Technical Synthesis of 1,5,9-Cyclododecatriene Revisited: Surprising

This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

Featured Article pubs.acs.org/joc

Cite This: J. Org. Chem. XXXX, XXX, XXX−XXX

Technical Synthesis of 1,5,9-Cyclododecatriene Revisited: Surprising Byproducts from a Venerable Industrial Process Frauke Thrun,† Volker Hickmann,† Christoph Stock,† Ansgar Schäfer,‡ Walter Maier,§ Martin Breugst,∥ Nils E. Schlörer,∥ Albrecht Berkessel,∥ and J. Henrique Teles*,† †

Process Research and Chemical Engineering, BASF SE, 67056 Ludwigshafen, Germany Quantum Chemistry, BASF SE, 67056 Ludwigshafen, Germany § Competence Center Analytics, Physics & Formulation, BASF SE, 67056 Ludwigshafen, Germany ∥ Department of Chemistry, Organic Chemistry, University of Cologne, Greinstraße 4, 50939 Cologne, Germany

Downloaded via 46.161.59.38 on August 26, 2019 at 12:40:44 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

‡

S Supporting Information *

ABSTRACT: The synthesis of 1,5,9-cyclododecatriene by selective trimerization of butadiene catalyzed by TiCl4 and ethylaluminum sesquichloride has been commercially used since 1965. Although thoroughly investigated, not all details of the mechanism are completely understood. The recent development of a new process to produce cyclododecanone involving oxidation of 1,5,9-cyclododecatriene with N2O has led to the serendipitous discovery of an array of hitherto unknown byproducts, formed in the trimerization of butadiene: eleven tricyclic C12H20 and one tetracyclic C12H18 hydrocarbons, three of which had never been described before. The identification of these byproducts became possible by using a combination of chemical enrichment, high-resolution distillation, 13C-2D-INADEQUATE NMR, and comparison with ab initio calculated spectra, thus demonstrating the power of these combined techniques. The identification of these byproducts contributes to a better understanding of the mechanism of this centrally important reaction.

■

icals like 4-cyclododecyl-2,6-dimethylmorpholine.8 After more than half a century of large-scale production and intensive study, one would expect that the trimerization of butadiene, and most of all the byproducts formed in this reaction, should be known in great detail. As we will show here, this turned out not to be the case. When butadiene is trimerized in the presence of ethylaluminum sesquichloride and TiCl4, the main product formed is 1,5,9-cyclododecatriene. Besides this main product, 1,5cyclooctadiene and 4-vinylcyclohexene are also formed as C8byproducts, and the latter are often separated and used as valuable compounds themselves. Furthermore, C16 and higher oligomers are also formed, but the complexity of the mixture does not allow the isolation of any valuable byproducts from this high boiling fraction which is therefore incinerated. A typical commercial sample of cyclododecatriene usually contains approximately 98.5% cis,trans,trans-1,5,9-cyclododecatriene (1), 1% all-trans-1,5,9-cyclododecatriene (2), and 0.3% cis,cis,trans-1,5,9-cyclododecatriene (3, Figure 1). The nature of the remaining 0.2% of impurities detected by gas chromatography was, until now, unknown. Due to their small amounts and to the fact that some of these byproducts are almost impossible to separate from cyclododecatriene, they

INTRODUCTION The trimerization of butadiene to 1,5,9-cyclododecatriene is technically the most important process giving access to medium-ring compounds. The formation of 1,5,9-cyclododecatriene was first observed by Reed in 1951, as a byproduct in the Ni-catalyzed cyclooligomerization of butadiene.1,2 However, it was not until the work of Wilke in 1963 that a good catalyst based on a mixture of ethylaluminum sesquichloride and titanium tetrachloride was discovered that made it possible to selectively synthesize 1,5,9-cyclododecatriene in good yield.3,4 The importance of this discovery can easily be judged by the fact that the first commercial plant for the production of 1,5,9-cyclododecatriene was built in 1965 in Germany, only 2 years after the first publication by Wilke, by the former Hüls (now Evonik) and closely followed by a second plant in the US in 1969 by DuPont (now Invista).5 The Evonik plant has been expanded several times and is still the largest in the world. Invista’s plant was recently closed, but other producers have stepped in, pushing the world capacity for 1,5,9-cyclododecatriene to around 70000 tons/year. 1,5,9-Cyclododecatriene is still a very important intermediate, mainly for the production of laurolactam and polyamide12, one of the most important specialty engineering plastics for automotive applications, but also for the production of macrocyclic musks, for example, oxacyclohexadec-12-en-2one6 or 3-methyl-cyclopentadec-5-en-1-one,7 and agrochem© XXXX American Chemical Society

Received: July 4, 2019 Published: August 16, 2019 A

DOI: 10.1021/acs.joc.9b01633 J. Org. Chem. XXXX, XXX, XXX−XXX

The Journal of Organic Chemistry

Featured Article

conventional route it still requires three steps using more expensive catalysts. The use of lithium iodide as a Lewis acid in the last step also poses problems for wastewater treatment. A variation of this process in which cyclododecatriene (1) is first partly hydrogenated to cyclododecene before being epoxidized to 8 and using a heterogeneous catalyst for the isomerization step has recently been proposed by Evonik.13 BASF developed an alternative two-step process for the preparation of cyclododecanone (Scheme 3). The key step of

Figure 1. Known main products from the butadiene trimerization.

were overlooked. Their serendipitous discovery, reported here, became possible through the special combination of steps used in a new process for the production of cyclododecanone, developed by BASF and taken into operation in 2009 (vide infra).9 The major use for commercially produced 1,5,9-cyclododecatriene (1) is in the synthesis of cyclododecanone, which in turn is the common intermediate for the above-mentioned products. The oldest process to produce cyclododecanone (6) from 1,5,9-cyclododecatriene (1) is composed of three steps (Scheme 1). In the first step, 1,5,9-cyclododecatriene is fully

Scheme 3. BASF Process for the Production of Cyclododecanone

Scheme 1. Classical Technical Process for the Production of Cyclododecanone

this process is the uncatalyzed oxidation of 1,5,9-cyclododecatriene (1) with N2O to give cyclododeca-4,8-dien-1one (9a,b) as a 1:1 mixture of the 4E,8Z (9a) and 4Z,8E (9b) isomers.14 The reaction of olefins with N2O is in many respects a remarkable transformation. In spite of the rather drastic reaction conditions, usually above 250 °C and high pressure, N2O exclusively reacts with olefins15,16 or alkynes.17 The reaction is best described as a (2 + 3) cycloaddition with subsequent loss of N2.18 The rate of the cycloaddition, which is the rate-determining step of the reaction, is known to be sensitive to the nature of the olefin. Even quite similar substrates such as cyclopentene and cyclohexene have been computed to have activation energies that differ by as much as 3.6 kcal·mol−1.19 We computed the activation energy for the reaction of N2O with either a cis or a trans double bond in 1,5,9-cyclododecatriene (1) and also for the reaction with the trans double bond of 4Z,8E-cyclododecadienone (9b). The transition states for the cycloaddition of N2O to double bonds have been optimized on density functional theory level using the TPSS functional with def2-TZVPP basis sets and the D3(BJ) correction for van der Waals interactions. At the optimized structures, more accurate energies have been calculated with the TPSSh hybrid functional, def2-QZVPP basis sets and D3(BJ) correction (for further details see the Supporting Information). The results are shown in Table 1. Inspection of Table 1 reveals the trans double bond of 1 as being the most reactive one. Additionally, it is also statistically

