Make your own free website on Tripod.com

Gas-Phase Reaction Apparatus

This apparatus is designed for reacting things in the gas-phase. It is large enough to make the ammount of product produced, worth the set up of this system. When building this apparatus, you must have some common sense on hand. You are not screwed if your local hardware store does have these exact peices, just know what the peices do and find a suitable substitute. Remember, when working with copper, everything is calculated to the outer diameter, not inner diameter like PVC. Also, you must know how to sweat copper pipes. I will not provide a guide to this as there are plenty on google and they all pretty much say the same thing. Always remember to use plumbers tape on any threaded connections.

 

Part One; Gas inlet and combustion tube

This part took me the most planning, but is fairly easy to do as there is only slight modification needed of some of the peices.

Materials:

1/2" OD copper tubing
1/2" x 1/2" x 1/2" T-connector
1/2" End plug
1" OD copper tubing, 24" long
1" to 1/2" reducer
1/4" OD copper tubing, 24" long
1/2" threaded connector, female, with 1/2" threads
1/2" Threaded male adapter, with 3/8" hose barb

 

 

 

 

 

 

 

First, you must cut a 7" long peice of the 1/2" tubing. Sweat this into the 1" to 1/2" reducer as shown

Set that aside to cool and grab your t-connector. Sweat the remaining ammount of 1/2" copper tubing into one of the ends, then cut it so that there is 1" of this tube sticking out of t-connector. Then, sweat on the copper end plug.

Drill a 1/4" hole in the center of this endcap. Just stuck the drill bit through once, you dont want this hole too big.

Now, sweat this t-connector onto the peice you first made with the 7" long copper tube

Take your 1/4" tubing and stick it through the 1/4" hole in the end cap. Push it through until 2.5" extend from the other side. This is measured from the edge of the reducer, not from the pipe.

Solder this copper tube into the end cap. Now, on the top of the t-connector, insert the remaining ammount of 1/2" copper tubing. Sweat this in, and then cut it off so there is an inch of copper tubing extending from the t-valve. Then, sweat your threaded female adapter on there with

Thread your 3/8" hose barb into this (with 1/2" threads). Be sure to use plumbers tape

Now sweat this peice onto the 24" long 1" OD copper tube. Look at the copper thing leaning up against the cabinet, not the potato launcher.

The last step is to sweat on a 1" male threaded adapter to the 1" OD copper pipe. The threads should be 1" and the connection to the pipe should be 1". It must be male otherwise some of your catalyst, if you use one, might get stuck in the threads as you load it if it were a female connector. You can see the pipe is still smoking, because I took a picture of it right after I soldered the fitting on.

 

Part Two; Combustion tube to condenser transition

This has its own section only because I wanted to keep the instructions for the condenser as short as possible. Every peice here should be available at the hardware store, you shouldn't need to improvise.

Materials:

1" OD copper pipe
1/2" OD copper pipe
1" Female threaded adapter, with 1" threads
1" to 1/2" reducer
1/2" 90degree elbow joint

 

 

 

 

 

First, cut a 2" long peice of the 1/2" copper tubing. Sweat this into the 1" to 1/2" reducer

Set that aside to cool. Cut a 7" long peice of the 1" copper tube and sweat this into the 1" female adapter (with 1" threads).

Once the two peices from above are cool, sweat the together as shown

Lastly, sweat on the 1/2" 90 degree elbow joint

 

Part 3; The condenser

This part takes the most work and the most materials in my mind. The condenser is in the form of a liebig condenser. It will have a 1" outer jacket, about 17" long (about 450mm) and a 1/2" inner tube, with 3/8" hose barbs for the cooling water connectors.

Materials:

1" OD copper tubing
1/2" OD copper tubing
2 1" X 1/2" X 1" T- connectors
2 1" to 1/2" reducers
2 1/2" to 1/2" threaded adapter
2 1/2" thread, 3/8" hose barb

 

 

 

 

 

 

First, cut a 2 3/8" peice of 1" copper tubing. Sweat this into one side of your T-connector.

Then sweat the 1" to 1/2" reducer on the other side of this 1" tube

Repeat the above two steps a second time to get another one of those connectors

Cut a 17" long peice of the 1" copper tubing, then sweat one of the above connectors onto one of the ends

Sweat the other connector that you made earlier onto the other side of this pipe.

This is the step where all the modifications take place. In the 1/2" side of your reducers, there is a little ride that keeps you from sliding a copper tube all the way through. You must take a rotary tool (or rat-tail file if you have the time) and grind this ridge out on both reducers. Once they are ground you, you should be able to slide a 1/2" peice of copper tubing all the way through. Cut a 30" long peice of copper tubing a push it through so that 1" of this sticks out of one of the reducers. It is tricky to sweat this into place as it is hard to get flux into joints, but if you're patient you will get it eventually. Sweat the tube into place and let it cool.

Once the condenser is cool, you can resume work on it. Into the top of one of the T-connectors, sweat in a peice of scrap 1/2" copper pipe. This scrap should be around 4" long or longer.

Cut the scrap off so that there is 1" sticking out of the t-connector

Now, onto this peice sticking out, sweat on the 1/2" to 1/2" threaded copper connector

Repeat the last 3 steps for the other side of the condenser, then let it cool down

Thread on your 1/2" threaded to 3/8" hose barb onto each side of the condenser. It is not neccesary to use 3/8" here, I just use 3/8" because that is the standard size I use in my lab for hose connections

That's it, you're done with the condenser. There are only a couple steps left to finish this whole apparatus.

Part 4; finishing the apparatus and checking it for leaks/possible problems

Materials:

Gas inlet and combustion tube

Combustion tube to condenser transition

Condenser

Flowing water source (for checking condenser)

Regular water source (for checking for leaks and checking condenser efficiency)

 

 

It would be wise to check your condenser for leaks before you finish the whole apparatus. Attach the water inlet to the bottom connector on the water jacket, and the water exit to the top. Run cold water through it for 20 minutes or until you see a visable leak. If a leak exists, fix it and run the water through again. If the leak is on a solder joint, you will have to wait for the water to dry up before you can patch it.

Once you're done leak testing the water jacket, its time to finish the apparatus. Sweat the combustion tube to condenser transtion onto the longest part of the exposed condenser tube.

The combustion tube to condenser trantion will now also be called the condenser since it is one peice. All you have to do is screw the condenser onto the combustion tube once you are ready to use this apparatus. It is threaded so that it can be stored easier and so you can load the catalyst in the tube when you need to.

To test the efficiency of the condenser, lead water vapor into the 1/4" inlet tube (which would normally be used for the limiting reactant). Heat the center of the combustion tube to 500C+ with water flowing through the condenser. Continue running water vapor through the heated combustion tube for 20-30 minutes. Hopefully most of the water you boiled into there will be in the receiving flask. If there is a significant ammount of water missing from the receiving flask, there might be a problem with your condenser or you might have a leak somewhere. Fix the leak if you find it and try again. If the water doesn't condense, rebuild the condenser but make it longer by about 10".

You are done and ready to begin gas-phase syntheses.. Good luck to you.