beefing reaction with aluminium

[cajun]

There has been a suggestion that adding a small amount of aluminium to a I2\RP\E reaction will help in evening out the reaction and generally helping it along. My query is wether this would produce adverse contaminents/toxins and if there is actually any benefit to the practice at all.

[embezzler]

That is news to me do you have any references for this?

[geezmeister]

I've tried it a number of times and never noticed any benefit from doing it. Since I went to the long wet reflux I haven't seen a need to try it again.

[wareami]

With the LWR, Ibee has since quit using alum on the rxn.
However...if the RP is weak or on the light(weight/ratio) side, one could always add the aluminum as an RP kicker.
That was why Ibee always used it in the past and wouldn't hesitate if the rxn was lacking or stalled.
Read this thread...

Post 349775 (missing)

(aztec: "Ratio Confusion", Stimulants) and I'll dig up some others from Jacked regarding the use of alum stirrers

[spectralshift]

Do a search for this file in the stim forum, the accompanying post is by "RaG".
hi.from.iodine-alumina.pdf

'Iodine reacts with a diverse group of unsaturated substrates in the presence of dehydrated alumina. Aromatic
substrates, for example, are iodinated a t room temperature by electrophilic aromatic substitution. The yields
of the iodinated products can be improved dramatically by running the reaction at 110 "C. Aniline, even at 100
"C, is unreactive, presumably because its nitrogen lone pair is complexed to surface aluminum cations or protons.
Alkenes react readily with HI, formed in the reaction of surface hydroxyls with I,, to form alkyl iodides by an
ionic mechanism involving carbocations. This is an excellent method for the synthesis of alkyl iodides from alkenes.
Alkynes, on the other hand, add I, (stereospecific, anti) under very mild conditions to form vinyl diiodides in
excellent yield. The behavior of Br, with cyclohexene on alumina is considerably different than that of I2 with
cyclohexene. Two products are formed: trans-l,2-dibromocyclohexane ( I ) , which is formed in solution during
workup, and trans-1-bromo-2-chlorocyclohexane (2), which is formed on the surface. The chlorine in 2 arises
from intrinsic chloride already on the alumina and CCl,, the solvent used to adsorb Br, onto alumina. Further
experiments demonstrate that cyclohexene undergoes intergranular hopping, but that Br, does not.'

I haven't looked over the article in ages, but by the looks of it they are talking about reactions on aromatics and not alcohols and amines like pfed. But still pfed has a benzene aromatic ring so theres a connection there.

I guess it would complicate ratios too...

Alumina isn't difficult to obtain at all,it's used in ceramics etc. Apparently it's a nice dessicant too, very hygroscopic, but doesn't dissolve in water, which is useful, because it means you can set it above a steaming flask without the steam dissolving the dessicant and polluting what is being dehydrated in the flask. (been there)
But most here will be hardpressed dehydrating it for re-use.

[Osmium]

Adding aluminum is a pretty dumb thing to do, unless you love emulsions during workup.

[spectralshift]

emulsions under what circumstances? from what?
can you give any direction on alumina?

[cajun]

white emulsions form in the reactive stage{so it is theorized of course}and presumably disappear with adequate post cleaning. But I now think geez is correct in its a waste of unecessary effort. If further investigation into this reveals something new I will pass it on and If something comes to light that those emulsions are a bit more threatening than anticipated a word in that regard is always appreciated

[MnkyBoy78]

I believe that Worlock mentioned the use of pop can tabs long ago in rxns were the rp was on the light side.

SWIM will use a small thin piece of alumium (not store bought foil) on rare occassions, in fact just recently when after 12 hours the flask contents were still a purplish/red color.  A 1" square piece was dropped in and the flask was warmed up again.  After about 7 - 10 min the alumium was no longer visiable (disolved).  The rxn was heated for an addional 2 hrs then worked up as usual.  Emulsion was not noted, but the NP and post rxn solution was filtered into the sep funnel.

Its not used all the time, but there may be a time when one is unsure of rxn completion where its use could be benifitial.

[SQUIDIPPY]

S/D over the years has  tried foil as well as pop tops. Even pure powdered Aluminum. He confirms Geez's findings. It is of no seeming advantage, nor does it seem to do any harm.

