[Enthalpy]

Hello you all!

Boctane is a synthetic rocket fuel designed to improve performance over kerosene.

Finally, I could find it to be bi-cyclobutane C₄H₇-C₄H₇, Smiles C1CCC1C2CCC2 (it's not bicyclo[3.3.0]octane aka octahydropentalene)
http://www.freepatentsonline.com/6415596.html
and hand-estimate its heat of formation to +35.4kJ/mol, not far from +55.1kJ/mol claimed there
http://www.propulsion-analysis.com/downloads/thermo/thermo.inp
At +35.4kJ/mol it would bring 4s more specific impulse than kerosene Rp-1 and 7s more than Jp10, combined with a higher density, and might be used by existing rocket stages, fine. As good as Syntin, probably cheaper.

First, would you know more: density, melting point, boiling point, flash point...?

And: how safe and cheap could it be to produce in hundreds of tons?

I believe cyclobutane is a by-product of natural gas or oil, isn't it? So could maybe a chlorine substitute a hydrogen, and later a chlorocyclobutane fuse with a cyclobutane? Is that safe and cheap, like 1M$ for 100t? Better ideas?

By the way, I'm not studying chemistry, so ready-to-use answers would be just fine. Thanks!
Marc Schaefer, aka Enthalpy

[Enthalpy]

Naphthenic crude oil contains around 50% cyclic alkanes. Then, textbooks cite cyclopropane and cyclobutane as examples, but they can't possibly be the most abundant... Probably enough cyclobutane to fly rockets.

Can you imagine a way to transform cyclobutane into cyclobutyl-cyclobutane? Substitute first with a bromine, maybe? Or an alcohol? Something workable in the 100's of tons.

[Honclbrif]

Yes, just hold on while I tell you how to make millions of dollars worth of rocket fuel, for free, over the internet.

I'll be right back.

[orgopete]

By the way, I'm not studying chemistry, so ready-to-use answers would be just fine.
…
Can you imagine a way to transform cyclobutane into cyclobutyl-cyclobutane? Substitute first with a bromine, maybe? Or an alcohol? Something workable in the 100's of tons.

How would you make ethane from methane in the 100's of tons? I won't even ask for it to be cheap, yet.

Wouldn't dicyclobutylacetylene be better yet?

[Enthalpy]

Yes, just hold on while I tell you how to make millions of dollars worth of rocket fuel, for free, over the internet.

I don't plan to earn a cent from that. But you can make millions from my idea
http://www.chemicalforums.com/index.php?topic=46384.0
put for free over the Internet.

[Enthalpy]

Wouldn't dicyclobutylacetylene be better yet?

Multiple bonds aren't desired because fuels are generally used in a jacket to cool the combustion chamber, and as the fuel gets hot, its multiple bonds would let it polymerize into some gum that prevents cooling, ending the game.

Triple bonds are said to make molecules able to detonate without an oxidizer, as acetylene itself does. This is excluded in a rocket.

In the early days, fuels like NC-CC-CN (three triple bonds, no hydrogen) were tried and abandoned because of boom. And as they lacked hydrogen, they weren't even efficient.

Summing these reasons, hydrocarbon fuels tend now to be quasi-alkanes; more energetic molecules are strained but have no multiple bonds.

[orgopete]

I concede that I am not a rocket scientist.

Let's look at what has been mentioned thus far.

Triple bonds are said to make molecules able to detonate without an oxidizer, as acetylene itself does. This is excluded in a rocket.

Wikipedia: "…showed that propyne would be highly advantageous as a rocket fuel for craft intended for low Earth orbital operations. This conclusion was reached based upon a specific impulse expected to reach 370 s if oxygen is used as oxidizer, a high density and power density, and the moderate boiling point, which causes the chemical to present fewer problems in storage than for example a fuel that needs to be kept at extremely low temperatures."

The problem is a generalization for which I don't agree. Acetylene may pose an explosive hazard, but just as picric acid and trinitrotoluene (TNT) are explosives, nitromethane is a fuel used in dragsters and race cars, one cannot simply draw an analogy that compounds with nitro-groups are explosives. Many are and many are not. In order to distinguish, one must understand the relationship between the compounds and its reactions.

