Hydroformylation-hydrogenation and hydroformylation-acetalization reactions catalyzed by ruthenium complexes

Article abstract of DOI:10.1016/j.molcata.2016.09.020

In this work, the catalytic activity of ruthenium II and III complexes containing chloride, pyridine, phosphine and CO ligands was investigated in the hydroformylation – hydrogenation and hydroformylation – acetalization reactions. The complexes mer-[RuCl₃(dppb)(H₂O)](1), mer-[RuCl₃(dppb)(4-Vpy)](2), mer-[RuCl₃(dppb)(4-tBupy)](3), mer-[RuCl₃(dppb)(py)](4), mer-[RuCl₃(dppb)(4-Phpy)](5), mer-[RuCl₃(dppb)(4-Mepy)](6), cis-[RuCl₂(CO)₂(dppb)](7), trans-[RuCl₂(CO)₂(dppb)](8), RuCl₃·xH₂O(9), [RuCl₂(PPh₃)₃](10) and [RuCl₂(PPh₃)₂(dppb)](11) were used as supplied or synthesized as previously described in the literature {Where PPh₃?=?triphenylphosphine, dppb?=?1,4-bis(diphenylphosphino)butane, py?=?pyridine, 4-Mepy?=?4-methylpyridine, 4-Vpy?=?4-vinylpyridine, 4-tBupy?=?4-tert-butylpyridine and 4-Phpy?=?4-phenylpyridine}. These complexes were used as a pre-catalysts in a hydroformylation catalytic system to produce C[sbnd]C, C[dbnd]O and C[sbnd]O bonds, where 1-decene resulted in a formation of respective alcohol and dimethyl acetals. Several reactions were performed in order to find the best reaction conditions presenting the best conversion (64% after 24?h). The 1-decene was also used as a substrate in two type tandem reactions labeled as: hydroformylation – hydrogenation (HH) and hydroformylation – acetalization (HA) reactions. The relationship between Ru – catalyst/substrate was 1:100, without free ligands or additives, in a controlled temperature and pressure. All the products of catalytic reactions HH and HA were analyzed by CG-FID with good yields.

Full text of DOI:10.1016/j.molcata.2016.09.020

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Journal of Molecular Catalysis A: Chemical
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Hydroformylation-hydrogenation and hydroformylation-acetalization
reactions catalyzed by ruthenium complexes
Claudia Rodriguesa, Fabio G. Deloloa, Jakob Norinderb, Armin Börnerb,c
,
André L. Bogadod,∗, Alzir A. Batistaa,∗
a Departamento de Química, Universidade Federal de São Carlos, Rod. W. Luiz Km 235, 13565-905 São Carlos, SP, Brazil
b Leibniz-Institut für Katalyse an der Universität Rostock e.V., A.-Einstein-Str. 29a, 18059 Rostock, Germany
c Institut für Chemie, Universität Rostock, A. Einstein-Str. 3a, 18059 Rostock, Germany
d Faculdade de Ciências Integradas do Pontal, Universidade Federal de Uberlândia, Rua vinte, 1600, CEP 38304-402 Ituiutaba, MG, Brazil
a r t i c l e i n f o
a b s t r a c t
Article history:
In this work, the catalytic activity of ruthenium II and III complexes containing chloride, pyridine, phos-
phine and CO ligands was investigated in the hydroformylation – hydrogenation and hydroformylation –
acetalization reactions. The complexes mer-[RuCl3(dppb)(H2O)](1), mer-[RuCl3(dppb)(4-Vpy)](2),
Received 14 June 2016
Received in revised form
14 September 2016
Accepted 14 September 2016
Available online xxx
mer-[RuCl3(dppb)(4-tBupy)](3),
mer-[RuCl3(dppb)(py)](4),
mer-[RuCl3(dppb)(4-Phpy)](5),
mer-
[RuCl3(dppb)(4-Mepy)](6), cis-[RuCl2(CO)2(dppb)](7), trans-[RuCl2(CO)2(dppb)](8), RuCl3·xH2O(9),
[RuCl2(PPh3)3](10) and [RuCl2(PPh3)2(dppb)](11) were used as supplied or synthesized
as previously described in the literature {Where PPh3 = triphenylphosphine, dppb = 1,4-
bis(diphenylphosphino)butane, py = pyridine, 4-Mepy = 4-methylpyridine, 4-Vpy = 4-vinylpyridine,
This paper is dedicated to Prof. Georgiy B.
