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<blockquote data-quote="MaD-DoC" data-source="post: 1304562" data-attributes="member: 56284">
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<li data-xf-list-type="ul">&nbsp; 
 
 
 
&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; aryl &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; group: A section of a&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; molecule derived from aromatic compounds like benzene or&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; methylbenzene &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g. the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; phenyl group is the simplest, C6H5-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; or <img src="http://www.docbrown.info/page15/phenylgroup.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; attacking ... &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; : A somewhat dramatic term&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; applied to the 'active' part of a reagent that directly interacts&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; with the organic 'substrate' molecule in question. You can use&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; phrases like 'nucleophilic attack'&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; or 'electrophilic attack'. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g. the &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; nucleophile OH- 'attacking' the positive carbon&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; of the polarised &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Cδ+-Clδ-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; bond in a nucleophilic substitution of halogenoalkane&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; or the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; positive part of the polarised &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Hδ+-Brδ-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; electrophile attacking the ∏ electrons of an alkene&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; double bond in an electrophilic addition reaction.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 'bimolecular'&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanism/kinetics : see&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; e.g. SN2 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; bond&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; fission: This&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; means breaking a bond between two atoms to give two 'fragments'&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (atoms, ions or molecules), but there are two modes of fission,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; depending on what happens to the original bonding pair of electrons.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; This is illustrated by the breaking of a C-Br (or C:Br) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; bond. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Heterolytic bond fission: The bonding&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; pair of electrons (: below) leaves with one of the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; fragments and usually leads to ion formation. This follows from&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; the bond polarity, Cδ+-Clδ- &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; due the difference in electronegativity (Cl &gt; C). &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (CH3)3C:Cl&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; ==&gt; (CH3)3C+ + &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; :Cl-&nbsp; &nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part II)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; <img src="http://www.docbrown.info/page15/heterofission.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Homolytic bond fission: The bonding&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; pair of electrons is 'split' between the two fragments with an&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; unpaired electron and usually leads to the formation of free&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; radicals initiated by heat or uv light.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; H3C:Cl ==&gt;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; H3C.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; + Cl.&nbsp; &nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part Ia)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
 
 
<img src="http://www.docbrown.info/page15/homofission.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; bromonium ion:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; A form of carbocation produced in the 1st step of the electrophilic&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; addition of bromine to an alkene. It involves a C-Br-C bonded&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; triangle which carries the positive charge. The addition of chlorine&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; proceeds in the same way via a chloronium ion. (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part Ib) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; carbocation &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp;&nbsp; (carbonium ion): A&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; positive ion derived from an organic molecule where the charge is&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; usually carried by a carbon atom e.g. the ethyl carbocation is CH3CH2+ ,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; and note that the three bonds from the carbon carrying the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; positive charge are in a trigonal planar configuration (2 x C-H&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; and a C-C in this case).