Sciencemadness Discussion Board - The Short Questions Thread (4)

What is calcium hydroxide soluble in. And for future reference, how to do find the solubility of chems in organic solvents and alcohols ect. I can never find it online.

[Edited on 10-2-2017 by TheNerdyFarmer]

Solubility data of inorganic materials in organic solvents is generally tough to find. They generally dissolve better in alcohols than in other organic solvents, and will dissolve best if there is a mismatch in size between the cation and the anion. Lithium salts will be more soluble than sodium or potassium salts, and tetraalkylammonium salts will be even more soluble. Ionic compounds with limited solubility in water are even less likely to dissolve in alcohols and other organic solvents. The exception to this is solvents which strongly coordinate metal cations, such as acetonitrile. Acetonitrile is an excellent solvent for many transition metal compounds (such as Copper(I) chloride, which is water-insoluble).

CharlieA - 11-2-2017 at 16:39

@zts16: The Mettler is a heck of a bargain. I remember the first time I had a chance to use one. I couldn't believe the difference between it and the double-pan balance with free weights that I had been using in school I admit I didn't read your blog entry thoroughly, but I would adjust the Vernier scale with the standard mass on the pan.
I might have to start looking a a Mettler

TheNerdyFarmer - 11-2-2017 at 17:09

Quote: Originally posted by DraconicAcid

Thank you for the information. I will have to look into more solvents like that.

JJay - 11-2-2017 at 19:33

What size thermometer well do you use for a 24/40 distillation adapter?

Geocachmaster - 11-2-2017 at 19:53

5.5cm looks like the best for the adapter I have. 5 and 6cm would work but would be under and over immersed, respectively. Next to a 10cm well for comparison.

Edit: I don't think you'll find a well of the right length, my perusing of eBay in the past for correct ones came up with nothing. Perhaps you should buy a 100mm or 200mm one, break off the excess, and flame the end close. I've never done any work with boro glass but I can't imagine it would be too difficult to close a tube.

[Edited on 2/12/2017 by Geocachmaster]

Texium - 11-2-2017 at 20:02

Quote: Originally posted by Sulaiman

I think that the last photo of your blog shows 005.0002 g

005.0 from the digital scale

the zero of the vernier scale on the right is between 00 and 01 of the main scale, so the next two digits are 00

the two scales are coincident at 2 on the vernier scale, the last digit

Yeah, you're correct. At the time I wrote that post, I didn't know how to read the final digit, but I looked it up the other day and came to that same conclusion upon reading it again.

JJay - 11-2-2017 at 20:50

5.5cm looks like the best for the adapter I have. 5 and 6cm would work but would be under and over immersed, respectively. Next to a 10cm well for comparison.

Edit: I don't think you'll find a well of the right length, my perusing of eBay in the past for correct ones came up with nothing. Perhaps you should buy a 100mm or 200mm one, break off the excess, and flame the end close. I've never done any work with boro glass but I can't imagine it would be too difficult to close a tube.

[Edited on 2/12/2017 by Geocachmaster]

I see a few sellers with 40mm ones on eBay, but that does seem to be too small except with a 24/29 adapter and 24/40 thermometer well.... I'm pretty terrible at glassblowing but that might be a good option.

Question.

TheNerdyFarmer - 12-2-2017 at 15:50

Is there a good full proof way to test for nitrites? I made what I believe is sodium nitrite but not sure if it is or not.

JJay - 12-2-2017 at 15:53

It's not foolproof, but a nitrite solution will form a precipitate with silver nitrate and not with lead nitrate.

I think there's a test that can be performed using tincture of iodine as well.

PHILOU Zrealone - 12-2-2017 at 16:49

Is there a good full proof way to test for nitrites? I made what I believe is sodium nitrite but not sure if it is or not.

Azo-dyes are a good way to test for nitrite via diazonium coupling reaction forming colorfull organic dyes.

Magpie - 12-2-2017 at 17:02

See p 3 of the "Preparation of ionic nitrites" thread, post of garage chemist.

