lotus

previous page: 17.4 References
  
page up: Chemistry FAQ
  
next page: 18.2 How do hand warmers work?, and how can I make one?

18.1 How do light sticks work?, and how can I make one?




Description

This article is from the Chemistry FAQ, by Bruce Hamilton B.Hamilton@irl.cri.nz with numerous contributions by others.

18.1 How do light sticks work?, and how can I make one?

From: perks@umbc.edu (Mark Perks) Date: 15 Sep 1994
Subject: Re: Chemiluminescence Sticks

Chemical Demonstrations [[1] v.1 p.146- ], by Bassam Shakhashiri, offers a
thorough discussion of Cyalume lightsticks. Professor Shakhashiri is at
the University of Wisconsin, Madison, I believe.

"The Cyalume lightstick contains dilute hydrogen peroxide in a
phthalic ester solvent contained in a thin glass ampoule, which is
surrounded by a solution containing a phenyl oxalate ester and the
fluorescent dye 9,10-bis(phenylethynyl)anthracene...When the ampoule is
broken, the H2O2 and oxalate ester react.."

From: chideste@pt.Cyanamid.COM (Dale Chidester) Date: Mon, 13 Mar 1995
Subject: Re: How to make chemical light ?

The following produce rather spectacular results. Chemicals are
available through Fluka and Aldrich. The dyes are expensive.

  Dyes:-
  9,10-bis(phenylethynyl)anthracene (BPEA) (yellow) [10075-85-1] Fluka 15146
  9,10-diphenylanthracene (DPA)             (blue)  [1499-10-1]  Fluka 42785
  5,6,11,12-tetraphenylnaphthacene (rubrene) (red)  [517-51-1]   Fluka 84027
  
  Other reagents required:-
  bis(2-carbopentyloxy-3,5,6-trichlorophenyl)oxalate (CPPO) 
                                              [75203-51-9]  Aldrich 39,325-8
  bis(2-ethylhexyl)phthalate (DOP) (solvent)        [117-81-7]   Fluka 80032
  sodium salicylate (catalyst)                      [54-21-7]    Fluka 71945
  35% hydrogen peroxide                             [7722-84-1]  Fluka 95299

Saturate solvent with dye and CPPO. Sonicate to help solvation. Start with
about 50 mg dye (BPEA, DPA or rubrene) in 10 g solvent with 50 mg CPPO and
5 mg sodium salicylate. CPPO is limiting reagent.
Put small quantity (20 drops) in a small vial and add equal volume of
hydrogen peroxide. Mix vigorously. There will be two phases. Avoid skin
contact! Don't cap tightly!

The following explanation of the chemistry was provided:-
From: sbonds@jarthur.claremont.edu (007)

All of the material below is taken from a chemical demonstrations book
[[1], v.1, p.146 ].

The oxidant is hydrogen peroxide contained in a phthalate ester solvent.
The concentration is very low, less than 0.5%. The fluorescing solution
consists of a phenyl oxalate ester and a fluorescent dye. The dye used is
9,10-bis-(phenylethynyl)anthracene (for green) or 9,10-diphenylanthracene
(for blue).

Here is the reaction sequence:

  1)  (Ph)-O-CO-CO-O-(Ph) + H2O2 --> (Ph)-O-CO-CO-O-OH + (Ph)-OH
  
  2)          (Ph)-O-CO-CO-O-OH  -->  O-O
                                      | |    +  (Ph)-OH
                                     OC-CO
  
  3)                 C2O4 + Dye  --> Dye* + 2CO2
  
  4)                        Dye* --> Dye + hv

In 1) The hydrogen peroxide oxidizes the phenyl oxalate ester to a
peroxyacid ester and phenol. The unstable peroxyacid ester decomposes to
the cyclic peroxy compound and more phenol in step 2). The cyclic peroxy
compound is again unstable and gives off energy to the dye as it decomposes
to the very stable carbon dioxide. The dye then radiates this energy as
light.

An alternative chemiluminescence demonstration involves the H2O2 oxidation
of lucigenin ( bis-N-methylacridinium nitrate [2315-97-1] Aldrich B4,920-3 ),
[ [1] v.1 p.180-185 ] which has recently been modified to provide a slow
colour change across the visible spectrum [2]. One of the reagents in that
lucigenin oxidation ( Rhodamine B ) is a mutagen and suspected carcinogen.

 

Continue to:













TOP
previous page: 17.4 References
  
page up: Chemistry FAQ
  
next page: 18.2 How do hand warmers work?, and how can I make one?