Hexane from Electronic Contact Cleaner

OTC Hexane From Electronics Cleaning Fluid
Hexane is a volatile, flammable liquid that is commonly used as a non-polar solvent in laboratories for extractions. It has the chemical formula C6H14 meaning it is a 6 carbon alkane. Its volatility and its solvency properties makes it ideal for cleaning off grease from electronic contacts to improve conductivity. This makes contact cleaner a convenient source of hexane for home chemists.

Theory:
The label on the contact cleaner states it contains the following compounds:
Ethanol 1-5%
n-Hexane 1-1%
Isohexane 80-90%
Carbon dioxide 2-5%
Petroleum distillates 1-10%

The best course of action to separate these components would be distillation. The boiling points of the components:
Ethanol 78.4˚C
n-Hexane 68.7˚C
Isohexane 60.3˚C
Carbon dixoide -56.6˚C
Petroleum distillates >80˚C

Since there is a difference of more than 20˚C between the desired product and the other compounds, simple distillations should be enough to separate out the hexane. Just to be sure, the mixture will be washed with water prior to distillations to remove the majority of the ethanol.

Equipment: 

• Hotplate 
• Stir-bar 
• 500ml 3-Neck round bottom flask
• Thermometer adapter 
• 300mm Liebig condensor 
• Vacuum take-off adaptor 
• Receiving flask 
• Thermometer 
• 2 Glass stoppers 
• 100ml Graduated cylinder
• 250ml Separatory funnel 

Chemicals: 

• 6 Cans contact cleaner
• 20g Magnesium sulfate (anhydrous) 
• Distilled water 

Procedure:

1. Half a can of contact cleaner is emptied into the separatory funnel. 
2. The contact cleaner is washed with 100ml of distilled water. 
3. The washed contact cleaner is emptied into the distillation setup. 
4. Heating is turned on and the contact cleaner began to distill over at 40˚C. 

5. The first fraction was collected between 40-60˚C, the second fraction between 60-70˚C, and the final fraction which was anything above 70˚C. 
6. The second fraction was kept as it contains our desired hexane. 
7. Steps 1-6 was repeated with the remaining cans of hexane. 
8. The combined fractions was dried with 20g of anhydrous magnesium sulfate. 
9. After drying, the combined fractions was redistilled and again the fraction between 60-70˚C was collected. 

OTC Source of Sodium Metaperiodate

Sodium periodate is a useful oxidizer with the formula NaIO4. (It actually exists in two forms, the meta- and the ortho-, but here we will only be dealing with the meta-version). It can even oxidise trivalent chromium all the way to hexavalent chromium. Although this chemical can be prepared using chlorine and sodium iodate, it requires the generation of large amounts of chlorine gas which may be inconvenient. But surprisingly, it can be found cheaply OTC as Autostrip Powder.

This discovery occurred totally on accident, I was visiting Taobao (Chinese version of eBay) and was looking for some printer parts. But that seller also happened to have this powder in stock. I didn't know what autostrip powder is at the time, but being a chemist the oxidising symbol immediately drew my attention. Upon clicking into the listing, I was met with the words: "UN1479 Oxidizing Solid N.O.S. (Sodium Metaperiodate) EC No: 232-197-6". More intrigued than ever, I hastily looked up the MSDS of a similar product which stated 60-100% sodium metaperiodate. Digging deeper I found the technical sheet for this particular brand of autostrip powder and under disposal methods it mentioned that this product is in fact 100% sodium metaperiodate. The 100g packet cost $2.50 ($4 including shipping) so this is a pretty cheap source.

Preparation of Neodymium Sulfate From Magnets

Extracting Neodymium From Magnets
There are many types of magnets in wide use, but currently the strongest permanent magnets are neodymium magnets, which are a sintered powder of an alloy made from neodymium, iron, and boron with the formula Nd2Fe14B. Thus, this makes it a convenient source of neodymium for the amateur chemist.

Theory:
The separation of the neodymium from the iron and boron occurs in a few different steps. First, the magnet is dissolved in some dilute sulfuric acid to form iron and neodymium sulfate. Meanwhile, the elemental boron is left behind since it is not soluble in dilute acid. Then the mixture is heated to take advantage of the inverse solubility of neodymium sulfate. While most substances (including iron sulfate) are more soluble at high temperatures, neodymium sulfate is unique in that its solubility decreases with increasing temperature. As the solution of the two sulfates is heated, the neodymium sulfate crystallizes out.

