Introduction ° ° ° : names halogen 0h11mn1s wmponnd general where colourless lii ) immiscible 1 more hydrogens halo alkanes , are replaced with halogen atoms : properties bit polar one hullide alkyl . liquid and molecules as heavier the l - than halogen water to - ✗ bonds ) bond are polarised due to the difference n h tf c 8 -1 > - a ↳ greater ability H polarity attract decreases from bonding L - F to elutions to c- I . as electronegativity decreases down the group . in elertnnegativity ot cand halogen atoms . Ot Uassitilhtion ° depends halogenoalkanes the on number of R - R y Naming begin e. it C - C 1 I H end akyl I nanites the g. R X - H two at to the carbon nearer cus I to groups the Br 1 lhzllllllzluzlnctlz I 3 4 5 b 2- bromo 2 - 5- methyl hexane bonded to the halogen tertiary ' R I l - bonded secondary primary R directly groups ' 1 - X that R - C - X 1 R are substituent equally whose distant name '' from comes the first end of the main alphabetically . . Preparations of halogen unlkanes his electrophilic audition wit nucleophilic substitution viii ) free UH elertwphilic radical of hydrogen of substitution addition alkanes I to 5042 an 1 akene phosphorus hallide . . alkenes hydro halogenation halogenation Yz + halogens HX with 11×1×2 of 1 with alcohols of ( Xz ) ( MX ) hnllides -1 HX 1- H X . ✗ = U n " 413 ✗ Br , ✗ H × a. Bv ,I : Markovnikov wit substitution 117 reflux of alcohol alcohol with R 1- - products on HX HX R > - X HW + ↑ nucleophile (2) warm with alcohol thionyl 1500127 chloride formation of union alkanes steamy white R - OH > 5042 -1 R U - + 502cg) + . tunes . HUCG ) both son and 1101 can mixture escape leaving pure of (3) heating reation for R of alcohol and hnlogenoalkcsne . hotline phosphorus U2 - oh PUS + R > - U + POU 3117 + MU ly ) r tou Iz I phosphorus Bvz containing product 1- 3rd - On separating + PX } phosphorus > 3k - ✗ containing 1- 1131703 ( l ) product with hnioalkane > fractional distillation . Viii ) free substitution radical ot reaction not + alkanes favoured a til gives lii ) multiple alkanes ot . it as reaction mixture a " Bra 1 Uz of _ halogen alkanes substitution often occurs ltnvther halogenation ) distillation fractional X + × - is - of - used to wlibht n ✗ = different the separate heat / , - Brin ¢ - products × + mechanism initiation BFT3v > - Br Br + - propagation n n I n c - n I - l i v - n - > n'it n - ' iii. ↑ n - - n - Bv + ¥ BV ' iii. M c - c - c- n - / iii > I . I n n - H y ' n' run c - c - - n + Bv - ÉiÉBv termination Bv ? " - Bu > Bv - Bv n n I n Br . ~ i - 1- . - I n C - - H > e Br I I n - e u - - ↑ i - n ↑ - n c- → 1 - I n - c- 1 n _ i - n n c- n - o - I n ↑ ↑ n l u - In 11 u n c- n - n - - 1 I n e - n n > n _ - c- n n - I c c n - e - n I I n o I - b n n - gn n n . - × tree radical carbon has substitution an electron , " not PMS charge . Physical 1- boiling in INCREASES ° 0 size of ° U halogen stronger → no branched . Ot stronger R - Bv atom area , branches hnlogcnoalkanc exposed to → R , - increases forces London as surface - elections move , becomes R increases carbons increases forces from DECREASES ° 2. molecular size london of number as INCREASES ° hiii ) hhlogenoalknnes points ° wit of Properties more needed energy to number , move energy of electrons needed to increases overcome uii ) soluble isoluble ° in in polar organic spherical more intermolecular forces , are short and reduced compact . solvents water , BUT cannot form the increases are bonds L solubility lil the overcome hydrogen bonds with water molecules . . bonus Use 1- hnlogenoalkanes of solvent As in in dry cleaning tvilhlowethane bin removing Freon -113 2- Flame ° in grease raw alkane + a material halogen atom CFCs l lpolyuhlowlthene) LLBVF] due to , ozone five ciii> tire extinguisher . plastic windows Tenon / electrical , - used in cable non - insulation stick extinguishers depletion Properties wit in . plastics for Lpoiytetvathuwethene > refrigerants banned is ) ? tihmmhbility venules greatly chlorofluorocarbons ) in ° manufacture to PTFE . . retardant PVL 4 circuit electronic LLFUZLFU ? bwmotvitnow methane 3- and engineering equipment chemically non low - uses inert flammable toxicity n'v7 Odour less cut volatile . ui) uii) hiii ) refrigerants frame Leaning ttnids ) retardant cleaning agent in in extinguisher eletwniie industries pans . CFCs ◦ ° Ozone vs inertness makes diffuses