A Halogenated Substance - 15-2-2017 at 16:48

The stopcock of my addition funnel very nearly got stuck but I managed to free with some careful rinsing and turning.

I'd like to prevent this in the future. Would it be wise to add a little glass joint grease to the stopcock every once in a while to prevent this? Are there more preferable ways to prevent this?

JJay - 15-2-2017 at 16:53

It's best not to use strong bases with glass stopcocks. I do keep my glass stopcocks lightly greased; that could be slightly problematic in some situation I suppose but seems to be ok most of the time. The problem I often run into is that PTFE has a high coefficient of expansion, so it can be hard to turn a warm PTFE stopcock.

Quick question: use of salicylic acid

Sulaiman - 16-2-2017 at 09:12

I have 30g pure salicylic acid that I will convert to oil of wintergreen and use on myself medicinally,
after I have done a quick run with a little of the 500g salicylic acid that I bought on a whim because it was cheap (500g = £5 total)

I am considering the synthesis of phenol and benzene, to keep as reagents.

I can't decide how much salicylic acid to keep, how much to convert to phenol and how much to benzene.
1/3 each ?
Which of the three do YOU use most of, and why, please.

PHILOU Zrealone - 16-2-2017 at 13:37

Keep it as salicylic acid...much safer, less volatile and less toxic.
And only when you are ready to make, if ever you make, dérivatives of benzene or phenol, you can effect transformation of some Salicylic acid to Benzen or Phenol...

If you plan to make trinitrophenol...no need to make phenol first...go straight from SA to TNP via H2SO4/HNO3 nitration.

[Edited on 16-2-2017 by PHILOU Zrealone]

Sulaiman - 16-2-2017 at 23:25

As much as I would like to experiment with tri-nitro-XXX and other energetics,
politically, it is not a good time or place - I'm even beginning to worry about potential precursors now

stupid fucking terrorists - ruining my hobby ... I'm considering declaring jihad on the scum.

I now agree, best to keep as much of the salicylic acid as-is for storage and just use enough for experiments as I go, thanks for the clarity.

fastbre4k - 17-2-2017 at 08:17

It is possible to do an Schmidt reaction in Ethylacetate?

PHILOU Zrealone - 17-2-2017 at 10:18

Quote: Originally posted by fastbre4k

It is possible to do an Schmidt reaction in Ethylacetate?

What would be the carboxilic acid, keton or aldehyd involved?

fastbre4k - 17-2-2017 at 17:22

I would like to know for all three

PHILOU Zrealone - 17-2-2017 at 18:50

I'm not sure but:
Maybe that the HN3 will attack the acetic moeity of the ethyl acetate...
CH3-CH2-O2C-CH3 + HN3 --?--> CH3-CH2OH + N3-CO-CH3
If this happens, then this would preclude the use or ethyl acetate for all 3 cases.

Maybe that the carbo acid will induce transesterification with the acetate...
R-CO2H + CH3-CH2-O2C-CH3 <====> CH3-CH2-O2C-R + CH3-CO2H
If this happens, then this would preclude the use of an acid with ethyl acetate...but would be no problem for the keton or aldehyd

The related alternative Schmid reaction with N2H4 and carbo-acid would be a no go since acethydrazide (CH3-CO-NH-NH2) would be formed aside with ethanol.
CH3-CO-NH-NH2 + HONO --> CH3-CO-N3 + 2 H2O

[Edited on 18-2-2017 by PHILOU Zrealone]

NitratedKittens - 20-2-2017 at 11:02

I have been doing the synthesis of pentanoic acid via the kmno4 oxidation of pentanol, would anyone like a procedure and writeup with pics and if so then where should i post it.

Texium - 20-2-2017 at 11:10

You can post it in Organic Chemistry, and if it is well-written and repeatable, it can stay there. If it has considerable flaws I will move it to Beginnings so that people can give you advice for your future write-ups. Either way, please do post it.

