Mustard oils formation

Figure 3.15 Mustard oil formation. After hydrolysis of glucosinolates, the unstable intermediates rearrange. In general, the main reaction products are isothiocyanates, but nitriles and thiocyanates are also produced.

Phenylisothiocyanate (phenyl mustard oil) [103-72-0] M 135.2, m -21 , b 95 /12mm, 117.1 /33mm, 221 /760mm, d 1.1288, n 1.64918. It is insol in H2O, but sol in Et2O and EtOH. If impure (due to formation of thiourea) then steam dist into a receiver containing 5-lOml of N H2SO4. Separate the oil, dry over CaCl2 and distil under vacuum. [Dains et al. Org Synth Coll Vol I 447 1941. ... 

GMELIN, R., VIRTANEN, A.I., A new type of en2ymatic cleavage of mustard oil glucosides. Formation of allylthiocyanate in Thlaspi arvense L. and benzylthiocyanate in Lepidium ruderale L. and Lepidium sativum L., Acta Chem. Scand., 1959, 13, 1474-1475. 

Hatschek, who concluded that viscosity can give some useful indication of compound formation. A mixture of stannic chloride (SnC ) and acetic acid has a very sharp maximum for equimolar amounts, and pronounced maxima are also found with mixtures of allyl and phenyl mustard oils with methylaniline and diethylamine, respectively. ... 

Advantages and disadvantages of using enzymes are summarized in Tab. 3.13. The stability of enzymes can be increased by immobilization. Fig. 3.7 shows as an example the formation of mustard oils through immobilized myrosinase. Mustard seeds contain myrosinase naturally. The higher yields resulting from the use of additional, immobilized enzyme make the process more economical. Immobilized lipase has... 

Fig. 3. 7 Formation of mustard oils from mustard seeds with the aid of immobilized myrosinase [30, 40]...

The primary amine formed in addition to the mustard oil combines with the add. Besides this reaction a second one takes place, viz. the amine formed acts upon some still undecomposed thiourea, resulting in the formation of a guanidine derivative ... 

Treatment of alkyl halides with alkali thiocyanates leads to replacement of the halogen with formation of thiocyanic esters (organic thiocyanates). However, it is impossible to foretell whether thiocyanic esters or the isothiocyanic esters ( mustard oils ) will be products by this method but in all cases the latter is the more stable, so that thiocyanates can be converted into isothiocyanates by heat. 

Intramolecular enantiosituselectivity is exemplified by the biosynthetic formation of the mustard oil glucoside sinigrin (60) in horseradish, " the deprotonation of N-Boc-pyrrolidine (62) with sec-butyllithium (s-BuLi)/(-)-sparteine, followed by methylation, "" and, the oxidation of enol 64. Intermolecular enantiosituselective transformations are exemplified by the hydrolysis of racemic N-dodecanoylphenylalanine p-nitrophenyl esters (( )-67) in the presence of tripeptide catalyst (Z)-L-Phe-L-His-L-Leu (68) in each of the latter two cases, only one (externally) enantiotopic carbonyl reacts preferentially. It should be pointed out parenthetically, that as a result of the enantiosituselectivity in these transformations, one has, in effect, kinetic resolution of ( )-67. The electron-impact induced elimination in acetate 71, and the oxidation of 73 exemplify intramolecular diastereosituselective transformations. The epoxidation of the mixture 76/77 is an example of an intermolecular diastereosituselective process at the same time that each substrate is subject to enantiositunonselectivity of the carbonyl sub-sites. 

Activity When G. is metabolized not only the corresponding mustard oils but also isothiocyanates are formed, the latter inhibit the accumulation of iodine and thus the formation of thyroid hormones G. may thus lead to hyperthyroidism and goiter, see also goi-trin. Growth disorders and loss of feathers are observed in fowl. For biosynthesis, see Lit.. ... 

Type III includes A9 isotherms with a singular maximum. According to metrical analysis, dependencies of this type are typical of systems where adduct formation constant, Kj oo. Mustard oil-amine is an example of this behavior. 

The Schiff base or enamine reaction has been employed to modify aldehydes and ketones by condensation with a primary amine (reaction 1) and to condense primary amines with a carbonyl compound (reaction 2). A similar reaction between primary amines and carbon disulfide yields isothiocyanates or mustard oils (reaction 3). These three possibilities for derivative formation will be discussed in this chapter. 

One example is the formation by phenol oxidases of quinoid compounds from phloridzin in Malus sp. after microbial infections. The quinones built are able to bind to proteins and may inactivate in this way exoenzymes of the invading microorganisms. A similar function may be attributed to hydrocyanic acid and mustard oils set free by degrading enzymes from cyanogenic glycosides and glucosinolates after the infection of several other plant species. 

SO that the ester which is always present even in freshly-prepared alcoholic solutions of mustard oil does not decompose quantitatively with ammonia- cal silver solution, with formation of sulphide of silver, but is partly pre- cipitated as a silver salt of the above-mentioned ester. Whilst this admixture, owing to its molecular weight 252, which differs but little from that of silver sulphide 248, cannot cause an appreciable error in the gravimetric determination, it cans s a considerable difference in the volumetric estimation, because in the formation of this ester salt only 1 atom of silver corresponds to 1 molecule of mustard oil, whereas for the conversion into silver sulphide, 2 atoms of silver are required, so that the titration results are obviously too low. 

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