into C- 01 a 637 persist them stratosphere the bonds atmosphere the by the catalyse for long periods . where , down broken are radicals free in Uv light breaking up ( fwm of sun ] ozone to form chlorine free radicals . layer > protective shield that absorbs most sun 's of the radiation UV . mechanism U) step 1 CU ✓✓ zFz U y t - CCI - note Fz - V7 step 2 chlorine : reacts with + U > . chlorine UO excessive hi > crop lii ) skin - exposure radicals 03 t to 40 light . Wz + 4- : damage > viii ) Oz regenerated are > UV + . cancer cataracts and manufacturing at the immune chlorine own ozone - 03 : clouding of the lens of system your eyes . tree radicals molecules homogenous . catalyst can destroy thousands at Action 1. 2. 3. taken banned protect to /reduce the use water find substitutes G) no - lii ) for chlorine HCFCS NFES electronic in industries . atoms with chlorine shorter Viii ) CFCs CFCs HFCS lefts less of layer cleaning system based e. g. use 03 life Lhydw fluorocarbons ] least at atoms in the one = H 03 atom 7 depletion atmosphere , ↓ potential destroyed in the atmosphere chyduotksouoethers ) fluorine replaces chlorine , compound move stable as c- F bonds are stronger . 1. Nucleophilic hi> lii ) substitution hydrolysis c- 0h7 viii) formation nitrites ot formation of general equation involves vii ) halogen hiii > carbon is 6-1 n' v7 carbon rate reaction of - I - is go# of more ✗ g. C - + :Nu ] 1 - y - c - X attracts , attacked of by a halo alkane F nucleophile - - electrons bonding 8- , with . different c- × U going : bonds explanation G) L :X + bonds electronegative I - Nu , elerhopnitiu , is c- MHz I : breaking CX ) amine primary _ bi ) c- CN ) : down the Vii ) bond length ↑ atomic size group , bonding electrons , increases further twin 1 INCREASES - t - Bv hiii ) thus less UV ) bond attracted strength ↓ to , the nucleus bond . energy ↓ I UV) I - c- I I v lesser energy needed to break C- × bonds . nucleus G) hydrolysis longest togas CkkYqqB•qpa•mgggEs-ñ otsaT-o.hr#gpm , ↓ : reagents conditions : under heat nucleophile : product : 1 NaOH aqueous aqueous contains = water KOH aqueous reflux i. OH alcohol ^ equation shaped tiny , unevenly of substance pieces : added R e. - X OH + - Y R - OH × + '- > Naoh + lHzlHz0U + Nau heat the mixture ionic (Mzuzu exception ↳ R : PTFE - with G) ☐ burrs more reason : ° ° Viii ) equation F : hydrolysis vii ) On + > - not does UMJCMZOU undergo - in hydrolysis poly tetrafluoroethylene : non - stick c- F as pan slowly than with hot NaOh fully negative HW partial negative material Naoh aqueous charge on on oxygen - is . + HW ? cuz £13 chloro dimethyl ethane - c- on + In] 1,1 - KOH [° " ] 11ft in } y 1 ' iii. oxygen : c bond the water in} oh } - U + reaction without evaporating utt the volatile organic compound : eq make move calmly without bump g. 0h3mn to liquid boil - dimethyl ethanol HU 11ft reaction very flush strong . . . Vii ) formation ° nitrite ot substituted halogen with ON - to I alkanonitn.ie/aky1 nitrile tovm cyanide solvent ↑ reagents conditions i nucleophile : products R UNAMI cyanide sodium reflux under T.CN nitrite : equation heat / cyanide potassium ethanol:c : : X - > KUN 1- R - CIN KX + ↓ contains one more carbon than lM3Yl2M3 bromo Uh} KBV + I CN 2- - LU3lhzU 2- X Ulslllz > KIN + Br 1- - : example 1. R 2- methyl propane nitrite methyl ethane KON + M3UHzUN > + KU propane nitrile ionic equation bllzbhzll : IBN t > that's why it with ✗ - is bonded , . Mt ↑ reduction reflux - in carboxylic acid to and R charged negative carbon is nitrite + MzMzcN /\ in R > - : → Lint 114 reducing agent . 11 dry ether c. IN > ethamiii n I R - e - 1 n - primary n amine I KCN 11 hydrolysis avid alkali > t reagents : dilute nvsoa dilute reagents : ! H . - o - Nhon P, , 114 R n aqueous - C n - O - acidification V r.io - n , naan -1 hiii ) formation of ° : overall heat : nucleophile c- - NHI MHz Nhs in pressure under container semen a T.NU : R : product ethanol it excess wnditions with substituted halogen reagent amine primary Nuz - : equation R ( amines - X + ) > 21443 R - Nnz Nha + × Fth UH ? ?? if what R r × - - × Nhs + + is H in - R not + in NY } excess ? can ← - > n R - I l n iyi - R n ✗ + R ' - n - N - > n iy - - - n N - R X + R ' - ii 1 R - R " R I > ' R - nx + reaction " amine n× + 630 ) R - prevent nucleophilic * l n R to ( 20 ) . . R nucleophile nx + further