hydrogenated to cyclododecane (4). The latter is subsequently oxidized with air, either neat or in the presence of boric acid, to give a mixture of cyclododecanol (5), and cyclododecanone (6). This mixture is then subjected to a catalytic dehydrogenation on a copper catalyst to transform cyclododecanol (5) to cyclododecanone (6).10 This process requires three chemical steps, and in particular, the oxidation step has a rather modest selectivity of only 88% even at a low conversion per pass of only 8.5%.11 Many efforts have been made to improve this process. UBE in Japan developed a sequence based on the monoepoxidation of 1,5,9cyclododecatriene with H2O2 to epoxide 7, followed by hydrogenation of the remaining double bonds and isomerization of the saturated epoxide 8 with LiI to cyclododecanone (Scheme 2).12 Although this process has a better yield than the Scheme 2. Alternative Process for the Production of Cyclododecanone

Table 1. Computed Activation Energies for the (2 + 3) Cycloaddition of N2O to Different Double Bonds at the TPSSh-D3(BJ)/def2-QZVPP//TPSS-D3(BJ)/def2-TZVPP Level of Theory

B

double bond

activation energy (kcal·mol−1)

trans double bond of 1 cis double bond of 1 trans double bond of 9b

22.4 26.0 23.6 DOI: 10.1021/acs.joc.9b01633 J. Org. Chem. XXXX, XXX, XXX−XXX


Featured Article

favored because there are two of these bonds in 1. After the first trans double bond of 1 has reacted to form 9, its remaining trans double bond becomes less reactive than a trans double bond in 1. For this reason, the oxidation of 1 can be performed at rather high conversions per pass (up to 20%) with only limited formation of diketones by double oxidation. The plant is thus operated in such a way that 1,5,9-cyclodecatriene (1) is only partly converted. After passing the reactor and removing unconverted N2O (and N2 formed), a mixture containing unconverted 1, the desired product cyclododeca-4,8-dien-1ones 9a/9b, and some byproducts is obtained. This mixture is fed to a continuously operated distillation tower that separates unconverted 1 as the low-boiler stream from the desired products 9a/9b and the byproducts, which are obtained as the high-boiling stream. Recovered 1 is then mixed with fresh 1 and recycled to the reactor. After several months of continuous operation, we noted that a single new peak, with a retention time in the GC just slightly higher than the retention time of 1 was steadily accumulating in the recycling loop of 1, reaching almost 3 area % at its highest concentration (see GC in the Supporting Information). Such a product had not been observed during process development, and we decided to clarify the nature of this byproductnot foreseeing that in the end we would find not one but 12 new byproducts.

Figure 2. All possible C12H18 isomers with the correct symmetry (computed Gibbs free energies in benzene relative to 1; M06-2X-D3/ def2-QZVP/IEFPCM(C6H6)//M06-2X-D3/6-31+G(d,p)/IEFPCM (C6H6)).

■

RESULTS AND DISCUSSION In a first attempt to establish the nature of the byproduct detected in the GC of the recycled 1 in the production plant, we used GC−MS and GC−IR. The GC−MS showed that the new substance was an isomer of 1 with the sum formula C12H18. The IR spectrum obtained from GC−IR was very simple and showed no indication of CC double bonds (see IR spectra in the Supporting Information). This means that the unknown substance must have a tetracyclic structure. Since the information from GC−MS and GC−IR was not sufficient to determine the structure, we used a GC with cryo-trap sample collector to isolate sufficient material to record a 13C NMR spectrum. In this method, the output of the gas chromatograph can be switched either to the FID detector or to a coldfinger cooled with liquid N2 where the substance corresponding to the unknown peak was collected. After 200 injections, the coldfinger was allowed to warm and was washed with a small amount of CDCl3. This solution was collected and used for the measurement of a 13C NMR spectrum. The 13C NMR spectrum (see the Supporting Information) obtained consisted of only eight peaks. There were four peaks for CH2 groups, two with double intensity (27.0 and 23.4 ppm) and two with single intensity (35.4 and 17.3 ppm). Furthermore, there were four peaks for CH groups, again two with double intensity (42.3 and 37.2 ppm) and two with single intensity (52.3 and 41.9 ppm). Unfortunately, due to the very small amount of material available, even after 11 h of measurement it was not possible to obtain a 13C-2D-INADEQUATE NMR spectrum, so we attempted to identify the substance by comparing the shifts with those of known C12H18 hydrocarbons with the same symmetry. The most stable C12H18 hydrocarbon is ethanoadamantane 10 (Figure 2).20 This hydrocarbon has the correct symmetry but the reported 13C NMR spectrum was different from that of our unknown molecule.21 In order to evaluate how many structures are possible, we used the program MOLGEN 5.022 to generate all possible structures containing six CH and six CH2 groups, with the only constraint being that no rings

smaller than 5-membered ones are present. The algorithm generated 106 structures, which is still a considerable number. Without the ring size constraint, the number of structures is larger than 1000, and just eliminating 3-membered rings still leads to 512 structures. As the unknown molecule survived the harsh conditions in the oxidation reactor, it is less likely that the structure contains strained three or four membered rings. From the 106 structures generated, the ones with the correct symmetry were selected, leaving only ten possible structures. These are shown in Figure 2. According to our calculations, all isomers are more stable than 1,5,9-cyclododecatriene 1 (for details see the Supporting Information). Their formation by isomerization of 1 would be in all cases thermodynamically feasible. Unfortunately, out of all the above isomers, only ethanoadamantane 10 has ever been synthesized. Isomer 11, which is the second most stable, is the only additional one to have been mentioned in a computational chemistry paper.23 All other isomers (12−17) have never been mentioned in the literature and do not have a CAS registry number. The most stable isomers, after ethanoadamantane 10, are compounds 11 and 12 (both computed to be 4.8 kcal mol−1 less stable than 10), but their computed 13C NMR spectra also did not match the one of our unknown substance. The calculated relative energies and 13C NMR spectra of all the isomers in Figure 2 as well as the computational details can be found in the Supporting Information. At this point, we thought that the only way to establish the structure of the unknown byproduct would be to isolate it by distillation in an amount sufficient to run a 13C-2DINADEQUATE NMR spectrum to establish the connectivity of the carbon skeleton. Unfortunately, the unknown byproduct is a high boiler relative to 1, making the isolation by distillation very difficult. Thus, we decided to chemically eliminate 1 from the mixture. The most convenient method proved to be treatment with an excess of 50% hydrogen peroxide in acetic C



Featured Article

Figure 3. Gas chromatogram of the mixture of saturated byproducts. Components a−j have a sum formula C12H20. Peak h is actually a mixed peak with two components h1 and h2. Component k has the sum formula C12H18 and corresponds to the unknown byproduct discussed above.