Shul’pin.
4-tBupy = 4-tert-butylpyridine and 4-Phpy = 4-phenylpyridine}. These complexes were used as
a
pre-catalysts in a hydroformylation catalytic system to produce C C, C O and C O bonds, where
1-decene resulted in a formation of respective alcohol and dimethyl acetals. Several reactions were
performed in order to find the best reaction conditions presenting the best conversion (64% after 24 h).
The 1-decene was also used as a substrate in two type tandem reactions labeled as: hydroformylation
– hydrogenation (HH) and hydroformylation – acetalization (HA) reactions. The relationship between
Ru – catalyst/substrate was 1:100, without free ligands or additives, in a controlled temperature and
pressure. All the products of catalytic reactions HH and HA were analyzed by CG-FID with good yields.
© 2016 Elsevier B.V. All rights reserved.
Keywords:
Ruthenium complexes
Tandem reaction
Hydrogenation
Hydroformylation
Acetalization
C-H functionalization
1. Introduction
ucts, which can be easily derived from these compounds such as
hemiacetals, acetals or carboxylic acids and their esters. Special
Transition-metal-catalyzed hydroformylation reactions consti-
tute one of the most powerful tools for C C bond formation in
organic synthesis of aldehydes [1]. Aldehydes are valuable final
products and intermediates in the synthesis of bulk chemicals
such as alcohols, esters, acetals and amines. Aldehydes, acetals
and alcohols are important aroma compounds used as ingredients
in numerous perfumes, flavors and foods [2]. Nowadays, millions
of tons of olefins are converted into aldehydes by hydroformyla-
tion reactions. Not only are aldehydes of enormous importance
as constituents of flavoring mixtures, but they are also prod-
hydroformylation protocols allow the one-step production of alco-
hols, which are also of crucial importance as aroma compounds
[3,4]. Scheme 1 describes the general route to prepare aldehyde,
alcohol and dimethylacetal by a hydroformylation – hydrogena-
tion and hydroformylation – acetalization reactions catalyzed by
ruthenium complexes.
In 1969 A.E. Shilov and co-workers showed that transition metal
complexes, such as Pt (II), can catalyze H/D exchange of alkenes
with solvent protons in homogeneous solution, thereby laying the
foundation for the now successful field of activation of C H bond
[7–9]. The substantial isolation of the products of oxidative addi-
tion of alkanes to transition metals was first achieved by Bergman
[10]. In toward of this view, very few [M(hydrido)(␴-alkyl)] com-
plexes are know, as they tend to undergo spontaneous elimination
of the alkane, which represents a step in the mechanism of the
∗
Corresponding authors.
E-mail addresses: bogado@ufu.br (A.L. Bogado), daab@ufscar.br (A.A. Batista).
http://dx.doi.org/10.1016/j.molcata.2016.09.020
1381-1169/© 2016 Elsevier B.V. All rights reserved.
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Scheme 1. Hydroformylation – hydrogenation (HH) and hydroformylation – acetalization (HA) reactions catalyzed by ruthenium complexes [5].
homogeneous catalytic hydrogenation of alkenes [6]. As a result,
the activation of terminal CH2 group by transition metal com-
plexes has the net effect of moving the C C group along the chain
of the molecule [11]. This is frequently a side reaction, desired or
not according to circumstances, in other types of catalytic alkene
reaction, such as hydrogenation or hydroformylation reactions. The
mechanism of alkene isomerization can occurs by two different
pathways, one by alkyl route, which require an M H bond and a
vacant site; and other one by allyl mechanism, which is adopted by
a metal fragment that have two vacant sites but no hydrides [11] . In
brief, in both mechanisms occur a C H activation, where the tran-
sition metal complexes are capable of catalyzing the 1,3-migration
of hydrogen substituent on alkene.
Ruthenium complexes have been applied to homogeneous
hydroformylation reactions, as catalysts or pre-catalysts, since
1965 by Wilkinson and co-workers [12]. Since then, several ruthe-
nium complexes containing varying ligands, such as CO, have been
reported [13,14]. In the literature, hydroformylation reactions cat-
alyzed by ruthenium complexes using different phosphines as free
ligands and other additives, e.g. LiCl, are occasionally quoted [1,15].
