Alkyne physical properties

Alkynes resemble alkanes and aUcenes m their physical properties They share with these other hydrocarbons the properties of low density and low water solubility They are slightly more polar and generally have slightly higher boiling points than the corre spondmg alkanes and alkenes... 

The physical properties (boiling point solubility m water dipole moment) of alkynes resemble those of alkanes and alkenes... 

Examples of physical properties of alkynes are given in Appendix 1. 

Physical properties of alkynes [49, p. 251] are essentially similar to those of alkanes and alkenes. These compounds are weakly polar and are insoluble in water, but they are quite soluble in organic solvents of low polarity (e.g., ether, benzene, CCl ). Chemically, alkynes are more reactive than alkanes but behave like alkenes. The triple bond appears to be less reactive than the double bond in some reagents while more reactive in others. In a chemical reaction, the triple bond is usually broken into a double bond, which may eventually split into single bonds. 

Alkenes and alkynes have physical properties similar to those of corresponding alkanes. 

Main-chain manipulation offers an opportunity to dramatically change the electronic and physical properties of the PAEs. Popular approaches are the introduction of meta linkages into the polymers, the introduction of aromatic hydrocarbons other than benzene, the introduction of heterocycles, and the substitution of a fraction of the connecting alkyne groups by double bonds. The last strategy leads to polymers that are hybrids between PPEs and PPVs. 

The chemistry of metal complexes featuring alkyne and alkynyl (acetylide) ligands has been an area of immense interest for decades. Even the simplest examples of these, the mononuclear metal acetylide complexes L MC=CR, are now so numerous and the extent of their reaction chemistry is so diverse as to defy efforts at a comprehensive review. " The utility of these complexes is well documented. Some metal alkynyl complexes have been used as intermediates in preparative organic chemistry and together with derived polymeric materials, many have useful physical properties including liquid crystallinity and nonlinear optical behaviour. The structural properties of the M—C=C moiety have been used in the construction of remarkable supramolecular architectures based upon squares, boxes, and other geometries. ... 

In particular, iminoboranes (XBNR) are isoelectronic with alkynes (XCCR). Well-known comparable pairs of isoelectronic species are aminoboranes (X2BNR2) and alkenes (X2CCR2), amine-boranes (X3BNR3) and alkanes (X3CCR3), borazines [(XBNR)3] and benzenes [(XCCR)3], etc. The structure of aminoboranes, amine-boranes, and borazines is well known from many examples. It has turned out that these BN species are not only isoelectronic, but also have structures comparable with the corresponding CC species. In the case of borazines, the aromatic character was widely discussed on the basis of theoretical and experimental arguments. The structural and physical properties of... 

The alkynes have physical properties essentially the same as those of the alkanes and alkenes. Table 1-9 gives the physical properties of some of the alkynes. The trends in melting points and boiling points are again apparent. 

Nomenclature of Alkynes—Physical and Chemical Properties of Alkynes... 

Comparison of Physical Properties of Alkanes, Alkenes, and Alkynes... 

Alkynes, carbon chains containing a carbon-carbon triple bond, have simitar physical property trends to alkanes and alkenes. They are only slightly more polar than alkenes and only slightly more soluble in water. 

Ionic liquids (Coni.) cations used for, 253 characteristics of, 252-253 chemical and physical properties, 251 green credentials, 253 hydroarylations of alkynes in, 273 Kamlet/Taft parameters for, 255 oxidation, 278-279... 

Alkynes have physical properties similar to alkanes. They are relatively non-polar, dissolve in non-polar solvents and are not very soluble in water. Only weak van der Waals interactions are possible between unsaturated molecules such as alkynes, and so these structures have low boiling points compared to other functional groups. 

Synthesis, reactions, and physical properties of stable mononuclear platinum and zirconium complexes of cyclohexyne reported prior to the late 1980s have been comprehensively covered in earlier reviews.2-8 More recently, reaction of the zirconocene complex of cyclohexyne with trimethyla-luminum and trimethylgallium has been reported to give 247 and 248, respectively [Eq. (36)].57-58 These products are novel because four atoms (carbons Cl and C3, the transition metal, and the main group metal) are covalently bonded to an sp2 hybridized carbon (C2) in a planar tetracoordi-nate fashion. Synthesis of this type of complex, which Erker describes as anti-van t Hoff/LeBel, does not require the strained cycloalkyne ring zirconocene complexes of acyclic alkynes react similarly.57-58... 

As might be expected, the physical properties of alkynes are very similar to those of alkenes and alkanes with the same number of carbons. For example, the boiling points of hexane. 1-hexene, and 1-hexyne are 69°C, 63°C, and 71°C. respectively. 

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