acid at 70 °C for 12 h (for details, see the Supporting Information). By doing so, 1 and all other unsaturated components contained in the mixture are transformed to epoxides and subsequently to (poly)ols, which are water soluble and high boiling and can thus be easily separated from the saturated unknown byproduct by extraction with toluene. Starting with a large sample of 1 taken from the recycle stream, it was possible to isolate 244 g of a mixture of saturated byproducts (see the Experimental Section and Supporting Information for details). Surprisingly, the GC analysis of the toluene extract revealed that in addition to the unknown hydrocarbon marked as k in Figure 3, there were another 11 hydrocarbons present that had hitherto been overlooked because they were obscured by the large peak of 1. The GC trace of this mixture is shown in Figure 3 with the major peaks labeled a−k. A first investigation of the mixture with GC−MS revealed that all the components a−j had the sum formula C12H20 and were thus formally reduction products of 1. Only component k, which was already visible in the GC of the recycle stream, was an isomer of 1 with a sum formula C12H18. GC−IR further confirmed that none of the components contained CC double bonds. The EI-MS and IR spectra of all the components can be found in the Supporting Information. The mixture was fractionated by using an automatically controlled distillation tower with approximately 100 theoretical separation stages. The tower was operated at very high reflux ratio (ca. 30:2 to 60:2) and operated around the clock. Within 6 weeks 50 fractions were collected. Since the difference in boiling points was very small (the difference in boiling point between the first and the last fraction was only 10 °C), none of the compounds could be obtained in pure state. Nevertheless, fractions could be obtained in which each of the components was concentrated enough to allow the measurement of 13C-2D-INADEQUATE NMR spectra and thus to determine the connectivity of the carbon atoms. Details of the distillation and of the NMR spectra can be found in the Experimental Section and in the Supporting Information.

Identification of Compounds a (18), g (19), h2 (20) and j (21). According to the 13C-2D-INADEQUATE data, four of the components, a, g, h2, and j, have a perhydro-asindacene framework (a and j are symmetrical, with only six 13C NMR signals, and g and h2 are unsymmetrical showing 12 separate signals). Five out of the six possible perhydro-asindacenes have been described in the literature.24 By comparison with the reported 13C NMR data we could assert that component a is trans,anti,trans-perhydro-as-indacene 18, component g is trans,anti,cis-perhydro-as-indacene 19, component h2 is trans,syn,cis-perhydro-as-indacene 20, and component j corresponds to the cis,anti,cis-perhydro-as-indacene 21 (Figure 4). The same assignment is also obtained based on the computed chemical shifts. See the Supporting Information for the complete set of data and correlation diagrams.

Figure 4. Structural assignment of byproducts a (18), g (19), h2 (20), and j (21).

The formation of byproducts with this carbon skeleton is not unexpected. Treatment of 1 with a mixture of Cp2TiCl2 and lithium aluminum hydride at 200 °C, which is postulated to lead in situ to the formation of titanium hydrides, leads to a mixture of three olefins with the same carbon backbone as 18− 21.25 In contrast, the treatment of 1 with triethylaluminum alone at 200−210 °C only leads to the formation of products with a different backbone, namely of a 5:4 mixture of tricycloD



Featured Article

[6.4.0.02,6]dodec-4-ene and tricyclo[7.3.0.03,7]dodec-4-ene in 85% yield.26 In our mixture, none of the products contained such a backbone. Identification of Compounds b (22) and c (23). Another family of byproducts includes components b and c, b being the major component in the byproduct mixture. According to the 13C-2D-INADEQUATE data, these components had a 1H-cyclopent[c]indene framework. Four isomers are possible with this framework, but only the two most stable ones in which the two five-membered rings are cis-fused are known in the literature (Figure 5).27 Again, a

pound d is a decahydro-1H-cyclopent[d]indene. Two isomers are possible with this structure. Only one isomer, the cis,transdecahydro-1H-cyclopent[d]indene, was described in 1984 by Tobe and co-workers,31 but the reported 13C NMR shifts do not fit to the ones observed for compound d. However, an excellent correlation was observed between Tobe’s data and those computed for the cis,trans-isomer (in CDCl3, see the Supporting Information). Compound d thus must be the hitherto unknown cis,cis-decahydro-1H-cyclopent[d]indene (26; Figure 7).

Figure 5. Structural assignment of byproducts b (22) and c (23).

Figure 7. Structural assignment of compounds d (26), e (27), and f (28).

comparison with the calculated 13C NMR spectra (see the Supporting Information) confirmed the original literature assignments. Compounds with the 1H-cyclopent[c]indene framework have never before been reported as products formed in the isomerization of 1, which makes the formation of 22 as the major byproduct even more surprising. Identification of Compounds h1 (24) and i (25). The third family of byproducts were components h1 and i. According to the 13C-2D-INADEQUATE data, these components had a dodecahydroacenaphthylene framework and are commonly known as ufolanes. Six different isomers are possible, but not all of them are known. Compound h1 is identical to the cis,cis,trans-ufolane 24 described by Boldt and co-workers in 1992 (Figure 6).28 For compound i, seven

On paper, 26 appears to be C2-symmetrical, and we observed, as expected, only seven signals in the 13C NMR spectrum. However, calculations predict an unsymmetrical structure with 12 distinct 13C NMR signals to be the most stable conformer. A C2-symmetrical conformer, which is also a local minimum, lies 3.3 kcal·mol−1 higher in energy, but the computed shifts do not give a good correlation with the observed ones. However, an excellent correlation is found with the averaged shifts of the unsymmetrical C1 conformer. The cis,cis-decahydro-1H-cyclopent[d]indene (26) thus has an unsymmetrical ground state which at ambient temperature appears symmetrical at the NMR time scale (see Supporting Information for details). To test this hypothesis, we performed a low temperature NMR experiment. Cooling a sample enriched in 26 in CD2Cl2 from 298 K down to 180 K allowed the detection of a considerable line broadening for the 13C signals at 37.7, 30.2, and 27.9 ppm. At the lowest temperature, for the resonance at 27.9 ppm, a splitting into two peaks becomes recognizable (see the Supporting Information for details). Component e has, according to the data from 13C-2DINADEQUATE NMR, a 2,8-tetramethylenebicyclo[3.3.0]octane framework. Since 12 signals were observed in the 13C NMR spectrum, the structure has to be unsymmetrical, and comparison with the calculated 13C NMR spectra establishes the structure as 27, a substance which was hitherto unknown, although our calculations predict this to be the most stable isomer with this framework. Inamoto and co-workers32 reported the synthesis of the symmetrical cis,endo-isomer, but without giving any 13C NMR data. Component f has, according to the 13C-2D-INADEQUATE data, the octahydro-2H-1,4a-ethanonaphthalene framework. Both possible isomers have been described by Kakiuchi and coworkers.33 A comparison between the reported and the calculated 13C NMR spectra (see the Supporting Information) again confirmed the assignments made by Kakiuchi and established the structure 28 for component f. Astonishingly, this is the highest energy isomer. Up to now, the formation of byproducts with the carbon frameworks of 26, 27, or 28 in reactions involving 1 as starting material has not been reported. Mechanistic Considerations. It is currently not clear why only some isomers are formed preferentially. Formally, the

Figure 6. Structural assignment of byproducts h1 (24) and i (25).

