3 (1.65 . 10-4 mol), P = 10 bar, T= 80 oC, time = 1.5 h, atime = 3 h
and Rh/PAA as catalyst.
3.2. Hydroformylation of 1,5-hexadiene
In the hydroformylation of 1,5-hexadiene under solventless conditions, using the catalytic system
Rh(acac)(CO)2/PPh3, the substrate was completely converted to dialdehydes. The main products
were octane-1,7-dial (4), 64%, and 2-Me-heptane-1, 8-dial (3), 29%, (Scheme 2, Table 2, entry
1).

CHO
CHO
CHO
CHO
[Rh]
1
CHO
H2 / CO
+
3
CHO
CHO
OHC
2
CHO
4
Scheme 2: Hydroformylation of 1,5-hexadiene
The same reaction carried out “on water” with the same catalyst showed an increase of the
unsaturated monoaldehyde (1) amount from 4 to 14%. Simultaneously, the yield of branched
dialdehydes (2 + 3) decreased from 32 to 23% with almost the same yield of the linear
dialdehyde (4) (63%) (Table 2, entry 2). The results obtained by using toluene as a solvent were
similar to solventless conditions with selectivity to linear aldehydes lower than in water (Table 2,
entry 3 and 4). The best regioselectivity towards the linear dialdehyde, octane-1, 7-dial (4, 69%),
was obtained by using the Rh/PAA catalyst in water (Table 2, entry 4). Similarly as in
hydroformylation of 1,7-octadiene, the reaction in water was faster with insoluble Rh(acac)(CO)2
than with soluble Rh/PAA.
For comparison, in the hydroformylation of 1,5-hexadiene and 1,7-octadiene, catalyzed by
Rh(acac)(CO)(PPh3)/PPh3 in toluene, the total yield of the dialdehyde reached 100% after 3 h,
and the l/b ratio was 1.8–2.1 [11]. The high yield of the dialdehyde was obtained in the
hydroformylation of 1,5-hexadiene by Botteghi et al. [15], using the catalytic system
o
RhH(CO)(PPh3)3/Xantphos (1:3) in toluene, at 60 C and 20 bar in a reaction time of 24 h. The
catalytic system Rh(acac)(CO)2/ tris(3,5-bis(trifluoromethyl)phenyl)phosphine was applied for

the hydroformylation of 1,5- hexadiene and 1,7-octadiene by S. Fujita et al. [29]. They received
the total yield of dialdehydes 30% and 50% respectively in toluene, and 90% for both substrates
in scCO2 at 60 oC and 40 bar, in a reaction time of 2 h. The l/b ratio was 1.5 and 0.6 respectively.
Thus, the good selectivity was obtained “on water” under relatively mild conditions.
Table 2. Hydroformylation of 1,5-hexadiene “on water”, under solventless conditions and in toluene.
Entry
solvent
Conversion
%
1 (E + 2 %
3 %
4 % 4/(2+3)
Z) %
1
2
-
100
100
100
100
4
3
2
3
2
29
21
27
15
64
63
60
69
2.0
2.7
2.0
4.1
Water
Toluene
Water
14
10
14
3
4a
Reaction conditions:1,5-hexadiene 1.5 mL (0.0126 mol), water 1.5 mL or toluene 1.5 mL as solvent,
Rh(acac)(CO)2 (1.58 . 10-5 mol), PPh3 (2.05 . 10-4 mol), T= 80 oC, H2:CO (1:1)= 10 bar, time = 1.5 h, a
Rh/PAA as catalyst, time = 3 h.
3.3. Hydroformylation of phenylacetylene and styrene
In the hydroformylation of phenylacetylene under solventless conditions by employing
Rh(acac)(CO)2 with a 13-fold excess of PPh3, the conversion was 28% with high
chemoselectivity of the hydrogenation product, styrene (17%) (Table 3, entry 1). In contrast, in
the “on water” reaction 3-phenylpropanal (3) and 2-phenylpropanal (4) were mainly formed
(Table 3, entry 2). Moreover, the total conversion was higher, 50%. High conversions, 98% and
o
94%, were obtained in water using Rh(acac)(CO)2 and Rh/PAA respectively at 100 C and 14
bar (Table 3, entries 5 and 6). Apparently, selectivity to the linear aldehyde, 3-phenylpropanal
(3), was also satisfactory (Table 3, entry 5 and 6). The results clearly showed that the reactions

