1-Methyl-1,2-dicyclopropylcyclopropane; Sintin; Synthin; Tsycklin
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||136.238 g·mol−1|
|Boiling point||158 °C (316 °F; 431 K)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|(what is ?)|
Syntin is a hydrocarbon with the molecular formula C10H16 used as a rocket fuel. It is a mixture of four stereoisomers (see below). It has a density of 0.851 g/mL, and a boiling point of 158 °C. Due to the presence of three strained cyclopropane rings, the molecule has a highly positive enthalpy of formation: ΔfH°(l)= 133 kJ/mol (980 kJ/kg, the average value for the isomeric mixture), bringing additional energy into the combustion process. It has advantages over the traditional hydrocarbon fuels, such as RP-1, due to higher density, lower viscosity and higher specific heat of oxidation.
Syntin was used in the Soviet Union and later Russia in 1980s-1990s as fuel for the Soyuz-U2 rocket. It was first synthesized in the USSR in the 1960s and brought to mass production in the 1970s. It was prepared in a multi-step synthetic process from easily obtained acetylcyclopropane:
After dissolution of the USSR, the production of this fuel was halted due to the expense of the synthesis.
Syntin is a molecule with two stereocenters at the central cyclopropane ring. Thus, the following four stereoisomers may exist:
In practice, the fuel has been used as mixture of all four stereoisomers.