separated 13C NMR peaks were observed experimentally, thus restricting the number of possible ufolane structures to three. Compound i was identified as the previously unknown cis,trans,cis-ufolane 25 by comparing the computed 13C NMR shifts for all three possible isomers with the measured shifts. Remarkably these two ufolane isomers are the only ones observed, although the trans,trans,trans-ufolane described by Boldt28 is the one we calculated as being the most stable ufolane isomer. Formation of products with the ufolane framework by isomerization of 1 has been described in the literature. Chachuat and co-workers reported the formation of two isomeric octahydroacenaphtenes by isomerization of 1 in the presence of polyphosphoric acid at 150 °C.29 Zakharkin and co-workers described the Koch carbonylation of 1 with formic acid in H2SO4 at room temperature to form decahydro2a(3H)-acenaphthylenecarboxylic acid.30 Identification of Compounds d (26), e (27), and f (28). The three remaining byproducts d−f were the most interesting ones. According to the 13C-2D-INADEQUATE data, comE



Featured Article

in energy than ethanoadamantane (10), which is the most stable C12H18 isomer.20 This means that the formation of 17 from 1 has to be a kinetically controlled process. This is also shown by the fact that even among the ten isomers with the same symmetry shown in Figure 2, 17 is the third highest in energy. The first hint as to why 17 is formed as the sole isomerization product came from the realization that of all the compounds in Figure 2, 17 is the only one that can be formed from 1 without breaking and reforming any CC bonds. To follow up on this idea, we enumerated all the possible C12H18 isomers which do not contain 3- or 4-membered rings or quaternary carbons and which can be obtained from a C12ring without breaking any CC bonds (see details in the Supporting Information). Altogether, there are 23 different structures. The latter were then sorted according to the number of H-shifts required to transform 1,5,9-cyclododecatriene (1) into each of these structures. It turned out that only five structures are topologically accessible with not more than one H-shift, and these are summarized in Table 2. Compounds 17 and 29−31 can topologically be obtained from 1 with just one H-shift, while 32 requires no H-shift at all.

byproducts a−j (18−28) all result from reduction of 1, so the question arises as to which reducing agent might be responsible for their formation. The most probable reductant is the ethylaluminum sesquichloride used as part of the catalytic system. It is known that, in order to obtain a competent catalyst for the trimerization of butadiene, it is necessary to generate aluminum hydrides which in turn can reduce Ti(IV) to the catalytically active Ti(III) species.34 In the case of ethylaluminum sesquichloride, the hydride formation occurs via β-elimination of ethylene, a reaction well-known for triethylaluminum.35 The aluminum hydrides, once formed, can reduce the Ti(IV) but in principle they can also hydroaluminate 1, and hydroaluminations are known to be catalyzed by TiCl4, the second component of the Ziegler− Natta catalyst system used. Based on the accumulation rates of compounds 18−28, a production rate was estimated and the amount of reduced products corresponds to ca. 0.1 mol/mol of ethylaluminum sesquichloride used or 0.033 mol/mol of ethyl groups. Although the hydroalumination of 1 has never been studied before, the hydroalumination of hexa-1,5-diene, which is a 1,5-diene like 1, with HAl(N(i-Pr)2)2 in benzene at room temperature leads to an isomerization, and - after quenching with D2O - to the formation of methylcyclopentane with 90% incorporation of deuterium.36 To probe whether this might be the route through which the reduced compounds 18−28 are generated, we collected a sample of the unquenched product from the butadiene trimerization reactor and quenched it with D2 O. After removing the unsaturated compounds by epoxidation (as described in the Experimental Section) the mixture of saturated components was analyzed using GC− MS(EI). The degree of deuterium incorporation was determined for each compound separately by measuring the ratio of the ions with m/z 165 and 164. All the compounds 18 to 28 are partially deuterated, but the degree of deuteration varies considerably, between just 2.6% for 23 up to 15% for 26. In all cases, only one deuterium atom is incorporated (see the Supporting Information for details). The low degree of deuterium incorporation is not unexpected because water is already present during the trimerization as a catalyst activator and can thus partly quench aluminum alkyl compounds formed as intermediates. However, the fact that all compounds 18−28 contain one and just one deuterium atom supports the assumption that they are formed by hydroalumination/ hydrolysis. Interestingly, the GC obtained from the sample taken right after the trimerization reactor contains all of the C12H20 components (a−j, 18 to 28) already in exactly the same ratio as found in the recycling loop of 1 around the oxidation reactor. It is thus reasonable to assume that these components are formed as byproducts in the trimerization of butadiene. Identification of Compound k (17). Component k is the only component which is an isomer of 1. According to the 13C2D-INADEQUATE data, it has the tetracyclo[7.3.0.02,7.06,10]dodecane structure 17 (Figure 2), an hitherto unknown substance. Building on a suggestion by Whitesides37 for hypostrophane, we name compound 17 as bishomohypostrophane. The calculated 13C NMR shifts for 17 agree very well with the measured shifts (see the Supporting Information), thus leaving no doubt about the proposed structure. The formation of bishomohypostrophane 17 as the sole tetracyclic isomer is at first sight quite surprising. According to our calculations, the isomerization of 1 to 17 is exothermal by 29 kcal·mol−1. Nevertheless, 17 is still 13.5 kcal·mol−1 higher

Table 2. C12H18 Isomers Obtainable from 1 with No More than One H-Shift, together with Their Parent Tricycles, and Their Relative Gibbs Free Energies (in Benzene and relative to 17; M06-2X-D3/def2-QZVP/IEFPCM(C6H6)//M06-2XD3/6-31+G(d,p)/IEFPCM(C6H6))

a

Positions to be attached to one another to obtain the compounds shown on the left are marked by a star.

All of the isomers shown in Table 2 can formally be generated from the C12-ring by first connecting two CC bonds to generate either the cyclopent[a]indene or the as-indacene backbone. From there, only a limited number of possibilities exist to connect the third CC bond without increasing the number of H-shifts required. These connections are shown in Table 2 by marking the carbon atoms to be connected with a star. Structures 17 and 30 are derived from cyclopent[a]indene and structures 29, 31 and 32 from the as-indacene backbone. These are the only five possible tetracyclic C12H18 hydroF