ran in two steps. The first step was the hydroformylation of phenylacetylene to produce
unsaturated aldehydes (enals) followed by the second step involving the hydrogenation of enals
to saturated aldehydes (as shown in Scheme 3). To make sure that the saturated aldehydes were
formed through hydroformylation followed by hydrogenation, we performed the
hydroformylation of styrene under the same conditions on water and under solventless conditions
(Table 3 entries 7-11). The obtained results were completely different; the reaction was faster,
and already in 1 h the conversion was complete (100%). Moreover, a higher regioselectivity to
the branched aldehyde was noted. This is in agreement with our previous study on the
hydroformylation of styrene on water and under solventless conditions [5, 38] as well as with
results obtained by other Authors [1]. The application of different H2 : CO ratio ( 1.5 : 1)
changed only slightly the 3/4 ratio (Table 3, entries 10 and 11). Although formation of aldehydes
by hydroformylation of styrene, product of hydrogenation of phenylacetylene, can not be
completely ruled out, the remarkable difference in selectivity suggested hydroformylation of
phenylacetylene as a first step of the reaction. Accordingly, saturated aldehydes were formed
through hydroformylation of phenylacetylene to unsaturated aldehyde followed by
hydrogenation.
The tandem hydroformylation/hydrogenation reaction of phenylacetylene exhibited a higher
regioselectivity to the linear aldehyde in the “on water” reaction than under solventless
conditions.

CHO
CHO
3-phenylprop-2-enal
3-phenylpropanal
[Rh]
1
3
CHO
CHO
H2
CO
+
+
+
Phenylacetylene
2-phenylprop-2-enal
2-phenylpropanal
+
4
styrene
2
Scheme 3: Hydroformylation of phenylacetylene

Table 3. Hydroformylation of phenylacetylene and styrene using Rh(acac)(CO)2 as a catalyst
Entry Substrate
Solvent t, h Conversion%
1%
2%
17
12
7
3%
4
4%
7
3/4 ratio
0.6
1a
2a
-
22
22
6
28
50
Water
-
4
2
1
1
21
26
49
58
53
21
22
17
27
25
13
15
44
38
39
79
78
83
68
70
1.6
3
4
50
1.73
1.1
Phenyl
acetylene
-
22
22
19
1
97
3
5
6b
Water
Water
-
98
1
1.5
94
2
1.4
7
100
100
100
100
100
0.26
0.28
0.2
8
Water
Water
-
1
9b
10c
11c
Styrene
1
1
5d
5d
0.4
Water
1
0.36
Reaction condition: phenylacetylene (1.5 mL, 0.0137 mol) or styrene 1.5 mL as substrate, water (1.5 mL),
[sub]/[Rh]=800, [L]/[Rh]= 13, T=100oC, P= 14 atm (H2: CO = 1:1), a T=80oC, P= 10 atm (H2: CO =
1:1), b Rh/PAA as catalyst, c P = 14 atm ( H2 : CO = 1.5 : 1 ), d Ethylbenzene.

