Syntin

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Structural formula
Structure of synthin
Mixture of stereoisomers without specifying the stereochemistry
General
Surname Syntin
other names

1'-methyl-1,1 ': 2', 1 '' - tercyclopropane

Molecular formula C 10 H 16
Brief description

colorless liquid

External identifiers / databases
CAS number 93223-46-2
PubChem 519050
ChemSpider 452765
Wikidata Q408418
properties
Molar mass 136.23 g mol −1
density

0.8504 g cm −3

boiling point

158 ° C

safety instructions
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Syntin is a rocket fuel based on a hydrocarbon with the empirical formula C 10 H 16 , which contains three highly strained cyclopropane rings .

Presentation and extraction

The synthesis of Syntin takes place in a multi-stage synthesis sequence in which the individual cyclopropyl units are formed and linked. Hydroxypropyl methyl ketone can be used as the starting compound, from which the first cyclopropyl unit is formed after conversion to chloride by nucleophilic substitution and subsequent cyclization under weakly basic conditions with the cyclopropyl methyl ketone. A subsequent dimerization in the presence of aluminum tri-tert.-butoxide leads to 1,3-dicyclopropyl-2-buten-1-one . A reaction with hydrazine hydrate gives 3,5-dicyclopropyl-5-methyl-4,5-dihydro- 1H- pyrazole. From this, the central cyclopropyl ring and thus the target compound is formed by distillation over potassium hydroxide at 190 ° C. with elimination of nitrogen . A mixture of isomers results from the synthesis.

Syntin synthesis 01.svg

The isomers can be separated by means of preparative chromatography .

properties

Syntin is a colorless liquid which, as a mixture of isomers, boils at 158 ​​° C under normal pressure. A boiling point of 80 ° C. is observed under reduced pressure of 6.5 kPa. Because of the three highly strained cyclopropane rings, the molecule has a high enthalpy of formation of Δ f H ° (l) = 131.6 kJ mol −1 or 966 kJ kg −1 for the trans isomer and Δ f H ° (l) = 134.1 kJ mol −1 or 984 kJ kg −1 for the cis isomer. It is therefore an endothermic compound with a high combustion enthalpy of −6353.7 kJ mol −1 for the trans isomer and −6355.9 kJ mol −1 for the cis isomer. The advantages over conventional hydrocarbons such as RP-1 are the greater density, lower viscosity and greater heat of combustion.

Stereochemistry

Syntin contains two stereocenters on a cyclopropane ring, so that two trans and two cis isomers exist. In practice, only the mixture of the four stereoisomers is relevant:

Syntin Stereoisomers Formulas V.1.svg

use

Syntin was used in the Soviet Union and Russia in the 1980s and 1990s as a fuel for the Soyuz rocket and the Buran . It was first synthesized in the USSR in 1960, and mass production began in the 1970s. It was made from common hydrocarbons in a multi-step synthetic process. After the collapse of the Soviet Union , the production of this substance became too expensive and therefore stopped.

Individual evidence

  1. ↑ a b c d e f A. P. Mesheheryakov, VG Glukhovtsev, AD Petrov: “Synthesis of 1-methyl-1,2-dicyclopropylcyclopropane” in Doklady Akademii Nauk SSSR 130 (1960) 779-781.
  2. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  3. ^ LI Smith, JS Showell: Cyclopropanes. XIV. Incidental Experiments and an Attention to Synthesize Dicyclopropyl in J. Org. Chem. 17 (1952) 839-844, doi : 10.1021 / jo01140a009 .
  4. ↑ a b c S.M. Pimenova, MP Kozina, VP Kolesov: The enthalpies of combustion and formation of cis- and trans-1-methyl-1,2-dicyclopropylcyclopropane in Thermochim. Acta 221 (1993) 139-141, doi : 10.1016 / 0040-6031 (93) 80531-E .
  5. ↑ В. Азов, Д. Воронцов: Последний бой углеводородов? ( Memento of May 4, 2014 in the Internet Archive ) in Новостей космонавтики 18 (2008) 44–46.

literature

  • AP Mesheheryakov, VG Glukhovtsev, AD Petrov: “Synthesis of 1-methyl-1,2-dicyclopropylcyclopropane”, Doklady Akademii Nauk SSSR , 1960 , 130 , pp. 779-781.
  • Yu. P. Semenov, BA Sokolov, SP Chernykh, AA Grigor'ev, OM Nefedov, NN Istomin, GM 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) , pp. 1089-1107.
  • V. Azov, D. Vorontsov: "The last battle of hydrocarbons?", Novosti Kosmonavtiki , 2008 , 18 , no. 2 (301), pp. 44-46.