Featured Article

results can also be found in the SI (sections 6, 11 and 12). The method used for the calculation of the NMR shifts follows a procedure recommended in literature.40 Procedure To Separate Saturated Byproducts from Excess 1,5,9-Cyclododecatriene. The starting material for the isolation was 1,5,9-cyclododecatriene taken from the recycle loop around the oxidation reactor after the plant had been in operation for some months. At this point the concentration of the unidentified byproducts had risen to about 13 wt % (based on the iodine number). A GC trace of the material as taken out of the plant can be found in the SI (Figure S3). For the reaction, a 6 L double walled mechanically stirred glass reactor was used, which was equipped with a reflux condenser, dropping funnel, and thermometer. Temperature control was achieved by circulating a thermostated heat transfer fluid in the mantle space. A sample of 1,5,9-cyclododecatriene taken from the recycle stream containing the unknown byproducts (527 g, ca. 3.22 mol, iodine number: 2155) and acetic acid (1 L) were filled in the reactor at ambient temperature. The mixture was warmed to 70 °C, and then H2O2 (50% aqueous solution, 587 mL, 9.92 mol, 3.1 equiv) was added at such a rate that the temperature of the reaction mixture was kept below 75 °C, which took approximately 2 h. The reaction mixture was then stirred for another 12 h at 70 °C. Then, 2 L of water and 1.5 L of toluene were added at 70 °C to the mixture and stirred for 15 min. Then, the aqueous phase was separated, and the organic phase was concentrated under vacuum to yield a colorless viscous liquid (154.9 g) which according to gas chromatography was free of cyclododecatriene, contained ca. 44% saturated byproducts, the remaining being unidentified high-boilers. The procedure was repeated until enough material was gathered for distillation. This crude mixture was used for distillation without any further purification. The procedure was repeated to obtain overall 244.7 g of product mixture, which was the minimum amount required for the distillation. Distillation Protocol for the Enrichment of Byproducts. The mixture as obtained in the previous step (244.7 g) was distilled under vacuum (3.0 mbar head pressure) on a column packed with 3 mm stainless steel wire mesh rings (column length 1.2 m, inner diameter 1.5 cm). The column was automatically controlled by a computer and was operated without interruption. To minimize heat losses, the column was equipped with a three-zone heating mantle. The temperature in each zone was automatically adjusted to 3 °C above the inner temperature of each zone. In total, the distillation time was 1016 h over which 49 fractions were collected (in sum 137.6 g, 56%). A total of 96.9 g (40%) remained in the sump. The reflux ratio was usually set to 30:2 (30 s reflux, 2 s fraction collection) during the day and to 60:2 overnight. The temperature in the sump was initially set to 89.1 °C and then carefully increased to 98.8 °C (fraction 43) and finally to 119.8 °C (fraction 49; blue curve in Figure S1). During the distillation time, the temperature at the top of the column rose from 63.8 to 72.8 °C (fraction 43) and finally to 74.1 °C (fraction 49; black curve in Figure S1). The distillation was stopped when some material solidified in the condenser (set to 10 °C) which was collected as fraction 50. The detailed composition of the fractions and the head temperature for each fraction can be found in the SI (Figure S1). Of the 50 distillation fractions collected, five fractions were chosen for detailed NMR analysis (fractions 6, 15, 29, 40, 50). A GC chromatogram of the starting material of the distillation can be found in the SI (Figure S2, solvent peak at 6.14 min rt). The inset in Figure S2 shows the enlarged region between 14.3−16.7 min retention time (GC conditions: 30 m DB-1701 column, inner diameter 0.32 mm; starting temperature 50 °C, then heat to 240 °C with 7 °C/min, keep 240 °C for 8 min). The chromatogram showed 11 larger peaks (components a−k) and a few minor peaks. As will be discussed later, component h is actually a mixture of two inseparable components h1 and h2. 13 C NMR from the Product Obtained by GC Cold-Trap Fraction Collection. In a first attempt at clarifying the structure of the unknown byproduct appearing at 21.585 min in the GC of the recycled 1,5,9-cyclododecatriene from the production plant (Figure

carbons that can be accessed from 1 by just connecting CC bonds and by shifting no more than one hydrogen atom. Saturated tricyclic products with an as-indacene backbone are indeed formed in the butadiene trimerization step (18-21), but no tricyclic saturated product with the cyclopenta[a]indene structure was found. This is quite remarkable because the isomerization of 1 with aluminum alkyls, albeit at temperatures above 200 °C, leads to the formation of monoolefins with both the cyclopent[a]indene and the asindacene backbone in a ratio of approximately 1:1.26,38,39 However, from all the tricyclic compounds with the cyclopent[a]indene backbone, only the minor isomer 21 has the syn geometry that would be required to allow a ring closure to a tetracyclic molecule. This might be the reason why neither 29, 31, or 32 are formed. On the other hand, the more strongly constrained asindacene backbone appears to more strongly favor the dehydroalumination required for the formation of 17. These considerations are of course speculative, but they do offer a basis to understand why 17 is the only tetracyclic hydrocarbon formed as a byproduct.

■

CONCLUSION Although the trimerization of butadiene to 1 has been intensively studied and has been used industrially for several decades, we were able to isolate and characterize 11 saturated tricyclic and one tetracyclic byproducts, some of which were hitherto unknown. Besides providing new insights into this important reaction, this work also demonstrates the power of 13 C NMR when combined with computation of the spectra to identify polycyclic saturated hydrocarbons.

■

EXPERIMENTAL SECTION

General Information. All NMR spectra were recorded in deuterated solvents (CDCl3 and C6D6) on a Bruker Avance III 500 (1H: 500.13 MHz, 13C: 125.77 MHz) or a Bruker Avance III HD spectrometer (1H: 700.31 MHz, 13C: 176.11 MHz) at 298 K unless indicated otherwise. Spectra were calibrated against the solvent signals: CDCl3: δC 77.00 ppm, δH 7.26 ppm; C6D6: δC 128.06 ppm, δH 7.16 ppm. The multiplicities of carbon peaks were determined using DEPT experiments. The carbon−carbon connectivity was determined using 13C-2D-INADEQUATE experiments. Note that in this paper, the enrichment of very minor hydrocarbon byproducts of a large industrial process, and the identification of these byproducts from mixtures is reported. Therefore, compound identifications typically rest on the comparison of experimental and computed 13C NMR data. The same holds for IR and EI-MS data which were determined from mixtures by GC−MS/IR coupling. The gas chromatographic separations were performed on an Agilent 5890 using a 30 m DB-1701 column with an inner diameter of 0.32 mm and using an FID detector. The temperature program was as follows: starting temperature 50 °C, then heat to 240 °C with 7 °C/ min, and finally keep the temperature at 240 °C for 8 min. The GC− MS(EI) was taken on an Agilent 6890N gas chromatograph equipped with a 5975 Inert XL mass selective detector and using with a Restek Rxi-5SilMS capillary column (30 m × 0.25 mm × 0.25 μm) and the following temperature program: start at 100 °C, isothermal at 100 °C for 3 min, heat up with a 5 °C/min ramp up to a final temperature of 280 °C. Data was acquired at a rate of 20 Hz. GC−IR were also performed on Agilent 5890 equipped with an IR detector. MS(EI) traces and IR spectra can be found in the SI (section 8). The GC enrichment was performed on an Agilent 5850 equipped with a cold trap fraction collector. Details of the assignment of the stereochemistry of the isolated compounds by comparison with computed and measured and, where available, published 13C NMR spectra can also be found in the SI (section 7). Details on all the computational G