NitratedKittens - 20-2-2017 at 12:14

Alright then, over the next week i will repeat the procedure while taking pictures then post

TheNerdyFarmer - 21-2-2017 at 06:10

I was cleaning my sintered funnel with a bit of piranha solution. After I thought that the hydrogen peroxide in the solution had decomposed, I rinsed it thoroughly with acetone. Now there is a small amount of white solid at the bottom of the flask that I fear may be acetone peroxide. If it is, what is a safe and proper way to get it out of the flask and dispose of it?

CalAm - 22-2-2017 at 08:38

From the sciencemadness wiki:

" Acetone peroxide can be rendered relatively benign by dissolving it in toluene. Even if the solution is saturated, there is almost no risk of detonation. "

JJay - 22-2-2017 at 08:45

What are ground glass reagent bottles good for? They don't seem airtight unless sealed with vacuum grease, and I don't want vacuum grease in my products... can they actually be used for long term storage of reagents?

TheNerdyFarmer - 22-2-2017 at 09:22

I was cleaning my sintered funnel with a bit of piranha solution. After I thought that the hydrogen peroxide in the solution had decomposed, I rinsed it thoroughly with acetone. Now there is a small amount of white solid at the bottom of the flask that I fear may be acetone peroxide. If it is, what is a safe and proper way to get it out of the flask and dispose of it?

Ok thanks i will get on that right away.

PHILOU Zrealone - 22-2-2017 at 14:32

Simply add more aceton and it will redissolve then trow into the toilet and flush...
Or simply collect when moist (I think there can't be much more than a few mg) so no risk of injury and put into a some toilet paper then light with a lighter...it will burn without explosion and make a tiny flash.

PHILOU Zrealone - 22-2-2017 at 14:46

Quote: Originally posted by JJay

What are ground glass reagent bottles good for? They don't seem airtight unless sealed with vacuum grease, and I don't want vacuum grease in my products... can they actually be used for long term storage of reagents?

Without grease, parafin oïl, candle wax or silicon oil...it is not 100% airtight and so any volatile, oxygen sensitive compounds are storable only for a limited amount of time (like wiskey carafe --> one year).

If you use the correct grease/viscous paraffin wax...it is unreactive and will remain onto the rough ground glass...then it can store for example concentrated HNO3...then use with care a pipette into the center to take the liquid without touching the sides of the bottle mouth to avoid contamination with the grease...some flasks do have the pipette integrated into the glass roded cap...

If your product is non volatile, non hygroscopic and non sensitive to air (O2, NH3 or CO2, volatile acids)...then it is OK without grease/wax

Sulaiman - 22-2-2017 at 15:33

often the vapours of stored liquids condense into the ground glass joint, sealing it somewhat.

one of my school chemistry memories is how during summer,
bottles of reagents with ground glass joints would 'vent' excess pressure occasionally by pushing up the stopper a little, releasing a puff of vapour.
I would not store ammonia solution, or conc. acids, especially HCl, in this way
as my chem. lab is also my 'workshop' and electronics lab,
and I value my tools and equipment

Panache - 28-2-2017 at 16:15

I want to use my oxy acetylene torch but running hydrogen instead of acetylene.
Is this completely unsafe? If anyone has direct experience with trying this what 'observations' would you remark on?

wg48 - 28-2-2017 at 18:19

I want to use my oxy acetylene torch but running hydrogen instead of acetylene.
Is this completely unsafe? If anyone has direct experience with trying this what 'observations' would you remark on?

I do not have any direct experience. However from memory the flame velocity of a hydrogen oxygen mixture is higher than oxygen acetylene mixture. That means flash back in a premixed torch is more likely but that can be corrected easily by increasing the gas flow or by using a nozzle with a smaller hole.

For safety you should be operating the torch with flashback arrestors in the gas lines, which may not work correctly for the higher flame velocity of hydrogen.

Panache - 28-2-2017 at 18:30

Quote: Originally posted by wg48

I want to use my oxy acetylene torch but running hydrogen instead of acetylene.
Is this completely unsafe? If anyone has direct experience with trying this what 'observations' would you remark on?