[invasivefungoids]

Aluminum will get eaten up during the rxn and turn grey and powdery, then even w/ a filter, it will screw up yer lye bath like osmium said.  A magnesium bar from yer local camping or army/navy store will do great for what yer lookin for.  Bake it in the oven for about 30 minutes on 350 to brittle it up--then shave it into the used red or even new red for a little extra bonus during the cook.

[steam]

g'day cajun, good to see you around...

I use a few small pieces of aluminium foil in my dream state rxn's - only when it's almost stopped reacting.

Adding a few small pieces at that time kick-starts the rxn again for me.

I sorta user it instead of increasing the heat for its' final convulsive conclusion.

I heard some time back about Aluminium and its Alzimers Effect on aged people who had used Al. pots all there life. THERE IS A LINK.(important imformation capilized to aid learning - sorry ppls)...So,
Using the Al. in a rxn does make one think.,and so I'm glad your've brought up the subject.

In so being, lets all consider 'Osium's' theory and use magneesium shavings instead.
I'll give it try and let you know how it goes.

Hey, you know when you hit upon such interesting subject matter as this - your've brought up a good subject...

>steam<
'cause_i'm_always_under_pressure!

[dwarfer]

there's plenty  of reason to NOT use Al,
but fear of Alzheimer's is not one of them.

There is no causal link between them.

The amyloid plaques have Al in them:
but that proves nothing.

Aluminum in the environment can NOT be
avoided, aluminum cookware or not.

[Old_Rip_Beak]

Actually, that nasty little prion disease (my $0.02) causes far more habit using zinc than Al.  Good luck living without zinc in your diet.  As a side note, somebody just patented evolving hydrogen in a soup of Al and NaOH.  He wasn't even a high school graduate.

Makes me wonder what he was up to...
~~Old Rip

[elfspice]

my money for the cause of the prion disease is infrasound altered manganese (to a different ionisation state) substituting for copper in the brain.

yes, aluminium is everywhere, clay contains it, for example.

NaOH + Al = stuff + H2 hm... is it hydrogen? dunno, i do know that aluminium oxide dissolves in a strong sodium hydroxide solution, and it fizzes too, but this is the formation of a hydroxide form a metal oxide and this, according to my rough stochiometry, means absorbing a hydrogen, which would imply the vapour is oxygen (but i may be wrong of course). I thought you only get hydrogen from putting a strong mineral acid on aluminium, as this forms the aluminium salt of the acid liberating the hydrogen (and incidentally this also releases some HCl if the acid is HCl because AlCl3(whatever) takes up a lot of water (similar to MgSO4 and NaSO4)

funny, i was just reading today in a history of chemistry book that for a long time they didn't know the difference between liberation of carbon dioxide and oxygen and hydrogen when mixing different things together. I remember doing the pop test... if it's hydrogen the gas pops out of the test tube when ignited, if it's oxygen a smouldering piece of wood ignites, and if it's carbon dioxide a flame is extinguished. (duh) I didn't bother finding out what the gas that was evolving was cos i was just cleaning some beer bottles that had aluminium foil on them and i noticed they fizzed in strong NaOH solution. A coffee jug i got today also fizzed in strong NaOH, except it seemed that the fizzing was coming from the part that was holding the steel strap around it.

[WizardX]

2 Al + 3 NaOH ==> 1&1/2 H2 + Na3Al2O3

Al2O3 + 2 OH ^- + 3 H2O ==> 2Al(OH)4 ^- Amphoteric metal hydroxides


2 Al + 6 NaOH ==> 3 H2 + 2 Na3AlO3   Basic overall

[praeseodymium]

As a side note, somebody just patented evolving hydrogen in a soup of Al and NaOH. He wasn't even a high school graduate.

Ha. That's funny. I did that when I was about 16 (which is a long time ago now.). never thought to patent it though (like who's gonna pay money to use that obscure bit of information?)

Incidentally it was also noticed that if the same reaction has added to it some acetone, a distinct odor of isopropanol is given off. I don't know what kind of yield etc. this produces but the acetone smell was overpowered. I wonder how far the reduction would go given some help with say some Zn or Fe or maybe a metal oxide composite as a hydrogen adsorbant.... and if this could be adapted to other uses. I guess someone has tried it all before.