maxpayne
Hazard to Self
Posts: 78
Registered: 15-11-2011
Member Is Offline
Mood: No Mood
|
|
Diazotization safety
When an amine reacts with nitrous acid and HX in aq. solution, diazonium compound is formed. If temperature is higher than 5°C, this compund is
unstable and N2 gas is formed, and halogen replaces the amine group.
Why this process do not cause dramatic energy release as is when diazonium compound is isolated as crystals and detonated?
|
|
|
Nicodem
Super Moderator
Posts: 4230
Registered: 28-12-2004
Member Is Offline
Mood: No Mood
|
|
Quote: Originally posted by maxpayne  | | If temperature is higher than 5°C, this compund is unstable and N2 gas is formed, and halogen replaces the amine group.
|
Where did you get that from? There is no such rule of the 5 °C. Diazonium compounds can either decompose immediately upon formation, deprotonate to
diazo compounds, or form isolable and stable salts at room temperature or higher. It all depends on their structure.
| Quote: | | Why this process do not cause dramatic energy release as is when diazonium compound is isolated as crystals and detonated? |
Obviously a reaction, even if highly exothermic, can never be as dramatic as a detonation. Reaction kinetics and shock waves make a world of a
difference.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
|
|
|
DraconicAcid
International Hazard
Posts: 4280
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
| Quote: | | Quote: Originally posted by Nicodem | | Quote: Originally posted by maxpayne | | Why this process do not cause dramatic energy release as is when diazonium compound is isolated as crystals and detonated? |
Obviously a reaction, even if highly exothermic, can never be as dramatic as a detonation. Reaction kinetics and shock waves make a world of a
difference. |
An exothermic reaction in solution has the solvent to absorb most of the heat generated. The heat given off by the decomposition of a substance in a
crystal is transferred only to the parts of the crystal surrounding the bit that gave it off, which heats those parts up dramatically and causing them
to decompose as well. Then they give off heat, destroying their neighbors, and so on, and so on. |
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
maxpayne
Hazard to Self
Posts: 78
Registered: 15-11-2011
Member Is Offline
Mood: No Mood
|
|
| Quote: Originally posted by Nicodem | | Quote: Originally posted by maxpayne | | If temperature is higher than 5°C, this compund is unstable and N2 gas is formed, and halogen replaces the amine group.
|
Where did you get that from? There is no such rule of the 5 °C. Diazonium compounds can either decompose immediately upon formation, deprotonate to
diazo compounds, or form isolable and stable salts at room temperature or higher. It all depends on their structure.
| Quote: | | Why this process do not cause dramatic energy release as is when diazonium compound is isolated as crystals and detonated? |
Obviously a reaction, even if highly exothermic, can never be as dramatic as a detonation. Reaction kinetics and shock waves make a world of a
difference. |
I get it from Wikipedia : Diazonium_compound
"In aqueous solution diazonium salts are unstable at temperatures above +5 °C; the -N+≡N group tends to be lost as N2 (nitrogen
gas)."
So, this is not a general rule?
|
|
|
maxpayne
Hazard to Self
Posts: 78
Registered: 15-11-2011
Member Is Offline
Mood: No Mood
|
|
| Quote: | | Quote: Originally posted by DraconicAcid | | Quote: Originally posted by Nicodem | | Quote: Originally posted by maxpayne | | Why this process do not cause dramatic energy release as is when diazonium compound is isolated as crystals and detonated? |
Obviously a reaction, even if highly exothermic, can never be as dramatic as a detonation. Reaction kinetics and shock waves make a world of a
difference. |
An exothermic reaction in solution has the solvent to absorb most of the heat generated. The heat given off by the decomposition of a substance in a
crystal is transferred only to the parts of the crystal surrounding the bit that gave it off, which heats those parts up dramatically and causing them
to decompose as well. Then they give off heat, destroying their neighbors, and so on, and so on. |
I did not expect such beautiful explanation! Thanks!! |
|
|
|
DraconicAcid
International Hazard
Posts: 4280
Registered: 1-2-2013
Location: The tiniest college campus ever....
Member Is Offline
Mood: Semi-victorious.
|
|
| Quote: Originally posted by maxpayne |
I get it from Wikipedia : Diazonium_compound
"In aqueous solution diazonium salts are unstable at temperatures above +5 °C; the -N+≡N group tends to be lost as N2 (nitrogen
gas)."
So, this is not a general rule? |
*Very* general. Some are more stable than others, and they can decompose by different pathways.
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
