Huang-Minlon

This reaction is discussed extensively in an eadier review (41). In the Huang-Minlon modification of the Wolff-Kishner reaction, a high boiling solvent such as diethylene glycol is used to achieve the required high temperatures (180—210°C) without the use of pressure equipment (42). The base is generally alkaU hydroxide or an alkoxide (43). 

Huang-Minlon, Sci. Sinica (Peking) 10, 711 (1961) Chem. Abstr. 56, 11047h (1962). 

WOLFF - KISHNER HUANG MINLON Reduction Reduction ol ketones to hydrocarbons by heating with NHaNH2 and aqueous KOH (Wotff-Kishnei) or KOH in ethytene glycol (Huang-Minlon)... 

According to Huang-Minlon, Makoshi s base (I) is coptisine, while Chou s base, B, is dl-tetrahydropalmatine and D and E are I- and dl-tetrahydrocoptisine respectively. 

The Huang-Minlon modification of the Wolff-Kishner reduction has been used innumerable times for the reduction of thiophenealde-hydes and thienyl Besides the few... 

The classical procedure for the Wolff-Kishner reduction—i.e. the decomposition of the hydrazone in an autoclave at 200 °C—has been replaced almost completely by the modified procedure after Huang-Minlon The isolation of the intermediate is not necessary with this variant instead the aldehyde or ketone is heated with excess hydrazine hydrate in diethyleneglycol as solvent and in the presence of alkali hydroxide for several hours under reflux. A further improvement of the reaction conditions is the use of potassium tcrt-butoxide as base and dimethyl sulfoxide (DMSO) as solvent the reaction can then proceed already at room temperature. ... 

The method of choice for the reduction of keto groups to methylenes remains the WolfT-Kishner reaction (2) or its modification discovered by Huang-Minlon (5). Originally, the hydrazone formation was carried out in a separate step, followed by... 

The deoxygenation of aldehydes and ketones to the corresponding hydrocarbons via the hydrazones is known as the Wolff-Kishner reduction.28 Various modifications of the original protocols have been suggested. One of the most useful is the Huang-Minlon modification, which substituted hydrazine hydrate as a safer and less expensive replacement of anhydrous hydrazine. In addition, diethylene glycol together with sodium hydroxide was used to increase the reaction... 

HTS transmission cables, 23 852-854 HTU values, 15 696 Huang-Minlon reaction, 13 569-570 Huckel molecular orbital theory (HMO), 16 736 Hue, 7 305... 

Huang-Minlon J. Am. Chem. Soc. 1946, 68, 2487. (the Huang-Minlon modification). 

Cagniant and Cagniant have reported that succinoylation of benzo[6]thiophene under Friedel-Crafts conditions yields a separable mixture of the y-ketobutyric acids 42a and 43a in a ratio of 9 1 (combined yield 85%). Huang-Minlon reduction of 42a to the butyric acid (90%) followed by cyclization of the derived acid chloride (90%) was reported to yield 4-keto-l,2,3,4-tetrahydrodibenzothiophene (44a) (69% overall). Likewise, acylation of benzo[6]thiophene with the ester chloride of succinic acid in carbon disulfide-aluminum chloride gave a separable mixture (80%) of the 2- and 3-y-ketobutyric esters. Two alternative... 

Cyclodehydration of 2-phenylthiocyclohexanone with a variety of reagents yielding 1,2,3,4-tetrahydrodibenzothiophene (64) as an oil has been reported,and represents the simplest way of obtaining this material (88%). Alternatively, reduction of 4-keto-1,2,3,4-tetrahydrodibenzothiophene under Huang-Minlon conditions affords 64 in high yield.Trace amounts of 64 were detected in the reduction of dibenzothiophene with calcium hexamine and during electrolysis in ethylenediamine-lithium chloride solution (Section III, C,4). Peracetic acid oxidizes 64 to its sulfone (65%), which... 

Octahydrodibenzothiophene (73) has been prepared by the following sequence. Friedel-Crafts acylation of 4,5,6,7-tetra-hydrobenzo[6]thiophene with succinic anhydride (87%) or with the ester chloride of succinic acid followed by hydrolysis (80%), yields the keto acid (74). Huang-Minlon reduction of 74 followed by cyclization of the derived acid chloride with stannic chloride yields l-keto-1,2,3,4,6,7,-8,9-octahydrodibenzothiophene (53) (Section V,A). Reduction of 53 gives 73 as a solid (overall yield 32%). 

The usual range of reactions has been recorded for the aldehydes of dibenzothiophene. Oxidation yields the corresponding acid, - reduction with LAH the corresponding alcohol, reduction under Huang-Minlon conditions the corresponding methyl compound, and two examples of the Cannizarro reaction have been described. ... 

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