Therefore, one of the main aims of this research was to attempt to
minimize the use of free ligands and additives in order to gener-
ate minimal residues in the synthesis of alcohols and acetals, using
olefins as precursors.
2. Experimental section
2.1. Materials and methods
Solvents were purified by standard methods. All reagents
used were of reagent grade or comparable purity, which
were supplied from commercial sources: RuCl3·xH2O, triph-
enylphosphine (PPh3), 1,4-bis(diphenylphosphino)butane (dppb),
pyridine (py), 4-methylpyridine (4-Mepy), 4-vinylpyridine
(4-Vpy), 4-tert-butylpyridine (4-tBupy) and 4-phenylpyridine
(4-Phpy) were used as received from Aldrich. All complexes
used as pre-catalysts in this research were prepared as
described in the literature: mer-[RuCl3(dppb)(H2O)](1) [17],
mer-[RuCl3(dppb)(4-Vpy)](2) [18], mer-[RuCl3(dppb)(4-tBupy)](3)
[18],
Phpy)](5)
cis-[RuCl2(CO)2(dppb)](7)
[19],
RuCl3·XH2O(9),
mer-[RuCl3(dppb)(py)](4)
[18], mer-[RuCl3(dppb)(4-Mepy)](6)
[19], trans-[RuCl2(CO)2(dppb)](8)
[RuCl2(PPh3)3](10) [20] and
[18],
mer-[RuCl3(dppb)(4-
[18],
[RuCl2(PPh3)2(dppb)](11) [21]. For the synthesis of the hydride-
ruthenium-CO complex (7ꢀ), the cis complex (7) was stirred under
H2 atmosphere for 24 h in a Schlenk flask. The yellow solid was
filtered off and dried in vacuum. [HRuCl(CO)2(dppb)] (7ꢀ): Yield:
90%. Calc. for C30H29ClO2P2Ru: C, 58.11; H, 4.71%. Found: C, 58.07;
1
H, 4.78%. 31P{ H} s = 8,50 ppm and 1H t = −10.5 ppm and IR (KBr)
In a previous study, our group published the syntheses, char-
acterization and catalytic activity of mer-[RuCl3(dppb)(N)] (where
N = derivatives pyridine ligands), in the hydrogenation of cyclo-
hexene, undecanal and cyclohexane carbaldehyde in non-aqueous
solutions [16].
ꢀ(Ru-CO) 2065 and 2008 cm−1 and ꢀ(Ru-H) 1952 cm−1
.
2.2. Instrumentation
Herein the catalytic activity of ruthenium II and III complexes
is described, in the tandem type reactions labeled as: hydroformy-
lation – hydrogenation (HH) and hydroformylation – acetalization
(HA). Different reaction conditions were used, which include dif-
ferent organic substrates, solvents, temperature and pressure to
produce aldehydes, alcohols and acetals.
Elemental analyses were performed in a Fison EA 1108 model.
The FTIR spectra of the powder complexes were recorded from
KBr pellets in the range of 4000 and 200 cm−1 range, in a Bomen-
Michelson FT MB-102 instrument.
The catalytic experiments were carried out in a HEL 8 × 16 mL
parallel reactor.
All NMR experiments were recorded on BRUKER DRX400 MHz
equipment; in a BBO 5 mm probe at 298 K, using CDCl3 (1H) and
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31P{ H}) as solvents, TMS for internal reference for 1H and
3.3. Screening of reaction conditions: synthesis of acetals
CH2Cl2
(
the signals were labeled as s = singlet and t = triplet.
In Table 3, the same reactions performed in Table 1 are listed,
however using MeOH as a solvent in order to produce dimethy-
lacetal instead of alcohol. It can be observed that by increasing
the pressure to 40 bar, the formation of the product 1f was also
increased, 18% in the best case, with 37% of selectivity at a rate
of 20 h−1. For the screenings of the acetalization reaction, the same
ruthenium complexes (1) to (6) were used, shown in Table 1 as pre-
catalysts in the hydroformylation of 1-decene 1a. The experiment
was carried out using a pressure of 20 or 40 bar, and as expected, by
increasing the pressure it was possible to diminish the formation of
the isomerized olefins 1b (n-decenes) and improve the formation
of the desired product, dimethylacetal 1f. However, the TOF values
decreased at a high pressure, reflecting in the conversion values.