Featured Article

GC−IR): 2942, 2893, 1460, 1296, 964, 841 cm−1. MS(EI): 162 (M+), 67 (M100). trans,anti,trans-Perhydro-as-indacene (18, Peak a in GC). 13 C{1H} NMR (176 MHz, CDCl3): δ 51.8 (CH), 47.4 (CH), 31.37 (CH2), 30.7 (CH2), 29.7 (CH2), 22.4 (CH2). Shifts in C6D6 can also be found in the SI (Table S2). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.1). IR (gas phase, from GC− IR): 2956, 2870, 1455 cm−1. MS(EI): 164 (M+), 121 (M100). trans,anti,cis-perhydro-as-indacene (19, peak g in GC). 13C{1H} NMR (176 MHz, CDCl3): δ 46.1 (CH), 45.8 (CH), 45.3 (CH), 40.0 (CH), 31.5 (CH2), 30.33 (CH2), 30.31 (CH2), 27.5 (CH2), 27.4 (CH2), 27.0 (CH2), 22.27 (CH2), 21.6 (CH2). Shifts in C6D6 can also be found in the SI (Table S7). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI on sections 6 and 7.7. IR (gas phase, from GC−IR): 2931, 2867, 1458 cm−1. MS(EI): 164 (M+), 136 (M100). trans,syn,cis-Perhydro-as-indacene (20, Peak h2 in GC). 13C{1H} NMR (176 MHz, CDCl3): δ 47.3 (CH), 43.1 (CH), 40.7 (CH), 38.9 (CH), 31.51 (CH2), 31.45 (CH2), 30.9 (CH2), 29.3 (CH2), 28.8 (CH2), 22.29 (CH2), 22.27 (CH2), 21.9 (CH2). Shifts in C6D6 can also be found in the SI (Table S10). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.8). IR and MS not resolvable due to overlap with 24. The IR spectrum of the mixture can be found in the SI (Figure S87). cis,anti,cis-Perhydro-as-indacene (21, Peak j in GC). 13C{1H} NMR (176 MHz, CDCl3): δ 41.7 (CH), 36.3 (CH), 31.6 (CH2), 30.0 (CH2), 27.2 (CH2), 22.1 (CH2). Shifts in C6D6 can also be found in the SI (Table S12). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI on sections 6 and 7.10. IR (gas phase, from GC−IR): 2954, 2876, 1458 cm−1. MS(EI): 164 (M+), 121 (M100). cis,cis-Perhydro-1H-cyclopent[c]indene (22, Peak b in GC). 13 C{1H} NMR (176 MHz, CDCl3): δ 52.5 (C), 49.4 (CH), 45.0 (CH), 39.4 (CH2), 36.3 (CH2), 34.4 (CH2), 31.7 (CH2), 31.43 (CH2), 27.1 (CH2), 26.0 (CH2), 24.4 (CH2), 23.0 (CH2). Shifts in C6D6 can also be found in the SI (Table S1). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.2). IR (gas phase, from GC−IR): 2943, 2871, 1460 cm−1. MS(EI): 164 (M+), 121 (M100). trans,cis-Perhydro-1H-cyclopent[c]indene (23, Peak c in GC). 13 C{1H} NMR (126 MHz, CDCl3): δ 53.6 (C), 49.9 (CH), 49.2 (CH), 38.9 (CH2), 32.9 (CH2), 31.4 (CH2), 30.8 (CH2), 30.1 (CH2), 27.72 (CH2), 26.4 (CH2), 25.5 (CH2), 23.1 (CH2). Shifts in C6D6 can also be found in the SI (Table S4). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.3). IR (gas phase, from GC−IR): 2937, 2870, 1456 cm−1. MS(EI): 164 (M+), 121 (M100). cis,cis,trans-Ufolane (24, Peak h1 in GC). 13C{1H} NMR (176 MHz, CDCl3): δ 48.6 (CH), 37.6 (CH), 35.5 (CH), 34.8 (CH), 32.6 (CH2), 31.6 (CH2), 30.8 (CH2), 30.4 (CH2), 29.3 (CH2), 26.5 (CH2), 26.1 (CH2), 22.3 (CH2). Shifts in C6D6 can also be found in the SI (Table S9). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.8). IR and MS not resolvable due to overlap with 20. The IR spectrum of the mixture can be found in the SI (Figure S87). cis,trans,cis-Ufolane (25, Peak i in GC). 13C{1H} NMR (176 MHz, CDCl3): δ 49.6 (CH), 39.8 (CH), 34.5 (CH), 32.7 (CH2), 27.1 (CH2), 26.1 (CH2), 22.6 (CH2). Shifts in C6D6 can also be found in the SI (Table S8). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.9). IR (gas phase, from GC−IR): 2928, 2887, 1458 cm−1. MS(EI): 164 (M+), 136 (M100). cis,cis-Perhydro-1H-cyclopent[d]indene (26, Peak d in GC). 13 C{1H} NMR (126 MHz, CDCl3): δ 51.7 (C), 40.6 (CH), 37.4

S3), a semipreparative GC method was used. The setup consisted of a standard gas chromatograph (Agilent 5850) combined with a cryogenic fraction collector. The sample collector was set to collect only the fraction at 21.585 min. After 200 injections, the cold trap was thawed and flushed with CDCl3. The obtained solution was then used to record a 13C NMR spectrum. The spectrum obtained can be found in the SI (Figure S4). In spite of 11 h of measurement it was not possible to obtain a 13C-2D-INADEQUATE spectrum due to the very low concentration of the solution. 13 C-2D-INADEQUATE Spectra of Chosen Fractions from Distillation and Derived Carbon Backbones. The fractions obtained in the distillation were around 2−3 g, so there was enough material from each fraction to perform 13C-2D-INADEQUATE experiments. All fractions contained more than one compound, but they were chosen in such a way that they contained no more than three major components. In this way, it was possible to assign all the relevant signals in each fraction. The spectra and the carbon connectivity derived from the 13C-2D-INADEQUATE experiments can be found in the SI (section 5). Since each fraction contains more than one compound, peak assignments for the first are shown in orange, for the second in green, and for the third in light blue. 1 H NMR spectra of the chosen fractions can also be found in the SI (also in section 5), but since the fractions were always mixtures and the compounds only contained aliphatic CH protons the signals all appeared between 0.85 and 2.35 ppm and showed a very complex and overlapping pattern, so no assignments were possible. Deuteration of the Unquenched Stream from the Butadiene Trimerization Reactor. For this experiment, a sample of approximately 0.5 L was taken in the production plant at a sampling point at the exit of the butadiene trimerization reactor but before the quench reactor, directly into a bottle containing 50 mL of D2O. The sample was left to react for a few hours with occasional shaking, and excess D2O was separated off by decantation. The organic phase was then treated with H2O2 and acetic acid as described above to remove 1,5,9-cyclododecatriene and any other unsaturated components. The organic phase (ca. 240 g) after removal of water and acetic acid was distilled under vacuum to obtain ca. 5 g of a low boiling fraction which contained compounds a−j, some monoepoxide of cyclododecatriene, and traces of cyclododecatriene. This fraction was used to determine the degree of deuteration by GC−MS (Figure S94). To determine the degree of deuteration, or more correctly the molar fraction of C12H19D, the ion traces 164.14 ± 0.2 au (M) and 165.14 ± 0.2 au (M + 1) were separately plotted and integrated. From the ratio of areas for the ion trace at M + 1 and M the molar fraction of C12H19D can be calculated. For a molecule with the sum formula C12H20 with natural abundances of 13C and deuterium, the M + 1 peak would have 13.3% of the area of the M peak. This is exactly the ratio observed with a reference sample which was quenched with water instead of D2O. The detailed results can be found in the SI (Table S20). Low-Temperature NMR Experiment with 26. NMR spectra were recorded in deuterated dichloromethane (CD2Cl2) on a Bruker Avance II+ 600 (1H: 600.2 MHz, 13C: 150.92 MHz). Experiments were run by cooling the sample from 298 to 180 K using a 5 mm triple resonance broadband probe for inverse detection with z gradient coil. The temperature dependent 13C NMR of a sample enriched in 26 (fraction 15 from the distillation) can be found in the SI (Figure S95). According to calculations, the following NMR peaks (the position given is that in CDCl3 at ambient temperature) should split on cooling (split in ppm is given in brackets): 21.5 (0.5), 27.66 (6.4), 29.9 (2.5), 37.4 (6.0) and 40.6 (1.3). Of these the peaks at 27.66, 29.9 and 37.6, i.e. exactly the ones with the largest predicted split, show considerable broadening at 180 K. However, even at 180 K the flipping is not yet frozen. Bishomohypostrophane (17, Peak k in GC). 13C{1H} NMR (176 MHz, CDCl3): δ 52.3 (CH), 42.3 (CH), 41.9 (CH), 37.2 (CH), 35.4 (CH2), 27.0 (CH2), 23.4 (CH2), 17.3 (CH2). Shifts in C6D6 can also be found in the SI (Table S11). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.11). IR (gas phase, from H



