Dialdehyde, hydrogenation

HighlinkSO . [Hoechst C lanese/ColtH -ants Suif.] Aliphatic dialdehyde hydrogen sulfide scavengers in natural gas and sour crude prod. 

Dissolve 7 g. of pure oleic acid in 30 ml. of dry ethyl chloride (chloroform may be used but is less satisfactory), and ozonise at about —30°. Remove the solvent under reduced pressure, dissolve the residue in 50 ml. of dry methyl alcohol and hydrogenate as for adipic dialdehyde in the presence of 0 5 g. of palladium - calcium carbonate. Warm the resulting solution for 30 minutes with a slight excess of semicarbazide acetate and pour into water. Collect the precipitated semicarbazones and dry the... 

The oxidative reaction of furan with bromine in methanol solution or an electrochemical process using sodium bromide produces 2,5-dimethoxy-2,5-dihydrofuran (19), which is a cycHc acetal of maleic dialdehyde. The double bond in (19) can be easily hydrogenated to produce the corresponding succindialdehyde derivative. Both products find appHcation in photography and as embalming materials, as well as other uses. 

The dialdehyde also underwent a Fischer cyclization with nitromethane and base to produce a mixture of four diasteriomeric nitropyranosides. The principal product was isolated by chromatography, hydrogenated usiag Raney nickel and then A/-acetylated to give... 

Dialdehydes 8 have been converted to y-lactones 9 in the presence of a rhodium phosphine complex as catalyst. The example shown below demonstrates that this reaction works also with aldehydes that contain a-hydrogen atoms. 

Hydrocarbon A, CLoIi14, has a UV absorption at Araax = 236 nm and gives hydrocarbon B, C10Hig, on catalytic hydrogenation. Ozonolysis of A followed by zinc/acetic acid treatment yields the following diketo dialdehyde ... 

The transformation of isoquinoline has been studied both under photochemical conditions with hydrogen peroxide, and in the dark with hydroxyl radicals (Beitz et al. 1998). The former resulted in fission of the pyridine ring with the formation of phthalic dialdehyde and phthalimide, whereas the major product from the latter reaction involved oxidation of the benzene ring with formation of the isoquinoline-5,8-quinone and a hydroxylated quinone. 

The product is 2,7-octadien-l-oI which can be dehydrogenated/hydrogenated internally to give 7-octenal, which can be hydroformylated to the dialdehyde, nonadialdehyde, and then hydrogenated to nonadiol. The initial product can be hydrogenated to 1-octanol the dialdehyde can be oxidized to the diacid. The catalyst used is Pd modified with the Li salt of monosulphonated triphenylphosphine. 

Electrophilic substitution of the ring hydrogen atom in 1,3,4-oxadiazoles is uncommon. In contrast, several reactions of electrophiles with C-linked substituents of 1,3,4-oxadiazole have been reported. 2,5-Diaryl-l,3,4-oxadiazoles are bromi-nated and nitrated on aryl substituents. Oxidation of 2,5-ditolyl-l,3,4-oxadiazole afforded the corresponding dialdehydes or dicarboxylic acids. 2-Methyl-5-phenyl-l,3,4-oxadiazole treated with butyllithium and then with isoamyl nitrite yielded the oxime of 5-phenyl-l,3,4-oxadiazol-2-carbaldehyde. 2-Chloromethyl-5-phenyl-l,3,4-oxadiazole under the action of sulfur and methyl iodide followed by amines affords the respective thioamides. 2-Chloromethyl-5-methyl-l,3,4-oxadia-zole and triethyl phosphite gave a product, which underwent a Wittig reation with aromatic aldehydes to form alkenes. Alkyl l,3,4-oxadiazole-2-carboxylates undergo typical reactions with ammonia, amines, and hydrazines to afford amides or hydrazides. It has been shown that 5-amino-l,3,4-oxadiazole-2-carboxylic acids and their esters decarboxylate. 

