- Email: [email protected]
Selective homologation of methanol catalyzed by transition metal complexes in methanol-amine solutions
Journd
of Molecular
Cctalysis,
I7 (1982)
331-
337
331
SELECTIVE HQMOLOGATIC?N OF METHANOL CATALYZED TRANSITTON METAL COMPLEXES Tr\(’METHANOL-AMXE SOLUTIONS M. J. CHEN*,
Argome (U.S_A_)
YH.ht. FEDER
N~tioncl
BY
and J. W. RATHKE
kbomtory,
Chemical
Engineering
Didion,
Argonne,
IL
60429
summary Trar.sition meti complexes of Mn, Rh, and Ru have been found to catalyze the homologation cf methanol in methanol-amine solutions at syn-gas pressures near 300 atm and temperatures near 200 “C. These catalysts are believed to operate by mechanisms similar to that proposed for Fe(CO),, and likewise produce CO2 as the oxygenated by-product and do not homologate the ethanol prcduct. The use of two metal complexes ‘agether as catalysts has also been examined. In a mixed Fe(CO),Mn,(CO),O catalyst solution, methanol is converted at a rate of 14% h-’ at 220 OC. Ethanol accounts for 72% of the product, the balance being methane. Additives such as phosphines and methyl iodide are found to affect the rate and the selectivity of these systems.
Introduction Transition me’tal-catalyzed homologation of methanol has been actively studied as a possible process for the production of ethanol 11 - 71. All of these studies are based on modifications of the HCo(CO), systems, which catalyze the homologation of methanol in accordance with reaction (1). The large effort focused on the cob& systems is not surprising, since the widely accepted mechanism for this catalyst invokes the protonation of methanol ti activate methyl groups, and for this step the unusually high acidity of HCc(CO), is regarded as essential [8, 9] . Our discovery [IO, 111 of the catalytic homologation of methanol in Fe(CO)ramine catalyst solutions according to reaction (2) has opened a new approach to this potenr;iaUy important chemical process. Eignificantly, ethmol and higher alcohols are not homologated with the new cat&y&_
*Author
to whom
correspondence
o30~-5roz/sz~oooo-ooGo/~o~_~5
should
be addressed.
@ Eketier Sequoia/Prided
in ?TIE NetherIan
332
CH,OH
+ Hz
+ 2CO
-
CH,CH20H
+ CO:!
(2)
The mechanism that we have proposed for the Fe(CO)s catalyst [lo] Is shown in Scheme 1. The nucleophile, HFe(CO)z , is quantitatively generated in step 1, which is fast and reversible. Methanol reacts with CO (step 5, base-catiyzed) to form methyl formate which further reacts with tridkylamine (step 6) to yield the methylanxnonium ion. The rate-limiting reaction between HFe(CO)i and NR3Mei (step 2) leads to HFe(CO)&e, which subsequently reacts with CO and H, (steps 3, 4, and 7) to give ethanol and to regenerate Fe(CO),. In step 8 trialkylamine is regenerated by the catalytic decomposition of the salt [NR3H] [HCOJ , without which the homologation reaction would be stoichiometric with respect to amines. The high selectivity for methanol homologation in this system is believed to be derived from step 6, which, for steric reasons, is much slower for ethyl formate. We wish to report here some transition metal complexes that have also been found to be active catalysts for selective homologation of methanol in methanol-amine solutions. These catalysts are believed to catalyze the reaction according to mechanisms similar to those proposed for Fe(CO)s.
METHANOL MeOH cod bs
NET REACTION HeOh + 2CO+ H, --alMeCHZOH +COz
MeCti,OH ETHANOL
Scheme
1.
333
Experimental
AH the chenicds
were of reagent grade and were used as received. autoclave (Autoclave Engineers, Inc.), provided with an eIectron.ic pressure transducer, was used in the study. A double-piston compressor (HaskeI Eng;neering) was used to transfer gases and to maintain pressure, and a precision metering pump (Laboratory Data Control) to transfer liquid. For experiments with continuous purging, a condenser (0.5 in ID and 3 ft long) fitted with a demister pad was used to prevent loss of vapor with the vent gas. In a typical experiment the autoclave was charged with the solution of intended cospasition and sealed. After thorough deaeration, the contents were brought to the desired temperature and pressure, usually within an hour. Liquid and gas sampIes ware taken at various intervals, and analyzed by GC. The products were identified by GC-MS and/or INMR spectroscopy. Glass electrodes for the comparative measurement of b&city were standardized with an aqueous pH 10 buffer solution. -4 300
ml MagneDrive
Re,4t.s
and discussion
For reaction mechanisms involving many steps, such as that shown in Scheme 1, it is likely that other transition metal complexes may promote only some of the steps that are necessary to complete the cycle, and therefore would not function as catalysts, alone. In order not to overlook any beneficial effects which may be derived from srrch complexes, they were tested as co-catalysts with Fe(CO),.