3.4. Hydroformylation of 1-hexyne
1-Hexyne reacted with moderate conversion and good chemoselectivity to saturated aldehydes
(Table 4). Higher regioselectivity towards heptanal (linear aldehyde) was obtained in the water
medium than under solventless conditions.
Table 4. Hydroformylation of 1-hexyne catalyzed by Rh(acac)(CO)2 under solventless conditions
and on water
Entry Solvent
Conversion
Heptanal %
2-Me-
l/b
Heptanoic acid
%
13
72
68
55
hexanal %
1a
2
-
6
2
3.0
2.4
3.6
2.3
5
4
4
5
-
48
50
35
20
14
15
3
4b
Water
Water
Reaction condition: 1-hexyne (0.013 mol), substrate/Rh = 800, PPh3/Rh = 13, (H2:CO)(1:1) = 16 bar, T
= 100 oC, water(1.5 mL), a (H2:CO)(1:1) = 10 bar, T = 80 oC, b Rh/PAA as catalyst.
3.5. Hydroformylation of 1-propen-3-ol
The typical reaction products of 1-propen-3-ol hydroformylation, tetrahydrofuran-2-ol (1), 2-
methylprop-2-enal (2a), 2-methylpropanal (2b), and propanal (3), are presented in Scheme 4. 4-
Hydroxybutanal undergoes fast cyclization to tetrahydrofuran-2-ol, and it was found only in this
form in the reaction mixture.

HO
HO
CHO
OH
H2
H2/CO
[ Rh ]
O
+
1
HO
-H2O
OHC
OHC
CHO
CHO
+
2b
2a
3
Scheme 4: Hydroformylation of 1-propen-3-ol
The results collected in Table 5 show that the hydroformylation of 1-propen-3-ol catalyzed by
the Rh(acac)(CO)2/PPh3 system gave an excellent regioselectivity towards linear aldehydes and
56% of cyclization product, tetrahydrofuran-2-ol (1), was formed within 3.5 h (Table 5, entry 1).
Quite different results were obtained in water, where the conversion increased to 83 and 85%
with the application of the catalyst precursors Rh(acac)(CO)2 and Rh/PAA respectively.
However, simultaneously, the 1/(2a+2b) ratio, illustrating reaction selectivity, decreased to 1.5
and 0.7 respectively (Table 5, entries 2 and 3). The change of the substrate-to-rhodium ratio from
800 to 600 and reducing pressure from 14 to 12 bar resulted in an enhancement of the reaction
rate and an increase in chemoselectivity (Table 5, entries 1 and 4). Lower chemoselectivity was
obtained by applying Rh/PAA as catalyst under solventless condition (Table 5, entry 5).

Table 5. Hydroformylation of 1-propen-3-ol “on water” and under solventless conditions catalyzed by
Rh(acac)(CO)2/PPh3 system
entry Sub:Rh Solvent t, h Conversion 1% (2a+2b)% 1/(2a+2b) 3% 4d%
%
1a
2a
800
800
800
600
600
-
3.5
4
57
83
85
92
56
45
32
83
52
1
7
4
4
8
Water
31
49
3
1.5
0.7
3a,c
4b
Water
4
-
-
2.5
3
27.7
5.7
2
6
5b,c
75
9
o
a
b
Reaction condition: [PPh3]/[Rh]= 6, T= 80 C, allyl alcohol (1.5 mL), solvent 1.5 mL P = 14 bar,
allyl alcohol (0.82 mL), P = 12 bar, c Rh/PAA as catalyst, d unidentified product.

3.6. Hydroformylation of 3-buten-1-ol
The hydroformylation of 3-buten-1-ol led to the expected products, 5-hydroxypentanal and 4-
hydroxy-2-methylbutanal, undergo cyclization to tetrahydropyran-2-ol (1) and 4-
methyltetrahydrofuran-2-ol respectively (2) (Scheme 5).
OH
O
OHC
OH
OH
H2C
5-hydroxypentanal
tetrahydro-2H-pyran-2-ol
but-3-en-1-ol
1
H3C
OH
OH
O
OHC
4-hydroxy-2-methylbutanal
H3C
OH
H3C
4-methyltetrahydrofuran-2-ol
butan-1-ol
2
3
OH
H3C
(2E)-but-2-en-1-ol
4
O
3,4-dihydro-2H-pyran
5
Scheme 5: hydroformylation of 3-buten-1-ol
o
At 60 C and 10 bar, the conversion of 3-buten-1-ol was 73%, and the selectivity to products 1
and 2 was 52% (1/2 ratio = 5.5) (Table 6, entry 1). Conversion and regioselectivity increased
(1/2 ratio = 10) with pressure increased to 14 bar (Table 6, entry 2). At an elevated temperature
(80 oC), conversion to 1 and 2 increased to 84%; however, the 1/2 ratio decreased to about 4 as a
result of the higher amount of the branched product (Table 6, entry 3).

