woelen - 20-8-2008 at 05:23
I have the opportunity to buy SiCl4 (500 ml) for only EUR 10 or so. However, I have no direct use for this chemical, but am wondering whether it is
useful to stockpile it or not.
I read that this stuff easily hydrolyses with water, giving SiO2 and HCl. It also can be used to make compounds like Si(OCH3)4, so-called orthosilcate
compounds.
Is this chemical interesting for the home lab? What kind of interesting syntheses can be done with it, or interesting experiments in general? Does the
burden of storing such a nasty and corrosive chemical outweigh the usefulness of this? Any comments are welcome.
I also am rather reluctant to use this chemical in my glassware. I can imagine that the SiO2, which is easily produced, clogs my glassware and is very
hard to remove.
------------------------------------------------------------
Similar questions I have about SnCl4. I was given 100 ml of this liquid. I already have this at home. It is a very mobile clear liquid, looking like
water, but more dense. I did not yet open the container (it is completely sealed, no leaking whatsoever). What interesting things can be done with
this? How nasty is it?
[Edited on 20-8-08 by woelen]
ScienceSquirrel - 20-8-2008 at 05:31
Well it fumes like stink in moist air and leaves everything covered in a fine dust of silica that is easily wiped off.
If you leave it in the bottle it just sits there. I worked in a lab that had several litres stockpiled in a cupboard under one of the fume cupboards.
The lab did organometallic things so I suppose it may have been used to prepare organosilicon compounds when they were a lot less available.
Tin tetrachloride is the starting material for alkyl tin compounds. Once again it fumes in moist air producing tin dioxide and hydrogen chloride. Some
alkyl tin compounds are quite toxic.
[Edited on 20-8-2008 by ScienceSquirrel]
benzylchloride1 - 20-8-2008 at 07:44
I made tetraethyl tin once out of a Grignard reagent made out of ethyl bromide and from tin(IV) chloride that I had made myself. It is an awful
smelling, toxic liquid. In low concentrations the smell resembles rotten garbage and is very hard to get rid of. The residues from tin(IV) chloride
can be readily removed from glassware. Also tetraphenyl tin can be made from tin (IV) chloride from chlorobenzene through a organosodium reagent
(phenylsodium). These are both standard laboratory experiments in some inorganic chemistry courses. I am taking inorganic chemistry this year, but I
highly doubt if one of the labs involves the preparation of organotin compounds. They are so concerned about safety at my university that they do not
conduct very many labs. This is one of the reasons I built a home lab.
Klute - 20-8-2008 at 07:49
SiCL4 can be used to make various functionalized silanes, and ortho silicates as you mentionned. These can be sued to make silica-supported
reagents/catalyst, which can most of the time simply be filtered off a reaction mixture and re-used or regenerated. There alot going on in the recent
litt about such compounds.
Maybe SiCl4 can also be used for chlorinations, formation of acyl chlorides etc, although I'm not sure it's strong enough. I hope someone more
experienced with silanes can comment further.
benzylchloride1 - 20-8-2008 at 07:55
Here is a small scale synthesis of tetraethyl tin and several other experiments that can be conducted with this compound:EXPERIMENT 3
PREPARATION AND REACTION OF TETRAETHYLTIN
This experiment will take two lab periods, the first involves the synthesis and isolation of tetraethyltin, Sn(C2H5)4, and the second involves two
subsequent reactions. It should be noted that organotin complexes are toxic and pungent to varying degrees, depending upon the number and nature of
organic groups bound to the metal centre. All preparations should be therefore carried out in a fume hood.
First Period:
Preparation of Tetraethyltin, Sn(C2H5)4
All glassware must be dry - wash with acetone and flush with nitrogen
1. In the fumehood, set up a 250 mL round bottom flask with stir bar, topped with a reflux condenser (Figure 1). The flask should be immersed in an
empty bath on top of a magnetic stirrer. Fit a gas inlet adapter connected to a nitrogen gas line to the top of the condenser.
SnCl4 fumes violently when exposed to moisture, forming SnCl4.H2O, - this addition should be performed quickly. Gloves should be worn and the
manipulation of this compound must be carried out in the fumehood only.
