[Enthalpy]

The cost of Boctane shall not be compared with kerosene but with the value of the payload capacity it brings.

That is, 5% more payload capacity can be sold for 5M$. 200t of fuel for two stages, needing no hardware modification, can be bought for up to this cost. This would allow 25$/kg.
Used at the upper stage only, 40t of fuel would bring 3% more capacity, sold for 3M$, so the maximum purchase cost is 75$/kg in this smaller quantity.
Some three-stage kerosene rocket can use even smaller quantities.
This price is a gross maximum, because companies want purchases cheaper than sales, and a fuel change costs more than its purchase.

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Maybe I should have explained that first:

Propellants make 90% of rockets' mass, and this proportion is very hard to increase. So 5% more payload cannot be obtained by 5% more kerosene, which would have been negligible. It needs a whole rocket (100M$ recurring cost) 5% bigger, plus a new design (many G$).

In fact, a flexible approach would let most payloads fly with normal RP-1. Sometimes a payload will need just more than the launcher's capacity, and only this customer pays Boctane up to the difference between a 5t and a 10t launcher. This means smaller and irregular amounts of Boctane, but sold for much money.

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Rocket's RP-1 http://en.wikipedia.org/wiki/RP-1 is cheap. Not as cheap as kerosene, because components that would make bubbles or gums at heat (when it flows in the combustion chamber's cooling channels) have been removed - among several other demands.

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So, cost would mean, a few times a year:
- Produce two trucks of Boctane for well under 3M$, or
- Eight trucks for well under 5M$

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Does it make sense to start with cyclobutane, as it seems available from petroleum, and connect two rings?

I vaguely imagine it could react with a bit of chlorine diluted in nitrogen or argon, possibly at room temperature and aided with light, to produce chlorocyclobutane which must condensate more easily than cyclobutane and chlorine.

Then, I figure diluted chlorocyclobutane would be brought to react with cyclobutane - did I read AlCl₃ catalyses this reaction?

[azmanam]

Sounds to me like you're looking for a reductive coupling of alkyl halides.  This is historically quite a challenging reaction due to lots of factors, not the least of which is competative beta-elimination of the alkyl halide to an alkene.

This paper describes such a coupling: http://dx.doi.org/10.1021/ol200617f.  Probably not cost effective, but it will likely do what you want.  BTW, bromocyclobutane is commercially available (though expensive).  Chlorination of cyclobutane is probably not good, due to frequent polyhalogenation.  AlCl3 does couple alkyl groups... but only to aromatic rings.  That is, one of the starting materials must be an aromatic ring (like benzene). It won't couple alkyl halides to cyclic alkanes.

Step 1: cyclobutane (however you obtain pure cyclobutane in bulk) + Br2 + light/heat --> bromocyclobutane
Step 2: bromocyclobutane (2 eq) + {conditions in linked paper} --> boctane
Step 3: Fly me to the moon (in other words)

ps, I want in on the patent

[fledarmus]

I believe the unsubstituted cyclobutane is made from irradiating ethylene with UV light

[Enthalpy]

I believe the unsubstituted cyclobutane is made from irradiating ethylene with UV light

Hope to understand it properly:
http://classes.yale.edu/chem225b/studyaids/pericyclic/pericyclic.htm
Ethylene is first excited by a photon around 171nm, and then it accepts to couple with an other ethylene to form cyclobutane.

And then I imagined to have some 1,3-butadiene vapour diluted in ethylene, and to excite butadiene around 217nm so it reacts with ethylene and forms Boctane...

But 6eV UV light must first be produced! I put some figures on the output power of 100,000 blue LED from DVD burners, tripling the photon energy, and got nothing at the end. 1kg/day if all light served
Other attempt with a deuterium arc lamp, the L1314 or L1835 by Hamamatsu:
http://jp.hamamatsu.com/resources/products/etd/pdf/L1314_L1835_TLSO1012E04.pdf
inject 150W electricity, obtain 15µW/cm2 UV under 230nm...   

With 100% energy efficiency from the mains to ethylene excited at 7eV, 1kg of cyclobutane would cost "only" 3.3kWh - still affordable, but not with efficiencies like 5% (Led+tripler) or 4ppm (Deuterium lamp), of which only a part is absorbed...

