Camphor hydrogenation

Present in citronella and valerian oils, tur penline, ginger, rosemary and spike oils. It is produced artificially by the elimination of hydrogen chloride from bornyl chloride (artifi cial camphor) or from isobornyl chloride, by the dehydrogenation of borneol and isobor-neol and by the action of elhanoic anhydride on bornylamine. Chiral. 

By oxidation with permanganate it forms pinonic acid, C,oH,<503, a monobasic acid derived from cyclobutane. With strong sulphuric acid it forms a mixture of limonene, dipentene, terpinolene, terpinene, camphene and p-cymene. Hydrogen chloride reacts with turpentine oil to give CioHijCl, bomyl chloride, artificial camphor . 

Chromic(VI) acid Acetic acid, acetic anhydride, acetone, alcohols, alkali metals, ammonia, dimethylformamide, camphor, glycerol, hydrogen sulflde, phosphorus, pyridine, selenium, sulfur, turpentine, flammable liquids in general... 

At pressures of 13 GPa many carbonaceous materials decompose when heated and the carbon eventually turns into diamond. The molecular stmcture of the starting material strongly affects this process. Thus condensed aromatic molecules, such as naphthalene or anthracene, first form graphite even though diamond is the stable form. On the other hand, aUphatic substances such as camphor, paraffin wax, or polyethylene lose hydrogen and condense to diamond via soft, white, soHd intermediates with a rudimentary diamond stmcture (29). 

Asymmetric Oiels-Alder reaction, ene reaction, hydrogenation, halogenatlon by means of chiral olelln, such as camphor derivative 1 or 2. 

The free base d(-f)6-phenyl-2,3,5,6-tetrahydroimida2o[2,1-bl thiazole Is dissolved in 112 ml of acetone and 178 ml of isopropanolic hydrogen chloride is added all at once. The hydrochloride crystallizes et once. After cooling to below 0°C, the salt is recovered by filtration and washed with acetone. The product weighs 75.2 g (0.312 mol), 91%, from the camphor-sulfonate, melting point 227 C to 227.5°C [alpM-H23.1°C (C = 15.H20). 

The titanocene dichloride complexes derived from the camphor- and pinene-annulated ligands 126 and 127 were tested as enantioselective hydrogenation catalyst and using 2-phenylbutene as substrate 2-phenylbutane was obtained with ee up to 34% [148, 149]. 

In bridged bicyclic ring systems, two rings share more than two atoms. In these cases, there may be fewer than 2" isomers because of the structure of the system. For example, there are only two isomers of camphor (a pair of enantiomers), although it has two chiral carbons. In both isomers, the methyl and hydrogen are cis. The trans pair of enantiomers is impossible in this case, since the bridge must be cis. The... 

Chromic acid and chromium trioxide Chlorine Acetic acid, naphthalene, camphor, glycerol, turpentine, alcohol or other flammable liquids Ammonia, acetylene, butadiene, butane or other petroleum gases, hydrogen, sodium carbide, turpentine, benzene or finely divided metals... 

Although there are now several catalysts useful for hydrogenation of saturated carbonyl compounds to alcohols (see Section XII), an alternative approach has involved initial hydrosilylation (Chapter 9 in this volume) followed by acid hydrolysis [Eq. (41)]. The area first developed using principally the RhCl(PPh3)3 catalyst (207-210), and has since proved particularly useful in asymmetric syntheses (see Section III,A,4). Besides simple aliphatic and aromatic aldehydes and ketones, the ter-pene-ketones camphor and menthone were stereoselectively reduced to mainly the less stable alcohols e.g., camphor gave 9 (209). 

Methyl methacrylate 4-Methylnitrobenzene 2- Methylpyridine Methylsodium Molybdenum trioxide Naphthalene 2-Naphthol Air, benzoyl peroxide Sulfuric acid, tetranitromethane Hydrogen peroxide, iron(II) sulfate, sulfuric acid 4-Chloronitrobenzene Chlorine trifluoride, interhalogens, metals Chromium trioxide, dinitrogen pentaoxide Antipyrine, camphor, phenol, iron(III) salts, menthol, oxidizing materials, permanganates, urethane... 

Knochel and coworkers synthesized a series of camphor-derived pyridine and quinoline P,N ligands. The catalysts 30 (Fig. 29.17) were used to hydrogenate substrates 1 and 2 in up to 95% and 96% ee, respectively [33]. The selectivities were moderate for other unfunctionalized alkenes however, a high enantioselec-tivity was reported for the hydrogenation of ethyl acetamidocinnamate 10 [34]. 

Figure 1-18. Gas chromatographic separation of a) synthetic racemic dihydromanicone rac- 44 b) natural 44, obtained by hydrogenation of material from the heads of M. rubida c) co-injected natural-44 and rac-44 d) synthetic (4 5,65 )-44 and e) co-injected synthetic (4RS,6S)-44 and rac-44. Chiral GC phase nickel(II)-bis[3-heptafluorobutyryl-(lR)-camphorate]. Signals 1 and 4 correspond to the pair of diastereomers (4 5,65)-44 signals 2 and 3 correspond to (4RS,6R)-44. Reprinted, with permission, by VCH, Ref. 63.

Dimethylbiphenyl-2,2 -dicarboxylic acid, l,l -binaphthyl-2,2 -diyl hydrogen phosphate, camphor-10-sulfonic acid, acenocoumarol, proglumide, Af-succinyl-1-phenylethylamine, 3,4-dihydro-4-(2-naphthyl)-1,3,6-trimethyl pyrimidine-2(lH)-one-5-carboxylic acid... 

Both cellulose and cellulose nitrate (CN) are linear, or two-dimensional, polymers, but the former cannot be softened because of the presence of multitudinous hydrogen bonds between the chain-like molecules. When used as an explosive the CN is essentially completely nitrated, but the material used by Parks and Hyatt was a dinitrate, still potentially explosive, but less so. Parks added castor oil and Hyatt added camphor to plasticize—reduce the effect of the hydrogen bonding—the CN, allowing it some flexibility. 

In this special field, earlier work had been done in other laboratories, such as by the Schering Company, Berlin (36), and by Ipatieff (37) in connection with his work on the hydrogenation of camphor and of other organic compounds. At both places, the favorable effect of alkali oxides and earth alkali oxides on nickel, cobalt and copper has been investigated. Similarly, Paal and his coworkers (38) have used a palladium-aluminum hydroxide catalyst in 1913 for the hydrogenation of double bonds. Bedford and Erdman (39) had reported that the catalytic action of nickel oxide is enhanced by the oxides of aluminum, zirconium, titanium, calcium, lanthanum, and magnesium. 

Langlois and co-workers (179) found the same exo stereochemical preference through double asymmetric induction of a related ene-lactone (1 )-145 with their well-explored and efficient camphor-derived oxazoline nitrone (150-146 (Scheme 1.32). They found the cycloaddition components form a matched pair and allowed kinetic resolution of the racemic lactone in up to 70% enantiomeric excess (ee). They suggest the selectivity for exo adduct 147 arises through destabilization of the endo transition state by a steric clash between dipolarophile ring hydrogens and the bornane moiety. 

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