Isothiocyanates, preparation properties

The preparation, properties, and reactions of isothiocyanates have been the subject of valuable, comprehensive reviews, which should be consulted for details. ... 

Immobilization. The fixing property of PEIs has previously been discussed. Another appHcation of this property is enzyme immobilization (419). Enzymes can be bound by reactive compounds, eg, isothiocyanate (420) to the PEI skeleton, or immobilized on soHd supports, eg, cotton by adhesion with the aid of PEIs. In every case, fixing considerably simplifies the performance of enzyme-catalyzed reactions, thus faciHtating preparative work. This technique has been appHed to glutaraldehyde-sensitive enzymes (421), a-glucose transferase (422), and pectin lyase, pectin esterase, and endopolygalacturonase (423). 

These compounds are readily prepared by the reaction of fluorescein isothiocyanate with the polypeptide in a DMSO/water mixture and fluorescein-polyacrylate conjugate (6) is prepared by the reaction of fluoresceinamine with polyacrylic acid by using the mixed anhydride method [150]. In all cases, the absorption and emission maxima were similar at 490 and 525 nm, respectively, and reflect the photophysical properties of fluorescein itself. 

Direct Synthesis reaction of, 6 395 fluoride, 21 235, 237, 239, 249 homopolyatomic cations, 17 82 ion, stereochemistry, 2 40-41, 44-45 isocyanates, preparation, 9 158 properties, 9 157 isothiocyanates, properties, 9 177 mixed valence compounds of, 10 375-381 crystal structure of, 10 376 diffuse reflectance spectrum of, 10 380 structure of Pb," ion, 10 381 nuclear magnetic shielding, 22 224 organometallic compounds, 2 82, 88, 89 oxide, neutron diffraction studies on, 8 231-233... 

CH3), which was converted with aqueous alkali to 5 -methyl-2 -thiouri-dine.233 Similarly, 3-ethoxyacryloyl isothiocyanate (LXXI, R = H, R" = C2H5) plus LXX yielded the tribenzoate ester of LXXIII (R = H) which was converted with sodium alkoxide or ammonia to 2 -thiouridine. These D-ribo-2 -thionucleosides exhibit ultraviolet spectral properties similar to those shown by l-methyl-2-thiouracil123 and an enzymically prepared sample of 2 -thiouridine.236 Treatment of 2 -thiouridine with monochloroacetic acid afforded uridine this finding permitted assignment of the l-(/ -D-ribo-furanosyl) structure to these 2-thiouracil nucleosides.233... 

Protein A is a specific protein isolated from the cell wall of Staphylococcus aureus whose characteristic property is the ability to react and to form precipitates with a variety of IgG molecules from several species. This interaction is reminia nt of the formation of antigen-antibody complexes, and has been used to study different aspects of immune response as well as cell surface structure and function For easier detection, Protein A is covalently coupled to fluorescein isothiocyanate (FITC). The commercial preparations of FITC-Protein A contain an avarage of 6 FITC substituent groups per molecule of protein. Such a degree of labeling does not affect the biological properties of the native protein. 

Starting from scaffold 178 linked to Rink amide resin, two libraries of psolaren analogs (181 and 182) were prepared from a common o-dianilino intermediate 180. The benzoimidazole ring of psolaren analogs 181 was formed upon treatment of 180 with aryl isothiocyanates in the presence of Die, whereas for analogs 182 cyclization was carried out with l,T-thiocarbonyldiimidazole (TCD) followed by S-alkylation with alkyl hahdes in the presence of Af,Af-diisopropylethylamine. The unique spectral properties of these coumarin derivatives indicated that they may be useful in photochemotherapy. 

Benzylamine (0.2 ml) dissolved in 3 ml of ethanol is mixed with 1.5 — 2 mmole of isothiocyanate and the mixture is gently boiled for 3 — 5 min. The product separated after cooling (or after addition of water) is isolated by filtration, and is crystallized from aqueous alcohol. If an oily product separates, the mixture should be undercooled and scratched intensely with a glass rode, or decanted, and a few drops of ethanol added to the remaining oil. If benzylamine is not available, or if the prepared derivative does not possess suitable properties, 1-naphthylamine or piperidine should be used. 

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