Benzaldehyde cyanohydrin

A few cyanohydrins and ethers of cyanohydrins occur naturally One species of millipede stores benzaldehyde cyanohydrin along with an enzyme that catalyzes its cleavage to benzaldehyde and hydrogen cyanide m separate compartments above its legs When attacked the insect ejects a mixture of the cyanohydrin and the enzyme repelling the invader by spraying it with hydrogen cyanide... 

Arnygdabn a substance present in peach plum and almond pits is a denvative of the R enantiomer of benzaldehyde cyanohydrin Give the structure of (/ ) benzaldehyde cyanohydrin... 

Benzaldehyde Cyanohydrin. This cyanohydrin, also known as mandelonitrile [532-28-5] is a yellow, oily Hquid, insoluble in water, but soluble in alcohol and diethyl ether. Mandelonitrile is a component of the glycoside amygdalin [29883-15-6] a precursor of laetdle [1332-94-7] found in the leaves and seeds on most Prunus species (plum, peach, apricot, etc). In 1832, mandelonitrile was the first cyanohydrin to be synthesized. 

In 1896, Emil Fisher found that 2,5-diphenyloxazole hydrochloride was precipitated by passing gaseous hydrogen chloride into an absolute ether solution of benzaldehyde and benzaldehyde cyanohydrin. The oxazole hydrochloride can be converted to the free base by addition of water or by boiling with alcohol. Many different aromatic aldehydes and cyanohydrin combinations have been converted to 2,5-diaryloxazoles 4 by this procedure in 80% yield. ... 

One of the earliest preparations of this ring system starts with displacement of the hydroxyl of benzaldehyde cyanohydrin (125) by urea. Treatment of the product (126) with hydrochloric acid leads to addition of the remaining urea nitrogen to the nitrile. There is thus obtained, after hydrolysis of the imine (127), the hydantoin (128). Alkylation by means of ethyl iodide affords ethotoin (129)... 

Benzaldehyde cyanohydrin is reacted with urea to displace the hydroxyl group of the cyanohydrin. That intermediate is treated with HCI to convert the urea nitrogen to a nitrile. The resultant imine is hydrolyzed to the phenylhydantoin. Alkylation with ethyl iodide gives ethotoin, as described by A. Pinner in Chem. Ber. 21, 2325 (1888). 

Warfarin sodium Benzal acetophenone Alkofanone Benzaldehyde Butalamlne HCI Chloramphenicol Fenipentol Isocarboxazid Oxacillin sodium Penicillin G benzathine Phenylpropanolamine HCI Tripelennamine Benzaldehyde cyanohydrin Ethotoin... 

Liu, J., Pscheidt, B., Avi, M. et al. (2008) Laboratory evolved biocatalysts for stereoselective syntheses of substituted benzaldehyde cyanohydrins. Chembiochem AEuropean Journal of Chemical Biology, 4 9 (1), 58-61. 

The main cyanogenic glycoside in laurel is prunasin, the P-o-glucoside of benzaldehyde cyanohydrin. The enzymic hydrolysis of prunasin may be visualized as an acid-catalysed process, first of all hydrolysing the acetal linkage to produce glucose and the cyanohydrin. Further hydrolysis results in reversal of cyanohydrin formation, giving HCN and benzaldehyde. 

Formation of benzaldehyde cyanohydrin creates a chiral C and produces a racemic mixture, which cannot be separated by fractional distillation. 

B) Quantitative Determination. In spirits from nut-fruits, the hydrocyanic acid is partly free and partly combined with benzaldehyde (cyanohydrin). That in the latter form is determined indirectly as the difference between the total and free amounts. 

The combined hydrocyanic acid — total less free acid, and 1 gram of combined hydrocyanic acid = 4-92 grams of benzaldehyde cyanohydrin. 

Benzaldehyde cyanohydrin formation shown below may involve rate-determining attack by either H+ or CN-. A p value of +2.3 was found for the rate of formation of cyanohydrins from a series of substituted benzaldehydes. Which step is rate determining Based on the fact that cyanohydrin formation does not occur in basic solution, write a complete mechanism for the process. 

In the first step of one synthesis of (D,L)-mandelic acid, benzaldehyde (I) is converted to mandelonitrile (II, or benzaldehyde cyanohydrin) ... 

PROBLEM The formation of benzaldehyde cyanohydrin shown in the example above is reversible. Draw a mechanism for the reverse reaction. 

The millipede Apheloria corrugata secretes a mixture of HCN and benzaldehyde to prevent other animals from eating it. The millipede stores mandelonitrile (benzaldehyde cyanohydrin) in a reservoir. When attacked, it discharges mandelonitrile through a reaction chamber containing enzymes that catalyze the conversion of the cyanohydrin to benzaldehyde and HCN. 

The benzaldehyde cyanohydrin required for this preparation is very conveniently made according to Ger pat 85,230 as follows Benzaldehyde is thoroughly shaken, best in a shaking machine for one-half hour, with an excess of concentrated sodium bisulfite solution The crystalline bisulfite addition product,... 

Inagaki M, Hiratake J, Nishioka T, Oda J (1989) Kinetic resolution of racemic benzaldehyde cyanohydrin via stereoselective acetylation catalyzed by lipase in organic solvent. Bull Inst Chem Res, Kyoto Univ 67 132-135... 

SYNS AMYGDALONITRILE BENZALDEHYDE CYANOHYDRIN BENZALDEHYDKYANHYDRIN (CZECH) HYDROXYPHENYLACETONITRILE NITRIL KYSELINY MANDLOVE (CZECH) PHENYL-GLYCOLONITRILE... 

A synthesis of nitriles from the cyanohydrins of aromatic aldehydes via the reduction of the corresponding a-halo cyanides has been proposed. As an example, benzaldehyde cyanohydrin is converted by the action of thionyl chloride to phenylchloroacetonitrile (80%). This substance is reduced with zinc in acetic acid to phenylacetonitrile (70%). ... 

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