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| Names | |
|---|---|
| Preferred IUPAC name 21-Methyl-11,21:22,31-tercyclopropane | |
| Other names 1-Methyl-1,2-dicyclopropylcyclopropane; Sintin; Synthin; Tsycklin; Tsiklin | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| Properties | |
| C10H16 | |
| Molar mass | 136.238 g·mol−1 |
| Density | 0.851 g/mL |
| Boiling point | 158 °C (316 °F; 431 K) |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Syntin is ahydrocarbon with themolecular formula C10H16 used as a rocket fuel. It is a mixture of fourstereoisomers (see below). It has a density of 0.851 g/mL, and a boiling point of 158 °C. Due to the presence of three strainedcyclopropane rings, the molecule has a highly positiveenthalpy of formation: ΔfH°(l)= 133 kJ/mol (980 kJ/kg, the average value for the isomeric mixture),[1] bringing additional energy into the combustion process. It has advantages over the traditional hydrocarbon fuels, such asRP-1, due to higher density, lowerviscosity and higherspecific heat of oxidation.
Syntin was used in theSoviet Union and laterRussia as fuel for theSoyuz-U2 rocket from 1982 until 1995.[2][3]
It was first synthesized in the USSR in 1959[1] and brought to mass production in the 1970s. It was prepared in a multi-step synthetic process from easily obtained acetylcyclopropane (the 3rd molecule):
After dissolution of the USSR, the production of this fuel was halted due to the expense of the synthesis. On September 3, 1995,Soyuz TM-22, the seventy-first and lastSoyuz-U2 rocket launched, being the last rocket fueled with Syntin.[3]
Syntin has two stereocenters at the central cyclopropane ring. Thus, four stereoisomers exist:
In practice, syntin is used as aracemic mixture (a mixture where all stereoisomers are present in equal amounts).