Equipment:

• Hotplate 
• Electronic mass balance 
• 100ml graduated cylinder 
• 250ml beaker 
• 150mm crystallizing dish 
• Buchner funnel 
• Vacuum pump 
• Vacuum filtration flask 
• Blowtorch 
• #120 Sandpaper 

Chemicals:

• Neodymium magnet (Acid amount is given for a 50.00g magnet) 
• 300ml dilute sulfuric acid ~30% (I used battery acid)
• Distilled water

Procedure: 

1. The magnet is heated strongly with the blowtorch until the curie temperature is reached and all magnetism is destroyed. 
   
2. The Ni-Cu-Ni coating on the magnet is removed using the sandpaper in order to allow the acid to better attack the metal. 
   
3. 200ml of the sulfuric acid is measured out using the graduated cylinder and poured into the beaker.
4. The magnet was placed into the acid and immediately a vigorous reaction is observed with plenty of effervescence. 
   
5. The beaker is allowed to sit overnight for the magnet to dissolve. (The magnet can also be broken into chunks to speed up this step)
6. After sitting overnight, the liquid is poured off and another 100ml of sulfuric acid is added to the beaker to dissolve the remainder of the magnet.
7. After again sitting overnight, the entire magnet should be completely dissolved, but if this is not the case repeat the procedure of adding acid and pouring off the solution. 
8. Crystals of iron sulfate that have formed inside the beaker are dissolved using 100ml of distilled water. 
   
9. All of the solutions are combined and a vacuum filtration is performed to remove the insoluble boron particles. 
   
10. The filtrate is poured into the crystallizing dish which is evaporated on the hotplate set to 120˚C (the solution cannot be boiled since bumping is a severe issue).
    
11. After 100ml of the solution has evaporated, the solution is vacuum filtered while hot to remove the neodymium sulfate that has precipitated out. 
    
    
    
12. The neodymium sulfate is washed with some boiling water to remove the last traces of iron sulfate. 
13. The remainder of the solution is again placed onto the hotplate until a further 100ml of water has evaporated and the filtering procedure is repeated. 
    
14. A third evaporation and filtering of the solution is performed just like the previous ones to recover the remainder of the neodymium sulfate. 
15. After three crystallizations there is very little neodymium sulfate still in solution and so no further recovery is performed. 

Result:

The first crystallization yielded 6.83g of product, the second crystallization yielded 9.37 grams of product, and the third crystallization yielded 3.60g of product. This totals to 19.80 grams of product total. (Right filter paper is 1st crystallization, vial is 2nd crystallization, left filter paper is 3rd crystallization) 

According to the formula stated above, the molar mass of "neodymium magnet" is (144.24*2)+(55.85*14)+(10.81*1)=1081g/mol. Thus, the 50.00g of magnet that I used is 0.04625 moles, and since each mole of "neodymium magnet" contains 2 moles of neodymium, there should be a theoretical 0.09251 moles of neodymium in the magnet. One mole of neodymium sulfate contains 2 moles of neodymium so a maximum theoretical 0.04625 moles of neodymium sulfate could have been produced. One mole of neodymium sulfate octahydrate has a mass of 720.794 grams so the theoretical yield is 33.34 grams. The yield of this experiment is 19.80 grams which is a 59.39% yield. The reason for this mediocre yield is that at first I attempted to boil down the solution which resulted in major losses from bumping. Otherwise, the yield would probably have been higher. 

Conclusion:

I feel that this was a pretty successful extraction and that the final product is reasonably pure. However, each crop of crystals is slightly different. The first crystallization resulted in a fluffy powder that is less crystalline compared to the second crop. The second crop is the most crystalline and the densest, while the last crop seems to be a mix of the first two. This confuses me and suggests that a recrystallization may be needed. 

Build A Workbench With Hand Tools

Many of us who like to tinker around with things want a reliable workbench. However, what if your main focus isn't woodworking, or you just don't have a circular saw/table saw? Well, don't worry, this tutorial will hopefully give you some ideas on what can be done with just hand tools.

I started work on the table legs with a few planks of white pine boards that were bought at B&Q. Any board will likely work, just use whatever is available to you.

















