CHE 206 Final

• Which factors determine the product in the halogenation of di-substitutedbenzene?


  Electronic and steric
• Predict the splitting pattern and their relative area in the 1H NMR spectrum of 2-butanone (methyl ethyl ketone)

  Triplet, 3H; singlet, 3H; quartet, 2H
• Identify the compound, whose IRcontains an intense signal at 1710 cm-1?

  d) 2-Hexanone
• In the Diels Alder reaction what is thechange?

  2 s-bonds and 1p-bond form
• Predict the splitting pattern and theirrelative area in the 1H NMR spectrumof 2-methylpropane.

  Doublet, 9H; multiplet, 1H
• In the synthesis of isopentyl acetate (viaFischer esterification) Why did you wash thereaction mixture with NaHCO3 after heating?

  to remove the unreacted acetic acid
• The rate-determining step in theiodination of 4 hydroxy acetophenone is theformation of _______ due to its ____.

  sigma complex, high ΔG‡
• Benzaldehyde will form____ and_____ if it is treated with KOH?

  Benzoic acid; Benzyl alcohol
• What is a phosphorous ylide?

  a negatively charged carbonattached to a positively chargedphosphorous.
• What type of diene is only reactivetowards Diels-Alder reactions?

  conjugated dienes in the s-cisconformation.
• In IR, a strong, sharp peak at ~1700 cm-1 is indicative of what functional group?

  carbonyl
• In the synthesis of Stilbene lab, we wash the reaction mixture after heating with Sodium thiosulfate, why?

  to remove phosphene.
• The first step of the reaction between the ylide and the carbonyl involves the formationof an intermediate called a betaine. T or F

  T
• Phosphorous likes to form five bonds and forms very strong bonds to carbon, thisresult in the formation of a Betaine. T or F

  F
• Smell of bananas is associated with amyl acetate. T or F

  F
• Smell of bananas is associated with isoamyl acetate. T or F

  T
• The benzyltriphenylphosphonium chloride is a phosphonium ylide (an ylide is a neutralmolecule with adjacent positive and negative charges) as a nucleophile. T or F

  F
• Generally, the formation of 𝑐𝑖𝑠-alkenes (𝑍-alkenes) result from non-stabilized ylides,whereas stabilized ylides yield predominantly 𝑡𝑟𝑎𝑛𝑠-alkenes (𝐸-alkenes). T or F


  T
• The alkyl triphenylphosphonium halide salts are prepared from triphenyl phosphineand an unhindered alkyl halide. T or F

  T
• The alkyl triphenylphosphonium halide salts are deprotonated with a strong base, likesodium ethoxide (NaOC2H5 ) or NaOH or BuLi to give the phosphorous ylide. T or F


  T
• Esters are compounds like carboxylic acids in which the hydroxyl group is replaced by an alkoxy group. T or F


  T
• E-stillbene


  Ans

  
• Methyl Salicylate


  Ans

  
• Isopentyl acetate


  Isoamyl acetate

  
• What are the three factors that affect the position of a peak in IR?

  strength of the bond, masses of the atoms involved in the bond, the type of vibration being observed
• 3 important characteristics of IR spectras:

  wavenumber, intensity, shape
• The wavenumber in IR spectroscopy depends on the ____ and the ___.

  bond strength; mass
• The region above 1500cm-1 is called the ___ region.

  Diagnostic
• In Infrared spectroscopy the shape of a concentrated solution of C3H7—OH is broad, due to Hydrogen Bonding. T or F

  T
• In Infrared spectroscopy covalent bonds with greater dipole (e.g. (e.g. C—Br) show stronger (more intense) signal, than bonds with weaker dipoles (e.g. C—C). T or F

  T
• Absorption spectroscopy measures the absorption of radiation, as a function of ___ or ___, due to its interaction with a sample.

  frequency; wavelength
• Absorptions observed in an IR spectrum are the result of ___ vibrations.

  bond
• Stronger bonds absorb at ____ frequencies because the bond is _____ to stretch.

  higher; difficult
• In Infrared spectroscopy the C—C bond is slightly weaker than the C=C bond, and hence C-C absorbs at a lower wave number (1200 cm-1) while C=C absorbs at a higher wave number (1600 cm-1). T or F


  True
• ___ can be used to dissolve a sample for 1H-NMR analysis.

  Chlorform-/D CDCl3
• In terms of the relative location of peaks in a 1H-NMR spectrum, _____ means to the right (higher magnetic field). _____ means to the left (lower magnetic field)

  upfield; downfield
• Williamson ether synthesis (Nerolin Lab) is an example of a ____ reaction where ____ is the nucleophile.

  Nucleophilic substitution; alkoxide
• Maleic anhydride


  Ans

  
• In the Diels Alder reaction _______ and _______ is the net change?

  1p-bond form & 2s-bonds form; 3p-bond break
• In a Diels Alder reaction, ____ dienes in the ___ conformation are most reactive.

  conjugated; s-cis