Ok great, I have flame arresters directly off the regulators on the bottles but there's about 10metres of hose after that, hydrogen cannot burn with an oxidant so at worst my torch might strike back.
Also I forgot to ask hydrogen oxygen mixtures burn at almost all proportions/ratio's (3-95% from memory) however what about detonation, do hydrogen oxygen mixtures detonate and is there a safe working pressure where the mixture will only burn not detonate. Converse from some people I don t want a detonation.

wg48 - 1-3-2017 at 08:08

Quote: Originally posted by wg48

I want to use my oxy acetylene torch but running hydrogen instead of acetylene.
Is this completely unsafe? If anyone has direct experience with trying this what 'observations' would you remark on?

Yes Hydrogen does not burn with out oxygen. However if for some reason one of the gases flows down the supply pipe of the other gas the flash back arrester will stop the gas flow and or stop a flame. Its particularly need when using an acetylene bottle because the oxygen can be at a much higher pressure than the acetylene.

Detonation: Most if not all fuel oxygen mixtures with the correct stoichiometry can detonate if ignited. Acetylene can even detonate in the absence of oxygen.

Assuming your torch is a regular oxy/acetylene torch it is the flow velocity thru the nozzle that must be higher than the flame velocity to prevent the flame travelling back in to the torch nozzle and possibly detonating in it. But that mixed gas volume in the torch is small and the torch is designed to withstand the occasional blowback . Hydrogen is less powerful than acetylene.

So NO there is not a hydrogen pressure to prevent blowback as it depends on both the hydrogen and oxygen pressure and the nozzle hole size ie flow velocity
i
The normal procedure is to light the torch with only the fuel on. Then adjust oxygen for the required flame. That will be near to stoichiometric and near to the fastest flame velocity. So you use a nozzle with an outlet diameter such that the gas flow is greater than the flame velocity or the flame will blow back into the torch. Too higher velocity and the flame will blow out.

Confused about distillation

Geocachmaster - 3-3-2017 at 08:36

I'm adapting a synth of ethyl acetoacetate from here. In the workup I am very confused about the distillations.

Quote:

The liquid divides into two layers the upper one, consisting of acetoacetic ester and unchanged ethyl acetate, is carefully separated and distilled collecting fraction passing at 100° C. The distillate is redistilled and collected in fractions, that distilling at 175-185° C is nearly pure acetoacetic ester.

The boiling point of ethyl acetoacetate is more than 100 degrees higher than ethyl acetate, so I wouldn't think very much would come over at 100 C. Am I missing something? Why would most of the product come over at 100 C in the first distillation, but then in the second one come over between 175 and 185 C?

Any answer is appreciated.

JnPS - 3-3-2017 at 09:22

Maybe the ethyl acetoacetate is being co-distilled with the ethyl acetate at the lower temperature and then fractionally distilled further from the resulting distillate? If there's a lot of unreacted ethyl acetate then that would explain why they're expecting a lot to come over at 100 C

ficolas - 5-3-2017 at 07:28

I want to remove a large amount of water from a solution, using calcium chloride, however I dont know what hydratate will form.
If I cool the solution to below 30C, hexahydratate should form? (Hexahydratate decomposes at 30C)
How long will it take? Is it something fast or slow?

DraconicAcid - 5-3-2017 at 08:27

If you have a large amount of water, you'll form saturated calcium chloride solution. It forms quickly, and you should be able to decant the organic layer. Sodium sulphate and other ionic drying agents will act similarly.

ficolas - 5-3-2017 at 10:01

Thanks, it doesnt work for what I wanted it for, but I learned something

I wanted to concentrate H2O2, and I saw somewhere that you could do it with drying agents like CaCl2, however if it separates completelly, I dont want it as I stay away from explosives, and if it doesnt separate at all, it doesnt work either.

KMnO4 solubility

TheMrbunGee - 7-3-2017 at 04:46

Why is there no solubility for KMnO4 in water after 60 C ?

byko3y - 7-3-2017 at 05:09

25 g/100ml at 65°C, 32 g/100 ml at 75°C. That's pretty much highest temperatures which allow more or less accurate measurement of KMnO4 solubility, at higher temperatures it quickly decomposes, thus leading to huge errors in measurement.

