Environmental Engineering Reference
In-Depth Information
hexahydro-1,2,3-triazole-1,5-a-pyrazine using the intramolecular cycloaddition of
azido group and alkenyl group. The cyclization reaction formed the C
N bond and
released nitrogen gas at the same time. The product pyrazine can be used to syn-
thesize piperazine and its derivatives. After treatments by alkylating and acylating
agents, the
-
final objective/target products are obtained.
Benzyl azide decomposed into various reactive intermediates, of which singlet
phenyl azene is the key one. Under illumination or being heated, azide agents and
ring compounds have ring expansion or contraction reactions. The ring expansion
or contraction reaction produces nitrogen-containing ring compounds or nitriles.
Under illumination, phenyl azide [
15
] produces 2-diethylamino-3-hydro-azepine in
diethylamide through the ring expansion, derivatives of 2-phenylamine in aniline/
trimethylamine, and derivatives of 2-amine in liquid ammonia. After ring expan-
sion, mesitylphosphatriafulven with three-membered ring reacts 1H-2-iminopho-
sphetes with four-membered ring [
16
]. Under illumination, the six-membered ring
of azido pyrazine becomes
ve-membered.
Under illumination or being heated, organic azides decompose into singlet and
triplet azenes. Singlet azenes can have insertion reaction with saturated hydrocar-
bons. The triplet azenes take the hydrogen atoms of alkane and produce free radicals.
Both react with C=C groups. Above reactions can immobilize the functional mole-
cules on the surface of substrates and get wide applied functional materials. The
available azido compounds for above reactions include alkyl/aryl, acyl, phosphoryl,
sulfonyl and silicyl azides, and ethyl azidoformate. The available base materials have
glass, silicon wafers, metals, nanoparticles, macromolecule spheres, and inert
polymaterials (membranes,
fibers, and nonwovens). Under illumination of ultraviolet
or being heated, polymers, natural polymers, enzymes, biological cells, luminescence
groups, and labeled molecules are immobilized, adhered, grafted, and coupled onto
the substrates. Cross-linking,
cation, introducing long chain
branching, and functionalization of polymers are achievable in melting processes.
Yan and Ren [
17
] used spin-coating method and C
rheology modi
H insertion reaction of
-
multiple
fluoro-substitute phenyl azide to get the covalent attachment of ultrathin
polypropylene membranes on silicon wafers. It supplied the possibility to conduct
biochemical reactions on silicon wafer surface and the surface modi
fl
cation of
biomedical measuring microdevices, and to improve biocompatibility, increase
adhesion, enhance robustness of silicon wafers. Zhu et al. [
18
] utilized azene
insertion reaction to bind chitosan molecules on the surface of polyactide (PLA)
membrane, and replicated them using heparin to prepare a new biomaterials, which
impedes the conglutination of platelets and strengthen the adhesion of cells. Hicke
et al. [
19
] activated the hyper
ltration membrane of polyacrylonitrile and its
copolymers using acyl azides and immobilized amyloglucosidase (AG) on the
super
ltration membrane. This membrane makes the hydrolysis of starch or malt
sugar and separation of products simultaneously. Weng et al. [
20
] obtained self-
assembled single molecular layers on titania membrane by introducing 3-amino
propyl phosphoric acid, then immobilized azido gelatin on titania membrane.
The titania membrane with azido gelatin has very good biocompatibility,
and potential application in biomedical area. Mehdinia et al.
