Oxazine is a heterocyclic compound containing one oxygen and one nitrogen atom in a double unsaturated six-membered ring. The presence of isomers depends on the relative position of the heteroatom and the relative position of the double bond. By extension, these derivatives are also called oxazines. Examples include ifosfamide and morpholine (tetrahydro-1,4-oxazine). Commercially available dihydro-1,3-oxazine is a reagent in the Meyers synthesis of aldehydes. Fluorescent dyes such as Nile Red and Nile Blue are based on aromatic benzoxazines. Cinnabar and cinnabaric acid are two naturally occurring dioxazines derived from the biodegradation of tryptophan. Nile red is an oxazine derivative fluorescent dye.
Figure 1. The 8 existing isomers of oxazine.
Dioxazine is a pentacyclic compound consisting of two oxazine subunits. A commercially important example is Pigment Violet 23.
Figure 2. Synthetic route to dioxazine dyes.
The benzoxazine formed by the reaction of phenol, formaldehyde, and primary amine polymerizes to form a polybenzoxazine network when heated to about 200 ° C (~ 400 ° F). The obtained high molecular weight thermosetting polymer-based composites can be used in applications requiring higher mechanical properties, flame resistance and fire resistance than epoxy resins and phenolic resins.
Cresyl violet is an organic compound with the chemical formula C19H18ClN3O. It is a basic dye used as a common staining agent in histology and as a histological staining agent in biology and medicine.
Figure 3. Chemical structure of Cresyl violet.
Cresyl violet is an effective and reliable stain for light microscopy. Initially, tissue sections are "defatted" by fractionation with ethanol. Then, the ethanol concentration is reduced to rehydrate. Finally, return to the water. Ethanol solution plays a role in distinguishing stains, causing myelin and other components to lose color, while the core retains color. It can also be used to find H. pylori. Intestinal mucin also absorbs this stain, although not as strong as Campylobacter-like bacteria. Cresyl violet is used to stain Heinz bodies in red blood cells or to stain neurons in the brain and spinal cord. It is used to prove Nissl substances in neurons and nuclei. In this effect, it is also commonly used as a counterstain to Luxol's firm blue, which stains myelin.
Figure 4. Cresyl violet stained partial brain section of a Macaque.