2. With nitrogen blowing through the apparatus, pipet into the flask through the side port, 0.8 mL SnCl4 (FH3)
(density = 2.226 g mL-1) using a disposable 1 in 1/100 mL pipet. Allow the SnCl4 to evaporate before removing the pipet from the fume hood.
3. Top the flask with a pressure-equalized addition funnel, and with stirring add 25 mL anhydrous diethyl ether (Fridge) via the dropping funnel. Fill
the bath with ice/water when you are ready to add the Grignard reagent. With nitrogen blowing through the apparatus, add, using the canula method, 20
mL 2.0M ethyl magnesium chloride (FH3) to the closed dropping funnel, and then shut off the nitrogen flow.
Add the Grignard solution dropwise to the ice-cold flask, continually stirring, over a period of about two minutes.The canula must be cleaned
immediately, follow instructions from your TA.
4. Remove the ice bath, and stir the solution for about 15 minutes, or until the solution comes to room temperature. Replace the dropping funnel with
a glass stopper, and remove the gas inlet from the condenser. Replace the ice bath and slowly add 5 mL 1.2M HCl (FH-M) to the reaction mixture via the
top of the condenser, followed by 10 mL H20.
Do not allow the reflux level to go above the glass jacket of the condenser.
5. Transfer the reaction mixture to a separatory funnel, and collect the ether layer in an Erlenmeyer flask. Rinse the reaction flask with diethyl
ether into the funnel if necessary, and again collect the ether layer. Dry the combined ether layers with MgSO4 (DS), and gravity filter into a
pre-weighed one-neck flask Wash the Erlenmeyer with ether, and remove the solvent of the combined filtrates by rotary evaporation.
Very Important:Your product has a very obnoxious odour and is toxic. Stopper the flask when transporting it out of the fume hood. Technique marks will
definitely be lost if the smell of tetraethyl tin permeates the laboratory.
6. Obtain a yield of your product, and store it until the next period, in a flask with a B19 stopper covered with "Parafilm" and placed in the
refrigerator.
Second Period:
Preparation of diethyltin dichloride, Sn(C2H5)2Cl2
1. Top a flask containing the tetraethyltin prepared in the first period with a reflux condenser fitted with a drying tube. Add a boiling chip (DS) to
the flask, and add to the product an equimolar amount of SnCl4, via pipette.
2. Reflux the solution at ~200°C for 15 min. using a thermowell, and allow it to cool. Replace the condenser with the drying tube, and immerse the
flask in a hot (low boil) water bath.
3. Add enough boiling octane (FH-M) to the flask to dissolve most of the white solid.
4. Suction filter the solution while hot. The solution containing your product will be easier to collect if the filter funnel and flask are heated
with a heat gun before the filtration.
5. Cool the flask and the product should crystallize as a white or grey solid. Transfer the product to a beaker, and collect and dry it by suction
filtration.
6.Obtain the yield and IR spectrum of this product.
This compound is moisture sensitive and may turn brown and viscous if left standing for too long. This will not affect the next reaction.
Preparation of Sn(C2H5)2Cl2 2(CH3)2SO
1. Dissolve a known amount of Sn(C2H5)2Cl2 in a minimum amount of anhydrous ether (Fridge) (about 10 mL ether per gram of solid). Pour this solution
into a solution of two equivalents dimethyl sulfoxide (FH-M) in 2-3 mL ether. Leave the mixture to stand and precipitate in the fridge .
2. Suction filter and obtain a percent yield and IR spectrum of Sn(C2H5)2Cl2 .2DMSO. The S-O stretching mode of uncoordinated (CH3)2SO occurs at
approximately 1100cm-1. Try to locate the S-O absorption in the spectrum of your complex.
From the change in frequency from the free species, suggest whether DMSO is coordinated to Sn through the S or O in your complex.
The synthesis can be done with out the Nitrogen atmosphere. Ethyl bromide is also easily made from NaBr, H2SO4 and 95% EtOH. I ran the synthesis using
starter fluid directly from the can as a substitute for diethyl eher. After adding a iodine crystal, the reaction started right up. I use magnesium
powder for all of my grignard reactions.