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Limonene hydroformylation

A tandem hydroformylation/carbonyl ene reaction can be observed in cases, in which substrates with at least two isolated oleftnic bonds are hydro-formylated at only one double bond selectively. Thus hydroformylation of limonene with PtCkCPPlH /SnCk/PPlH or PtCl2(diphosphine)/SnCl2/PPh3 gives a mixture of two diastereomeric alcohols upon carbonyl ene reaction of the intermediate aldehyde, (Scheme 36). Best results are achieved with a PtC Cdppb) complex. The mechanism of the final intramolecular cycli-zation step resembles an acid catalyzed carbonyl ene reaction [89]. [Pg.98]

HP IR measurements have recently been reported by workers at Sasol for cobalt-catalysed 1-dodecene hydroformylation reactions using bicyclic phosphines (4) derived from (R)-(+)-limonene [68]. Using Fourier deconvolution to separate absorptions due to [HCo(CO)4] and [Co2(CO)7(phosphine)], it was possible to estimate the ratio of modified [HCo(CO)3(phosphine)] to un-modified [HCo(CO)4] in the catalytic mixture, using peak areas. Values of this ratio ranged from ca. 2-20, depend-... [Pg.124]

Selective hydraformylation of nonconjugated dienes can be carried out such that the least-hindered double bond reacts. Thus citronellene (entry 6) and 2,6-dimethyl-l,5-heptadiene both undergo preferential reaction at the least-substituted double bond, the hydroformylation of citronellene patterned after that of 3-methyl-1-pentene (Table 1) and the hydroformylation of 2,6-dimethyl-l,5-heptadiene to citronellal following that of 2-methyl-1-pentene, avoiding placing the formyl group at the quaternary carbon. The reaction of limonene (entry 8) shows similar behavior. [Pg.922]

For centuries, monoterpenes have been widely used as odorants. Due to their molecular weight and their low boiling points, obtaining related odorant substances through derivatization is obvious. An effective method is the hydroformylation of limonene, a-pinene, a-terpinene, and myrcene. A comparison of the activity in hydroformylation of the four molecules was done in the 1960s using a cobalt catalyst with pressures of around 250 bar and a reaction temperature of 150°C (Scheme 13). [Pg.115]

The second double bond is not hydroaminomethylated because of the mild conditions at 80°C and 80 bar and due to steric hindrance [51]. Graebin describes seven different products of the hydroaminomethylation of limonene [52]. The reaction time was reduced to 10 h by optimization of the catalyst including stepwise hydroformylation for 5 h and hydrogenation with pure hydrogen gas for 5 h. Isomerization was reduced by adding triphenylphosphine as ligand. [Pg.119]

Graebin CS, Eifler-Lima VL, da Rosa RG (2008) One-pot synthesis of secondary and tertiary amines from R(+)-limonene by tandem hydroformylation/reductive animation (hydroamino-methylation). Catal Commun 9 1066—1070. doi 10.1016/j.catcom.2007.10.008... [Pg.128]

Using phosphite-modified rhodium catalysts, otherwise unreactive alkenes, such as 2-methyl-l-hexene, limonene and cyclohexene, are hydroformylated under mild conditions. " 2-Methyl-1-hexene, for example, yields almost exclusively 3-methylheptaldehyde, which is in contrast to the result of cobalt catalysis where a compound with a quaternary carbon is formed (Scheme 12). [Pg.1022]

Conversion of teipenes to aldehyde derivatives by hydroformylation has been studied extensively. Hydroformylation of limonene is practiced commercially by Celanese [34]. Limonene aldehyde has a citrus odor and is used in soaps and lotions. Spirambrene is manufactured by Givaudan and Vigrai by hydroformylation of 2-carene [35, 36]. Tollens reaction of the resulting aldehyde gives a diol which is converted to the acetal with acetone. Spirambrene has a woody, spicy odor and is a component of perfumes. [Pg.42]

Sterically demanding phosphites such as tris(o-t-butylphenyl) phosphite and phosphites with low basicity such as tris(hexafluoroisopropyl) phosphite were found to give high rates of hydroformylation even in the case of less reactive olefins such as 2-methyl-1-hexene, limonene, or cyclohexene (249). [Pg.1122]