Sulaiman - 7-3-2017 at 05:47

Quote: Originally posted by TheMrbunGee

Why is there no solubility for KMnO4 in water after 60 C ?

google gave me this;

4 KMnO₄ + 2 H₂O = 4 KOH + 4 MnO₂ + 3 O₂

JnPS - 9-3-2017 at 20:18

Can somebody download/share this article?

α,β-Unsaturated Aminoketones. VIII.1 Reaction of Primary Amines with 1,3-Diketones and Bromine Derivatives of Benzalacetophenone. Ethylene Imines
Norman H. Cromwell, Robert D. Babson, and Charles E. Harris
Journal of the American Chemical Society 1943 65 (3), 312-315
DOI: 10.1021/ja01243a003

It supposedly contains the full procedure for the paraphrased version (found in the Vogel's Organic chem book from the SM library) on a schiff base prep formed from benzaldehyde and an methylamine. I'm still in the process of figuring out how to get access to acs publications trough my university but would like to read this article during spring break to prepare for the procedure

Separation of potassium nitrite from nitrate

gluon47 - 11-3-2017 at 15:24

I've been following this procedure to produce potasium nitrite (link). I've just filtered off the lead(ii) oxide by product and discovered a fair amount of what looks like unreacted lead metal powder. This means I'll have a fair amount of nitrate in my potassium nitrite solution.

I could evaporate down the solution to get crude potassium nitrite, but I want my product as pure as possible. I know methanol works quite well for separating nitrite from nitrate, but unfortunately I don't have any.

How else could I go about separating and purifying my nitrite from nitrate?

any help would be greatly appreciated

ficolas - 12-3-2017 at 17:39

Is there any viable oxidizer to form H2SO4 fron SO2 other than H2O2?

JJay - 12-3-2017 at 19:00

I've read about people doing it with nitric acid. The impurities will be much more volatile than the sulfuric acid and can be removed by distillation.

Can alcohols and carboxylic acids be brominated with antimony tribromide?

RogueRose - 12-3-2017 at 22:49

Quote: Originally posted by ficolas

Is there any viable oxidizer to form H2SO4 fron SO2 other than H2O2?

Depending on how much you need to convert you could look into an ozone (O3) generator. I've seen inexpensive chineese ones that sell for $30-50 that supposedly produce 5g per hour = 120g / day and also ones that do 12g per hour = 288g per day. Some homemade units on youtube can produce A LOT like 200g+ per hour but they run in the kilowatt rang for power consumption and are very dangerous (high voltage & high current) if not properly used.

ficolas - 13-3-2017 at 04:58

Quote: Originally posted by RogueRose

Quote: Originally posted by ficolas

Is there any viable oxidizer to form H2SO4 fron SO2 other than H2O2?

Is the concentration of the ozone enough for it to be dissolved in cool water, so that I dont have to mix the two gases, I instead can just dissolve them?

I think ill perform some experiments with thr SO2, scrubbing it (with NaOH?) to see if I can work with it safely.

Also, can I use some metal to burn the sulfur inside, or do I need to use glass because of corrosion?

[Edited on 13-3-2017 by ficolas]

Free Radical Reaction

Meltonium - 16-3-2017 at 17:22

In a free radical reaction, is it better to use a shorter wavelength? For example, in free radical reaction using chlorine gas, would it be better to use 200nm wavelength light or would it be better to use 400nm light?

[Edited on 3-17-2017 by Meltonium]

byko3y - 17-3-2017 at 04:27

You should use the lenght of wave suitable for your exact reaction/compound. AFAIK, the best wavelength for chlorine is 340 nm, maximum wavelength is somewhere at 490 nm, which is where chlorine starts to absorb light, so 400 nm is perfectly fine.

Phenylacetaldehyde

fastbre4k - 18-3-2017 at 08:40

Will Phenylacetaldehyde Polymerize when stored solved?