■

(CH2), 29.9 (CH2), 27.66 (CH2), 21.5 (CH2), 20.4 (CH2). Shifts in C6D6 can also be found in the SI (Table S3). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.4). IR (gas phase, from GC−IR): 2954, 2932, 2875, 1462 cm−1. MS(EI): 164 (M+), 121 (M100). trans-Perhydrocyclopent[cd]azulene (27, Peak e in GC). 13C{1H} NMR (176 MHz, CDCl3): δ 54.9 (CH), 43.5 (CH), 43.0 (CH), 42.5 (CH), 35.6 (CH2), 35.3 (CH2), 34.6 (CH2), 32.9 (CH2), 32.6 (CH2), 32.2 (CH2), 32.0 (CH2), 26.6 (CH2). Shifts in C6D6 can also be found in the SI (Table S5). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.5). IR (gas phase, from GC− IR): 2957, 2927, 2878, 1458 cm−1. MS(EI): 164 (M+), 121 (M100). cis-Perhydro-2H-1,4a-ethanonaphthalene (28, Peak f in GC). 13 C{1H} NMR (176 MHz, CDCl3): δ 48.4 (CH), 39.9 (C), 39.3 (CH2), 38.2 (CH), 37.5 (CH2), 29.1 (CH2), 28.3 (CH2), 26.8 (CH2), 25.4 (CH2), 22.8 (CH2), 22.29 (CH2), 19.3 (CH2). Shifts in C6D6 can also be found in the SI (Table S6). Assignment of the shifts to the individual carbon atoms based on comparison with calculated spectra can be found in the SI (sections 6 and 7.6). IR (gas phase, from GC−IR): 2933, 2870, 1459 cm−1. MS(EI): 164 (M+), 135 (M100).

■

REFERENCES

(1) Reed, H. B. W. Production of cycloolefinic compounds. US Patent US2,686,209, Aug 10, 1954. (2) Reed, H. B. W. The Catalytic Cyclic Polymerisation of Butadiene. J. Chem. Soc. 1954, 1931−1941. (3) Wilke, G. Cyclooligomerization of butadiene and transition metal π-complexes. Angew. Chem. 1963, 75 (1), 10−20. (4) Rona, P. The Synthesis and Reactions of the 1,5,9-Cyclododecatrienes. Intra-Sci. Chem. Rep. 1971, 5 (2), 105−142. (5) Oenbrink, G.; Schiffer, T. Cyclododecatriene, Cyclooctadiene, and 4-Vinylcyclohexene. Ullmann’s Encyclopedia of Industrial Chemistry; Wiley-VCH Verlag, 2012; DOI: 10.1002/ 14356007.a08_205.pub2. (6) Fankhauser, P.; Fantini, P. Use of unsaturated macrocyclic ketones as perfume ingredients. US Patent US5,266,559, Nov 30, 1993. (7) Demole, E.; Mahaim, C.; Blanc, P. A. Use of cyclopentadecenone isomers as a perfuming ingredient. US Patent US5,354,735, July 12, 1994. (8) Koenig, K. H.; Pommer, E. H.; Sanne, W. Novel fungicides: Nsubstituted tetrahydro-1,4-oxazines. Angew. Chem. 1965, 77 (7), 327− 333. (9) Jopp, K. From Saulus to Paulus − BASF produces Cyclododecanone for the first time by using Nitrous Oxide as the Raw Material. PROCESS 2010, 2, 40−41. (10) Oenbrink, G.; Schiffer, T. Cyclododecanol, Cyclododecanone, and Laurolactam. Ullmann’s Encyclopedia of Industrial Chemistry; Wiley-VCH Verlag, 2009; DOI: 10.1002/14356007.a08_201.pub2. (11) Micoine, K.; Meier, R.; Herwig, J.; Roos, M.; Haeger, H.; Cameretti, L.; Doering, J. Process for preparing cyclododecanone. US Patent US9,533,932, Jan 3, 2017. (12) Sugise, R.; Doi, T.; Nishio, M.; Niida, S.; Matsumora, T. Process for the preparation of cyclododecanone. US Patent US6,861,563, Mar 1, 2005. (13) Micoine, K.; Meier, R.; Herwig, J.; Betard, A.; Quandt, T. Catalyst system for producing ketones from epoxides. US Patent US9,637,436, May 2, 2017. (14) Teles, J. H.; Roessler, B.; Pinkos, R.; Genger, T.; Preiss, T. Method for producing a ketone. US Patent US7,449,606, Nov 11, 2008. (15) Bridson-Jones, F. S.; Buckley, G. D.; Cross, L. H.; Driver, A. P. Oxidation of Organic Compounds by Nitrous Oxide, Part 1. J. Chem. Soc. 1951, 2999−3008. (16) Bridson-Jones, F. S.; Buckley, G. D. Oxidation of Organic Compounds by Nitrous Oxide, Part 2. Tri- and Tetra-substituted Ethylenes. J. Chem. Soc. 1951, 3009−3016. (17) Buckley, G. D.; Levy, W. J. Oxidation of Organic Compounds by Nitrous Oxide, Part 3. Acetylenes. J. Chem. Soc. 1951, 3016−3018. (18) Starokon, E. V.; Dubkov, K. A.; Babushkin, D. E.; Parmon, V. N.; Panov, G. I. Liquid Phase Oxidation of Alkenes with Nitrous Oxide to Carbonyl Compounds. Adv. Synth. Catal. 2004, 346, 268− 274. (19) Hermans, I.; Moens, B.; Peeters, J.; Jacobs, P.; Sels, B. Diazo chemistry controlling the selectivity of olefin ketonisation by nitrous oxide. Phys. Chem. Chem. Phys. 2007, 9, 4269−4274. (20) Fărcaşiu, D.; Wiskott, E.; Osawa, E.; Thielecke, W.; Engler, E. M.; Slutsky, J.; Schleyer, P. v. R.; Kent, G. J. Ethanoadamantane. The Most Stable C12H18 Isomer. J. Am. Chem. Soc. 1974, 96 (14), 4669− 4671. (21) Osawa, E.; Engler, E. M.; Godleski, S. A.; Inamoto, Y.; Kent, G. J.; Kausch, M.; Schleyer, P. v. R. Bridgehead Reactivities of Ethanoadamantane. Bromination and Solvolysis of Bromides. J. Org. Chem. 1980, 45 (6), 984−991. (22) Gugisch, R.; Kerber, A.; Kohnert, A.; Laue, R.; Meringer, M.; Rücker, C.; Wassermann, A. MOLGEN 5.0, A Molecular Structure Generator. In Advances in Mathematical Chemistry and Applications; Bask, S. C., Restrepo, G., Villaveces, J. L., Eds.; Bentham Science Publishers, 2015; Vol. 1 (revised ed.), pp 113−138.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.9b01633.

