1.2.6- Thiadiazines spectra

The IR spectrum of 8 has been reported (63FRP2166), and the UV spectra of some 1,2,3-benzothiadiazines have been reviewed (70CRV593). Mass spectrometry has been used to establish the structure of 1,2,3-thiadiazines 24, and the fragmentation pattern enabled the alternative isothiazol-N-imines to be ruled out (750MS579). 

In the 15N NMR spectrum of the systems (29 X = O or S) the chemical shifts of the nitrogens at position 1 correspond reasonably well with the nitrogen signals in benzo[c]-l,2,5-oxadiazole ( —35.6 ppm) and benzo[c]-l,2,5-thiadiazole (49.1 ppm). The nitrogens at position 3 appear to be deshielded by the effect of nitrogen at position 4. In the thiadiazine rings the pyridine-like nitrogens at... 

Carbothialdine" i.e. 4,6-dimethylperhydro-l,3,5-thiadiazine-2-thione, the reaction product of acetaldehyde with ammonia and carbon disulfide, has been known a long time (260, 288). Various structures have been proposed for it (83, 143, 164, 234). It was also known that this product may be obtained from acetaldehyde and ammonium dithiocarbamate and that two moles of aldehyde are necessary for the reaction. The reaction products of other aldehydes and amines had also been investigated with a view to elucidating their structure (31, 108). However, Ainley and co-workers (1) in 1944 were the first to determine the structure with certainty. The instability of "carbothialdines made it difficult to determine their structure by chemical means. It was by comparison of its U.V. spectrum with that of similar compounds such as (CCII) that the formula of perhydro-l,3,5-thiadiazine-2-thione (CCIV) was established, which accounts quite well for its properties. It is accepted... 

As expected from its C NMR spectrum (see Section 6.14.3.1.2), which is indicative of a high electron density at C-6, bromination of 1,5-diphenyl-U, 2,4-thiadiazine 1-oxide (88) in chloroform solution furnishes the 6-bromo-derivative (89) in good yield (60%) <90JCS(PI)447>. The 1,5-diphenyl-U , 2,4-thiadiazin-3(4//)-one (87) behaves in a similar manner. In contrast, the 12, 2,4-thiadiazine... 

Other than a detailed analysis of the N NMR spectrum of 3-phenylazo-li/-4,l,2-benzo-thiadiazine (21) (Section 6.17.7.2.2.2) no other N NMR spectral data for 1,3,4-oxadiazines or their thio-analogues appear to have been published. Nitrogen-15 chemical shift data (with respect to CH3NO2) for azo-compound (21) are appended to (21) <90MRC1027>. 

The strong IR absorptions at 3430 v(OH), 3230 v(NH), and 1520 cm" v(C=N) and the weak v(0=0) at 1630 cm , have been suggested to indicate that in the solid state 2,6-dimethyl-5,6-dihydro-2//-l,3,5-thiadiazin-4(37/)-one exists mainly as the lactim form (41). However, from the symmetry of the PMR spectrum in d -DMSO, which shows a solitary doublet methyl resonance at... 

Thiadiazines 78 (R = Me, Bn) showed an unusual NH/CH tautomerism in dichloromethane or chloroform solution. The tautomerism is indicated by the additional appearance of two doublets for the corresponding two geminal protons attached to C-4 in the H NMR spectrum (tautomer 79). The C NMR spectrum displays the correlated CH2 signal around 40 ppm however, at lower temperatures, the NH form 78 is preferred in solution. In the solid state, too, only the NH tautomer 78 is present. X-Ray analysis of 78 (R = CsHn, R = Me) showed that this tautomer is stabilized by intermolecular hydrogen bonding <2003JOC3817>. 

Thiadiazines 41 do not have preferred conformations. NMR data reveal that they are in ring and N-conforma-tional equilibrium at room temperature. The NMR spectrum of compound 41c at —90°C in THF-r/g revealed no preferred conformation as the CH3 and SCH2N resonances were averaged (THF = tetrahydrofuran). 

Chem. Descrip. Tetrahydro-3,5-dimethyl-2H-1,3,5-thiadiazine-2-thione CAS 533-74-4 EINECS/ELINCS 208-576-7 Uses Bactericide for use in coatings, adhesives, emulsions, day slurries, leather food-contact paper/paperboard food-contact slimidde Features Broad-spectrum protects against bacterial attack during shipping and storage... 

Decarboxylation of P-keto-esters is facile in aqueous DMSO, but in less reactive cases decarboxylation is accelerated by sodium chloride. Condensation reactions of dibenzocycloheptadienone (334) with aromatic aldehydes have been reported. Syntheses of the heterocyclic carboxylic acids (335) have been described. No effect of the heterocycle s ring current on the chemical shifts of the methylene protons could be detected in the n.m.r. spectrum of the nonamethylene-thiadiazine dioxide (336), which was prepared from cyclododecane-l,3-dione. ... 

The starting material for the synthesis of Taurolin is 2-aminoethanolsulphonic acid (Taurin) which by the addition of 2 m NH3 and 3 M CH2O in a condensation reaction is converted to Taurolin. The spectrum of effectiveness corresponds to that of formaldehyde, however, according to findings of Myers et al (1980) and All wood Myers (1981) the activity of Taurolin is considerably greater than that of formaldehyde apparently the 4-hydroxymethyl-1,1-dioxoperhydro-1,2,4-thiadiazine which is released in the first step on hydrolysis of Taurolin plays an important role in the mechanism of Taurolin s antimicrobial activity. 

Dimethyl-tetrahydro-l,3,5-2H-thiadiazine-2-thione has a broad spectrum of high activity which covers bacteria, fungi and yeast, indicating that the substance is a specialised formaldehyde-releasing compound. 

The spectrum of activity is attractive for application in a number of industrial systems, e.g. as a broad spectrum microbidde which prevents fungal blooms in metal working fluid systems. However, there are limitations, including the finding that 3,5-Dimethyl-tetrahydro-l,3,5-2H-thiadiazine-2-thione is very unstable at increased temperatures. Under alkaline conditions it is found that more decomposition products are formed than under pH neutral conditions (e.g. wet-end system). 

METASOL D3T is a preservative effective against a broad spectrum of bacteria and fungi in coatings, clay slurries, adhesives, glues, latex, emulsions, casein, and titanium dioxide slurries. Chemically, the product is tetrahydro-3,5-dimethyl-2H-l,3,5-thiadiazine-2-thione. 

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