Cyclohexane catalyzed

The hydroxylation of octane and cyclohexane catalyzed by Ti-MMM-1, a mixed- phase material (TS-1 and Ti-MCM-41) containing both micro- and mesopores, with aqueous H202 was reported by Poladi et al. (223). Ti-MMM-1 was found to be more active and selective in these hydroxylations than either Ti-MCM-41 or TS-1 the yield of alcohol was higher (Table XXVII). 

Figure 5.26 Proposed catalytic cycle for the hydrogenation of benzene to cyclohexane catalyzed by the SHB immobilized Rh -Pd7Si02. (Redrawn from Barbaro et al. [126].)...

Fig. 11 Synthesis of (+)-(lfi,6S)-cw-8-oxabicyclo[4.3.0]nonan-7-one from cw-l,2-bis(hydroxy-methyl)cyclohexane catalyzed by HLADH. The cofactor NAD+ is regenerated by the system pyruvate/L-LDH...

Figure 28. Scheme showing the mechanism of hydroxylation of cyclohexane catalyzed by Mn porphyrins. 

Catalytic Oxidation of Cyclohexane Catalyzed by Mononuclear Iron(ii) and Iron(iii) Complexes using H2O2 as the Primary Oxidant ... 

Fe(opba)]20 catalyzes the oxidation of cyclohexane and adamantane with total yields up to 5 % based on the oxidant after 24 h with a ratio A/K of 0.9 and a ratio 3°/2° of 3 (84). These results are in line with a mechanism involving hydroxyl radicals as transient intermediates. In the oxidation of cyclohexane catalyzed by [Fe(tpca)(H20]20 (C104)2, the average alcohol-to-ketone ratio is equal to 7, which is much higher than the value characteristic of radical chain oxidation (54). Also, the stereospecificity observed in the oxidation of cis- and trans-l,2-dimethylcyclohexane (up to 97% retention of configuration) points toward the involvement of a metal-based oxidant (83). A few other complexes showing low to moderate catalytic activity in the oxidation of cyclohexane and/or adamantane are listed in Table IV. 

OXIDATION OF CYCLOHEXANE CATALYZED BY POLYHALOOENATED Af4D PERHALOOENATED IRON PORPHYRINS... 

In 2000, Collman and Brauman reported on a series of competitive oxidation studies using the P-450 model complex [(TPFPP)FeCl] (TPFPP=wso-tetrakis (pentafiuorophenyl)porphinato dianion) and iodosylarenes PhIO and CeFsIO, as well as (diacetoxyiodo)benzene PhI(OAc)2 [46]. For example, in oxidations of 1 1 mixtures of cyclohexane/di2-cyclohexane catalyzed by [(TPFPP)FeCl], ratios of kj k2 are 5.8 for PhIO and 4.3 for CeFsIO as primary oxidants, respectively. This and other data suggest that the active species that transfer oxygen atoms involve metal complexes of the iodosylarenes, probably of the same type of structure as those presented above. In 2000, Nam presented evidence for two distinct reactive... 

X-W Wu, Y Oshima, S Koda. Aerobic oxidation of cyclohexane catalyzed by Fe(in)(5,10,15,20-tetrakis(pentafluorophenyl)porphyrinX71 in sub- and supercritical CO2. Chem Lett 1997 1045-1046, 1997. 

The following acid-catalyzed cyclizations leading to steroid hormone precursors exemplify some important facts an acetylenic bond is less nucleophilic than an olelinic bond acetylenic bonds tend to form cyclopentane rather than cyclohexane derivatives, if there is a choice in proton-catalyzed olefin cyclizations the thermodynamically most stable Irons connection of cyclohexane rings is obtained selectively electroneutral nucleophilic agents such as ethylene carbonate can be used to terminate the cationic cyclization process forming stable enol derivatives which can be hydrolyzed to carbonyl compounds without this nucleophile and with trifluoroacetic acid the corresponding enol ester may be obtained (M.B. Gravestock, 1978, A,B P.E. Peterson, 1969). 

The oxidation of cyclohexane to a mixture of cyclohexanol and cyclohexanone, known as KA-od (ketone—alcohol, cyclohexanone—cyclohexanol cmde mixture), is used for most production (1). The earlier technology that used an oxidation catalyst such as cobalt naphthenate at 180—250°C at low conversions (2) has been improved. Cyclohexanol can be obtained through a boric acid-catalyzed cyclohexane oxidation at 140—180°C with up to 10% conversion (3). Unreacted cyclohexane is recycled and the product mixture is separated by vacuum distillation. The hydrogenation of phenol to a mixture of cyclohexanol and cyclohexanone is usually carried out at elevated temperatures and pressure ia either the Hquid (4) or ia the vapor phase (5) catalyzed by nickel. 

Oxidation catalysts are either metals that chemisorb oxygen readily, such as platinum or silver, or transition metal oxides that are able to give and take oxygen by reason of their having several possible oxidation states. Ethylene oxide is formed with silver, ammonia is oxidized with platinum, and silver or copper in the form of metal screens catalyze the oxidation of methanol to formaldehyde. Cobalt catalysis is used in the following oxidations butane to acetic acid and to butyl-hydroperoxide, cyclohexane to cyclohexylperoxide, acetaldehyde to acetic acid and toluene to benzoic acid. PdCh-CuCb is used for many liquid-phase oxidations and V9O5 combinations for many vapor-phase oxidations. 