&nbsp;&nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part Ib) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; chain&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; reaction &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; : Here the term is often&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; used in the context of highly reactive free radicals, where in a&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; reaction step, one radical brings about a chemical change and forms&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; another reactive radical to continue the reaction. (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part Ia) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g. a chain&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; propagation step in uv/Cl2 chlorination of alkanes &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; CH3.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; + Cl2&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; ==&gt; CH3Cl + &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; .Cl&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; where the chlorine radical &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; .Cl &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; can continue the reaction.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; E1:&nbsp; Shorthand for an elimination reaction in which the rate determining step&nbsp; involves just one of the reactant molecule or intermediate (X) and the&nbsp; rate is independent any other reactant or intermediate.&nbsp;&nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part II) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; This results&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; in overall 1st order reaction kinetics: e.g. rate = k2[X]&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; E2:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Shorthand for a nucleophilic substitution reaction in which the rate&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; determining step is a bimolecular collision of two reactant&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; molecules or intermediates (X and Y) and the rate is&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; independent any other reactant or intermediate.&nbsp;&nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part II) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; This&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; results in overall&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 2nd order reaction kinetics: e.g. rate = k2[X][Y]&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; electron&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; shift:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; see use of arrows in mechanisms &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; electronegativity: The electron&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; attracting power of an atom in a covalent bond situation.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; One of the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; most common scales used is the Pauling electronegativity&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; and a selection of values is listed. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Na 0.9,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Al 1.5, C 2.1, H 2.1, P 2.1, &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; S 2.5, Br 2.8, Cl 3.0, N 3.0, O&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; 3.5, F 4.0&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">The&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; concept is important when considering polar bonds, which&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; arise when there is a significant electronegativity difference&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; between two atoms in a bond. The bigger the difference, the more&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; polar the bond. Polar bonds can determine how a molecule reacts&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; in terms of which part of the structure of a molecule changes,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; how reagents react and what reagents the molecule will react&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; with. The more electronegative atom carries the &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; d-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; charge e.g. ... &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; The Cδ+&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; in the polar bond Cδ-Clδ-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; in halogenoalkanes are susceptible to nucleophilic&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; attack by electron pair donors.