Chapter 16 Organic Synthesis Flashcards
How to heat a reaction under reflux (equipment)
What is better than a bunsen burner (importwnt)
What to ensure not on top (imortwnr)
What else to add befor starting to boil( important)
- a clamp, bunsen burner, liebig condensee, water, ROUND BOTTOM / PEAR LEAF SHAPED FLASK
- a clamp attches the condensed by neck, connected to flask upright.
Bunsen burned underneath, however a HEATING MANTLE IS BETTER AS NO NAKED FLAME
3) ensure there is no STOPPER AT TOP OR ELSE BUILD UP IN PRESSUEE CAUSINF EVERYTHING TO BREAK
4) ENSURE YOU HAVE ANTI BUMPING GRANULES IN LIQUID , stops large bubbles forming from bottom and everything shaking glass
When doing water in and water out where shiuldnyou always do
Water in at bottom ! This ensures water travels against gravity and no air bubbles, whooe thing is covered
How to clamp in reflux
Losely as glass fragile and VERTICAL!
What is the poijt of reflux
Often reactions happen better at faster temps for activiation enedgy, so reflux is done but this ensures no volatile components ESCAPE THE FLASK, reactant or product it all condenses when reaches its temp
Whats point of distillation
This is to purify a product, and assuming impurities have different boiling points, the pure product will boil and escape while rest stay
Most volatile gas leaves first, and yku can confirm by checking temp on thermometer atatched to still head
How to set up distillation roughlyn
- two clamps, when clamped to reactant flask with either heatijg mantle or bunsen burner snd wire gause underneath
- here flask connected to condenser, with a thermometer pocket in top so you add a thermometer and measure expected temp at which pure product supposed to boil st etc
Then cindenser go all the way to other clamp snd is clamped , attached is a recieved where product falls down inti a flask - again water in is bottom , yiu have to do fhis at an angle so if falls to gravity
- make sure no gals between jointd (add grease) and you can start
How to purify organic product like we did when making haloalkane jn class?
1) removing aqeuos layer
Mix them in separating funnel, ensure tap is closed and invert so they mix, letting off pressure by opening tap
- here eventually aqeuos layer (water snd acid etc) and organic product will settle as they are nkt solible. Can test by adding water
- now remove aqeuos layer until organic.
How to purify organic product like we did when making haloalkane jn class?
2) removing excess acid
To remove excess acid sodium hydrogen carbonate to react with acid rinmake salt water and co2
- release the co2 by releasing pressure and keep doing this
- remove lower aqeuos layer again
And repeat this a few times to ensure NO ACID LEFT BEHIND
How to purify organic product like we did when making haloalkane jn class?
3) a final wash but using what?
We use water ti finally wash it , removing any SALT PRODUCED LEFT BEHIND as this will dissolve etc
- separate aqeuous layer again
How to purify organic product like we did when making haloalkane jn class?
4) drying product
There still maybe some aqeous content left as you cant be exactly accurate , thus you add a DRYING AGENT such as anhydrous sodium sulfate
Add some half spatula at a time, until solid stop clumping, this isnhow you know all the water id gone, but fint sdd tio much or it will saturate and you will lose product
How to purify organic product like we did when making haloalkane jn class?
5) FINAL PURIFICATION DISTILLATION
1) final distillation ensured anythin st all left behind including drying agent, etc left. Sometimes even the orginal organic compund
2) distill and only collect what your product boiling point is!
Now you can perform calculations
How to purify product alk steps summaried into one
1) separate from separating funnel after initak mix
2) treat frw times with sodium hydrogen carbonate and separate
3) water wash
4) add anhydrous sodium sulfate to dry
5) distill for final
