Science Buddies: "Ask an Expert"

https://www.sciencebuddies.org/science- ... background
Hi

Im working on this for regional science fair project
I have some HUGE questions about this

1. Why ONLY does science buddies mention 5-aminophthalic acid, not 3-aminophthalic acid?
Because only here (https://www.sciencebuddies.org/science- ... background) mention 5-aminophthalic acid, whereas all of the other sites are talking about 3-aminophthalic acid and I searched that 5aminophtalic acid and 3 aminophtalic are different.

2. Also, in the reaction scheme (Figure 1) in that link, what is used for oxidizer? is it a solution containing hydrogen peroxide (H2O2) and hydroxide?

3. What is the difference of sodium peroxide and a solution containing hydrogen peroxide (H2O2) and hydroxide as an oxidizer for luminol? In which condition, which oxidizer does forensic scientist use for luminol reation?

4. What temeperature of luminol does forensic science use to detect blood?

Thank you

Hi Hahmmyeongjo,

The compound structure labeled “5-aminophthalic acid” in figure 1 of the project procedure is the same as 3-aminophthalic acid. You can confirm this by comparing the structure in figure 1 with the one shown here:

http://www.chemspider.com/Chemical-Structure.71803.html

My suggestion is that you use the name 3-aminophthalic acid in your project report and display. This is the preferable name for this compound.

Hydrogen peroxide (H2O2) is the oxidizing agent. Oxygen replaces two of the nitrogen atoms as shown in the second reaction step in figure 1. The hydroxide reacts with the luminol to form the dianion shown in the first reaction step. Both hydroxide and peroxide must be present to make the luminol reaction work.

I think that the luminol reaction works at room temperature.

I hope this helps. Please ask again if you have more questions.

A. Norman