Survey
of Cafalysfs
As a reference for these survey experiments, -we have used a methanol solution containing 2.0 M N-methylpiperidine (MeNCsHlO) and 0.10 M Fe(CO), (expt. 1). Low iron catalyst concentration* was used so that acceleration of the homologation reaction by the addition of a second transition mete! complex or other additives could be easily detected_ After reaction for 6 h et 200 OC and 300 atm 3:X CO/K,, 34 mmol EtOH and 73 mmol C3H4 were produced, corresponding to a turnover frequency? of 1.1 h-r. Among the individual catalysts examined. Rh13 has the hi&est catalytic activity, with a turnover frequency of 6.1 h-* (T12hk 1). RhCl,- 3K,O is less active but affords a better selectivity for ethanol production. In these Rh catiyst solutions some side products are &so produced’. The mm OE the *Low iron cablyst concentration appezrs to prom&e methane production, at the expense OFet&tact production. TThe turnover frequency is dekecf as the sum of EtOH and CJ& (in mol) prcrdrrced per h per g-atom of tie’d c&aIyst. %3ese products have not yet been identified.
334 TABLE Reactivity Expt. No_
1 and selectivity
patterns
Complex (mmol)
Fe(CO),-
(16-O)=
S
Reaction time
Pm&l&S
(h)
ClHSOHb (mmol)
6.0
CHc (mmol)
(h-‘)
73
1.1
30 (2ld)
2.0
2.0
42
19
6.1
(5.3) c.d
3.4
26
26
O-96
6.0
102
22
0
0
17
19
0.38
50
2.5
(11.5)
Cr(CO)h
(16.0)
6.0
F
(16.0) (32.0)
6.0
Mfil(CO),,, Me1 (80.0)
34 160 ( 160d)
Turnover frequency
6.0
RhIJ ( 5.0)=qe
Mnl(CO)lo
catalystsa
(16.0)
RhCl,-3H,C
Rua[CO),=
for various
(11.5)
6.0
300
‘200 OC and 300 atm (3rl) CO/Hz with continuous soiu tions (160 ml) contain 2.0 IM Wmethylpiperidine. b Includes HC02Et. =Gas purging was not used. dTrimethylamine replaces N-methylpiperidine. eVolume of solution = 50 ml.
gas purge
of 600
0.90 0
ml/min.
Catalyst
side products (on a carbon number basis) is comparable to the ethanol produced_ With RhI, as the catalyst, Rh(CO)& [I21 is initially formed and is then converted, in 2 h, into an unidentified rhodium carbonyl species with uco at 1970 cm-’ (s), 2000 cmn-’ (sh) and 2050 cm-’ (w). into HRu,(CO)TI ]13] under the Ru,(CO) 11 is partially converted reaction conditions_ This catalyst is not very different from Fe(CO)s in its catalytic activity for methane! homologation. Mn,(CO) r0 forms Mn(C0); [14] under such conditions and also shows a reactivity comparable to that of Fe(COj,. However, the selectivity for ethanol production is greatly improved in the manganese system. This improvement probably reflects the more favorable formation of Mn-acyl compfexes in step 3. The sektivity between EtOH and CHq production is determined by step 3 (Scheme 1) and the relative rates of eliminations of CH4 and CH,CHO from the respective metal-Jlcyl and metal-acyl complexes. Chromium hexacarbonylhas no catalytic activity for methanol conversion under these reaction conditions. The result-s of experiments with mixed metal catalysts are shown in Table 2. Et is interesting to note that in the Mnz(CO)ro-Fe(CO)s catalyst system, ‘the sum of C&OH and CH4 (397 mrnol, expt. 2-1) aceeds the sum of these products expected from the individual catalysts (231 mmol, as calculated from expts. 1-l and -5). and the product selectivity reflects
335 TAgLE Reactivity
2 and se!ectivity
Ear mixed
catiysts”
Egpt.