&nbsp;&nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; mechanisms Part II)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; The Cδ+&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; in the polar bond &gt;Cδ+=Oδ-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; in aldehydes/ketones/acyl chlorides etc. are susceptible&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; to nucleophilic attack by electron pair donors.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (see mechanisms Part&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; III)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; The&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; polarised hydrogen bromide molecule, Hδ+-Brδ-, acts as an electrophile by proton donation in which the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; proton (H atom) of the HBr acts as a H+&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; ion and accepts a pair of electrons to form an C-H bond.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; (see mechanisms Part Ib)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; electrophile: A 'reagent' atom, ion or molecules that can&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; accept a pair of electrons (Lewis acids) from an 'electron rich'&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; part of a molecule like the ∏ electrons of an alkene or arene. They acts as Lewis acids, electron&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; pair acceptors when interacting with molecules such as alkenes and&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; arenes. (see alkene&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mechanisms or aromatic&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; mechanisms) &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
<ul>
<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g. &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Br2,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; CH3CH2+, Br+, SO3,&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; H-OSO2OH, Hδ+-Brδ-&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; electrophilic&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; attack: The&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; interaction of an electrophile reagent (electron pair acceptor)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; interacting with an electron pair donor prior to forming the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; products of that mechanism step e.g. 'attacks' on .... &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Alkenes&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; <img src="http://www.docbrown.info/page15/attack01.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; or <img src="http://www.docbrown.info/page15/attack02.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; or <img src="http://www.docbrown.info/page15/attack03.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" /> &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
<ul>
<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; above&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; are three examples of electrophilic attack on alkenes &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (see alkene mechanisms)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; Arenes <img src="http://www.docbrown.info/page15/attack04.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; or <img src="http://www.docbrown.info/page15/attack05.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; or <img src="http://www.docbrown.info/page15/attack06.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; or <img src="http://www.docbrown.info/page15/attack07.gif" alt="" class="fr-fic fr-dii fr-draggable " style="" />&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
<ul>
<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; and &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; four examples of electrophilic attack on benzene, the&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; simplest arene or aromatic hydrocarbon.&nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; aromatic mechanisms)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
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</ul>
<ul>
<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; &nbsp; electrophilic&nbsp; addition: An electrophilic&nbsp; reagent adds to a molecule to give the product (without any elimination).&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
<ul>
<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; e.g.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; hydrogen bromide adding to an alkene &gt;C=C&lt; + HBr =&gt; &gt;CH-CBr&lt;.&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
<ul>
<li data-xf-list-type="ul">&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; (see &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; alkene mechanisms)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; 
</li>
</ul></li>
</ul></li>
</ul></blockquote>