Again, remember, I am not a rocket scientist. I don't purport to have any special knowledge. In the patent Enthalpy cited, the Russian authors cited a 2% improvement over kerosene. If you research this a little further in Wikipedia, you would find the Russian space program had used a cyclopropane derivative at one time, but with the collapse of the USSR, they could no longer afford to use in in their space program. Even in the US space program, simply using a more highly purified kerosene was abandoned as too costly.

It looks as though even rocketry is limited by the laws of conservation of energy, but in an indirect way. Probably the real law is about the "bang for your buck". You can get ton quantities of kerosene by distilling crude oil. How cheap must cyclobutyl cyclobutane be in order to make a 2% improvement in performance economically favorable?

If think if Entropy can answer this question, then chemists or more likely chemical engineers can predict whether it can be done. Let me point out, it isn't a question of whether it can be done, the Russian rocket scientists already used it. The challenge is to compete with kerosene. Can you synthesize (and purify) something when the competition is distilled directly from crude oil? Want to buy a nice bridge over the East River?

[Enthalpy]

Third forum in 3 days that asks me about propyne.

Propyne has never been used as a rocket fuel, and won't be, because it's an explosive.
One single man (Dunn) imagines it could be advantageous, and seems to be followed by Internet users. Nothing more.

Nitromethane is abandoned as a rocket fuel because it's an explosive. Pity, people hoped to have a monopropellant.

What Dragsters do in kg quantities is their business. Rockets with 1000t propellants don't take such risks.
Even N₂O has exploded and killed one worker recently on a rocket.

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Syntin had allegedly 3 cyclopropane linked to an other, plus a pair of methyl. Rumours, not direct testimony, claim it was too expensive.

Cyclobutyl-cyclobutane has practically the same performance, and apparently cyclobutane can be isolated from crude oil. Being widely ignorant about synthesis, I imagine cyclobutane is the difficult part of the task, and fusing the rings the easier part.

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For a 5t payload paying 100M$ its launch, Boctane could bring 200-400kg performance more depending on how many stages can afford it - performance varies more than 2%. It means that from time to time, one payload can fly on a launcher or not. You may translate it to 5M$ more value per launch.

If 20t can be produced for 2M$ then the upper stage would use it. If 300t can be produced for 5M$ then the lower stage would use it as well.

The stuff is interesting enough that Atlas V wants to switch to it.

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That's a long discussion already for a question I imagined to be elementary... Let me repeat it:

Can two cyclobutane rings be linked to produce this Boctane, in 100t quantity, for a few M$?

Thanks!

[Enthalpy]

No answer...

Is this too difficult?

Or is it too easy for you?

Wrong sub-forum, maybe... But I have no intention to become a chemist, so an answer obvious for everyone else would be fine to me!

[fledarmus]

The only synthesis for spiro[3.3]heptane I have been able to find so far uses methylenecyclobutane for a starting material. Yields are pretty good, at close to ~80%, but the starting material is ~$100/gm and it uses a zirconium catalyst. I don't think it is practical for a multi-ton synthesis.

[Enthalpy]

Thank you!

Accordingly, Russian rocket builders didn't try to make spiro molecules - though spiroheptane would bring performance indeed. Too expensive even for a very-last stage.

Boctane is to be Cyclobutyl-Cyclobutane C₄H₇-C₄H₇ (I try to attach a picture), which should be easier to produce.

[orgopete]

No answer...

Is this too difficult?

Or is it too easy for you?

Wrong sub-forum, maybe... But I have no intention to become a chemist, so an answer obvious for everyone else would be fine to me!

The challenge is the landscape. It is virtually being assumed that the Russians, Europeans, and NASA don't know what they are doing. Don't they know that bicyclobutane is a superior and cheap rocket fuel that can be readily prepared in multi-ton quantities?