Concern for the conservation of energy and materials maintains high interest in catalytic and electrochemistry. Oxygen in the presence of metal catalysts is used in CUPROUS ION-CATALYZED OXIDATIVE CLEAVAGE OF AROMATIC o-DIAMINES BY OXYGEN (E,Z)-2,4-HEXADIENEDINITRILE and OXIDATION WITH BIS(SALI-CYLIDENE)ETHYLENEDIIMINOCOBALT(II) (SALCOMINE) 2,6-DI-important industrial method, is accomplished in a convenient lab-scale process in ALDEHYDES FROM OLEFINS CYCLOHEXANE-CARBOXALDEHYDE. An effective and useful electrochemical synthesis is illustrated in the procedure 3,3,6,6-TETRAMETHOXY-1,4-CYCLOHEX ADIENE. ... 

It has generally been assumed that phosphorous oxychloride-pyridine dehydrations, the elimination of sulfonates, and other base catalyzed eliminations (see below) proceed by an E2 mechanism (see e.g. ref. 214, 215, 216). Concerted base catalyzed eliminations in acyclic systems follow the Saytzelf orientation rule i.e., proceed toward the most substituted carbon), as do eliminations (see ref 214). However, the best geometrical arrangement of the four centers involved in 2 eliminations is anti-coplanar and in the cyclohexane system only the tran -diaxial situation provides this. 

A monoacetate can be isolated by continuous extraction with organic solvents such as cyclohexane/CCI4. Monoacylation can also be achieved by ion exchange resin or acid-catalyzed transesterification. 

The main process for obtaining adipic acid is the catalyzed oxidation of cyclohexane (Chapter 10). 

The first series of soluble oligo(/ ara-phenylene)s OPVs 24 were generated by Kern and Wirth [48] and shortly after by Heitz and Ulrich [49]. They introduced alkyl substituents (methyls) in each repeat unit and synthesized oligomers 24 up to the hexamer. Various synthetic methods, like the copper-catalyzed Ullmann coupling, the copper-catalyzed condensation of lithium aryls, and the twofold addition of organomelallic species to cyclohexane-1,4-dione, have been thereby investigated. 

A general preparation of 2-acetonyl-2,4,6-triaryl-2//-thiopyrans 58 was discovered in the reaction of corresponding 2,4,6-triarylthiopyrylium perchlorates with ethanolic acetone catalyzed with various dialkylammonium salts (86GEP235455, 86JPR573). This preparative procedure was successfully extended to cyclohexane- and cyclopentane- 1,2-diones as the carbonyl components (89JPR853 90GEP280324). The action of bases on thiopyrylium salts may caused their dimerization to thiopyranyl derivatives under suitable conditions (89KGS479). 

Ammonolysis of PET involves the reaction of PET with ammonia at temperatures of 70-180°C, usually under pressure in EG. The ammonolysis of PET postconsumer bottles has been canied out at temperatures in the range of 120-180°C and a pressure of ca. 2 MPa for 1-7 h. The TPA diamide formed may be converted to terephthalonitrile. Terephthalonitrile may be hydrogenated to form p-xylylenediamine and l,4-bis(aminomethyl)cyclohexane.12 A low-pressure PET ammonolysis process in EG has been developed. The process is catalyzed by 0.5 wt% zinc acetate at a temperature of 70°C and a PET-NH3 ratio of 1 6 (w/w). The yield of TPA diamide was 87%. 

Intramolecular cycloadditions of furans are a useful method for creating an oxygenated cyclohexane ring in rigid cycloadducts. Thus, a MeAICI2-catalyzed intramolecular reaction [40] of compounds 34 leads stereoselectively to tricyclic cycloadducts (Equation 3.8). The reaction yield is strongly dependent on the quantity of the catalyst and the type of substituent at the olefmic double bond. Cycloadduct 35 (R = R2 = Me, Ri = R3 = R4 = H) was then converted [40b] into 1,4-epoxycadinane (36). 

The chemoenzymatic synthesis of the analgesic U-(—)-50,488 [41] and new C2-symmetric bisaminoamide ligands derived from N,N-disubstituted trans-cyclohexane, ,2-diamine [41] has been possible by a CALB-catalyzed resolution using ethyl acetate as solvent and acyl donor [42]. 

Other important derivatives for the preparation of (i-aminoacids are the corresponding P-aminonitriles. Lipase-catalyzed N-acylations of racemic cis-2-aminocyclopentane and cyclohexane carbonitriles with 2,2,2-trifluoroethyl butanoate have been successfully carried out in organic solvents and ionic liquids [53], PSL yielding better results than CALB (Scheme 7.29). 

In 1982, Breslow and coworkers reported the first example of iron-catalyzed nitrene C-H bond insertion [29]. They used [Fe(TTP)] as catalyst and PhINTs as nitrene precursor to achieve C-H bond amination of cyclohexane. However, the product yield was low (around 10%). Subsequently, the same authors found that iminoio-dane 7 derived from 2,5-diisopropylbenzenesuIfonamide underwent intramolecular C-H amination efficiently with [Fe(TPP)Cl] as catalyst at room temperature, giving the insertion product in 77% yield (Scheme 29) [85]. 

Substituted 1-hydroxy cyclohexane-1-carboxyhc acids, which could be prepared from the corresponding cyanohydrins by acid hydrolysis as described above, are important as pharmaceuticals and plant-protective agents. Although the compounds derived from 2- and 3-cyclohexanones have two stereogenic centers, stereoselective syntheses of these interesting products have been published only very recently. " Completely unexpected are the results of HNL-catalyzed additions to 4-substituted cyclohexanones, which do not possess a prochiral center. The (R)-PaHNL-catalyzed addition affords almost exclusively fran -isomers, whereas with (5 )-MeHNL cA-addition is favored (Table 4). ... 

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