In the literature, it can be observed that it is common to add
organic ligands (e.g. phosphines) and additives (e.g. LiCl) [14,22] in
order to improve the yield. According to this, xantphos was added as
a free phosphine and LiCl as an additive. It can be observed in Table 4
that the conversion increased considerably, but the formation of n-
decenes (the isomerization of 1-decene) also increased and they
were kept as main products, with selectivity around 50%. On the
other hand, the formation of the desired product, dimethylacetal,
remained low.
As it was not possible to observe any significant changes in
the results using xantphos and LiCl, more attention was given
to the reactions without free phosphine or additives in order to
attempt to reduce the generated waste. The best results of the
synthesis of undecanal dimethylacetal were obtained using high
pressure (100 bar) of syngas (H2/CO 1:1) and a high temperature of
160 ◦C, within 24 h, when complexes (2) and (10) were used as pre-
catalysts, see Table 5. As expected, the TOF values were decreased,
at a rate of 4.2 h−1, but the amount of the desired product increased
considerably.
GC analysis was run on a Shimadzu CLASS-VPTM instrument
using an Agilent HP-5 column (30 m, 0.32 mm diam., 0.25 ␮m
film); carrier gas; H2, flow rate; 0.9 mL/min. GC program for 1-
decene derivatives: 50 ◦C (2 min) 10 ◦C/min until 180 ◦C, thereafter
30 ◦C/min until 320 (5 min).
2.3. Catalytic experiments
Hydroformylation experiments were carried out in a HEL
8 × 16 mL parallel reactor. The mixture substrate/Ru complex was
prepared in situ. The reactor was purged with Ar (5 × 2 bar) and
with syngas (5 × 5 bar). The reactor was filled with 20, 40, 90
or 100 bar syngas (CO/H2 = 1:1) and heated to 120 or 160 ◦C.
The pressure was kept automatically at the maximal pressure
of each reaction after reaching the maximum temperature. After
the reaction time ended (5 or 24 h), the reactor was cooled to
room temperature. The autoclave was charged with Ru-cat (0.03
or 0.015 mmol), substrate (3 or 1.5 mmol), solvent (3 or 6 mL).
The upper organic layer was analyzed by GC-FID. To promote
hydroformylation – hydrogenation (HH) and hydroformylation –
acetalization (HA), simple modifications were carried out in the
hydroformylation protocol experiment when necessary. For details
see the footnote of each table.
3. Results and discussion
3.1. Screening of reaction conditions: synthesis of alcohol
For the screening of reactions, 1-decene (1a) was used as a
reagent yielding isomerization products n-decenes (1b), decane
(1c), n- or i-undecanal (1d) and n- or i-undecanol (1e). The
substrate/Ru-cat hydroformylation solutions were prepared in
situ. In order to identify the optimal solvent, experiments were
performed screening three solvents (CH2Cl2, toluene and N-
methyl-2-pyrrolidone (NMP)). In an attempt to find the optimal
pressure, two experiments were performed increasing the syngas
pressure from 20 to 40 bar (Table 1). The hydroformylation of the
3.4. Variation of ruthenium catalysts in acetalization
Eleven ruthenium II and III complexes, containing various
ligands, were applied as pre-catalysts to hydroformylation-
acetalization reactions of 1-decene in order to obtain the maximal
conversion of the isolated product of undecanal dimethylacetal 1f.
Thus, various reactions were carried out and the results showed
that (2) and (10) reported good results, and more than 60% of
isolated undecanal dimethylacetal was produced. This is very
promising due to the fact that acetals are products of high economic
value [23].
C
C
C bond, in the reagent 1-decene, occurred to form C C, C O and
O bonds in the aldehyde/alcohol products (See Table 1).
Complexes (1) and (4) were the most active complexes, which
gave 32% of maximal conversion, with TOF average of 6.2 h−1. It
can be observed in Table 1 that the main product is the isomer-
ized olefins in all reactions. The formation of desired products
(1d + 1e) was 6% (isolated yield) in the best case, using (3) and (4) as
pre-catalysts with a syngas pressure of 40 bar. Table 1 shows that
by increasing the syngas pressure from 20 to 40 bar, the desired
product (1d + 1e) also increases, but not as significantly, therefore
additional catalytic experiments were conducted to improve the
conversion and product yields.