From my experience, you are far more likely to be successful by utilizing something that has already been shown to work over something that even experts might predict should work but has never been demonstrated to work. Bicyclobutane is apparently a known compound based upon the patent previously cited. That seems a far better starting process than any thought of joining two cyclobutanes. My instinct is that any chemists here would suggest you can forget bicyclobutane as an alternate to kerosene on a cost basis if it is gives only a 2% improvement. However, I could be wrong. How was it prepared?

No matter, let's try it based upon hypothetical economics. Let us assume that cyclobutane can be dimerized into bicyclobutane in a single step and in 100% yield. Let us further assume cyclobutane is commercially available in ton quantities at the same price as kerosene. All that is needed is to turn the crank and we're off.

The cost to turn the crank on this process is $25/kg. That seems reasonable based upon my experience. If some of the other chemists with industrial experience can suggest another value, that is fine also. We had used a slightly higher value 15 years ago. This is where I got the $25/kg value from. http://greenchem.uoregon.edu/ACSGoingGreenSite/PDFs/20050315TuesPM/1336Cue.pdf

My experience tells me you cannot couple cyclobutane, cyclobutane is going to be far more expensive than kerosene, the known route to bicyclobutane is going to be costly in processing steps, and I respect that if Russia gave up on their cyclopropyl rocket fuel when costs had to included in their rocket program, then virtually any other hydrocarbon would have a difficult time to compete with kerosene on a cost per payload basis.

If the board were to apply the same standard to this topic, then not being a chemist would never be sufficient for not providing a shred of input. I doubt anyone thought cyclobutane could be dimerized. If cyclobutane is being asked to join together, give at least one other example or principle that would even suggest this to be a reasonable reaction. Once you do that, I think you will find a number of chemists will be happy to help you do a cost estimate from the raw material costs, reagents, reactions, and yields.

I faced this challenge working in the agchem industry. If a farmer could buy weed control for $15/acre, then if you had a herbicide that you need to apply 1 lb/acre, you need to be able to make it for $7.50/lb in order to make a profit. That will limit you to very simple compounds. However, if you only needed 0.1 lb/acre, then you could be profitable if you could prepare it for $75/lb. There is no magic to know your compound has to be extremely potent in order to compete on a cost basis. Here, the competition is crude oil. You distill it a couple of times.

[Enthalpy]

Thanks for the input!

The aim isn't to be cheaper than kerosene, but more efficient. The added payload capacity is quite more than proportional to the fuel performance, and should be compared with launch charges, of which present kerosene costs are nothing.

Syntin, which contained three cyclopropane rings linked to an other, had been used. Excessive cost is suggested by one source without reference. It could just be that two professors knew how to produce it, and when Russia stopped paying their wages, one became a mammoth ivory smuggler and the other a Siberian tiger hunter. Anyway, isn't a string of C3 rings more difficult to produce than of C4?

As Atlas V plans to switch to Boctane, maybe it makes economical sense.

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So you consider the C4 ring will break open as soon as we near some halogen?

[Enthalpy]

I could read Boctane's data published by Katorgyn, that is at the source.

Heat of formation is +80cal/g (I estimated +77cal/g)
Density 828kg/m3. Viscosity 2.4cPs @+20°C.
Melt -54.5°C / Flash +20°C / Boil +134°C / Autoig +205°C / Decomp +430°C

[Honclbrif]

I'm a chemist and not an economist, but given that we know:

1. The cost of kerosene
2. The cost of the increased payload which boctane will provide

It seems pretty easy to put a definite dollar value on how much boctane can cost and still be economical. Have you run these numbers yet?

Modification:

My reasoning is if you could double your payload with boctane, you could then charge up to double the price for kerosene for it and still count it as an economical fuel. So, can boctane be produced for double the price of kerosene?

Modification 2:

http://www.indexmundi.com/commodities/?commodity=jet-fuel, the cost of jet fuel (which as I understand it is basically kerosene) as of 8/30/2011 was about $1/kg. Assuming orgopete's estimate of $25/kg is reasonable, can boctane provide 25 times the performance?