Amines are another important group of analytes. Mellbin and Smith [72] compared three different fluorescent reagents, dansyl chloride, 4-chloro-7-nitrobenzo-1,2,5-oxadiazole, and o-phthaldialdehyde, for derivatization of alkylamines. The dansyl tag was found to be the most effective. Hamachi et al. [73] described the application of an HPLC-POCL method for determination of a fluorescent derivative of the synthetic peptide ebiratide. Another comparative study was done by Kwakman et al. [74], where naphthalene-2,3-dialdehyde and anthracene-2,3-dial-dehyde were evaluated as precolumn labeling agents for primary amines. The anthracene-2,3-dialdehyde derivatives were not stable, especially in the presence of hydrogen peroxide, and the POCL detection of these derivatives was therefore... 

An application of this strategy to the synthesis of the antifungal metabolite ( )-avenaciolide 182 is shown in Scheme 4183. The photoadduct in this case, 178, was hydrogenated and hydrolyzed to give 179. Reaction of 179 with vinylmagnesium bromide and subsequent manipulation afforded aldehyde 180, which could be transformed via ozonol-ysis, epimerization of the dialdehyde and acidification of the dialdehyde acetonide to protected bis(lactol) 181. Oxidation and methylenation then afforded the desired target 182. 

The hydrogenation of HMF in the presence of metal catalysts (Raney nickel, supported platinum metals, copper chromite) leads to quantitative amounts of 2,5-bis(hydroxymethyl)furan used in the manufacture of polyurethanes, or 2,5-bis(hydroxymethyl)tetrahydrofuran that can be used in the preparation of polyesters [30]. The oxidation of HMF is used to prepare 5-formylfuran-2-carboxylic acid, and furan-2,5-dicarboxylic acid (a potential substitute of terephthalic acid). Oxidation by air on platinum catalysts leads quantitatively to the diacid. [32], The oxidation of HMF to dialdehyde was achieved at 90 °C with air as oxidizing in the presence of V205/Ti02 catalysts with a selectivity up to 95% at 90% conversion [33]. 

Over the last decade, dialdehyde-nitromethane cyclization has established itself as a generally applicable and preparatively satisfactory method for the synthesis of nitrocyclanols, nitrosugars and nitrosugar nucleosides which on hydrogenation are easily converted to the corresponding amino-derivatives... 

Curiously, however, reaction of the dialdehyde (94b) with ethyl nitroacetate under practically identical conditions — aqueous ethanol in the presence of sodium acetate and sodium carbonate at pH 8.6 — takes a different course. The compound, isolated in 34% yield, constitutes a monoaddition product to one aldehyde group, as evidenced by the formation of a triacetate after hydrogenation and acetylation. It has been assigned structure (95) 5 ) and, as such, is a C-substituted derivative of the hemialdal form (94a) of the dialdehyde. Though some NMR data were cited as proof of this formulation 58) two alternatives, (96) and (97) respectively, cannot be ruled out. Of these, structure (97) derived from... 

Addition of 4-pentenyllithium to the dione 65 gave the ds-diol 71 which was converted to the (Z)-l,2-disubstituted cyclododecene 72a. Hydroboration-oxidation and chromium trioxide oxidation provided the dialdehyde 72b whose McMurry ring closure, followed by partial catalytic hydrogenation gave the (Z)[10.10] precursor 73. Treatment of this (Z)-olefin 73 with HzS04-Ac0H in benzene was reported to effect conversion into [10.10]betweenanene (61b) of 95% purity and high yield. 

Phenanthrenequinone has been prepared by treatment of phe-nanthrene with chromic acid in acetic acid 5 potassium dichromate in sulfuric acid 3-6 hydrogen peroxide in acetic acid 6 7 and selenium dioxide above 250°.8 It can also be prepared from benzil with aluminum chloride at 120° 9 and from biphenyl-2,2 -dialdehyde with potassium cyanide.10... 

The best approach to unsubstituted 4//-pyran (5) is from glutaric dialdehyde and hydrogen chloride, which gives up to a 40% yield of 5. Intermediate 23 is not isolated.9,19,57 This procedure was successfully extended to the preparation of 4-methyl-4//-pyran.7... 

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