‘Ccl-c2talysk’b
Reaction
NO.
(mmol)
(h)
time
Roduck C*H&H jmmol)
1
Mnl(CO)lo
2
RhClz-3K20
3
Mnz(CO),o RhQ-3&O
(11.5)
Rux(C0)1z MOM NiE+
330
67
(16.0)
6.0
160
(l’r.5) (16.0)
6.0
309
42
(5-3)
6-O
60
150
6.0
34
69
2.0
7
27
6.0
0
0
(16.0) (16.0).
R%(CO),o
6.0
CHS (mmol)
(8.0)
Mnz(C0110 (11.5) P(n-Bu)s (46)
6.0
330
38
=Reaction a: 200 “C and 300 atm 3:l CO/Hz. The reactor was purged with the same CO/Hz mixture at 600 ml/min. bAll the catzlvat solutions (160 ml) container! 15.0 mm01 Fe(CO)S and 320 mmo! MeNCSH~O except-for Expt. 3 in which no Fe(CO)S uas added.
that of M~Q(CO)~,-, catalyst. The Mn-Fe catalyst system is further discussed in the following section. For RhCI,-Fe(CO),. RhC13-Mn2(CO),0 and Ru, (C0),2-Fe(CO)S catalysts (expt. 2-2, -3, and -41, the rates and selectivities are not very different from those expected from the combined catalytic activities of the individual ca+dysts. It is concluded that in the solutions of these mixed metal catalysts (Mn2(CO)10-Fe(CO)S excepted), the individual catalyst acts more or less independently. Addition of Mo(CO), or NiBr, to Fe(CO& catalyst soWzion (expts. 2-5 and -6) seems to have very Little effect on the rate or the selectivity for the conversion of methanol. Re,(CO),, however, inhibits the catalytic activity of Fe(CO& completely. The effects of additives on these reactions has also been briefly examined. Addition of P(n-Bu)3 to Fe(CO)S (2:1, expt. l-7) results in the reduction by half of the catalytic activity_ Addition of F(n-Bu)3 to the Mn,(CO)lO-Fe(CO), catalyst solution (expt. 2-S), however, has little effect on its catalytic activity. Addition of methyl iodide increases the rate of methanol conversion by a factor of 3 in the manganese catalyst solution (expts. 1-5 and -8), but has no effect on the selectivity. Because of the compiexity of the catalytic reactions and ‘he limited data avaiIable, it is not very useful to speculate on how these additives function mechanistically. It suffices to say that further increases in rate and in ethanol sekctivity in these systems may be expected from the use of suitable additives.
335
lh,(CO),o-Fe(CO),
catalyst systems Among all the transition metal colmplexes surveyed in this stildy, Mn,(CO) ,0 appears to be the most- interesting. In contrast to other (Fe, Rh, and Ru) catalyst solutions, in which the concentrations of methyl formate (1.3 M) and methylammonium ion (1.5 - 2.0 M) are at or close to their equilibrium concentrations, the Mnl(CO)r,, catalyst solutions in expt. l-5 (
Acknowledgements This research was supported by the Office of Chemical Science, Division of Basic Energy Sciences, U.S. Department of Energy. We thank Ms. D. *We h*.ve shown that [NRxH,* HCoT] is rapidly decomposed in the presence of Fe(CO)5. **The LWOcompounds eccount for over 99% of the organic products.
337 TABLE
3
Rates znd selectivities Expt. No.
for m'ked
fWCW510 (M)
1
0
2 3 4=
0.1 9.75 0.75
Fe(CO)S/Mnz(CG)re
catalyst
solutions”
Reaction time
Products
TurnoveP
(h)
EtOH (mmol)
CH4 (mmol)
(h-l)
6.0 6.0 6.0 2.0
102 330 423 199
22 67 80 79
0.90 2.9 3.6 11.0
frequency
aCatiyst solutions (160 ml) contain 0.075 M ~Mrra(CO),e and 2.0 M MeNCsHra; reaction at 200 OC and 300 atm (3:l) CO/Ha with continuous gas purging at 600 ml/min. bFe(CO)s not included in the calculation. =Reaction at 220 “C!; 1,3-di(l-methyl-4-piperidyl)propane replaces N-methylpiperidine. The reactor was not purged.
