chapter11_notes0

chapter11_notes0 - CHEM 257 Learning Objectives Chapter 11...

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Unformatted text preview: CHEM 257 Learning Objectives Chapter 11 1. Know how to read an infrared spectrum and identify strong, medium, and weak peaks as well as the fingerprint region. 2. Understand the measure of wavenumber and that the typical range of an infrared spectrum is 4000 to 400 cm". 3. Be able to identify functional group peaks for alkanes, alkenes, alcohols, aromatics, ethers, amines, aldehydes, ketones, and carboxylic acids. 4. Be able to calculate the hydrogen deficient index from the molecular formula of an unknown compound. Sections: 11.1—11.4 P_roblems: 11.2—11.3, 11.12—11.23 Infrared Spectroscopy Chapter 11 Electromagnetic Spectrum TA B 1 E 1 1 .1 Wavelength, Frequency, and Energy Relationships of Some Region: at the Electromagnetic Spectrum 1:»; III-7 5x Ittr7 fix Mir? 1x III-T I ‘*--_. ‘r’isilrlelighl r-..e-"' Radiu- --.._ -_--' times . . | | Wan-lrngrhtm] axle-Iv axle-H 3x104! sue-N “104' Mine axle-I- sue-T 3 3x101 axrn' nine new" Fflqtlel'rq' [He] II)“ rel'I 10W rir"l re“- rn" rel! rel“I an“ lfl" rut In? In | I | I | . I | ' | . | I l'irtt'rm'fltjfrrrul]Arr-cm" um" “<10: rxln" -|t-c|tr‘ axln‘ “(In-1 {Mfr-5 +3110" -l=-<Ifl" -I><Ifl'" 43-611?” “HI?” I I I I I 3 I | I | I | | finflrlghtl: 21:11 khn'fl'llqu‘fienl. Innlll right: m hmwnkJabllJLfil Molecular Vibrations Atoms joined by covalent bonds are continually rotating and vibrating relative to each other. Energies associated with these vibrations are quantized, that is only specific vibrational energies are allowed. These energies are from 2 to 10 kcal per mole. These energies correspond to frequencies in the infrared region between 4000 and 400 cm'1. \ v“ \ ' f .r II V. 11/ Q, 121/ Symnurlrit‘ Sll‘t‘lt‘hillg Stir-mining Rm‘king x 1-1 / hm, / I: “N Ezra C: p \ ”\ A A Asymim'lric Sll'trlt‘h ing “flagging 'I'wisling “ 11/ *3” IiN fix Il\" Stretching vibrations Bending vibrations Absorption & Polarity For a bond to absorb IR radiation: 1. The frequency of radiation must match the frequency of a bond vibration. 2. The bond undergoing vibration must be polar. 3. The greater the polarity, the stronger the absorption. Weakly polar bonds are observed, although the absorption is weak. Infrared Spectrometer: Alkanes %T C—H bend C—H stretch 0—H bend 3600 2800 2000 1600 1200 800 400 “cm-rm .0135- ?I. Jr II Ji- J J}. I 1.5. E. 55 l J' I P til 11 I'...‘ I! 'I-I Ii IE L? 1! Pi 2| :‘1' x I IF?""'1I'"V.-t' K J '_ , but-am alkyd Emupu ' '. I: ' “in in most organic p : mulccuh than: peaks ' 1 : will In: amen-ed ' "I" ; ; in many IR sprain : ' - J I finding l- | l ' . . ¢ 5 . hmldlll ' .1; ‘H. I J i {.“H 4 I W sIrct-z‘hing a _—— m m am am 320:: m m: m m mu mu: 1m um um um um: no: can no “mm” Alkenes %T 3600 Ilium 1.3.55 __{Lflji 21-11. _ __. _E __ .__._f...___fi_ _E__ 5‘?__'5_ 3.- __._ F—fi min-WI rlmfimww‘ filfiwml {a I "m mum“ ' [Humming fibnllouhfl: ' 7“: '"' i I ‘m'lgnbflfln nflbcuhcflvcdluith aim a _ ‘5'" ' _ mumfimmnrinl all-null I .' El It film-111m nth '. . mthnnd I I; i : anu-nmhu I /' .- J I I'm: Fromm ' Z - || '1' umhndmnhr i I . : '3 Chad - EII‘EIE 1mg / : | “uryllc aliphatic - t I I . I -n_ I ‘ -/"'J L H mam . I“ I I l gin-Idling _r' I flmmhmfl mu m m m m m m m m m nu ma mm In: C—H stretch 2800 C=C—H 2000 oveflones C=C stretch 1600 mm [cm-1| 1200 3- 9 I303 IIIICI 800 13- 400 u 1:. 