I've always had a bad feeling about photochemistry in ton amounts. It works if you have free Sunlight over hectares, and converters that multiply spontaneously for free.

[Enthalpy]

...reductive coupling of alkyl halides...challenging...This paper describes such a coupling: http://dx.doi.org/10.1021/ol200617f.  Probably not cost effective...Chlorination of cyclobutane is probably not good...AlCl3 does couple alkyl groups... won't couple alkyl halides to cyclic alkanes.

Oops, the paper wants such things, which indeed don't look cheap
http://en.wikipedia.org/wiki/File:Ni%28cod%292.png
http://en.wikipedia.org/wiki/File:PyBOX.png

Chlorination: I had hoped dilution would prevent multiple halogenations, and to begin with, let the reaction make Pshhhhh instead of Boom. But I have absolutely nothing against bromine! Maybe the undesired HX elimination leading to a double bond is less frequent with halogeno-cyclobutane, as cyclobutene is energetically unfavourable.

Step 3: Fly me to the moon (in other words)
ps, I want in on the patent

Too late for a patent! Patentable material must be new, which means, unpublished. In other words, I don't seek a patent.
But the Moon, sure! With present technology, a trip equivalent to the Apollo mission would fit in this launcher:
http://saposjoint.net/Forum/viewtopic.php?f=66&t=2554&start=20#p30805
it's the spaceship underprice.

[Enthalpy]

From its aspect, I could imagine that Boctane dissolves Cubane, and in bigger amounts than the 18%wt Cubane in Hexane. This would make Boctane even more attractive... as soon as Cubane is produced in big quantities at a reasonable price.

Agip is rumoured to have dissolved some Cubane in a competition gasoline before it was forbidden or detected, so at least some 10kg can be made presently, for a few M$. Still some way to go maybe?

And if Cyclobutane dissolves Cubane in good amounts, it could improve an already excellent propellant, especially if this keeps Cyclobutane liquid to a higher temperature.

[Enthalpy]

Edit to my bizarre hopes to produce UV light: normal people have already better methods.

For instance a low-pressure mercury lamp produces 90% of its light at 254nm:
http://www.photochemicalreactors.co.uk/immersion.htm
from these figures, power efficiency is 13% at this wavelength.

254nm is short of butadiene's broad 217nm absorption peak, but other sources (zinc?) may fit better.

By the way, I'm not sure ethylene would fuse with butadiene at the end instead of the centre, as the two double bonds aren't local. But if butadiene (or hexatriene, fits 254nm) wants to produce a ladderane
http://en.wikipedia.org/wiki/Ladderane
I have absolutely nothing against it, of course...

[Enthalpy]

In this paper, people reacted two 1,3-Butadiene under UV light to obtain trans-1,2-Divinyl-Cyclobutane:
http://www.orgsyn.org/orgsyn/prep.asp?prep=cv5p0528
with a good material efficiency, and using a 450W lamp for 72h to obtain 100g.

(a) No ladderane was obtained, though a little bird tells me they tried.
(b) A medium-pressure Hg lamp is 7% efficient, and each produced molecule needed 26 photons.
http://www.photochemicalreactors.co.uk/immersion.htm
(c) This means 0.5M€ electricity for 10t of fuel, still acceptable for an upper stage.
In mass-production, I suppose they would irradiate less and separate earlier the product from the reactants, saving light.
In addition, Divinyl-Cyclobutane is available industrially (cas=6553-48-6) and some cheaper synthesis may exist.
(d) I naively imagine Divinyl-Cyclobutane can further react with Ethylene under UV light to obtain trans-1,2-Dicyclobutyl-Cyclobutane
(e) Divinyl-Cyclobutane and other unsaturated compounds aren't wanted in a rocket fuel. But if Dicyclobutyl-Cyclobutane dissolves in Dicyclobutane and widens its liquid range, it would be welcome - in addition to Cyclobutane and maybe Cubane.

Comments please?

[Enthalpy]

Boctane improves the specific impulse over kerosene, but in the US the RD-180 engine pushes a first stage, and there density is equally important. Imagine a rocket whose mass is cut by 2.718 as its (realistic) first stage burns its propellants: then, 1% more propellants brings as much as 1% faster ejection speed.