■

Featured Article

Procedures to separate saturated byproducts from excess cyclododecatriene; distillation protocol for the enrichment of byproducts; 13C-2D-INADEQUATE spectra and derived carbon backbones; computed 13C NMR spectra and energies of possible isomers; correlation diagrams of measured and computed 13C NMR spectra; IR and MS spectra; low temperature 13C NMR spectra of 26; enumeration of C12H18 isomers derivable from a C12-ring; computational details (PDF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Martin Breugst: 0000-0003-0950-8858 Albrecht Berkessel: 0000-0003-0470-7428 J. Henrique Teles: 0000-0002-7843-5675 Author Contributions

W.M. and N.S. performed the NMR measurements. M.B. and A.S. performed the ab initio calculations. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This research work was supported by BASF SE. We thank the operators of BASF’s cyclododecanone plant in Ludwigshafen and our laboratory staff for their experimental support and endless patience. Additional support from the Fonds der Chemischen Industrie (Liebig Fellowship to M.B.) is gratefully acknowledged. We are grateful to the Regional Computing Center of the University of Cologne for providing computing time of the DFG-funded High Performance Computing (HPC) System CHEOPS as well as for their support. I



Featured Article

(23) Evtushenko, A. V.; Molchanova, M. S.; Smirnov, B. B.; Shlyapochnikov, V. A. Computer generation and theoretical study of alicyclic caged structures without small-size cycles. Russ. Chem. Bull. 1996, 45 (10), 2302−2308. (24) Vorob’eva, N. S.; Pekhk, T. I.; Zemskova, Z. K.; Petrov, A. A. Stereochemistry of vicinal perhydroindacene and perhydrotriphenylene. Neftekhimiya 1989, 29 (5), 658−64. (25) Tureček, F.; Hanuš, V.; Sedmera, P.; Antropiusová, H.; Mach, K. Structures of the Tricyclododecenes Prepared by the Catalytical Intramolecular Cyclisation of 1,5,9-Cyclododecatriene. Tetrahedron 1979, 35, 1463−1467. (26) Tolstikov, G. A.; Yur’ev, V. P.; Salimgareeva, I. M.; Kuchin, A. V. New synthesis of alkyl derivatives of adamantane. Bull. Acad. Sci. USSR, Div. Chem. Sci. 1974, 23, 1552−1553. (27) Compounds b and c have previously been described as compounds 101 and 102 in the supporting material of: Kakiuchi, K.; Ue, M.; Tsukahara, H.; Shimizu, T.; Miyao, T.; Tobe, Y.; Odaira, Y.; Yasuda, M.; Shima, K. Novel Rearrangement of 5,6-Disubstituted Bicyclo[4.2.0]octan-2-ones with AlCl3. Application to Total Synthesis of (±)-5-Oxosilphiperfol-6-ene and (±)-Silphiperfol-6-ene. J. Am. Chem. Soc. 1989, 111, 3707−3712. (28) Boldt, P.; Arensmann, E.; Blenkle, M.; Kersten, H.; Tendler, H.; Trog, R.-S.; Jones, P. G.; Döring, D. Synthesis of Stereoisomeric Ufolanes. Chem. Ber. 1992, 125, 1147−1157. (29) Chachuat, J. P.; Noaille, A.; Rull, T. Preparation of a Bicyclic Diamine from 1,5,9-Cyclododecatriene. Bull. Soc. Chim. Fr. 1977, 11− 12 (Part2), 1137−1141. (30) Zakharkin, L. I.; Zhigareva, G. G.; Ovseenko, S. T. Carboxylation of 1,5,9-cyclododecatriene by Koch reaction to give perhydroacenaphthenecarboxylic acids. Neftekhimiya 1996, 36 (6), 526−530. (31) Tobe, Y.; Iseki, T.; Kakiuchi, K.; Odaira, Y. A New Strategy for Construction of Angularly Fused Tricyclic Ring Systems. Transannular Bond Formation of Bicyclic Enones via Photochemical Intramolecular Hydrogen Abstraction. Tetrahedron Lett. 1984, 25, 3895−3896. (32) Inamoto, Y.; Takaishi, N.; Fujikura, Y.; Aigami, K.; Tsuchihashi, K. The Structures of Two Major Intermediates in Trifluoromethanesulfonic Acid-Catalyzed Rearrangement of Tricyclo[5.2.2.02,6]undecane. Chem. Lett. 1976, 5, 631−634. (33) Kakiuchi, K.; Tsugaru, T.; Takeda, M.; Wakaki, I.; Tobe, Y.; Odaira, Y. Acid-Catalyzed Rearrangement of [m.3.2]Propellanols. J. Org. Chem. 1985, 50, 488−493. (34) Breil, H.; Heimbach, P.; Kröner, M.; Müller, H.; Wilke, G. Synthesis of 1,5,9-cyclododecatrienes. I. Catalytic conversion of olefins. Makromol. Chem. 1963, 69, 18−40. (35) Smith, W. L.; Wartik, T. Investigation of the Thermal Decomposition of Triethylaluminium. J. Inorg. Nucl. Chem. 1967, 29, 629−645. (36) Ashby, E. C.; Noding, S. A. Hydrometalation. 3. Hydroalumination of Alkenes and Dienes Catalyzed by Transition Metal Halides. J. Org. Chem. 1979, 44 (24), 4364−4371. (37) Lee, T. R.; Wierda, D. A.; Whitesides, G. M. The Reduction of C* Bonds Proceeds with Retention of Configuration: Stereochemical Investigation of the Heterogeneous Reduction by Dideuterium of (Homohypostrophene)neopentyl(2-norbornyl)platinum(II) Complexes on Platinum Black. J. Am. Chem. Soc. 1991, 113, 8745−8753. (38) Yur’ev, V. P.; Kuchin, A. V.; Salimgareeva, I. M.; Kozhevnikova, G. A.; Kleiner, V. I.; Tolstikov, G. A. Transformations of some Olefins Under the Influence of Organoaluminum Compounds. Bull. Acad. Sci. USSR, Div. Chem. Sci. 1974, 23, 2460−2463. (39) Yur’ev, V. P.; Tolstikov, G. A.; Kuchin, A. V.; Yakovleva, T. O.; Khvostenko, V. I.; Galkin, E. G.; Rafikov, S. R. Isomerization of olefins in the presence of organoaluminum compounds. Doklady Akad. Nauk SSSR 1974, 215, 1397−1399. (40) Willoughby, P. H.; Jansma, M. J.; Hoye, T. R. A guide to smallmolecule structure assignment through computation of (1H and 13C) NMR chemical shifts. Nat. Protoc. 2014, 9, 643−660.

J


Technical Synthesis of 1,5,9-Cyclododecatriene Revisited: Surprising

Recommend Documents