Alkyne
An alkyne is a type of hydrocarbon compound that contains at least one carbon-carbon triple bond. Alkynes are unsaturated hydrocarbons and are known for their reactivity, especially in chemical reactions that involve breaking or forming carbon-carbon bonds. They are important building blocks in organic synthesis and are used in the production of various industrial and consumer products.
5 Key excerpts on "Alkyne"
eBook - ePub- James G. Speight(Author)
- 2010(Publication Date)
- Gulf Professional Publishing(Publisher)
...Alkanes can have straight or branched chains, but without any ring structure. 2. Alkenes (olefins) are unsaturated hydrocarbons insofar as not all of the carbon valencies are satisfied by another atom and have a double bond (C=C) between carbon atoms. Alkenes have the general formula C n H 2 n, assuming no ring structures in the molecule. Alkenes may have more than one double bond between carbon atoms, in which case the formula is reduced by two hydrogen atoms for each additional double bond. For example, an alkene with two double bonds in the molecule has the general formula C n H 2 n – 2. Because of their reactivity and the time involved in crude oil maturation, alkenes do not usually occur in petroleum. 3. Alkynes (acetylenes) are hydrocarbons which contain a triple bond (C≡C) and have the general formula C n H 2 n – 2. Acetylene hydrocarbons are highly reactive and, as a consequence, are very rare in crude oil. 4. Cycloalkanes (naphthenes) are saturated hydrocarbons containing one or more rings, each of which may have one or more paraffinic side chains (more correctly known as alicyclic hydrocarbons). The general formula for a saturated hydrocarbon containing one ring is C n H 2 n. 5. Aromatic hydrocarbons (arenes) are hydrocarbons containing one or more aromatic nuclei, such as benzene, naphthalene, and phenanthrene ring systems, which may be linked up with (substituted) naphthene rings and/or paraffinic side chains. 5.1. Bonding in hydrocarbons Since carbon adopts the tetrahedral geometry when there are four σ bonds, only two bonds can occupy a plane simultaneously. The other two bonds are directed to the rear or to the front of the plane...
eBook - ePub- Jeffrey Gaffney, Nancy Marley(Authors)
- 2017(Publication Date)
- Elsevier(Publisher)
...The simplest Alkyne, ethyne (HC CH) with two carbon atoms and two hydrogens atoms, was discussed earlier (Fig. 13.6). The Alkyne with three carbon atoms, propyne, has the molecular formula; HC C CH 3. Butyne, with four carbon atoms, has two structural isomers: 1-butyne (HC C CH 2 CH 3) and 2-butyne (CH 3 C C CH 3). Because the sp. hybridized carbon atoms have a linear geometry, there can be no cis- and trans-isomers in the Alkynes. Notice that 1,3-butadiene will be a structural isomer of the butynes, as they will all have the same molecular formula: C 4 H 6. One group of hydrocarbons that are cousins to the alkanes is the cycloalkanes with the general formula of C n H 2 n. Cycloalkanes are monocyclic alkanes consisting of carbon and hydrogen atoms bonded with single bonds in a molecular structure containing a single ring. The ring structure is considered to be the alkane backbone, which can also include branched side chains off the ring. Since the carbon atoms are joined together in a ring structure, two hydrogen atoms are lost from the parent alkane. This gives them one site of unsaturation with the same general molecular formula as the alkenes. So, a cycloalkane is a structural isomer of the corresponding alkene with the same molecular formula. The cycloalkanes have similar chemical properties as the saturated alkanes but, since they have two less hydrogens than the alkanes, they are technically unsaturated hydrocarbons. Cycloalkanes are named in the same manner as the normal alkanes. The simple cycloalkanes containing three to six carbon atoms are shown in Fig. 13.9. The structures shown in Fig. 13.9 are given in bonding notation and do not represent the actual structures of the molecules, which are not flat but are puckered in an attempt to achieve the109.5 degrees bonding angles of sp 3 hybridized alkanes...
eBook - ePub- Graham Patrick(Author)
- 2004(Publication Date)
- Taylor & Francis(Publisher)
...Thus, the double bond is made up of one σ bond and one π bond (Figure 1). The Alkyne functional group consists of a carbon carbon triple bond and is linear in shape with bond angles of 180° (Figure 2). The two carbon atoms involved in the triple bond are both sp hybridized, such that each carbon atom has two sp hybridized orbitals and two p orbitals. The sp hybridized orbitals are used for two σ bonds while the p orbitals are used for two π bonds. Thus, the triple bond is made up of one σ bond and two π bonds. Figure 1. Structure of an alkene functional group. Figure 2. Structure of an Alkyne functional group. C=C Bond The C=C bond is stronger (152 kcal mol −1) and shorter (1.33 Å) than a C–C single bond (88 kcal mol −1 and 1.54 Å respectively). A C=C bond contains one σ bond and one π bond, with the π bond being weaker than the σ bond. This is important with respect to the reactivity of alkenes. Bond rotation is not possible for a C=C double bond since this would require the π bond to be broken. Therefore, isomers of alkenes are possible depending on the relative position of the substituents. These can be defined as cis or trans, but are more properly defined as (Z) or (E) (see Section D2). Alkenes are defined as mono-, di-, tri-, or tetrasubstituted depending on the number of substituents which are present. The more substituents which are present, the more stable the alkene. C≡C Bond The bond length of a carbon carbon triple bond is 1.20 Å and the bond strength is 200 kcal mol −1. The π bonds are weaker than the σ bond. The presence of the π bonds explains why Alkynes are more reactive than alkanes. Properties Alkenes and Alkynes have physical properties similar to alkanes. They are relatively non-polar, dissolve in nonpolar solvents and are not very soluble in water...
