Sulfur and nitrogen atoms

Problem 24.20 Draw an orbital picture of thiazole. Assume that both the nitrogen and sulfur atoms are sp2-hybridized, and show the orbitals that the lone pairs occupy. 

Fig. 12 Fragment of crystal structure of Bu4N+[NCS, TCP] salt showing close contact of nitrogen and sulfur atoms with the acceptor moiety (Han et al. private communication)...

The FAD-containing monooxygenase catalyzes oxidation of nucleophilic nitrogen and sulfur atoms in a diverse array of organic compounds. The enzyme... 

Very few publications are available on the reactivity of substituents attached to the ring nitrogen and sulfur atoms of thiadiazole. The N-benzyl group in (107) can be removed with AICI3 to give the cyanamide (108) and the antiviral compound (109) on further treatment with base <92MI 410-01 >. 

Biochemical displacement reactions include all of the hydrolytic reactions by which biopolymers are broken down to monomers as well as most of the reactions by which the monomers are linked together to form polymers. Addition reactions are used to introduce oxygen, nitrogen, and sulfur atoms into biochemical compounds and elimination reactions often... 

The constant x depends on the class of compound (e.g., aromatic vs. aliphatic), ry is the number of specific atoms (e.g., C or Cl), y is a constant specific to that atom and how it is bonded, rij is the number of certain bonds or structural types (e.g., double or triple bonds or branching), and z is a constant specific to these bonds or structural elements. Lyman et al. (1982) gives a full account of this approach and recommend it as the preferred method when no partition coefficient data are available. However, this method is dated and does not include functional groups containing oxygen, nitrogen, and sulfur atoms. 

Heterocyclic compounds, especially those which contain nitrogen and sulfur atoms, possess potent sensory qualities at low concentrations. They are formed in foods by thermal decomposition and interaction of food components. The identification of many long-chain alkyl-substituted heterocyclic compounds suggests that their formation mechanisms directly involve lipids or lipid decomposition products. 

Thiazoles are somewhat unique among the Maillard products because they contain nitrogen and sulfur atom in same ring. The presence of thiazole... 

X-ray determinations of the dithiocarbamates 264a and 266b reveal a TBP structure, with the nitrogen and sulfur atoms in the axial positions664,665. The 2-ethylpyridyl and 3-thienyl-2-(3-oxazolinyl) hgand chelate the tin, while the dithiocarbamate is monodentate. The N — Sn interaction in the latter is weaker and the extent of distortion from a TBP structure is larger (Table 47). 

PROTONS ON OXYGEN, NITROGEN, AND SULFUR ATOMS. EXCHANGEABLE PROTONS... 

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