Author Topic: purity of pool calcium hypochlorite  (Read 3506 times)

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  • Guest
purity of pool calcium hypochlorite
« on: June 21, 2004, 08:53:00 AM »
In pursuit of an easy route to benzyl chloride, the easiest method appears to be refluxing equal masses of toluene and calcium hypochlorite at 100 C, in a boiling water bath.  Members have previously stated that they have used pool tablet chlorinators as their source of calcium hypochlorite, however I have looked through over 12 US suppliers and 3 UK suppliers and have not been able to find pure calcium hypochlorite in pool chlorinators, the two most common concentrations are 73% and more commonly 65%.  Even several science suppliers which have very large selections of chemicals offer no more than 65%.  I was curious if the reference to equal masses of hypochlorite and toluene reffered to the 65% material or the pure material, if it even exists.  Have any members here used the 65% successfully?


  • Guest
It maybe for active chlorine content?
« Reply #1 on: June 21, 2004, 11:49:00 AM »
I'm no expert in pool chlorination but chlorinating agents are sometimes marked with their 'active chlorine' content. In case of pure Ca(OCl)Cl it is 56%, but calcium hypochlorite composition may vary thus it might have more hypochlorite anions, depending on the preparation/isolation method.


  • Guest
« Reply #2 on: June 22, 2004, 12:50:00 AM »
Swim was researching the exact same thing today and managed to come across 62% Calcium hypochlorite. As long as we are on the same topic concerning benzyl and benzal chloride. He was only able to find LiOCl (lithium hypochlorite) with a purity of 29% in the "spa" section.

Nicodem, so any Calcium hypochlorite above 56% should work?

Or should he bee looking harder to find a purer form? You guys are constantly reading Swim's mind. Swim went to start a new post and low and behold, someone beat him to it!  ::)

I'm sure this is the post you are referring to:

Post 496271

(elfspice: "toluene --> benzyl chloride --> benzaldehyde", Stimulants)

Instead of posting questions in the above thread, Swim thought it would bee best to post them here.

He did manage to find 99% NaBr in the pool section.

In the above linked thread, it mentions the use of KBr and H2SO4 to create benzyl bromide. Will the NaBr work as a substitute?

What is the purest form of LiOCl available OTC? What percentage should he bee looking for?


Edit: My bad! After searching through google, Swim found these:

According to the above links, looks like 30-35% for the LiOCl and 65-70% for the Ca.(OCl)2 is top purity.


  • Guest
Don't know
« Reply #3 on: June 22, 2004, 04:40:00 AM »
I just wanted to say that maybe that percentage does not indicate the Ca(OCl)Cl content but the content of 'active chlorine' since this stupid concept is more useful for pool chlorinations than the concept of purity.
The hypochlorite/toluene patent uses an excess of toluene anyway so the purity of calcium hypochlorite is not a real problem.


  • Guest
uh oh
« Reply #4 on: June 22, 2004, 11:01:00 AM »
The most common pool hypochlorite is 65-70%, and the link says that that's the dihydrate.  That's bad I think because the patent calls for dry or anhydrous bleaching powder or calcium hypochlorite.  I think the reaction has a greater possibility for runaway with the dihydrate and thus larger explosion risk.  The link also said that it is available in 75-80%, and I know a supplier that sells pool hypochlorite in both 68% and 73%, so perhaps the 73% is anhydrous?  It also mentioned that bleaching powder was only 35-37%, and the loomis patent in this thread

Post 34398

(Satan: "benzyl chloride from hypochlorite salts", Chemistry Discourse)

calls for dry bleaching powder so if you bought 68% pool material you would most likely have to adjust your ratios.