3.5. Variation of alcohols in acetalization
For the synthesis of cyclic acetals, ethylene glycol or 1,3-
propanediol were used as a solvent. After 24 h under a pressure
of 90 bar, the crude product was extracted with pentane/Et2O (1:1;
3 × 5 mL). The organic phase was washed with aqueous NaHCO3
(2 × 5 mL). Therefore, 1,3-propanediol afforded a higher yield of the
corresponding acetal, 59% isolated yield with 84% of selectivity. In
the presence of ethylene glycol, 24% of isolated yield was obtained,
53% of selectivity (See Table 6). Apparently the formation of a six −
membered ring is thermodynamically favored over the formation
of a five-membered ring acetal [24].
3.2. Variation of substrates: synthesis of alcohol
In order to synthesize alcohols using olefins as initial material,
the reactions with 1-decene 1a and cyclohexene 2a were per-
formed. Due to the fact that the three solvents tested (See Table 1)
did not allow sufficient conversion, it was decided to use THF and
propylene carbonate (PC). Moreover, higher pressure and temper-
atures were applied than the experiments described in Table 1. The
results, listed in Table 2, shows that the conversion of 1a and 2a
was quantitative, but only 2a provided the product with a high
yield (92% of 2e in THF, with rate of 92 h−1).
3.6. Structure and reactivity of the pre-catalysts
It is known that mer-[RuCl3(dppb)(H2O)], as well as mer-
[RuCl3(dppb)(N)] [N = pyridine and derivatives] are reduced, in the
presence of H2, forming the binuclear compounds, [RuIIICl(dppb)-
(␮Cl)3-RuIICl(dppb)] and [RuCl(dppb)-(␮Cl)3-Ru(dppb)(4-Vpy)]
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Table 1
Conversion data (%) of 1-decene 1a, n-decenes 1b, decane 1c, undecanal – including isomers 1d and undecanol – including isomers 1e, using (1) to (6) complexes as
pre-catalysts.
Pre-catalysts
Pressure (bar)
20
Solvent
Conversion%a
TOF h−1c
1b%b (S%)d
1c% (S%)d
1d + 1e%b (S%)d
CH2Cl2
Toluene
NMP
CH2Cl2
Toluene
NMP
CH2Cl2
Toluene
NMP
CH2Cl2
Toluene
NMP
CH2Cl2
Toluene
NMP
CH2Cl2
Toluene
NMP
30
24
21
4.0
5.0
8.0
12
18
16
13
32
32
10
9.0
21
9.0
10
6.0
6.0
4.8
4.2
0.8
1.0
1.6
2.4
3.6
3.2
2.6
6.4
6.4
2.0
1.8
4.2
1.8
2.0
1.2
24 (80)
17 (71)
17 (81)
3.0 (75)
2.0 (40)
5.0 (63)
4.0 (33)
12 (67)
10 (63)
4.0 (31)
25 (78)
13 (41)
3.0 (30)
4.0 (44)
19 (90)
2.0 (22)
6.0 (60)
5.0 (83)
0
0
<1.0
0
0
0
0
0
<1.0
0
<1
1
0
0
<1.0
0
0
0
0
0
0
(1)
20
40
40
20
20
(2)
(3)
(4)
(5)
(6)
0
2 (25)
1
1
6 (37)
1
1
6 (19)
1
0
2 (9.0)
0
0
<1
0
Reaction conditions: Ru-cat 0.03 mmol, 1-decene 1a 3 mmol, H2/CO 20 or 40 bar, solvent 6 mL, 120 ◦C, in 5 h.
a
GC yield.
b
Calculated yield by internal standard (IS = dodecane).
c
TOF (h−1) turnover frequency = npro/(ncat × t). where npro = mol number of product, ncat = mol number of catalyst and t = reaction time (h−1).