1a. 1? 1e. :1 212: Jran I x’ “‘3 r n ' .I "-.I ' .IE. I mu m Alcohols %T O—H stretch C—O stretch 3600 2800 Inga. H, 1'? n :1: a a: a as. ‘- 'I' I I I I l I 1' T I : 2-". ' t' H mrmrhing *- _ "twinge" hind-ml] “mlthmfl mmmmmmraW-HMFWHN 2000 am:- 1600 1200 Hfl'.‘ ' - ‘ l- r " ' HIHIII'IL fitrcghmg I 1: I" :ilrnlml] 1m lm lm IM ['33: mums rm' 'I 800 I? 1! 400 H 15 H5 1: 1! I? ilfi' Ethers %T C—O—C stretch C—O—C stretch 3600 2800 3‘1: 5'6 E'J' 5"! F'il 3 3:: i in I'm. . . . . . . . . t.‘-."-‘-..'-\."-'— _--.—._ .._._. -- -- _ x ‘ l 'I' I '. : illM'l'lfi‘ nr . - I I 'I' I rim-whng H t I ' II II. aux-Idling |.'-' mmmmnmmmwmrmrm 2000 FEED “III 1600 Tn‘mlillg 'IIIIII - —" ailfl'lt'hing 'IIIII 132'] “IVE—MEIHHM'H 1200 IIIIZI 400 --_. 1:. 1: ug 19 fit I“ E'IF’? JED Benzenes %T C=C—H oveflones C—H stretch (aromatic) (aromatic) C=C stretch (aromatic) 3600 2800 2000 1600 1200 800 400 IIEIIDIIETEFIIS WEE- :‘fi. FT 9B 5"} J '11: -1 If. 5 5‘1 *5 T 3 ‘11 ID 1| 1? [J 1-t 15. 1F, 1:! 1.315 N r: anan -"'n'" -'-" r_"""1"""""' I ‘ t__‘,.__2 , T ' . ' I : Indlmtm m a : 'rwnfl'llr ring I i = I I I f . T I I _ t 'h {‘_ " - fill'rtrhmg El __l i . r d— I L'u‘mu'llir} H I “"1" : IH‘Ildmg ‘I- I I _ I I '3' {I'lmm'l'nfl . {ul'nmum‘} 1003 am} am:- arsm 3H0 m race mm m: m m: we um um 1m: 1:03 am am +9:- WflmHflEflflm "]- Amines %T W W N—H bend C_N N—H stretch stretch 3600 2800 2000 1600 1200 800 400 mam-rm: .35- ?G :"F .35- :‘5 :I 3'4 Il- Il-h 5 1"; B- i" H '5 lb lI'I I? 'I] 'II 15 1G 'IJ' 1519 El .91? “(L . . . . . . . . . . . . . . . . . . . . . . . . . . “rm—h“? ;_ __._.-. . - - _,, . _ F___. Jun ‘2‘. . r": ' x . E ' * 1.._..'.-+I-l II. ' F' . , 'I' = - - Tannin-rs _ a. = - girrmllynw I u ahm-[nimin \ t I, - 1 .l. llll'll'li'flIDI't - H I - I 'r , I . 1 IJ-l'l'lillllfl - E - - J E , _ leullllg .- "'l"""' L—H ME” Sll't'tfl‘tlllfl , ' I_ - .' {lqillllilllt} I 5'” l"- ""3 m m m m 13m mm mm mm m F'P'II 9cm 1am 1am um 1m: 1w: an: m: 45-: 'II'I'II'IIIUIl-Illfiifll"! Ketones %T C=O stretch 3600 2800 2000 1600 1200 800 400 mm H 2r :5 H :I. :55 4: 4.5 5 55 5 :I' a '3 m 1| 1: 13 H 15 15131519 :In Hw-—-‘H_ ff_ _- -__......'\- _ - . .. H _I I. _u. _ I, _ - I _ I __._‘___ x _-. “a! 1‘ . ._,J I - .-' I . ' -I .- . I I L' H I 1 .. I I. | I . I .l I i r I I J I u I I :_ —- l -‘ I I I ‘3 ‘ {1} I F ' T t I _.._ (“_H ll'tll‘hll'lh I fitrutrhing I <1. . «my m: m m 325:: m m 95m m am am new “50:: ram 120:: nm am can :55 wnmwm [m- 'I Carboxylic Acids O—H stretch C=O stretch 3600 2800 2000 1600 1200 800 400 “CENTRE! 21. :5 :I: M 99 a 3‘: I 1'.- 5. 5-3. 5 I a 9 m n '2 1: n1 IL re. rr '3 19 war: 1.)}. . . . . . . . . . . . . . . . . . . . . . . . “a ,. _ . "l r - ' . .- 1. ‘3' 'I I I 'u. I- - - A . 'I' . H I _ I. . l ' _ I w _ _. - I . . I _ 'r _ U T .- . ' .I. . _ [HI—II u - MIN.” Ntl'rtrhmg . - {Ilyill'ngrll IHIJ'Ldll'tn sln'lrhing c. . 4.1m m1: sum-J 14-5: :33:- mo rum 9m: 9m m 993.: mu:- 1m 1m lat-J um am m:- 4.113 manual-[Hanan Hydrogen Deficiency Index Hydrogen wiciency Index is equal to the total number of rings and multiple bonds in a molecule. 20+2—H Index of hydrogen deficiency = 2 C = number of carbons H = number of hydrogens and halogens If nitrogen is present... 2C+2+N-H Index of hydrogen deficiency = 2 C = number of carbons H = number of hydrogens and halogens N = number of nitrogens ...
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