eBook - ePub- Tony Farine, Mark A. Foss(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
...You may also have used propane (C 3 H 8) and butane (C 4 H 10) as fuels in portable heaters and cookers. Take a moment to draw the structures of butane and propane. Now check your diagrams against Figure 3.10. Figure 3.10 The structural formulae of methane, butane and propane. Hydrocarbons that contain double or triple bonds are said to be unsaturated. This is a reference to the fact that the molecule contains less than the maximum number of substituents. The multiple bond could be chemically broken and further hydrogen atoms added, a process called hydrogenation. You will find reference is made to it on the back of margarine tubs. In this case, hydrogenation ensures that margarine remains solid at room temperature. Alkenes contain a double bond; the simplest member of this family is ethene (C 2 H 4), the structure of which is shown in Figure 3.11. Note that alkenes are named using the suffix –ene. Alkynes contain a triple bond; the simplest member of this group is ethyne (C 2 H 2), the structure of which is also given in Figure 3.11. Once again, note that the family to which this molecule belongs is given by the use of a suffix – in this case, it is –yne. You may be more familiar with ethyne by its alternative name, acetylene – the gas used in welding torches. Figure 3.11 The structural formulae of ethene and ethyne. So are hydrocarbons important in health care? The alkanes, alkenes and Alkynes are among the simplest organic molecules. In health care, we are interested in the function of the body, which contains some very complex organic molecules. You will no doubt encounter them later in your studies, but it would be too much to introduce them now. Many, such as saturated fats, contain chains of carbon atoms such as the alkanes and some, such as polyunsaturated fats, contain double bonds such as the alkenes. If you learn about the simpler organic molecules now, you will find it easier later on to understand the structure of more complex molecules found in the body...
eBook - ePub- Christian Vargel(Author)
- 2020(Publication Date)
- Elsevier Science(Publisher)
...C 6 H 5 C 2 H 5 ; Ethylene, C 2 H 4 ; Ethylene, oxide, (CH 2) 2 O; Fatty acids; Fresh water; Heptane, C 7 H 16 ; Hexane, C 6 H 14 ; Hydrocarbons; Isobutane, C 4 H 10 ; Isoprene; Kerosene; Lime mud; Liquid natural gas (LNG); Methane, CH 4 ; Methyl esters; Microbiologically influenced corrosion (MIC); Naphthenes; Naphthalene, C 10 H 8 ; Octane, C 8 H 18 ; Paraffins; Pentane, C 5 H 12 ; Pinene; Propane; Propylene, C 3 H 6 ; Rubber; Seawater; Styrene, C 6 H 5 C 2 H 3 ; Sulphates; Terebenthine; Terphenyl,. C 6 H 5 C 6 H 4 C 6 H 5 ; Toluene, C 6 H 5 CH 3 ; Vegetable oils; Water; Xylene, C 6 H 4 (CH 3) 2 1.1 Alkanes 1.2 Alkenes 1.3 Alkynes 1.4 Arenes or aromatic hydrocarbons 1.5 Terphenyls 1.6 Cyclic, non-benzenic hydrocarbons 1.7 Engine fuels 1.7.1 Conventional fuels 1.7.2 Biofuels 1.8 Petroleum industry 1.9 Drilling muds References Hydrocarbons are the main constituents of crude oil and natural gas. They are used as fuels and lubricants and are the raw materials for the production of plastics, solvents and industrial chemicals. Hydrocarbons are organic chemical compounds composed only of carbon and hydrogen. Depending on how the carbon atoms are bonded together, hydrocarbons can be aliphatic or cyclic. The aliphatic compounds include alkanes (C n H 2n+2), alkenes (C n H 2n) and Alkynes (C n H 2n − 2), depending on the number of unsaturated C–C bonds in the molecule. Cyclic compounds include aromatic hydrocarbons and cycloparaffins (non-benzenic hydrocarbons). Hydrocarbons are chemically relatively inert and, therefore, have no action on aluminium. They are insoluble in water. 1.1...