o
In a water medium, at 80 C and 14 bar, the hydroformylation of 3-buten-1-ol catalyzed by
Rh(acac)(CO)2/PPh3 was less efficient although good selectivity was noted (Table 6, entry 4).
Under the same conditions, Rh/PAA performed much better giving the highest yield of 1 (82%)
selectivity (Table 6, entry 5).
Table 6. Hydroformylation of 3-buten-1-ol “on water” and under solventless conditions
entry
1a
Solvent
-
Conversion%
t, h
1.5
2.5
2
1%
44
60
67
69
82
2%
8
1/2
5.5
10
4
3%
9
4%
6
5%
6
73
96
97
86
94
2b
6
9
11
6
10
3
3c
-
17
8
4
4c
Water
Water
3.2
3
8.6
9
4
5
5c,d
9
1
1
1
a
Reaction condition: 3-buten-1-ol (1.5 mL), water (1.5 mL), [substrate: Rh] = 800, [PPh3: Rh] = 6, T=
60 oC, P = 10 bar, b T = 60 oC, P = 14 bar, c T = 80 oC, P = 14 bar, d Rh/PAA as a catalyst.
Hydroformylation of 1-buten-3-ol gave a cyclic product, 2-hydroxy-5-methyltetrahydrofuran (1),
as the main one. Interestingly, under solventless conditions it was formed with 99% yield. In
water the selectivity was lower and 17-18% of alcohol was transformed to the branched
aldehyde, identified in a cyclic form (2). The results were almost the same with Rh(acac)(CO)2
and with Rh/PAA.
OH
OH
H2/CO
[Rh]
O
O
+
OH
O
OH
1
2
Scheme 6: Hydroformylation of 1-buten-3-ol

Table 7. Hydroformylation of 1-buten-3-ol “on water” and under solventless conditions
entry
Solvent
-
Conversion%
1%
97
2%
-
1
2
99
98
99
Water
Water
77
18
17
3a
78
Reaction condition: water (1.5 mL), [substrate: Rh] = 500, [PPh3: Rh] = 13, T= 80 oC, P = 10 bar, 3h, a
Rh/PAA as a catalyst.

3.7. Hydroformylation of 5-hexen-1-ol and undec-1-ol
The solventless hydroformylation of 5-hexen-1-ol was carried out using Rh(acac)(CO)2 with a 6-
fold excess of PPh3 at a substrate-to-rhodium ratio of 800, 10 bar, and 80 oC. As expected, linear
and branched hydroxy aldehydes (7-hydroxyheptanal and 6-hydroxy-2-methylhexanal) were
formed without the formation of cyclic acetals [39, 40] (Scheme 7).
OH
OHC
OH
+
H2 / CO
[ Rh ]
32%
OH
12%
3%
CHO
OH
+
OH
13%
8%
OH
Scheme 7: Hydroformylation of 5-hexen-1-ol
The hydroformylation of undec-1-ol performed at 14 bar resulted in formation of 73-87% of 12-
hydroxydodecanal (linear product) and 11-12% of the branched one, 11-hydroxy-2-methylundecanal. The
results obtained under solventless conditions and “on water” were very similar.
Table 8. Hydroformylation of undec-1-ol “on water” and under solventless conditions
entry Solvent Conversion
%
12-hydroxydodecanal %
11-hydroxy-2-
methylundecanal 2%
1
2
-
100
95
85
73
87
11
12
11
Water
Water
3a
100
Reaction condition: water (1.5 mL), [substrate: Rh] = 500, [PPh3: Rh] = 13, T= 80 oC, P = 10 bar, 3h, a
Rh/PAA as a catalyst.