Selectivity = yield of product/conversion × 100; CH2Cl2–methylene chloride; NMP − N-methyl-2-pyrrolidone.
d
Table 2
Conversion data (%) of 1-decene 1a, cyclohexene 2a, undecanol − including isomers 1e and ethanol cyclohexane 2e, using the complexes (1) and (5), as pre-catalysts.
c
Pre-catalyst
Substrate
Solvent
Conversion%a
TOF (h−1
)
Product
Product%b (S%)d
(5)
(5)
THF
PC
99
4.1
4.2
23 (23)
16 (16)
100
(1)
THF
100
4.2
92 (92)
Reaction conditions: Ru-cat 0.015 mmol, 1-decene 1a or cyclohexene 2a 1.5 mmol, H2/CO 90 bar, solvent (THF—tetrahydrofuran and PC—propylene carbonate) 6 mL, 160 ◦ C,
in 24 h.
a
GC yield.
b
Calculated yield by internal standard (IS = dodecane).
c
TOF (h−1) turnover frequency = npro/(ncat × t); where npro = mol number of product, ncat = moles number of catalyst and t = reaction time (h−1).
d
Selectivity = yield of product/conversion × 100.
to ꢀ(Ru-CO) at 2065 and 2008 cm−1 and one band attributed to ꢀ(Ru-H)
at 1958 cm−1, see Figs. 1 and 2 in the Supplementary material (SM).
The presence of hydride was also observed in the 1H NMR spectrum,
which was observed as a triplet at ␦ −10.8, which is in agreement
with the heteronuclear coupling between the hydride and biphos-
phine ligand (dppb), (see Fig. 3 SM). The presence of a singlet at ı
11.8 in the 1H NMR is attributed to the dissociation and protona-
tion of the N-heterocyclic ligand. Therefore, these results suggested
[17,18,25]. Concerning this point of view, after the reaction with
the pre-catalyst (5) described in Table 5, the solvent was evapo-
rated and the obtained solid was dried. This isolated yellow solid
labeled as (5ꢀ) was analyzed using IR and 1H NMR techniques. The
compound (5ꢀ) showed three strong bands in the IR spectra at 2051,
1988 and 1968 cm−1, which were attributed to ꢀRu-CO, ꢀRu-CO and
ꢀRu-H bonds, respectively [26,27]. The IR spectra of the synthesized
compound [HRuCl(CO)2(dppb)](7ꢀ) presented two bands attributed
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Table 3
Conversion data (%) of 1-decene 1a, n-decenes 1b, decane 1c, undecanal dimethylacetal – including isomers 1f, using (1) to (6) complexes, as pre-catalysts.
Pre-catalysts
Pressure (bar)
Conversion%a
TOF h−1c
1b%b (S%)d
1c%
1f%b (S%)d
(1)
(2)
(3)
(4)
(5)
(6)
20
20
40
40
20
20
86
68
32
49
78
54
34
27
13
20
31
22
46 (53)
37 (54)
14 (44)
18 (37)
46 (59)
27 (50)
<1
<1
<1
<1
<1
<1
3.0 (3.0)
4.0 (6.0)
12 (38)
18 (37)
6.0 (8.0)
5.0 (9.0)
Reaction conditions: Ru-cat 0.03 mmol, 1-decene 1a 3 mmol, H2/CO 20 or 40 bar, MeOH 6 mL, 120 ◦ C, in 5 h.
a
GC yield.
b
Calculated yield by internal standard (IS = dodecane).
c
TOF (h−1) turnover frequency = npro/(ncat × t); where npro = mol number of product, ncat = mol number of catalyst and t = reaction time (h−1).
Selectivity = yield of product/conversion × 100.
d
Table 4
Conversion data (%) of 1-decene 1a, n-decenes 1b, decane 1c, undecanal dimethylacetal – including isomers 1f, using (1) and (2) complexes as pre-catalysts.
d
d
Pre-catalyst
Additives
Conv. (%)a
TOF h−1c
1b%b
1c
%
1f%b
(S%)
(S%)
–
100
95
100
96
100
100
95
20
19
20
19
20
20
19
71(71)
56 (59)
61 (61)
55 (57)
64 (64)
58 (58)
49 (52)
0
0
0
0
0
0
0
2.0 (2.0)
3.0 (3.0)
1.0 (1.0)
3.0 (3.0)
1.0 (1.0)
2.0 (2.0)
4.0 (4.0)
(1)
Xantphos
LiCl
Xantphos + LiCl
–
(2)
LiCl
Xantphos + LiCl
Reaction conditions: Ru-cat 0.015 mmol, 1-decene 1a 1.5 mmol, H2/CO 40 bar, MeOH 6 mL, 160 ◦C, in 5 h, Xantphos 2%, LiCl 20%.
a
GC yield.
b
Calculated yield by internal standard (IS = dodecane).
c
TOF (h−1) turnover frequency = npro/(ncat × t); where npro = mol number of product, ncat = mol number of catalyst and t = reaction time (h−1).