A line was drawn perpendicular to the edge of the board. This determines the length of the table leg, which ultimately determines the height of the table. I decided for my legs to be 80cm tall, because that seemed to be optimal given my height. Yours will obviously vary based on how tall you are. As a rule of thumb, the top of the workbench should come up to the crease of your wrist when your hands hang down by your side. However, the only way to tell is with frequent use. If you develop back pain or other issues it means your bench is not at the right height.


The wood was then clamped onto a wooden stool using C-clamps and a scrap piece of wood. This is to prevent the clamp from denting the wood. A simple handsaw was used to cut down the predawn line. Caution should be taken to go slowly to prevent splintering the board, especially towards the end.








After being cut off from the main board, the plank still has to be cut lengthwise (rip cut) to from 2 thinner boards. The 2 thinner boards will be joined in an L shape to form a leg. A line was drawn down the middle of the board (hard to see in the picture). This line is not in the center because the thickness of the board has to be compensated for. This cut would normally be hard to make with a hand saw, but the next step will show you how.






In order to make a long straight cut with a hand saw, a guide has to be set up. This is nothing more than 2 boards clamped on either side of the cut, with just the width of the saw in between. This prevents the blade from wandering during the cutting process. It is best for the two boards to have a factory straight edge as the guide.







This is the result after cutting, notice how straight the edge is. That would not have been possible without the guide in place.












Repeat the above steps until you have 4 sets. Here is a preview on how they will be joined together.












To attach the two pieces of the leg together, angle brackets will be used. To help locate where they will go, a line is drawn 15cm from each end of the board.











A clamp over the bracket will be very helpful in preventing it from slipping or moving while a screw is driven in.












Once one side of the bracket is attached, the second piece of wood can be clamped so that the next set of screws can be driven. Do this with all the legs.











In order to attach the legs to the tabletop, a framework has to be attached first. This can be made with some simple wall stud lumber as shown on the right.











It is advisable for a lip to be left on the table. This allows materials to be easily clamped to the workbench. I decided to make my lip 3.5cm wide.











Cut the wall studs to length using the handsaw like before. Exactness is not very important, as this is just to reinforce the legs.













All of the wall studs cut to length and laid out for reference.

















Pilot holes are drilled 2.5cm away from the ends, and 1.5cm from the side of the board. A larger drill bit is used to countersink the heads of the screws. If you own a countersink bit, that will work too.










Screws are now driven into the pilot holes drilled last step. Make absolutely certain that the screws you use only penetrate the tabletop halfway.












Brakets will be used to attach the table legs to the tabletop.













First use pencil to mark the location of the screws on the leg and also on the table top.












Then screw the bracket onto the leg. Use a clamp if necessary to hold the bracket in place.













Lastly, screw the legs onto the table.

















The workbench is done!

Synthesize Potassium Dichromate

Make Potassium Dichromate

Potassium dichromate is an orange colored inorganic salt of chromium in its 6+ oxidation state. It can be used in to increase chlorate production efficiency in a chlorate cell. Below I will be producing potassium dichromate from the characteristic green oxide that is well know for being nearly impossible dissolve and produce useful salts out of. 

   2KNO₃  + Cr₂O₃  --------> K₂Cr₂O₇ + 2NO 

Calculations:

1 mol of potassium nitrate is 101.10 grams

1 mol of chromium oxide is 151.99 grams

I will run the reaction on a 0.25 molar scale

50.55grams of potassium nitrate will react with 38.00grams of chromium oxide to make a theoretical of 73.55 grams of potassium dichromate.

Materials:

•  2 250ml beakers

•  50.55g potassium nitrate

•  38.00g chromium oxide

•  100ml fused quartz beaker

•  Blowtorch

•  Electronic mass balance

•  Funnel

•  Filter paper
•  Hotplate 

Procedure:

1.   Weigh out 50.55g of potassium nitrate and place into the fused quartz beaker. 

2.   Weigh out 38.00g of chromium oxide and mix with the potassium nitrate in the quartz beaker.

3.   Clamp using a metal clamp either in a fume hood or outdoors.

4.   Heat strongly with the blowtorch until the potassium nitrate has melted. 

5.   Continue heating and brown nitrogen dioxide vapors should start to be evolved. Keep even heating until no more nitrogen dioxide vapors are produced. 