Bulky monophosphite hgands proved to be very useful for the functionalization of very unreactive substrates. Already in their first study van Leeuwen and Roobeek obtained relatively high rates for the hydroformylation of substrates such as cyclohexene and limonene. [8]. Van Rooy performed a systematic study to the rhodium catalyzed hydroformylation of substituted alkenes and compared the reaction rates with the triphenylphosphine system [42]. The bulky monophosphite derived catalyst was up to two orders of magnitude faster and gave acceptable rates using substrates for which the Wilkinson hydrofomylation catalyst gave hardly any activity. [Pg.55]

Limonene was reacted with syngas to give a bicyclic alcohol in a hydroformylation-cyclization tandem reaction (Scheme 1.53) [60]. In this approach, there was no need to isolate the intermediate aldehyde. Diastereomers were formed in nearly equal amounts (47 53). [Pg.60]

The so-called LIM ligands were claimed by Sasol for cobalt-catalyzed hydroformylation (Scheme 2.6) [21]. They represent P-alkyl derivatives of 4,8-dimethyl-2-phospha-bicyclo[3.3.1]nonane and can be produced as a mixture of diastereomers by radical-mediated /iti-Markovnikov addition of PHj to (S)- or (/ )-limonene and final reaction of the yielding LIM-H with a long-chain terminal olefin [22]. The last step can be initiated by a radical chain initiator (AINB) or proceeds with the assistance of a strong base [23]. [Pg.83]

In a patent by Mitsubishi, it is available via hydroformylation of limonene and subsequent acid-catalyzed intramolecular cyclization of the aldehyde [1]. The alcohol can also be produced in one step by Pt/Sn-catalyzed hydroformylation, suggested by a protocol of Gusevskaya and coworkers (Scheme 5.123) [2, 3]. Platinum and tin are essential for the cychzation in the last step. Alternatively, the tandem reaction has been investigated in detail with rhodium complexes based on PPhg, P[0(o-fBu)Ph]3, or PPTS (pyridinium / -toluenesulfonate)... [Pg.495]

Scheme 6.29 Hydroformylation of (fl)-(+)-limonene under different reaction conditions. ... Scheme 6.29 Hydroformylation of (fl)-(+)-limonene under different reaction conditions. ...
X-Terpineol can be considered as a hydrate of limonene. Indeed, it is available by Markovnikov addition of trifluoroacetic acid to the latter, followed by hydrolysis [141]. The alcohol has a pleasant odor similar to lilac and is a constituent of cajuput, pine, and petitgrain oil. For technical applications, it is produced from a-pinene by acid-catalyzed isomerization/hydration [142]. Hydroformylation of a-terpineol has been conducted with an unmodified Rh catalyst at 69bar (Scheme 6.45) [132]. Under the conditions applied, besides the expected cyclic carbaldehydes also a linear aldehyde with a tertiary alcoholic group were obtained. The reaction product was distilled, and the main fraction collected showed a woody and nutty aroma with minty and floral topnotes. [Pg.557]

Dimethyl-bicyclo[3.3.1]non-7-en-2-ol could be obtained via the hydroformylation of limonene (see above) and subsequent acid-catalyzed intramolecular cyclization of the aldehyde (Scheme 6.76) [197]. The alcohol, which has a strong menthol-like smell, can be alternatively produced in one step by the effect of syngas on limonene in the presence of a homogeneous Pt/Sn catalyst... [Pg.576]

The modified cobaItoctene hydroformylation using phosphanes derived from limonene was investigated at 170°C and 85bar H2 CO = 2 l. The composition of cobalt complexes in the reaction mixtures was deduced from IR and NMR spectra and correlated to the products of the hydroformylation reaction 7]. [Pg.163]

Increasing the concentration of triphenylphosphane was found to accelerate the rhodium-catalyzed hydroformylation of conjugated dienes, such as isoprene and myrcene. The hydroformylation of the nonconjugated diene, limonene, followed a contrary tendency common to the most of alkenes [57,58]... [Pg.172]


See other pages where Limonene hydroformylation is mentioned: [Pg.436]    [Pg.148]    [Pg.375]    [Pg.89]    [Pg.306]    [Pg.307]    [Pg.299]    [Pg.490]    [Pg.389]    [Pg.454]    [Pg.548]    [Pg.548]    [Pg.577]    [Pg.577]    [Pg.370]    [Pg.148]   
See also in sourсe #XX -- [ Pg.922 ]

See also in sourсe #XX -- [ Pg.4 ]

See also in sourсe #XX -- [ Pg.4 ]




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