Selectivity = yield of product/conversion ×100.
d
Table 5
Conversion data (%) of 1-decene 1a, n-decenes 1b, decane 1c, undecanal dimethylacetal − including isomers 1f, using (1) to (11) complexes as pre-catalysts.
Pre-catalysts
Conversion (%)a
TOF h−1c
1b (%)b (S%)d
1c (%)
1f (%)b (S%)d
1
2
3
4
5
6
7
8
9
93
100
99
97
99
93
98
91
100
99
3.8
4.2
4.1
4.0
4.1
3.8
4.1
3.8
4.2
4.1
4.1
30 (32)
13 (13)
33 (33)
39 (40)
33 (33)
49 (53)
30 (31)
30 (33)
36 (36)
14 (14)
15 (15)
1
<1
<1
<1
<1
0
0
<1
0
31 (33)
61 (61)
38 (38)
50 (52)
51 (52)
44 (47)
38 (39)
25 (27)
30 (30)
65 (65)
54 (54)
10
11
4
1
98
Reaction conditions: Ru-cat 0.015 mmol, 1-decene 1a 1.5 mmol, H2/CO 100 bar, MeOH 6 mL, 160 ◦ C, in 24 h.
a
GC yield.
b
Calculated yield by internal standard (IS = dodecane).
TOF (h−1) turnover frequency = npro/(ncat × t); where npro = mol number of product, ncat = mol number of catalyst and t = reaction time (h−1).
Selectivity = yield of product/convertion × 100.
c
d
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Table 6
Conversion data (%) of 1-decene 1a, n-undecanal 1d, 2-decyl-1,3-dioxalane – including isomers 1 g and 2-decyl-1,3-dioxane – including isomers 1 h, using complex (5), as
catalysts.
Pre-catalyst
Solvent
Conversion (%)a
TOF h−1c
Product
Products%b (S%)d
5
Ethylene glycol
1,3-propanodiol
45
70
1.9
2.9
1g
1h
24 (53)
59 (84)
Reaction conditions: Ru-cat 0.015 mmol, 1-decene 1a 1.5 mmol, H2/CO 90 bar, solvent 6 mL, 160 ◦ C, in 24 h.
a
GC yield.
b
Calculated yield by internal standard (IS = dodecane).
c
TOF(h−1) turnover frequency = npro/(ncat ×t); where npro = mol number of product, ncat = mol number of catalyst and t = reaction time (h−1).
Selectivity = yield of product/conversion × 1000.
d
that the complexes from (1) to (6), mer-[RuCl3(dppb)(N)] react with
9), CAPES (Coordenac¸ ão de Aperfeic¸ oamento de Pessoal de Nível
Superior, Brazil. Project 18782/12-4) and Fapesp (Fundac¸ ão de
Amparo à Pesquisa do Estado de São Paulo) and FAPEMIG (Fundac¸ ão
de Amparo à Pesquisa do Estado de Minas Gerais) for the financial
support. They would also like to acknowledge the Leibniz-Institut
für Katalyse an der Universität Rostock e.V., Rostock, Germany.
similarity, when they are applied to hydroformylation reactions.
However, it can be observed that the behaviors of the complexes
have a different performance, related to the conversion value, in
mild conditions of reactions, such as low temperature and low pres-
sure of syngas (see Tables 1 and 3). At first glance, these adverse
results are attributed to displacement of the N-heterocyclic ligand,
which is a kinetic pathway with a singular rate constant for each
ligand. (see the results in Tables 2, 4 and 5). In other words, in severe
conditions of temperature and pressure, the kinetic limiting path-
way could be another one, where the real catalytic species could be
obtained in situ without spending much time. However, it is well
known that catalysts, which are generated in a fast condition, can
increase the amount of side products. This behavior was observed in
some reactions described above where the TOF number was around
30 h−1. However, when the TOF number was controlled at lower
rates, the amount of the desired products increased considerably,
with selectivity over 80%.
Appendix A. Supplementary data
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.molcata.2016.09.
020.
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