Hydrogenation and Deoxygenation

Hydrogenation and Deoxygenation. Nickel boride, produced in situ by the action of sodium borohydride on nickel(II) chloride, has been used to carry out a two-step hydrogenolysis of allylic alcohols via reductive cleavage of the trimethylsilyl ethers. Tertiary alcohols may be deoxygenated in reasonable yields by means 

Miscellaneous Reactions. The adduct (19) from dimethylformamide and benzoyl chloride converts alcohols into formate esters in generally good yields. 

Complexes of 3-acetyl-2-oxazolone (20) and organozirconium compounds have been found to acylate polyols with excellent 

A series of diphenyImethanols has been converted into the corresponding diphenylacetic acids by carboxylation with carbon monoxide in a strong acid medium of formic and concentrated 

Treatment of alcohols with chlorine and sulphur in the presence 

---

Mechanisms related to cellulose-derived biofuels focus on the chemistry offuran derivatives. Beyond the unimolecular decompositions and oxidative reactions discussed previously in this section, furan derivatives can undergo a wide variety of other reactions. They are transformed by pyrolytic, hydrolytic, and other chemical processes to longer chain ethers (R1OR2) and aldols (hydroxyaldehydes and hydroxyketones, Ri(0H)R2C(0)R3). These oxygenated species are then converted through hydrogenation and deoxygenation processes to liquid HC fuels (alkanes). 

Nitropyridazines are reduced catalytically either over platinum, Raney nickel or palladium-charcoal catalyst. When an N-oxide function is present, palladium-charcoal in neutral solution is used in order to obtain the corresponding amino N-oxide. On the other hand, when hydrogenation is carried out in aqueous or alcoholic hydrochloric acid and palladium-charcoal or Raney nickel are used for the reduction of the nitro group, deoxygenation of the N- oxide takes place simultaneously. Halonitropyridazines and their N- oxides are reduced, dehalogenated and deoxygenated to aminopyridazines or to aminopyridazine N- oxides under analogous conditions. 

The plausible deoxygenation routes for production of diesel like hydrocarbons from fatty acids and their derivates are decarboxylation, decarbonylation, hydrogenation and decarbonylation/hydrogenation. The main focus in this study is put on liquid phase decarboxylation and decarbonylation reactions, as depicted in Figure 1. Decarboxylation is carried out via direct removal of the carboxyl group yielding carbon dioxide and a linear paraffinic hydrocarbon, while the decarbonylation reaction yields carbon monoxide, water and a linear olefinic hydrocarbon. 

The deoxygenation of 86 to benzene can also be accomplished with lithium aluminum hydride. Conversion of 157 to the parent aromatic hydrocarbon has been brought about with hydrogen and platinum at 0°C. 

To further increase the overall yield of the process, a second step can be added in which dihydroxylated by-products, hydroquinone and catechol, are treated with hydrogen and partially deoxygenated to phenol, which is recycled back to the process (Scheme 13.4) [23]. 

Reductive radical elimination (Barton deoxygenation) of the 3, 4 -xanthate derivative of neamine (70) has been used to prepare the key intermediate 71 (compounds 70, 71) for the synthesis of the 3, 4 -dideoxyneamine analog gentamine Cia [52]. In this synthesis, a precursor possessing free hydroxyl groups at positions 3 and 4 was treated with a mixture of carbon disulfide, aqueous sodium hydroxide, and methyl iodide in DMSO to afford compound 70. Subsequent reduction of 70 with tributyltin hydride furnished the olefin 71, which affer cafalyfic hydrogenation and deprofecfion was converted to gentamine Cia. 

Quinoxaline mono-iV-oxides result from the partial reduction of the di-N-oxides. Among reagents that have been used for this purpose are hydrogen and a metal catalyst, phosphorus trichloride, and sodium dithionite. Thus 2-methylquinoxaline 1-oxide has been prepared by partial hydrogenation of the di-JV-oxide quinoxaline-2-carboxyanilide 1-oxide has been prepared from the partial deoxygenation of the 1,4-dioxide with phosphorus trichloride and quinoxaline-2-carboxylic acid... 

---