3.8. Hydroformylation of 2-allylphenol
2-Allylphenol was hydroformylated to the linear aldehyde, 4-(2-hydroxyphenyl)butanal (1), with
the yield 70-80% at 14 bar. The branched aldehyde undergo cyclization to 2-methylchroman-2-ol
(2). The selectivity to the linear product was higher in water, l/b = 4, than under solventless
conditions (l/b = 2.2). At the lower pressure, 10 bar, conversion was only 44% and comparable
amounts of linear and branched products were formed.
OH
OH
O
O
OH
H2/CO
[Rh]
+
1
2
Scheme 8: Hydroformylation of 2-allylphenol
Table 9. Hydroformylation of 2-allylphenol
entry Solvent Conversion 4-(2-hydroxyphenyl)butanal
3-methylchroman-2-ol
%
(1) %
24
(2) %
20
1
2a
-
44
-
100
100
100
69
31
3a
Water
Water
80
20
4a,b
70
30
Reaction condition: water (1.5 mL), [substrate: Rh] = 500, [PPh3: Rh] = 13, T= 80 oC, P = 10 bar, 3h, a
14 bar, bRh/PAA as a catalyst.
3.9. Rhodium species formed during hydroformylation
1
Rhodium species present in the reaction mixture were identified by means of H NMR
measurements. The 31P NMR (500 MHz) spectrum measured after the hydroformylation reaction

of diolefins, alkynes, and unsaturated alcohols showed the presence of a doublet at 32.2 ppm
(J(Rh-P) = 135 Hz), assigned to HRh(CO)2(PPh3)2 [41].
4. Conclusions
In conclusion, the hydroformylation of diolefins, alkynes, and unsaturated alcohols was
investigated for the first time under solventless conditions and in “on water” reactions by
applying the catalytic systems Rh/PAA (water-soluble) and Rh(acac)(CO)2 (water-insoluble)
with an excess of a commercially available and inexpensive hydrophobic phosphine (PPh3)
ligand. The main advantage of the studied procedures was complete elimination of the organic
solvent.
We demonstrated that the hydroformylation of diolefins can be very efficiently performed in
water, where the dialdehydes were the desired products obtained in excellent yields with
excellent selectivities. Regioselectivity towards the linear aldehyde increased in the “on water”
reaction. It can be therefore suggested that aggregation of hydrophobic PPh3 molecules around
the active rhodium center facilitates formation of linear alkyl and acyl intermediates and, finally,
linear aldehydes are produced.
We also demonstrated that such methodologies can be applied for alkynes to produce saturated
aldehydes in high yield and selectivity. Saturated aldehydes, the final reaction products, were
obtained through hydroformylation followed by hydrogenation. Good regioselectivty towards the
linear aldehyde was found in the “on water” reaction.
We also demonstrated that the hydroformylation of unsaturated alcohols can be carried out very
efficiently in water, and under solventless conditions. In the hydroformylation of 1-propen-3-ol,
an excellent chemoselectivity and regioselectivity towards tetrahydrofuran-2-ol under solventless

conditions was obtained. In contrast, the hydroformylation of 3-buten-1-ol exhibited a better
regioselectivity towards tetrahydropyran-2-ol in “on water” reaction than under solventless
conditions.
Hydroxyaldehydes produced during the hydroformylation of 1-propen-3-ol, 3-buten-1-ol and 1-
buten-3-ol (short chain) undergo transformation to cyclic acetals, whereas the hydroformylation
of 5-hexene-1-ol and undec-1-ol (long chain) leads to hydroxyaldehydes without the formation
of cyclic acetals.
The influence of water on the hydroformylation of unsaturated alcohols can be related to their
hydrophobic or hydrophilic properties. For example, the selectivity enhancement was not
observed in hydroformylation of water-soluble 1-propen-3-ol while for 2-allylphenol higher
selectivity was noted in water.
The performed studies indicate that the final composition of hydroformylation performed in
water depends on hydrophobic effect comprising aggregation of substrate molecules and
aggregation of hydrophobic phosphine used as modifying ligand.

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