[QUOTE="MaD-DoC, post: 1304562, member: 56284"] [LIST] [*][LEFT] [B][FONT=Comic Sans MS][SIZE=2]aryl [/SIZE][/FONT] [/B] [FONT=Comic Sans MS][SIZE=2] group: A section of a molecule derived from aromatic compounds like benzene or methylbenzene [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT] [FONT=Comic Sans MS][SIZE=2] e.g. the phenyl group is the simplest, [B]C6H5[/B]- or [IMG]http://www.docbrown.info/page15/phenylgroup.gif[/IMG][/SIZE][/FONT] [/LEFT] [/LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]attacking ... [/SIZE][/FONT] [/B] [FONT=Comic Sans MS][SIZE=2] : A somewhat dramatic term applied to the 'active' part of a reagent that directly interacts with the organic 'substrate' molecule in question. You can use phrases like '[B]nucleophilic attack[/B]' or '[B]electrophilic attack[/B]'. [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]e.g. the [B] nucleophile OH-[/B] 'attacking' the positive carbon of the polarised [/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS] Cδ+-Clδ[/FONT][FONT=Comic Sans MS]-[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2] bond in a nucleophilic substitution of halogenoalkane[/SIZE][/FONT] [/LEFT] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]or the positive part of the polarised [B] H[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ+-Brδ[/FONT][FONT=Comic Sans MS]-[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2] [B]electrophile[/B] attacking the ∏ electrons of an alkene double bond in an electrophilic addition reaction.[/SIZE][/FONT] [/LEFT] [/LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]'[I]bimolecular[/I]' [/SIZE][/FONT] [/B][FONT=Comic Sans MS][SIZE=2]mechanism/kinetics : [B]see e.g. SN2[/B] [/SIZE][/FONT] [/LEFT] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]bond fission[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2]: This means breaking a bond between two atoms to give two 'fragments' (atoms, ions or molecules), but there are two modes of fission, depending on what happens to the original bonding pair of electrons. This is illustrated by the [B] breaking of a C-Br[/B] (or C:Br) [B] bond[/B]. [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][B][SIZE=2] Heterolytic bond fission[/SIZE][/B][SIZE=2]: The bonding pair of electrons ([B]:[/B] below) leaves with one of the fragments and usually leads to ion formation. This follows from the bond polarity, [B]C[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ+-Clδ- [/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2] due the difference in electronegativity (Cl > C). [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2] e.g. [B] (CH3)3C:Cl[/B] ==> [B](CH3)3C+[/B] + [B] :Cl-[/B] (see [B] mechanisms Part II[/B])[/SIZE][/FONT] [/LEFT] [*] [LEFT][FONT=Comic Sans MS][SIZE=2][IMG]http://www.docbrown.info/page15/heterofission.gif[/IMG][/SIZE][/FONT] [/LEFT] [/LIST] [*] [LEFT][FONT=Comic Sans MS][B][SIZE=2] Homolytic bond fission[/SIZE][/B][SIZE=2]: The bonding pair of electrons is 'split' between the two fragments with an unpaired electron and usually leads to the formation of free radicals initiated by heat or uv light.[/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]e.g. [B] H3C:Cl[/B] ==> [B]H3C.[/B] + [B]Cl.[/B] (see [B] mechanisms Part Ia[/B])[/SIZE][/FONT] [FONT=Comic Sans MS][IMG]http://www.docbrown.info/page15/homofission.gif[/IMG] [/FONT] [/LEFT] [/LIST] [/LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]bromonium ion[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2]: A form of carbocation produced in the 1st step of the electrophilic addition of bromine to an alkene. It involves a C-Br-C bonded triangle which carries the positive charge. The addition of chlorine proceeds in the same way via a chloronium ion. (see [B] mechanisms Part Ib[/B]) [/SIZE][/FONT] [/LEFT] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]carbocation [/SIZE][/FONT] [/B] [FONT=Comic Sans MS][SIZE=2] (carbonium ion): A positive ion derived from an organic molecule where the charge is usually carried by a carbon atom e.g. the ethyl carbocation is [B]CH3CH2+[/B] , and note that the [B]three bonds from the carbon carrying the positive charge are in a trigonal planar configuration[/B] (2 x C-H and a C-C in this case). (see [B] mechanisms Part Ib[/B]) [/SIZE][/FONT] [/LEFT] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]chain reaction [/SIZE][/FONT] [/B] [FONT=Comic Sans MS][SIZE=2] : Here the term is often used in the context of highly reactive free radicals, where in a reaction step, one radical brings about a chemical change and forms another reactive radical to continue the reaction. (see [B] mechanisms Part Ia[/B]) [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]e.g. a chain propagation step in uv/Cl2 chlorination of alkanes [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]CH3[COLOR=#ff0000].[/COLOR] + Cl2 [/SIZE][/FONT][/B] [FONT=Comic Sans MS][SIZE=2] ==>[B] CH3Cl + [COLOR=#ff0000] .[/COLOR]Cl [/B] [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2] where the chlorine radical [B][COLOR=#ff0000] .[/COLOR]Cl [/B] can continue the reaction.[/SIZE][/FONT] [/LEFT] [/LIST] [/LIST] [/LIST] [*] [LEFT] [B][FONT=Comic Sans MS][SIZE=2]E1[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2]: Shorthand for an [B]elimination reaction[/B] in which the rate determining step involves just one of the reactant molecule or intermediate ([B]X[/B]) and the rate is independent any other reactant or intermediate. (see [B] mechanisms Part II[/B]) [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]This results in overall [B]1st order reaction kinetics[/B]: e.g. [B]rate = k2[X][/B][/SIZE][/FONT] [/LEFT] [/LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]E2[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2]: Shorthand for a nucleophilic substitution reaction in which the rate determining step is a bimolecular collision of two reactant molecules or intermediates ([B]X[/B] and [B]Y[/B]) and the rate is independent any other reactant or intermediate. (see [B] mechanisms Part II[/B]) [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2] This results in overall [B] 2nd order reaction kinetics[/B]: e.g. [B]rate = k2[X][Y][/B][/SIZE][/FONT] [/LEFT] [/LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]electron shift[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2]: see use of [B]arrows[/B] in mechanisms [/SIZE][/FONT] [/LEFT] [*] [LEFT][FONT=Comic Sans MS][B][SIZE=2] electronegativity[/SIZE][/B][SIZE=2]: The electron attracting power of an atom in a covalent bond situation.