Capillary tubes for melting point determination

j_sum1 - 20-3-2017 at 20:32

I am the proud owner of a Thiele tube. I also purchased a bunch of capillary tubes to go with it -- but without checking the diameter first. They are very slender at 0.9mm ID (They actually look smaller than that.)
I think I need a wider tube just to get most crystalline substances in there.
What is the standard used?
And does anyone know of a good supplier? I spotted a pack of 100 2.4mm ID tubes that were going to set me back more than 50AUD by the time shipping was included. That seems a bit excessive to me.

gdflp - 20-3-2017 at 20:55

Quote: Originally posted by j_sum1

I am the proud owner of a Thiele tube. I also purchased a bunch of capillary tubes to go with it -- but without checking the diameter first. They are very slender at 0.9mm ID (They actually look smaller than that.)
I think I need a wider tube just to get most crystalline substances in there.
What is the standard used?
And does anyone know of a good supplier? I spotted a pack of 100 2.4mm ID tubes that were going to set me back more than 50AUD by the time shipping was included. That seems a bit excessive to me.

That's a bit on the small side, but it doesn't actually sound too bad. I've got a tube of authentic melting point tubes sitting here and the OD is ~1.5mm. 2.4mm sounds a bit big, especially for the ID, and $50 is ridiculous(even considering it's aussie dollars

).

I'd try running some melting points on a few well characterized compounds(benzoic acid, vanillin, etc.) and see how accurate your results are. If they look good, those tubes will be fine, filling them is always a pain in the ass, I doubt it could get much harder

A Halogenated Substance - 21-3-2017 at 16:57

When boiling down a ferrous chloride solution, I added some steel wool to prevent the conversion of iron(II) to iron(III) by the air. The solution was made from previously dissolved iron nails in HCl. However, as the boiling progressed, the solution went dark brown signifying the reaction to iron(III) chloride.

The conversion did seem to start from the surface of the solution. Did heat help the conversion of iron(II) to iron (III) progress faster?

CaCl2 and ethyl acetate?

Geocachmaster - 21-3-2017 at 17:42

About an hour ago I added a few scoops of CaCl2 to ~50ml of ethyl acetate thinking that I would leave it to dry overnight. I was so sure that CaCl2 was compatable because I had read somewhere that ethanol could be removed from EtAc with calcium chloride. Upon reading this I now am doubtful because it does not say calcium chloride can be used. I wanted some dry EtAc for tomorrow so...

Will CaCl2 work for drying ethyl acetate or should I use another drying agent?

mayko - 22-3-2017 at 16:22

I've made a couple pounds of Fe2O3 from precipitating an iron solution with base (ammonia/sodium carbonate), oxidizing with peroxide, and heating to dryness. The thing is, the red powder seems to be strongly magnetic! I'm still scratching my head about this; the solutions had been filtered to remove suspended iron particles. The best I've come up with is some leaves might have fallen into the solid as it was being heated down over charcoal outside, and the carbon reduced the oxide to metallic iron. However, the magnetism is spread throughout the powder, and I haven't been able to mechanically separate it into magnetic and non-magnetic portions. Any idea what's going on?

Liamatpm - 22-3-2017 at 16:26

Will CaCl2 work for drying ethyl acetate or should I use another drying agent?

Yes it should work. And if it doesn't it was worth a try.

A Halogenated Substance - 22-3-2017 at 16:27

Quote: Originally posted by mayko

I've made a couple pounds of Fe2O3 from precipitating an iron solution with base (ammonia/sodium carbonate), oxidizing with peroxide, and heating to dryness. The thing is, the red powder seems to be strongly magnetic! I'm still scratching my head about this; the solutions had been filtered to remove suspended iron particles. The best I've come up with is some leaves might have fallen into the solid as it was being heated down over charcoal outside, and the carbon reduced the oxide to metallic iron. However, the magnetism is spread throughout the powder, and I haven't been able to mechanically separate it into magnetic and non-magnetic portions. Any idea what's going on?

Do you think that you could've produced magnetite?

http://www.sciencemadness.org/smwiki/index.php/Iron(II,III)_oxide

A Halogenated Substance - 22-3-2017 at 16:31