Now, at an existing stage, a denser fuel can keep the tanks and the turbo-pump (but not the throat, the nozzle... neglected here). The rocket weighs more (who cares) but the engine pushes proportionally more and keeps all pressures as it pumps the same volume (yes, one pump is slightly mismatched).

Here I keep the fuel's volume, a big handicap for amines. It's re-optimized once for RP-1 instead of the Russian RG-1. The RP-1' heat of formation here is unfair but I compare the other fuels anyway.

In the following table (log in to see it), Deta is DiEthyleneTriAmine, tm-triazinane is 1,3,5-trimethyl-hexahydro-triazine, Teda is TriEthyleneDiAmine and Hexamine is Hexamethylene Tetramine. The latter two are solids but I want to dissolve some in an amine to densify it.

While Boctane is good, dirt-cheap cis-Pinane and Deta are as good, and the common missile fuel JP-10 even better here. Even 10% or 20% of dissolved Teda or Hexamine should improve further. These chemicals are already mass-produced.

Marc Schaefer, aka Enthalpy

[Enthalpy]

I had believed that plain cyclobutane is available from petroleum or coal, just because many textbooks state "naphthenic crudes include cyclic alcanes. Examples of cyclic alcanes are cyclopropane, cyclobutane..."

but several better books about oil tell clearly that no cyclopropane nor cyclobutane was found in crude oil, even naphthenic. I've been naive, sorry.

Then, fusing two plain cyclobutane to produce Boctane looks like a bad idea, since the synthesis of cyclobutane in tons amount seems to be as difficult, or even more, than other compounds like methylene-cyclobutane or dimethylene-cyclobutane, which lead to propellants at least as interesting as Boctane.

So without producing first cyclobutane:

Either optimize photochemical synthesis on the big scale. Use butadiene and ethylene to get a mix of vinyl-cyclobutane and divinyl-cyclobutane and maybe cyclobutane, then a welcome mix of cyclobutyl-cyclobutane (Boctane) and dicyclobutyl-cyclobutane and possibly cyclobutane;

Or save the thousands of lamps, go some cyclobutane-related route like methylene-cyclobutane derivatives, obtained from allenes and alkenes, and produce better fuels than Boctane, like spirohexane or dispirooctane derivatives. To my untrained eyes, methods described in the old US patent 4,031,152 look usable for tons or products. Or aren't they?

Unless, of course, the inventors of Boctane as a rocket fuel have a better production method.

These hydrocarbons are only for cases where amines aren't acceptable.

[curiouscat]

Why not make it from coupling  1-bromo-3-chlorocyclobutane and sodium via Wurtz. Wikipedia says yields are 95%.

http://www.orgsyn.org/orgsyn/prep.asp?prep=cv6p0133

How to make 1-bromo-3-chlorocyclobutane I've no clue!

[Enthalpy]

Orgsyn proposes there to make bicyclo[1.1.0]butane which is too unstable for a rocket. You know, they use to carry 200t of fuel, plus the 500t of oxygen that complete the perfect show:
http://www.youtube.com/watch?v=WsVzpE7ltb8
this one was a solid booster. Liquids make a shorter but more intense show.

And because rocket engineers find this less fun than a Buster Keaton movie, they exclude propellants like hydrogen peroxide or nitromethane that are harmless in gram quantity.

Accordingly, Boctane is cyclobutyl-cyclobutane, or H₇C₄-C₄H₇. Two C₄ rings linked.

Plain Cyclopropane is about the limit of stability. Cubane would be perfect if scalable and affordable. A Russian company develops acetylene, but diluted in ammonia - hope its' stable, yuk anyway.

[curiouscat]

Just wanted to draw it out:



This is the one you want to make?

[Enthalpy]

Yes, this one, claimed to have a good combination of stability, liquid range, performance, density. Or a methylated variant, which should lower the melting point.

The description of an attempted photosynthesis from butadiene and ethylene is coming.

[Enthalpy]

This (if you're logged in) is already a sketch of the photosynthesis from butadiene and ethylene as I dare to imagine it. Explanations are to come very soon.

Marc Schaefer, aka Enthalpy