Unsaturated acids, hydrogenation

Castor Oil, Hydrogenated, Since ricinoleic acid is an unsaturated acid, hydrogen can be added to its... 

Chlorosulfonic acid Saturated and unsaturated acids, acid anhydrides, nitriles, acrolein, alcohols, ammonia, esters, HCl, HF, ketones, hydrogen peroxide, metal powders, nitric acid, organic materials, water... 

The fatty acids obtained from the process can be used directly or further manipulated for improved or modified performance and stabiUty. Hardening is an operation in which some fraction of the unsaturated bonds present in the fatty acids are eliminated through hydrogenation or the addition of H2 across a carbon—carbon double bond. This process was initially intended to improve the odor and color stabiUty of fatty acids through elimination of the polyunsaturated species. However, with the growth in the use of specialty fatty acids, hydrogenation is a commercially important process to modify the physical properties of the fatty acids. 

P-Hydroxy-A-norpregn-3(5)-en-2-one (7) A solution of the hydroxy-methylene steroid (5) (24.8 g) dissolved in 240 ml of acetic acid and 240 ml of ethyl acetate is ozonized at — 10° with one molar equivalent of ozone. The resulting solution is diluted with 240 ml. of water and 60 ml of 30 % hydrogen peroxide and allowed to stand overnight. The solution is diluted with 1.5 liters of water and extracted with 3 x 700 ml portions of ethyl acetate. The combined extracts are washed with water, saturated sodium chloride solution, dried over sodium sulfate and concentrated to dryness under vacuum, leaving 23.4 g of a colorless amorphous residue of crude diacid. This material shows a maximum in the ultraviolet spectrum at 224 mp (s 6,400) indicating a 53 % yield of unsaturated acid (6). It is used without further purification. 

Cinnamic Acid.—The reaction, which takes place when an aldehyde (aliphatic or aromatic) acts on the sodium salt of an aliphatic acid in presence of the anhychide, is known as Perkin s reaction, and has a ery wide application. Accoid-ing to the result of Fittig s researches on the properties of the unsaturated acids described below, the reaction occurs in two steps. The aldeh) de forms first an additive compound with the acid, the aldehyde caibon attaching itself to the n-carbon ii.e.i nevt the carbovyl) of the acid. A saturated hydiOKy-acid is formed, which is stable, if the a-carbon is attached to only one atom of hydrogen, as in the case of isobutync acid,... 

Compound A, C H O, was found to be an optically active alcohol. Despite its apparent unsaturation, no hydrogen was absorbed on catalytic reduction over a palladium catalyst. On treatment of A with dilute sulfuric acid, dehydration occurred and an optically inactive alkene B, Q iH14, was produced as the major product. Alkene B, on ozonolysis, gave two products. One product was identified as propanal, CH3CH2CHO. Compound C, the other product, was shown to be a ketone, CgHgO. How many degrees of unsaturation does A have Write the reactions, and identify A, B, and C. 

To be eligible to living anionic polymerization a vinylic monomer should carry an electron attracting substituent to induce polarization of the unsaturation. But it should contain neither acidic hydrogen, nor strongly electrophilic function which could induce deactivation or side reactions. Typical examples of such monomers are p-aminostyrene, acrylic esters, chloroprene, hydroxyethyl methacrylate (HEMA), phenylacetylene, and many others. 

These transition-metal catalysts contain electronically coupled hydridic and acidic hydrogen atoms that are transferred to a polar unsaturated species under mild conditions. The first such catalyst was Shvo s diruthenium hydride complex reported in the mid 1980s [41 14], Noyori and Ikatiya developed chiral ruthenium catalysts showing excellent enantioselectivity in the hydrogenation of ketones [45,46]. 

Hydrogenation of unsaturated acids and their methyl esters... 

Hydrogenation of various unsaturated acids and esters catalysed by 1% Pd/Si02 and 10 bar pressure and 293 K... 

Although cinchona-modified Pd showed no enantioselectivity in the hydrogenation of the methyl esters of the unsaturated acids, the hydrogenation of methyl pyruvate occurred with a modest enantiomeric excess... 

Heteropoly acids can be synergistically combined with phase-transfer catalysis in the so-called Ishii-Venturello chemistry for oxidation reactions such as oxidation of alcohols, allyl alcohols, alkenes, alkynes, P-unsaturated acids, vic-diols, phenol, and amines with hydrogen peroxide (Mizuno et al., 1994). Recent examples include the epoxidations of alkyl undecylenates (Yadav and Satoskar, 1997) and. styrene (Yadav and Pujari, 2000). 

M., Humphrey, G.R. et al. on the long term factory process for the production of a prostaglandin D2 receptor antagonist - unprecedented asymmetric hydrogenation of an indole Fxo-Cyclic Trisubstituted a,(i-Unsaturated Acid. 

IrCl(PPh3)3 or IrCl(CO)(PPh3)2 or phenylacetic acids Hydrogenation of unsaturated aldehydes to 714... 

The enantioselective hydrogenation of a,p-unsaturated acids or esters, using 5wt% Pt/Al203 or Pd/Al203 commercial catalysts doped with cinchonidine (CD), was deeply investigated to evidence the specific activity of Pd or Pt and the role of the reaction parameters and solvent polarity. Finally, the steric and electronic effects of different substituent groups were also studied. 

The enantioselective hydrogenation of oc,p-unsaturated acids (or their esters) and a-ketoesters, mainly pyruvates, (Figure 1) is a subject of high industrial relevance in the pharmaceutical and agrochemical areas, considering the very different activity of pure enantiomers (1,2). However, the former reaction has been up to today less investigated, evidencing a lower enantioselectivity (maximum ee 38% in comparison to 90% for the ethyl pymvate) (3,4). 

Chiral heterogeneous catalysts, although have lower enantioselectivity and stability than homogeneous catalysts, are often preferable because of their handling and separation properties (5). Aim of this work was to shed light on the enantioselective hydrogenation of a,p-unsaturated acids or their... 

Another important factor in the hydrogenation of a,p-unsaturated acids was the solvent by increasing the polarity of the solvent used (n-hexane < toluene < methyl acetate < THF < methanol) a progressive decrease in ee was observed. This was probably due to the fact that H2 and the a,p-unsaturated acids were more soluble in the apolar solvents and also that CD was present in the open conformation, the enantioselective conformation (8). In fact, the highest conversion and ee were obtained with n-hexane (Figure 2). 

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