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),[1] 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.

Preferred IUPAC name
Other names
1-Methyl-1,2-dicyclopropylcyclopropane; Sintin; Synthin; Tsycklin
3D model (JSmol)
  • InChI=1S/C10H16/c1-10(8-4-5-8)6-9(10)7-2-3-7/h7-9H,2-6H2,1H3 ☒N
  • InChI=1/C10H16/c1-10(8-4-5-8)6-9(10)7-2-3-7/h7-9H,2-6H2,1H3
  • CC1(C2CC2)C(C3CC3)C1
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 their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

Syntin was used in the Soviet Union and later Russia as fuel for the Soyuz-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):

Syntin synthesis 01

After dissolution of the USSR, the production of this fuel was halted due to the expense of the synthesis. On September 3rd 1995, Soyuz TM-22, the seventy-first and last Soyuz-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 a racemic mixture (a mixture where all stereoisomers are present in equal amounts).

See alsoEdit


  1. ^ a b A.P., Mesheheryakov; V.G., Glukhovtsev; A.D., Petrov (26 September 1959). СИНТЕЗ 1-МЕТИЛ-1,2-ДИЦИКЛОПРОПИЛЦИКЛОПРОПАНА ["Synthesis of 1-Methyl-1,2-Dicyclopropylcyclopropane"] (PDF) (in Russian). Institute of Organic Chemistry, UdSSR Academy of Sciences. pp. 779–781. Retrieved 22 July 2022.
  2. ^ ЖРД РД-107 и РД-108 и их модификации [Liquid Rocket Engines RD-107/108 and their modifications]. (in Russian). Retrieved 22 July 2022.
  3. ^ a b Последний бой углеводородов? [The last battle of hydrocarbons?] (PDF). Volume 18, No 2. (in Russian). Novosti Kosmonavtiki. 2008. pp. 44–46. Archived from the original (PDF) on 20 September 2009.


  • A. P. Mesheheryakov, V. G. Glukhovtsev, A. D. Petrov, “Synthesis of 1-methyl-1,2-dicyclopropylcyclopropane”, Doklady Akademii Nauk SSSR, 1960, 130, 779-81.
  • Yu. P. Semenov, B. A. Sokolov, S. P. Chernykh, A. A. Grigor'ev, O. M. Nefedov, N. N. Istomin, G. M. Shirshov, “Multiple strained-ring alkane as high-performance liquid rocket fuel”, RU 2233385, C2 20040727.
  • T. Edwards, “Liquid Fuels and Propellants for Aerospace Propulsion: 1903-2003”, Journal of Propulsion and Power, 2003, 19(6), 1089-1107.
  • V. Azov, D. Vorontsov, "The last battle of hydrocarbons?", Novosti Kosmonavtiki, 2008, 18, No. 2 (301), 44-46.