[/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]One of the most common scales used is the [B]Pauling electronegativity[/B] and a selection of values is listed. [/SIZE][/FONT] [/LEFT] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]e.g.[B] Na 0.9[/B], [B]Al 1.5[/B], [B]C 2.1[/B], [B]H 2.1[/B], [B]P 2.1[/B], [B] S 2.5[/B], [B]Br 2.8[/B], [B]Cl 3.0[/B], [B]N 3.0[/B], [B]O 3.5[/B], [B]F 4.0[/B][/SIZE][/FONT] [/LEFT] [*][LEFT][FONT=Comic Sans MS][SIZE=2]The concept is important when considering [B]polar bonds[/B], which arise when there is a significant electronegativity difference between two atoms in a bond. The bigger the difference, the more polar the bond. Polar bonds can determine how a molecule reacts in terms of which part of the structure of a molecule changes, how reagents react and what reagents the molecule will react with. The more electronegative atom carries the [/SIZE][/FONT][B] [FONT=Comic Sans MS][SIZE=2] d[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2][B]-[/B] charge [B]e.g.[/B] ... [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]The [B]C[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2][B]+[/B] in the polar bond [B]C[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][B][FONT=Comic Sans MS][SIZE=2]-Cl[/SIZE][/FONT][/B][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2][B]- [/B]in halogenoalkanes are susceptible to nucleophilic attack by electron pair donors. (see [B] mechanisms Part II[/B])[/SIZE][/FONT] [/LEFT] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]The [B]C[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2][B]+[/B] in the polar bond >[B]C[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2][B]+=O[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2][B]- [/B]in aldehydes/ketones/acyl chlorides etc. are susceptible to nucleophilic attack by electron pair donors. (see [B]mechanisms Part III[/B])[/SIZE][/FONT] [/LEFT] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]The polarised hydrogen bromide molecule, [B]H[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2][B]+-Br[/B][/SIZE][/FONT][SIZE=2][B][FONT=Comic Sans MS]δ[/FONT][/B][/SIZE][FONT=Comic Sans MS][SIZE=2][B]-[/B], acts as an electrophile by proton donation in which the proton (H atom) of the HBr acts as a [B]H+[/B] ion and accepts a pair of electrons to form an C-H bond. (see [B]mechanisms Part Ib[/B])[/SIZE][/FONT] [/LEFT] [/LIST] [/LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2][B] electrophile[/B]: A 'reagent' atom, ion or molecules that can accept a pair of electrons (Lewis acids) from an 'electron rich' part of a molecule like the [/SIZE][/FONT][B][FONT=Comic Sans MS][SIZE=2]∏[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2] electrons of an alkene or arene. They acts as Lewis acids, electron pair acceptors when interacting with molecules such as alkenes and arenes. (see [B]alkene mechanisms[/B] or [B]aromatic mechanisms[/B]) [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][SIZE=2][FONT=Comic Sans MS]e.g. [B] Br2[/B], [B]CH3CH2+, Br+, SO3, H-OSO2OH, H[/B][/FONT][B][FONT=Comic Sans MS]δ[/FONT][/B][FONT=Comic Sans MS][B]+-Br[/B][/FONT][B][FONT=Comic Sans MS]δ[/FONT][FONT=Comic Sans MS]-[/FONT][/B][/SIZE] [/LEFT] [/LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]electrophilic attack[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2]: The interaction of an electrophile reagent (electron pair acceptor) interacting with an electron pair donor prior to forming the products of that mechanism step e.g. 'attacks' on .... [/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]Alkenes[/SIZE][/FONT] [/B] [FONT=Comic Sans MS][SIZE=2] [B] [IMG]http://www.docbrown.info/page15/attack01.gif[/IMG] or [IMG]http://www.docbrown.info/page15/attack02.gif[/IMG] or [IMG]http://www.docbrown.info/page15/attack03.gif[/IMG] [/B][/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]above are [B]three examples of electrophilic attack on alkenes [/B] (see [B]alkene mechanisms[/B])[/SIZE][/FONT] [/LEFT] [/LIST] [*] [LEFT][B][FONT=Comic Sans MS][SIZE=2]Arenes [IMG]http://www.docbrown.info/page15/attack04.gif[/IMG] or [IMG]http://www.docbrown.info/page15/attack05.gif[/IMG] or [IMG]http://www.docbrown.info/page15/attack06.gif[/IMG] or [IMG]http://www.docbrown.info/page15/attack07.gif[/IMG][/SIZE][/FONT] [/B] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]and [B] four examples of electrophilic attack on benzene[/B], the simplest arene or aromatic hydrocarbon. (see [B] aromatic mechanisms[/B])[/SIZE][/FONT] [/LEFT] [/LIST] [/LIST] [/LIST][LIST] [*] [LEFT] [B][FONT=Comic Sans MS][SIZE=2]electrophilic addition[/SIZE][/FONT][/B][FONT=Comic Sans MS][SIZE=2]: An electrophilic reagent adds to a molecule to give the product (without any elimination).[/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2]e.g. hydrogen bromide adding to an alkene [B]>C=C< + HBr => >CH-CBr[/B]<.[/SIZE][/FONT] [/LEFT] [LIST] [*] [LEFT][FONT=Comic Sans MS][SIZE=2](see [B] alkene mechanisms[/B])[/SIZE][/FONT] [/LEFT] [/LIST] [/LIST] [/LIST] [/QUOTE]

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