McCullough for assistance and Mr. S. Roth for helptil
in the experimental discussions.
work, Professor
J. Halpern
References 1
2 3 4 5 6 7 8 9 I.0
11 12 13 14
G. S. Koerrner and W. E. Slinkerd, I&. Eag. Ckem. Prod. Res. Dew., I7 (1978) 231. Ger. Offen. 2 625 627 (1976) to L. H. Slaugh (Shell Interuationale Research Maatschappij B-V.); Chem. Abstr.. 8 7 (1977) 5373e. U.S. Patent 4 133966 (1979) to W. R. Pretzer, T. F_ Kobylinski and J. E. Bozik (Gulf Research and Development Co.); Chem. Abstr., 90 (19'79) 120998m. U.S. Patent 4 PI I837 (1976) to P. D. Taylor (Celanese Corp.); Chem. Abstr.. 90 (1979) 103398y. Ger. Offen. 2 823 309 (1978) to J. L. Barclay and E. R. Gane (British Petro!eum Co_ Ltd.) Cfiem. Abstr.. PO (1979) 86729n. U.S. Patent 4 277634 (1981) to W. E. Walker (Union Carbide Corp.); Chem. Abstr.. 95 (1981) 97043~. U.S. Patent 4 171 461 (1979) to C. M. Bar&h (Air Products and Chemicals, Inc.); Chem. .45str_, 91 (1979) 210886~. F. Piacenti and M. Bianchi, in E. Wender and P. Pino (eds.), Organic Syntheses uic MetaI Carbonyls, Vol. 11, Wiley, New York, 1977, p_ 1. D. Slocum, in W. Jones (ed.), Catalysis in Organic Syntheses, Academic Fress, New York, 1980, p_ 245. M. J. Chen and H. M. Feder, in W. Moser (ea.), Cutatysis of Organic Reactions, Marcel Dekker, New York, 1981. p. 273; FE.J. Chen. H. M. Feder and J. W. Rathke, J. Am. Chem. Sot.. in press. U.S. Patent 4301312 (1981) to A. M. Fe&r and M. J. Cnen (U.S. Department of Energy). D. Forster, Itzorg. Clrem.. 8 (1969) 2556. B. F. G. Johnson, J. Lev&., P. R. Raithby end G_ Suss. J. Chem. Sot. Dalton (1979) 1356. J. C. Hileman, D. K Huggins and H. D. Kaesz. Inorg. Chem. 2 (1962) 933.
Trans.,
of Molecular
Cctalysis,
I7 (1982)
331-
337
331
SELECTIVE HQMOLOGATIC?N OF METHANOL CATALYZED TRANSITTON METAL COMPLEXES Tr\(’METHANOL-AMXE SOLUTIONS M. J. CHEN*,
Argome (U.S_A_)
YH.ht. FEDER
N~tioncl
BY
and J. W. RATHKE
kbomtory,
Chemical
Engineering
Didion,
Argonne,
IL
60429
summary Trar.sition meti complexes of Mn, Rh, and Ru have been found to catalyze the homologation cf methanol in methanol-amine solutions at syn-gas pressures near 300 atm and temperatures near 200 “C. These catalysts are believed to operate by mechanisms similar to that proposed for Fe(CO),, and likewise produce CO2 as the oxygenated by-product and do not homologate the ethanol prcduct. The use of two metal complexes ‘agether as catalysts has also been examined. In a mixed Fe(CO),Mn,(CO),O catalyst solution, methanol is converted at a rate of 14% h-’ at 220 OC. Ethanol accounts for 72% of the product, the balance being methane. Additives such as phosphines and methyl iodide are found to affect the rate and the selectivity of these systems.
Introduction Transition me’tal-catalyzed homologation of methanol has been actively studied as a possible process for the production of ethanol 11 - 71. All of these studies are based on modifications of the HCo(CO), systems, which catalyze the homologation of methanol in accordance with reaction (1). The large effort focused on the cob& systems is not surprising, since the widely accepted mechanism for this catalyst invokes the protonation of methanol ti activate methyl groups, and for this step the unusually high acidity of HCc(CO), is regarded as essential [8, 9] . Our discovery [IO, 111 of the catalytic homologation of methanol in Fe(CO)ramine catalyst solutions according to reaction (2) has opened a new approach to this potenr;iaUy important chemical process. Eignificantly, ethmol and higher alcohols are not homologated with the new cat&y&_
*Author
to whom
correspondence
o30~-5roz/sz~oooo-ooGo/~o~_~5
should
be addressed.