6.   Once cool, invert the beaker and tap on a piece of paper, a slug of potassium dichromate and unreacted reagents should fall out. 

7.   Heat 150ml of water to boiling and add the slug, stir until most of the potassium dichromate has dissolved. 

8.   Filter the resulting solution while hot to remove unreacted chromium oxide. 

9.   Evaporate the filtrate until dry, be prepared for creep, where by capillary action the crystals crawls up and out the sides of the beaker. 

Conclusion:

The end result is about 30g of reasonably pure potassium dichromate. However, as the solubility curve of potassium nitrate and that of potassium dichromate are rather similar there may still be some potassium nitrate contamination. Also, I think I got a poor yield because I did not heat the beaker long enough. 

Closing Remarks:

1. Remember that this experiment requires the use of a QUARTZ beaker, or at least a ceramic crucible. Using a normal borosillicate glass beaker will result in breakage. 
2. Heat for as long as you can see brown fumes. I didn't heat mine enough which is why I had a poor yield. 
3. Potassium dichromate is TOXIC and is CARCINOGENIC. Wear gloves when handling and also limit exposure to dust. 
4. Hexavalent chromium needs to be reduced with a suitable reducing agent for clean up. I use sodium sulfite. 
5. Chromium is a heavy metal and waste should not be poured down the drain. Instead, evaporate it down and place it into a container for later disposal at a waste treatment facility. 

Synthesize Methyl Salicylate (Wintergreen)

Methyl Salicylate, also know as Oil of Wintergreen is a minty smelling oil naturally produced by wintergreen trees. It is used in many ointments used to treat joint pain. Today we will be making it artificially using methanol and salicylic acid. This is a fischer esterification reaction. 

Materials:

• 2 beakers
• 50.00 grams of salicylic acid
• 40ml of concentrated sulphuric acid
• 250ml of methanol
• 100ml graduated cylinder
•  Hotplate
• Electronic mass balance
• 500ml three-neck round bottom flask (RBF)
• 50ml one-neck round bottom flask (RBF)
• 150mm evaporating dish
• 250ml separatory funnel
• 200ml ice cold water
• 200ml saturated sodium bicarbonate solution
• 300mm Allihn condenser

       Procedure:

1. Weigh out 50g of salicylic acid and add to the RBF.
2.  Measure out 250ml of methanol and add the methanol to the RBF containing salicylic acid.
3.  Mix until all of the salicylic acid has been dissolved.
4.  Measure out 40ml of concentrated sulfuric acid with the graduated cylinder.
5. Add the sulfuric acid slowly and with a lot of stirring to the RBF. Be careful and add it slowly because the dissolution of sulphuric acid in methanol is very exothermic and if too much is added too quickly it may cause uncontrollable boiling. My mixture turned purple because of iron contamination in my drain cleaner grade sulphuric acid. If you use reagent grade this should not happen.
   
6. Set up a reflux apparatus with a condenser and reflux for 1.5 hours.
   
   
   
7. After refluxing for 1.5 hours, dismantle the reflux and pour the contents into the evaporating dish.
8. Set the evaporating dish on the hotplate set at 55C and evaporate off half the volume of methanol.
9. At this point you should see two layers forming, transfer it to the separatory funnel.
10. Add 200ml of ice cold water to the separatory funnel, cap and shake. Let it stand for a few minutes. 
11. Drain the bottom layer of crude methyl salicylate into a beaker. Discard the upper aqueous layer. 
12. Transfer the methyl salicylate back into the separatory funnel, then wash with 100ml of saturated sodium bicarbonate solution. Repeat with another 100ml of saturated sodium bicarbonate.
13. Transfer the crude methyl salicylate into a 50ml RBF and set up for simple distillation. Be careful if using plastic keck clips as methyl salicylate boils at 220 degrees celsius and plastic clips can melt.
14. Distill the methyl salicylate until no more liquid remains in the distillation flask.

I ended up with about 30ml of completely clear methyl salicylate which is about a 65% yield. The oil smells very much like Listerine. However, you should not eat it because it is toxic and an amount as low as 5ml can cause death. 

*Procedure taken and adapted from Nile Red's video on Youtube:

https://www.youtube.com/watch?v=lJLP2bcXDqY