What is a liquid?

I recently had dinner with some chemists and after a bit of red wine the question "What is a liquid?" popped up. The reason the question popped up is the gas sulfur hexaflouride. I had never heard of this stuff before but allegedly you can float solid objects on top of it. Intuitively, I would say that if a ship can sail in it it's a liquid but things clearly aren't that simple. There's quite a few videos with this stuff on the web. In this particular video they float an object on some SF6 in a fish tank (I'm assuming the video is not a hoax). So what is the definition of a gas/liquid? Obviously it' a density thing. Did anyone out there pay attention when they had physical chemistry and would they care to explain it to a simple preparative chemist? Also what is the least dense liquid out there? Besides pentane (0.626 g/cm3) I can't come up with much that has a density below 0.7. D!

Fun with singlet oxygen

So finally I'm back fresh and invigorated after numerous bottles of awesome South Australian Wine. I'd like to recommend Primo Estate/Joseph, Kay Brothers, Pertaringa and Leconfield/Richard Hamilton in McLaren Vale and Langmeil, Rockford and Richmond Grove in Barossa Valley. Anyway, first day back at work I did a photolysis as we often do were I work. In other words a diene is irradiated in the presence of oxygen and a triplet sensitiser (in this case Rose Bengal). I love this reaction because it's absolutely beautiful. Check it out man:
Now the above reaction is obviously totally irresponsible and was only on for less than a minute so that I could take the picture. We are dealing with a fancy piece of glassware that has oxygen bubbling through it whilst two flood lamps are hammering photons away generating singlet oxygen and in the process heating the fume hood up big time. Hence, aluminium foil on the bottom of the hood is required to literally avoid a melt down and I'll be hooking a pump up that sends ice water through the cooling jacket. Moreover, I'm synthesising an endoperoxide - AAaARRRrGGGHhHh PEROXIDE - yeah I know but they are really quite stable. In fact our friends at the defence force haven't been able to blow them up so we aren't too worried. However, to avoid any nasty surprises we try not to make more than 5-10 grams of endoperoxides at any time. So as I said totally irresponsible hence I proceed to wrap this beautiful reaction up in two blasts shields covered in aluminum foil, pull the sash down and hook a cooling box/pump up to the glass ware and the final set up looks like this:
Well at least I know it's beautiful behind all that plastic and aluminium foil. This particular day I was doing the following photolysis:

Reactions of this type generally work quite well giving yields in the 40-70% range and since dienes are easily accessible using classic Wittig chemistry we consider making endoperoxides quite trivial. So why was I making this particular endoperoxide? Well if I told you I would have to kill you. There should be a paper coming out later this year featuring amongst others this particular endoperoxide turning into a supa cool cyclopropane in one (yes one) synthetic step so keep your eyes open for that paper. Some of you are probably wondering what Rose Bengal is. Behold the halogenated beast:We tend to use the bis-triethyl ammonium salt (as shown) because it is nicely soluble in organic solvents such as dichloromethane. D!

Off to McLaren Vale (and Barossa Valley)

As someone pointed out I'm a slacker. I'm off to McLaren Vale for a bit of a wine adventure returning on Thursday and departing the same day for another little wine adventure in Barossa Valley. I expect to tune my brain to chemistry again in a weeks time. I really have to talk a bit about some TEMPO oxidations and Mannich reactions I've been messing around with lately. So come back in a week or so for the lowdown. D!