Overig
Prepform synthesis lab 1b experiment 4.4 part 2
Prepform synthesis lab 1b experiment 4.4 part 2
[Meer zien]Voorbeeld 2 van de 5 pagina's
Voorbeeld 2 van de 5 pagina's
In winkelwagengesponsord bericht van onze partner
Voorbeeld van de inhoud
Synthesis lab 1b (MOL126)Preparation form experiment 4.4b
Lisa Verhoeven, s1014716
13-3-2022
Chemiluminescent reactions of
oxalic esters with hydrogen
peroxide
Experimental aim
The aim of this experiment is to determine how certain chemical factors influence the light output of
the chemiluminescent reaction of oxalic esters with hydrogen peroxide in the presence of a
fluorescer. These chemical factors are the identity of the oxalic ester and the fluorescer, the pH,
sodium salicylate or triethylamine (TEA) catalysis, and temperature.
Background
Chemiluminescence is the process whereby light is produced via a chemical reaction with the
evolution of minimal heat. It is fueled by the reaction of an oxalic ester with hydrogen peroxide,
which generates the intermediate 1,2-dioxetanedione. This intermediate can undergo a
decarboxylation reaction to produce two carbondioxide molecules which releases a large amount of
energy. The addition of a fluorescer to this reaction allows the excitation of an electron of this
fluorescent molecule into the excited state by the energy that the reaction releases. Subsequently,
decay of the excited state and return to the ground state comes with the emission of a photon that
we can detect.
The reaction rate of the oxalic ester reacting with the hydrogen peroxide can be determined by the
total light output of the reaction, as this is directly proportional to the reaction rate. It is known that
the type of flueorescer, the identity of the oxalic ester and fluorescer, the purity of the oxalic ester,
the addition of a catalyst, as well as the pH influence the rate of this reaction.
To investigate the dependence of the reaction rate on the oxalic ester type, various types of oxalic
esters have been synthesised by performing the reaction with different phenols. The oxalic esters
bis(2,4,6-trichlorophenyl)oxalate, bis(2,4-dichlorophenyl)oxalate, bis(2,4,6-tribromophenyl)oxalate,
and bis(vanillyl)oxalate have been synthesised (fig. 1). The fluorescers that will be investigated are
Anthracene, 9,10-dibromoanthracene, 9,10-diphenylanthracene, 9,10-bis(phenylethynyl)anthracene
and rubrene (fig. 1).
, Figure 1. Oxalic esters and fluorescers used.
Hydrogen peroxide reacts with oxalic esters to produce the high energy intermediate (HEI) 1,2-
dioxetanedione. As mentioned previously, 1,2-dioxetanedione can rapidly undergo a decarboxylation
reaction to yield two carbondioxide molecules (fig. 2). This decomposition of the HEI is very
exothermic because it is accompanied by the release of a lot of ring strain, and because
carbondioxide is very low in free energy. The exact mechanism of fluorescer excitation has been
debated quite extensively, and has been implicated to vary per type of HEI formed. However, for 1,2-
dioxetanedione, it is almost certain that it excites the fluorescer via the chemically initiated electron
exchange luminescence (CIEEL) mechanism.
Figure 2. Mechanism of the fluorescent reaction, with bis(2,4,6-trichlorophenyl)oxalate as an example.
Experimental
1. Prepare a solution of oxalic ester in dimethylphtalate (DMP) (1.25mL, 0.05M) and a solution
of fluorescer in DMP (0.5mL, 1gL-1)
2. Mix the oxalic ester solution with the fluorescer solution
3. Add to this solution a solution of hydrogen peroxide in t-butanol (0.5mL, 10%) to start the
reaction perform this under various conditions; see scheme
4. Monitor the light output of each reaction, as well as the chemiluminescence lifetime and the
time it takes to initiate chemiluminescence
Dit zijn jouw voordelen als je samenvattingen koopt bij Stuvia:
Bewezen kwaliteit door reviews
Studenten hebben al meer dan 850.000 samenvattingen beoordeeld. Zo weet jij zeker dat je de beste keuze maakt!
In een paar klikken geregeld
Geen gedoe — betaal gewoon eenmalig met iDeal, creditcard of je Stuvia-tegoed en je bent klaar. Geen abonnement nodig.
Direct to-the-point
Studenten maken samenvattingen voor studenten. Dat betekent: actuele inhoud waar jij écht wat aan hebt. Geen overbodige details!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper lisaverhoeven80. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €2,99. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 69052 samenvattingen verkocht
Opgericht in 2010, al 15 jaar dé plek om samenvattingen te kopen