substitution , ' ' I as 11° ) R " - act * ' n R ni n - NH4X > ''' NÉR " + ✗ - ' R [ quaternary ammonium salt ] stops stage at primary 2- Elimination reagents conditions H neat : products i. 0h / base and X equation s KOU requires → proton acceptor eliminated much higher temperature nucleophilic substitution . from carbon adjacent 2 ¢ ¢ + - - 4=4 > NaOh call ) n - atoms Max + U Lsalt iii. i - than : ✗ ' reflux or are - ' 1 alkenes : as NaOh ethanol iu : o - o - e o - - 1h ↓nsBv e 1 n - + NaOH Lalu ) , HW + water ) and u - c - c - c - ( = , _ u n c - - c - 5- l LL 'm, 'n thins n i if ↑↑↑↑↑ > can show - l - n ' '^ cis-trans isomers Nau + ° substituted highly move e. g. ,Bv Guzman alkene product elimination uh ] reaction > predominates cmajov product lHzCh= Chul } 2- bromo butane but Lmajov mechanism on why 1 - as base -2 - + hw ] M30HzlU=Mz + but one - l - ene product ) ? i. OH I n n i allow for the formation of ohonble ↑ ⑤✓→ u - elimination bond . ↑ ↑ Y=c " uhhh Htcpwton c - c - c - " Br " > n - - o - ' ' n n n + no -11 + :B ↑ accepts ) 3. Nucleophilic information general bit requires Vii ) i. Nu " a with reacts Liv ) hence W) order → U' 7 lii ) , by size ↑ : , LR - ✗ 7 substitutes and L at the polarised are reactivity atomic group substrate attacked of " leaving Viii ) hnlogenoalkanes two ISN ) mechanism substitution - X bond SN mechanism a mechanism : : C atom , CX ) is to get product . LR electrophilic nucleophiles R bond - U → R length - ↑ Bv , → bond R - 2 strength major pathways 5N , halogen tertiary primary haiogenoalkane haioycnonllcane . ↓ , bond energy ↓ , easier to break . - Nu ) rate sNZ G) determining bit takes his inversion place both → rate mechanism particles 2 . a single reacting the process t.no step carbon intermediates > . . : nucleophile hnlogenoalkane and after by concentration of in involved are R both - and × rate the determining hiii ) vespertine ' the / leaving group hi) chlorine l away . C- a bona broken with C- OH partially LV) b- U Wi ) chloride Wii) configuration , bond formed partially more electronegative > moves biv ) bona fully ion broken departs , b- OH bond formed . carbon inverts completely . carbon the of wntiyurationot Lthe atom hydrogen atom 's arrangement ) bonding electrons . begins order of ↳ ↳ to invert reactivity more . } 2nd order inn chlorine to step : 6) backside attack Unions in at bimolecular → ot involves information general Viii ) step reaction akyl groups akyl groups shield connected reacting to the carbon reacting carbon from incoming , slower the nucleophile reaction . . completely . rxn hi> Snl reaction information general in distinct 2 Vii ) takes viii ) steps → rate ot intermediate carbocation . . : nalogenoalkane only → process formation of a halogenoalkane tertiary place in unimoleuulav involves , in involve only affected reaction determining rate } _ 1st order ✓✗n halogen alkane of concentration by step mechanism e. 2- chloro g. ° equation Lshows U H - c - c - products and reactants c - n + i. OH - formation of n C - - - I non} ↑ H ' > !^ in - c- ' n E- reacts rapidly with ↑ - n + - c :u lush shape carbocation c - c - n + in ' n' wish CEC - n I (2) - - carbocation Tito H ) only ii"↑ > titnin 47 hydrolysis - n 111 n KOH tag ) with 2- methyl propane - : trigonal plhnnav nucleophile ↳ electrophilic - 42007 form to alcohol . attracts nucleophilic c- atom i. On _ ions i. on ↓ u n - I c c ' - I I nous order ↳ of more l c on it u t - - > n I l u 1 n - c - u l c - c ' ' ' n n n - n reactivity stable tertiary the carbocation carbocation most , move reactive ] nicely substituted it is the , higher the reactivity . Optical isomerism chiral 4) Lii ) reaction halogenoulkane tertiary some Snl in show can optical isomers . nnlogenoalkane has e. a chiral carbon , binned not to any H M3 g. I * H3cnzcuzc.sc ' in ↳ this case race mix lurch , product mixture : formed mixed is 50150 mixture e. g. ° mirror image and original . of race 2 . Mirai enantiomers . OH ] LULNUZ )lUzU13 /\ Whl . Nh ] in ethanol Ch ]U1BuCUzUt3 > Naoh / Kou caq ) ethanol it My UTWN > 042013 KCN ethanol icy NaOH / WON > 614-1 ( un > 1h2m } cn=cnU1zWl } UV reduction 1- LUzlM=cuMz , UtlhlMzNHz)Ulrbn3 CMCMLCOOH ) lurch } Difference Reaction between Pathway SN ' SNZ and Diagrams form carbocation % ↳ one step , no intermediate ↳ two distinct steps .
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