@ Eketier Sequoia/Prided
in ?TIE NetherIan
332
CH,OH
+ Hz
+ 2CO
-
CH,CH20H
+ CO:!
(2)
The mechanism that we have proposed for the Fe(CO)s catalyst [lo] Is shown in Scheme 1. The nucleophile, HFe(CO)z , is quantitatively generated in step 1, which is fast and reversible. Methanol reacts with CO (step 5, base-catiyzed) to form methyl formate which further reacts with tridkylamine (step 6) to yield the methylanxnonium ion. The rate-limiting reaction between HFe(CO)i and NR3Mei (step 2) leads to HFe(CO)&e, which subsequently reacts with CO and H, (steps 3, 4, and 7) to give ethanol and to regenerate Fe(CO),. In step 8 trialkylamine is regenerated by the catalytic decomposition of the salt [NR3H] [HCOJ , without which the homologation reaction would be stoichiometric with respect to amines. The high selectivity for methanol homologation in this system is believed to be derived from step 6, which, for steric reasons, is much slower for ethyl formate. We wish to report here some transition metal complexes that have also been found to be active catalysts for selective homologation of methanol in methanol-amine solutions. These catalysts are believed to catalyze the reaction according to mechanisms similar to those proposed for Fe(CO)s.
METHANOL MeOH cod bs
NET REACTION HeOh + 2CO+ H, --alMeCHZOH +COz
MeCti,OH ETHANOL
Scheme
1.
333
Experimental
AH the chenicds
were of reagent grade and were used as received. autoclave (Autoclave Engineers, Inc.), provided with an eIectron.ic pressure transducer, was used in the study. A double-piston compressor (HaskeI Eng;neering) was used to transfer gases and to maintain pressure, and a precision metering pump (Laboratory Data Control) to transfer liquid. For experiments with continuous purging, a condenser (0.5 in ID and 3 ft long) fitted with a demister pad was used to prevent loss of vapor with the vent gas. In a typical experiment the autoclave was charged with the solution of intended cospasition and sealed. After thorough deaeration, the contents were brought to the desired temperature and pressure, usually within an hour. Liquid and gas sampIes ware taken at various intervals, and analyzed by GC. The products were identified by GC-MS and/or INMR spectroscopy. Glass electrodes for the comparative measurement of b&city were standardized with an aqueous pH 10 buffer solution. -4 300
ml MagneDrive
Re,4t.s
and discussion
For reaction mechanisms involving many steps, such as that shown in Scheme 1, it is likely that other transition metal complexes may promote only some of the steps that are necessary to complete the cycle, and therefore would not function as catalysts, alone. In order not to overlook any beneficial effects which may be derived from srrch complexes, they were tested as co-catalysts with Fe(CO),.
Survey
of Cafalysfs
As a reference for these survey experiments, -we have used a methanol solution containing 2.0 M N-methylpiperidine (MeNCsHlO) and 0.10 M Fe(CO), (expt. 1). Low iron catalyst concentration* was used so that acceleration of the homologation reaction by the addition of a second transition mete! complex or other additives could be easily detected_ After reaction for 6 h et 200 OC and 300 atm 3:X CO/K,, 34 mmol EtOH and 73 mmol C3H4 were produced, corresponding to a turnover frequency? of 1.1 h-r. Among the individual catalysts examined. Rh13 has the hi&est catalytic activity, with a turnover frequency of 6.1 h-* (T12hk 1). RhCl,- 3K,O is less active but affords a better selectivity for ethanol production. In these Rh catiyst solutions some side products are &so produced’. The mm OE the *Low iron cablyst concentration appezrs to prom&e methane production, at the expense OFet&tact production. TThe turnover frequency is dekecf as the sum of EtOH and CJ& (in mol) prcrdrrced per h per g-atom of tie’d c&aIyst. %3ese products have not yet been identified.
334 TABLE Reactivity Expt. No_
1 and selectivity
patterns
Complex (mmol)
Fe(CO),-
(16-O)=
S
Reaction time
Pm&l&S
(h)
ClHSOHb (mmol)
6.0
CHc (mmol)
(h-‘)
73
1.1
30 (2ld)
2.0
2.0
42
19
6.1
(5.3) c.d
3.4
26
26
O-96
6.0
102
22
0
0
17
19
0.38
50
2.5
(11.5)
Cr(CO)h
(16.0)
6.0
F
(16.0) (32.0)
6.0
Mfil(CO),,, Me1 (80.0)
34 160 ( 160d)
Turnover frequency
6.0
RhIJ ( 5.0)=qe
Mnl(CO)lo
catalystsa
(16.0)
RhCl,-3H,C
Rua[CO),=
for various
(11.5)
6.0
300
‘200 OC and 300 atm (3rl) CO/Hz with continuous soiu tions (160 ml) contain 2.0 IM Wmethylpiperidine. b Includes HC02Et. =Gas purging was not used. dTrimethylamine replaces N-methylpiperidine. eVolume of solution = 50 ml.
gas purge
of 600
0.90 0
ml/min.
