Acetamido groups

Sulphanilamide, the simplest member of a large series of bacteriostatic drugs, can readily be prepared by the following reactions. Acetanilide, when treated v ith an excess of chlorosulphonic acid, gives p-acetaniidobenzencsulphonyl chloride (Reaction A), w hich readily reacts with ammonia to give p-acetamido-benzenesulphonamide (Reaction H). The acetamido-group in the latter... 

H transfer from the methyl to the exocyclic nitrogen of the acetamido group. 

Protecting the amino group of an arylamine in this way moderates its reactivity and per mits nitration of the ring to be achieved The acetamido group is activating toward elec trophilic aromatic substitution and is ortho para directing... 

Sheinker and his collaborators have studied the effect of replacing the hydrogen atoms of the acetamido group with halogen atoms on the tautomeric equilibrium of compounds of this type by using infrared and ultraviolet spectroscopy. Table VII summarizes... 

Thus, because of the acetamido groups, there are more intra- and inter-chain hydrogen bonds in 3 and 4 than in 1 and 2. Because of the polarity problem, the chitin I— II transition is also irreversible, as in the case of cellulose. 

The solubility of chitin is remarkably poorer than that of cellulose, because of the high crystallinity of chitin, supported by hydrogen bonds mainly through the acetamido group. Dimethylacetamide containing 5-9% liCl (DMAc/IiCl), and N-methyl-2-pyrrohdinone/LiCl are systems where chitin can be dissolved up to 5%. The main chain of chitin is rigid at room temperature, so that mesomorphic properties may be expected at a sufficiently high concentration [67,68]. 

One of the simplest ways to prepare a chitin gel is to treat chitosan acetate salt solution with carbodiimide to restore acetamido groups. Thermally not reversible gels are obtained by AT-acylation of chitosans N-acetyl-, N-propionyl- and N-butyryl-chitosan gels are prepared using 10% aqueous acefic, propionic and bufyric acid as solvents for treatment with appropriate acyl anhydride. Both N- and 0-acylation are found, but the gelation also occurs by selective AT-acylation in the presence of organic solvents. 

Combined treatment of atrazine with ozone and H2O2 resulted in retention of the triazine ring, and oxidative dealkylation with or without replacement of the 2-chloro group by hydroxyl (Nelieu et al. 2000). Reaction with ozone and hydroxyl radicals formed the analogous products with the additional formation of the acetamido group from one of the N-alkylated groups (Acero et al. 2000). 

P212121 Z = 4 D, = 1.362 R = 0.162 for 2112 intensities. The structure is very similar to that found308 for air-dried vitamin B12 crystals. Two water molecules move into phosphate oxygen-atom positions when the phosphate in the precursor is removed, and one acetamido group in contact with these water molecules in the vitamin is rotated out of the way in the phosphate. The disposition of the a-D-glycosyl bond between the D-ribosyl group and the 5,6-dimethylbenzimidazole is anti (—45°), and the conformation of the D-ribosyl group is 2T3 (P = 352.1 rm = 47.1). The orientation about the exocyclic, C-4 -C-5 bond is g+ (53°). 

Fig. 4—A comparison of the H-D antigenic component and the receptor for influenza virus hemagglutinin, which are a-NeuGc-(2 — 3)-/ -Gal and a-NeuAc-(2 — 3)-/ -Gal, respectively, on the backbones / -D-Gal-( 1 — 4)-jS-d-G1cNAc-( 1 -> 3)-jS-D-Gal-(l - 4)-d-G1cNAc (sialyl i), yS-D-Gal-(l — 4)-yJ-D-GlcNAc-(l - 6)-D-Gal (sialyl I). The CH3 of the acetamido group of Ar-acetylneuraminic acid, which is a CH2OH group in iV-glycolyl-neuraminic acid, is shown.

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