That propellant are a class of saturated hydrocarbons or tricyclic alkanes, that is, with two carbon atoms (carbon is a chemical element from the family of crystallogens, symbol C,…) Bridgehead (A bridge is a construction that makes it possible to cross a depression or an obstacle (course…) and four branches connecting them, including a branch containing no atom (an atom (from Greek ατομος, atomos, “which one cannot…) They are defined and named [m.n.p]Propellanes (propellanes are a class of saturated hydrocarbons or tricyclic alkanes…) in reference to their systematic name (In the life sciences and natural history, systematics is the science standing for…), tricyclo[m.n.p. 01,m+2]Alkanes (alkanes are saturated hydrocarbons. That is, they are not…), the term propellanes deriving from the English “propeller” due to their resemblance to a “propeller” (Helix comes from the Greek and means helix “spiral. A Object of the form …)” and with the suffix ane from alkanes.
They are characterized for the youngest by the presence of a geometry (geometry is that part of mathematics that studies the figures of space…) called tetrahedron (The tetrahedron (from Greek tetra : four) is a body composed of four triangles, from the …) inverted (pyramidal) on the bridgehead carbons and therefore by severe angular and steric constraints making them very reactive. For these reasons, they are intensively studied by organic chemistry (organic chemistry is a branch of chemistry concerned with the scientific study of…). The simplest propellants are those [1.1.1]propellant (C5H6) and [2.2.2]propellant (C8H12).
Propellers are a specific class of paddlelanes for which a branch is nil: [m.n.o]propellant = [m.n.o.0]paddle track.
1,3-Dehydroadamantanes are indeed [3.3.1]Adamantane family propellanes (adamantanes or tricyclo[3.3.1.13,7]Decane is a crystalline, colorless compound with a…)
connection
The central carbon-carbon bond [1.1.1]Propellane connecting two carbons of symmetry (Generally, the term symmetry refers to the existence, in a…) pyramid has a length (The length of an object is the distance between its two ends…) of 160 μm (154 μm for an unrestricted intermediate circuit). The energy (in a general sense, energy means anything that makes it possible to do work, gain energy, etc.) of this bond is still a matter of debate and varies from 270-250 kJ/mol (59-65 kcal/mol) to 0, das is completely non-binding. However, the energy of the diradical is calculated to be 335 kJ/mol (80 kcal/mol) higher. Recently, the nature of this bonding in this molecule (A molecule is an electrically neutral chemical assembly of at least two atoms that …) has been explained in terms of “charge transfer bonding”.
[2.2.2]propellant
The synthesis of the next homologue, the [2.2.2]Propellane from Philip Eaton’s group, famous for their synthesis of cubane, predates that of [1.1.1]Fuel (1973). The synthesis (Scheme 3) consists of two Wolff rearrangement reactions.
Diagram 3. Synthesis of the skeleton (The skeleton is a rigid animal framework that serves as a support for the muscles. It is at the…) of [2.2.2]propellant
This propellane is also unstable. At ambient temperature (temperature is a physical quantity measured with a thermometer and…), its half-life (time is a concept developed by humans to understand it…) (Half-life is the time that a substance needed (drug, radioactive nucleus or other) to …) in relation to its isomerization into the alicyclic amide 3.11 is 28 minutes (Primary form of a document: Law: One minute is the original of a …). Its strain energy is estimated at 390 kJ/mol (93 kcal/mol).
[1.1.1]propellant
the [1.1.1]Propellane was first synthesized in 1982 by converting the 1,3-dicarboxylic acid of bicyclo[1.1.1]Pentane (Pentane is a linear alkane with the formula C5H12.) 1.1 via a Hunsdiecker reaction to the corresponding dibromide 1.2 followed by a coupling reaction with n-butyllithium (n-butyllithium (abbreviated n-BuLi) is the most important of the reactants…) as shown in the diagram 1. The product is separated by chromatography (chromatography is an analytical chemical separation technique that…) on a column at -30°C (!)
Figure 1. Synthesis of [1.1.1]propellant
another synthetic route begins with the addition of dibromocarbene across the double bond of 3-chloro-2-(chloromethyl)propene 1.6 followed by deprotonation with methyllithium (lithium is a chemical element, symbol Li and atomic number 3.) and nucleophilic substitution in 1.7 which is not isolated but kept in solution at −196 °C.
The instability of this propellane is evidenced by its thermal isomerization to 3-methylenecyclobutene 1.5 (at 114°C with a half-life of 5 minutes) and by its spontaneous reaction with acetic acid (acetic acid (from Latin acetum) or ethanoic acid is a carboxylic acid of…) to form a cyclobutane 1.4.
The strain energy is estimated at 427 kJ/mol (102 kcal/mol).
Polymerization (Polymerization refers to the chemical reaction or process that makes it possible…)
the [1.1.1]Propellane is a monomer for the polymerization reaction [n]Staffanen. A radical polymerization (The (through) radical polymerization is a chain polymerization initiated by methyl formate and benzoic anhydride peroxyl like…) forms a distribution of oligomers (diagram 2), but a polymerization by “anionic addition” with n-butyllithium forms a real polymer (A polymer (etymology: from Greek pollus, several, and meros, part) is one…). The diffraction (diffraction is the behavior of waves when they hit an obstacle that doesn’t belong to them…) X of this polymer shows that the CC bond connecting the monomers is only 148 pm long.
Scheme 2. Synthesis of staffanes