Catalyst
side products (on a carbon number basis) is comparable to the ethanol produced_ With RhI, as the catalyst, Rh(CO)& [I21 is initially formed and is then converted, in 2 h, into an unidentified rhodium carbonyl species with uco at 1970 cm-’ (s), 2000 cmn-’ (sh) and 2050 cm-’ (w). into HRu,(CO)TI ]13] under the Ru,(CO) 11 is partially converted reaction conditions_ This catalyst is not very different from Fe(CO)s in its catalytic activity for methane! homologation. Mn,(CO) r0 forms Mn(C0); [14] under such conditions and also shows a reactivity comparable to that of Fe(COj,. However, the selectivity for ethanol production is greatly improved in the manganese system. This improvement probably reflects the more favorable formation of Mn-acyl compfexes in step 3. The sektivity between EtOH and CHq production is determined by step 3 (Scheme 1) and the relative rates of eliminations of CH4 and CH,CHO from the respective metal-Jlcyl and metal-acyl complexes. Chromium hexacarbonylhas no catalytic activity for methanol conversion under these reaction conditions. The result-s of experiments with mixed metal catalysts are shown in Table 2. Et is interesting to note that in the Mnz(CO)ro-Fe(CO)s catalyst system, ‘the sum of C&OH and CH4 (397 mrnol, expt. 2-1) aceeds the sum of these products expected from the individual catalysts (231 mmol, as calculated from expts. 1-l and -5). and the product selectivity reflects
335 TAgLE Reactivity
2 and se!ectivity
Ear mixed
catiysts”
Egpt.
‘Ccl-c2talysk’b
Reaction
NO.
(mmol)
(h)
time
Roduck C*H&H jmmol)
1
Mnl(CO)lo
2
RhClz-3K20
3
Mnz(CO),o RhQ-3&O
(11.5)
Rux(C0)1z MOM NiE+
330
67
(16.0)
6.0
160
(l’r.5) (16.0)
6.0
309
42
(5-3)
6-O
60
150
6.0
34
69
2.0
7
27
6.0
0
0
(16.0) (16.0).
R%(CO),o
6.0
CHS (mmol)
(8.0)
Mnz(C0110 (11.5) P(n-Bu)s (46)
6.0
330
38
=Reaction a: 200 “C and 300 atm 3:l CO/Hz. The reactor was purged with the same CO/Hz mixture at 600 ml/min. bAll the catzlvat solutions (160 ml) container! 15.0 mm01 Fe(CO)S and 320 mmo! MeNCSH~O except-for Expt. 3 in which no Fe(CO)S uas added.
that of M~Q(CO)~,-, catalyst. The Mn-Fe catalyst system is further discussed in the following section. For RhCI,-Fe(CO),. RhC13-Mn2(CO),0 and Ru, (C0),2-Fe(CO)S catalysts (expt. 2-2, -3, and -41, the rates and selectivities are not very different from those expected from the combined catalytic activities of the individual ca+dysts. It is concluded that in the solutions of these mixed metal catalysts (Mn2(CO)10-Fe(CO)S excepted), the individual catalyst acts more or less independently. Addition of Mo(CO), or NiBr, to Fe(CO& catalyst soWzion (expts. 2-5 and -6) seems to have very Little effect on the rate or the selectivity for the conversion of methanol. Re,(CO),, however, inhibits the catalytic activity of Fe(CO& completely. The effects of additives on these reactions has also been briefly examined. Addition of P(n-Bu)3 to Fe(CO)S (2:1, expt. l-7) results in the reduction by half of the catalytic activity_ Addition of F(n-Bu)3 to the Mn,(CO)lO-Fe(CO), catalyst solution (expt. 2-S), however, has little effect on its catalytic activity. Addition of methyl iodide increases the rate of methanol conversion by a factor of 3 in the manganese catalyst solution (expts. 1-5 and -8), but has no effect on the selectivity. Because of the compiexity of the catalytic reactions and ‘he limited data avaiIable, it is not very useful to speculate on how these additives function mechanistically. It suffices to say that further increases in rate and in ethanol sekctivity in these systems may be expected from the use of suitable additives.