  • Guest
Ex-pool service person
« Reply #5 on: June 22, 2004, 09:00:00 PM »
Well I think I can be of some help in this area since I was in the pool service industry for some 12 years.  However what I am posting right now is from memory and from a service manual that I had handy (manual for service not chemical compositions)therefore IS NOT guaranteed to be 100% correct.  But I will verify my statements tomorrow as soon as the distributors around here open and will report back tomorrow whether or not the initial statements that I made today could be verified.
  That being said calcium hypochlorite can be aquired in its pure form from pool suppliers without any special requirements being met...all you should have to do is to walk in and ask for calcium hypochlorite or sometimes it is packaged in smallers packs and called pool shock treatment with the active ingredients being calcium hypochlorite.  If you find that it appears that it is only 65% or around that...that is the amount of available chlorine present when it is placed in water.  And the reason it isn't 100% is because there is calcium present as well which contributes nothing to the chlorine content. 
  So basically what they are explaining to the homeowner or pool service person is by weight the amount of elemental chlorine available at the time it is mixed with water is 65%.   The reason why they do that is so that the person can compare the chlorine content of a mixture to another...such as calcium hypochlorite (65%) to lithium hypochlorite (35%) or liquid chlorine(12.5%)  this way you can compare different chemicals to each other and figure out which is most cost effective for your individual use and will also be suitable for the body of water it is intended to be used on.  Because you wouldn't want to use calcium hypochlorite in a spa application due to the likelyhood of extreme overchlorination, since the content is so'd probably end up using something like trichlor or liquid in small amounts or possibly lithium hypochlorite.
  So what you are likely to see on most packaging is the available chlorine content of a given if you can find the compound that they have called simply "calcium hypochorite" with the 65% on the label...that is what they are asking for in the reaction asking for calcium hypochlorite.  Be forewarned though...calcium hypochlorite is some nasty stuff if it is handled carelessly.  First and foremost NEVER ever handle calcium hypochlorite with your hands unprotected.
  Two reasons for this are-#1 calcium hypochlorite WILL support ignition with just about ANY petroleum based hand cream or lotion. #2 safe lab practices dictate not handling chems such as that by unprotected means.  You might think that sounds funny...but don't be stupid and actually try it on purpose...they had a training video for pool service personnel that showed a technician doing just that and within minutes he had flaming hands...and even after seeing that our local distributor had a new employee try it just to see if it was true....well he found out the hard way it was indeed true.
  Calcium hypochlorite should NOT be allowed to come in contact with ANY combustible material as it is a strong oxidizer and can start a fire without a flame and this doesn't always occur instantly in fact most of the time it happens slowly and can be overlooked until it is too late and the fire has already begun.  Always clean up any spills immediately and if by some accident it does come in contact with your skin follow the emergency procedure stated on the container...which among other things will say to flood the area with plenty of water.
  It come in many different sizes all the way from 1lb bags to 100lb plastic lined cardboard drums.  If you are unsure how to go about asking for it...just ask for calcium hypochlorite and tell them it is for chlorinating your rather large pool or you can tell them it is to clear up your algae infested pool...but I would imagine they wouldn't ask anything since it is so common for people to use and it isn't a suspicous chemical. 
  If your wanting to aquire sodium bromide for the purpose of the elemental bromine it has...that too should be able to be found at any major pool chemical supplier.  It is typically used as an algacide in pools by pool service persons that haven't become aware yet that it will work quite well initially as an algacide but over a short period of time it converts their stablized chlorine pool into a unstablizable bromine pool.  Once the bromine is in the water it doesn't leave it stays there and everytime you add chlorine to the water it is immediately used by the bromine to reenergize itself and burn off contaminents thereby eliminating any chlorine residual which results in a pool that no longer will hold a chlorine residual and therefore cannot be properly maintained in a outdoor setting since bromine cannot be protected from sunlight the way chlorine can you'll end up having to drain it and start all over again...hopefully with this new found knowledge so the same mistake isn't repeated :-(
  The other use for sodium bromide is in a newly filled spa that is either indoors or is covered...and in this application the new water is treated with the necessary amount of sodium bromide to establish a bromine base in the water and then bromine tablets are used to chlorinate. The reason I said to chlorinate is because the typical bromine tablet is a mixture of bromo and chloro compounds which is designed to introduce both into the water but the bromine is the one that is used to sanitize and the chlorine part is used soley to reactivate the bromine. 
  Sodium bromide can be found in sizes ranging from say under one pound to as much as 25 lbs...again the larger size is much more cost effective then the smaller last time I bought the 25 pound which was like 5 years ago it went for around $80 which led to going directly to my local chemical supplier and aquiring it for around $60.  Well I think that is enough rambling for one post...if you have anymore questions that pertain to the pool industry and chemicals used in it or whathaveyou...feel free to ask and I will answer them as best I can.  Good Luck and Bee safe.  Pyrex out of the pool industry ;-)


  • Guest
calcium hypochlorite risks - runaway, explosion
« Reply #6 on: June 24, 2004, 04:13:00 AM »
- explosions can occur from:
1.local overheating of the reaction. This says never to use a burner or a hotplate alone for heating here but always a air bath or heating mantle/lab jack. Overhead stirring is a good idea.
2. hypochlorite not being completely covered with toluene. This happens when the hypochlorite is very coarse or if the hypochlorite is exposed to air by too strong (vortex) stirring. Stirring is good but not highspeed.
3. the reaction is exposed to (UV)-light. Dont do this in the sun or near a strong lightsource.
4. a combination of the before named conditions. This is most probable.

It was Ymir who told this times ago and I agree with him. Water is not the only if a reason at all for explosions. Water will cause ringchlorinations though.

Runaways occur:
- if one is not able to remove the heatsource completely from the flask quick when the reaction kicks in, say as soon as the first bubbles are to be seen.
- always during this reaction because its how it runs. A "medium scale runaway reaction" would be correct I assume. Thats the reason why a powerful condensor is essential or one will blow away half the toluene for nothing....

- use a hot-air pistol powered airbath for heating
- use a combination of two condensors stacked. First a Liebig or a plain tube and then a Allighn, Dimroth or similar. Anyways, loosely fill the your condensor in parts with glasswool. (if two are used, the Liebig/tube is to be filled) This serves as an  demister.

Ymirs writeup is a must read. Search and read.