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The activation energy for thermal E-Z isomerization is 150–190 kJ mol −1 for stilbene, meaning that temperatures above 200°C are required to isomerize stilbene at a reasonable rate, but most derivatives have lower energy barriers (e.g. 65 kJ mol −1 for 4-aminostilbene). The activation energy of the electrocyclization is 73 kJ mol −1 ...
E)-Stilbene itself is of little value, but it is a precursor to other derivatives used as dyes, optical brighteners, phosphors, and scintillators. [25] Stilbene is one of the gain mediums used in dye lasers. [26] 4,4 ′-diamino-2,2 ′-stilbenedisulfonic acid is a popular optical brightener used in some laundry detergents.
For stilbene and other chemicals containing a double-bond linker between the two aromatic rings, the excited structure can undergo reversible cis-trans isomerization. Although only cis structures can undergo the cyclization step themselves, trans structures can isomerize in situ and then cyclize. [ 2 ]
Spiropyran and Merocyanine undergo ring opening/closing mechanisms upon photo irradiation. Diarylethene and donor-acceptor Stenhouse adducts exhibit changes in color upon photoisomerization. Stilbene is a model photoswitch for studying photochemistry. A photochromic compound can change its configuration or structure upon irradiation with light.
Since the factors underlying these desiderata are at odds, tuning of the catalyst properties has proven difficult. Shown below are several of the most successful catalysts along with the yields and enantiomeric excess for their use in synthesis of (E)-stilbene oxide. [5] [2] chiral catalysts for the Johnson–Corey–Chaykovsky reaction
It is a white, water-soluble solid. Structurally, it is a derivative of trans-stilbene, containing amino and sulfonic acid functional groups on each of the two phenyl rings. The compound is a popular optical brightener for use in laundry detergents. It is produced by reduction of 4,4′-dinitro-2,2′-stilbenedisulfonic acid with iron powder. [1]
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Two major classes are trans–cis (or E–Z) conversion, and open-closed ring transition. Examples of the former include stilbene and azobenzene . This type of compounds has a double bond , and rotation or inversion around the double bond affords isomerization between the two states. [ 13 ]