335
lh,(CO),o-Fe(CO),
catalyst systems Among all the transition metal colmplexes surveyed in this stildy, Mn,(CO) ,0 appears to be the most- interesting. In contrast to other (Fe, Rh, and Ru) catalyst solutions, in which the concentrations of methyl formate (1.3 M) and methylammonium ion (1.5 - 2.0 M) are at or close to their equilibrium concentrations, the Mnl(CO)r,, catalyst solutions in expt. l-5 (
Acknowledgements This research was supported by the Office of Chemical Science, Division of Basic Energy Sciences, U.S. Department of Energy. We thank Ms. D. *We h*.ve shown that [NRxH,* HCoT] is rapidly decomposed in the presence of Fe(CO)5. **The LWOcompounds eccount for over 99% of the organic products.
337 TABLE
3
Rates znd selectivities Expt. No.
for m'ked
fWCW510 (M)
1
0
2 3 4=
0.1 9.75 0.75
Fe(CO)S/Mnz(CG)re
catalyst
solutions”
Reaction time
Products
TurnoveP
(h)
EtOH (mmol)
CH4 (mmol)
(h-l)
6.0 6.0 6.0 2.0
102 330 423 199
22 67 80 79
0.90 2.9 3.6 11.0
frequency
aCatiyst solutions (160 ml) contain 0.075 M ~Mrra(CO),e and 2.0 M MeNCsHra; reaction at 200 OC and 300 atm (3:l) CO/Ha with continuous gas purging at 600 ml/min. bFe(CO)s not included in the calculation. =Reaction at 220 “C!; 1,3-di(l-methyl-4-piperidyl)propane replaces N-methylpiperidine. The reactor was not purged.
McCullough for assistance and Mr. S. Roth for helptil
in the experimental discussions.
work, Professor
J. Halpern
References 1
2 3 4 5 6 7 8 9 I.0
11 12 13 14
G. S. Koerrner and W. E. Slinkerd, I&. Eag. Ckem. Prod. Res. Dew., I7 (1978) 231. Ger. Offen. 2 625 627 (1976) to L. H. Slaugh (Shell Interuationale Research Maatschappij B-V.); Chem. Abstr.. 8 7 (1977) 5373e. U.S. Patent 4 133966 (1979) to W. R. Pretzer, T. F_ Kobylinski and J. E. Bozik (Gulf Research and Development Co.); Chem. Abstr., 90 (19'79) 120998m. U.S. Patent 4 PI I837 (1976) to P. D. Taylor (Celanese Corp.); Chem. Abstr.. 90 (1979) 103398y. Ger. Offen. 2 823 309 (1978) to J. L. Barclay and E. R. Gane (British Petro!eum Co_ Ltd.) Cfiem. Abstr.. PO (1979) 86729n. U.S. Patent 4 277634 (1981) to W. E. Walker (Union Carbide Corp.); Chem. Abstr.. 95 (1981) 97043~. U.S. Patent 4 171 461 (1979) to C. M. Bar&h (Air Products and Chemicals, Inc.); Chem. .45str_, 91 (1979) 210886~. F. Piacenti and M. Bianchi, in E. Wender and P. Pino (eds.), Organic Syntheses uic MetaI Carbonyls, Vol. 11, Wiley, New York, 1977, p_ 1. D. Slocum, in W. Jones (ed.), Catalysis in Organic Syntheses, Academic Fress, New York, 1980, p_ 245. M. J. Chen and H. M. Feder, in W. Moser (ea.), Cutatysis of Organic Reactions, Marcel Dekker, New York, 1981. p. 273; FE.J. Chen. H. M. Feder and J. W. Rathke, J. Am. Chem. Sot.. in press. U.S. Patent 4301312 (1981) to A. M. Fe&r and M. J. Cnen (U.S. Department of Energy). D. Forster, Itzorg. Clrem.. 8 (1969) 2556. B. F. G. Johnson, J. Lev&., P. R. Raithby end G_ Suss. J. Chem. Sot. Dalton (1979) 1356. J. C. Hileman, D. K Huggins and H. D. Kaesz. Inorg. Chem. 2 (1962) 933.
Trans.,