CHEMISTRY 104 – Help Sheet #4 Chapter 24 (Part III) Prepared by Dr. Tony Jacob http://www.chem.wisc.edu/areas/clc (Resource page) Nuggets: Functional Groups (Part II); Reactions (Part I) FUNCTIONAL GROUPS (the last 6): CO -containing or N-containing functional groups (Not all functional groups may be covered by each instructor; your instructor will clarify the ones you are responsible for.) Functional Group Suffix Formula Other Info Aldehyde (an)al COR H or RCHO carbonyls (i.e., contains CO) are polar e.g., 3-chloro-1-butanal O Cl1234 Ketone (an)one COR R' or R(C=O)R’ (R ≠ H and R’ ≠ H); polar e.g., 4,5-dimethyl-3-hexanone O123456methylmethyl Carboxylic acid (an)oic acid COR O H or RCOOH R COOHR COO-H++ (R can be a H); acidic; pH < 7; H-bonding; polar 3,3-dimethyl-1-butanoic acid HOO1234 Ester (an)oate COR O R' or R(COO)R’ (R can be a H; R’ ≠ H); polar; often smell nice; R’ named 1st + “yl” then COR O R' named 2nd + “anoate”; e.g., ethylbutanoate OOethyl123412but + anoate Amide --- COR N R'R'' or R(CO)NH2 polar; usually amides are not named in Chem 104 Amine “amine” NRR'R" 1˚ (primary), 2˚ (secondary), 3˚ (tertiary) NR3+ H2O NR3H++ OH- (basic; pH > 7); all but 4˚ have H-bonding; polar alphabetize groups + “amine”; 1 R must ≠ H; e.g., ethylpropylamine NH1212ethyl propyl3 Aldehyde: contains a carbonyl (C=O) with at least one H attached; COR H or R—CHO Ketone: a carbonyl (C=O) with no H attached; COR R' or R—CO—R'; R and R' ≠ H otherwise it’s an aldehyde Carboxylic acid: a carbonyl (C=O) with a OH attached; COR O H or R—COOH; R can be a H; creates an acidic solution (pH < 7); can dissociate a H+: R COOHR COO-H++; can undergo H-bonding; has resonance with the COO- group: --COOCOO Ester: R—(COO)–R’ COR O R'; R' ≠ H otherwise it’s a carboxylic acid; many esters smell pleasant Amide: R—(C=O)–NR’R” COR N R'R''; R’, R” can be H; H-bonding Amine – N with a C attached to it; NRR'R"; H-bonding; creates basic solution (pH > 7) primary (1˚): N has 1 C attached; secondary (2˚): N has 2 C attached; tertiary (3˚): N has 3 C attachedCOMMON NAMES (each instructor will clarify which commons names, if any, you are expected to know) = CH3CHCH3 isopropyl = H3C C CH3CH3 tert-butyl (t-butyl) H2C CH2 ethylene (ethane) HC CH acetylene (ethyne) H2C CH CH3 propylene CH3OH methyl alcohol (methanol) CH3CH2OH ethyl alcohol (ethanol) OH isopropyl alcohol H C COH OHHHH ethylene glycol H C COH OHCHH HHOH gycerol (glycerin) OH H formaldehyde OH acetaldehyde COH benzaldehyde O acetone HOOH formic acid H COO- formate ion OOH acetic acid H3C C OO- acetate ion OOH benzoic acid CH3 toluene styrene xylenes OH phenol NH2 aniline REACTIONS (The instructor may not cover all of the reactions below.) 1. COMBUSTION (complete); Clue: O2 is reactant; “burn”; “combustion”) (CxHy or CxHyOz) + O2 → CO2 + H2O (1st balance C then H then O) 2C8H18(g) + 25O2(g) → 16CO2(g) + 18H2O(g) Incomplete Combustion (if covered): (CxHy or CxHyOz) + O2 → CO + H2O (1st balance C then H then O) 2C2H6(g) + 5O2(g) → 4CO(g) + 6H2O(g)2. ALKENES/ALKYNES – ADDITION; add H2, Cl2/Br2, HCl/HBr, H2O, or HOCl/HOBr across the double bond; Clue: C=C or C≡C and H2, Cl2, Br2, HCl, HBr, H2O add H2 alkene + H2 € Pt, Pd, Rh, Cgraphite →      alkane Pt, Pd, Rh, or Cgraphite+H2HH add Cl2 or Br2 alkene + X2 → dihaloalkane +Cl2ClCl add HCl/HBr; can yield multiple products alkene + HX → haloalkane +HClClCl+HH add H2O; can yield multiple products alkene + H2O € H2SO4 →   alcohol +H2O+OHOHH2SO4HH ALKYNES – ADDITION; same reactions as alkene addition; can be 2 separate steps or 1 combined step alkyne + H2 € Pt, Pd, Rh, Cgraphite →      alkene + H2 € Pt, Pd, Rh, Cgraphite →      alkane or alkyne + 2H2 € Pt, Pd, Rh, Cgraphite →      alkane +HCl+HCl+ + +ClHHClCl ClH HClHHClHClCl H +2HCl Note: during the alkyne addition rxn, it’s generally not possible to isolate the alkene product; so it’s more accurate to show: +2HCl+ +ClHHClCl ClH HClHHCl 3. AROMATIC – SUBSTITUTION; substitute NO2, Cl/Br or –CH3/–CH2CH3 for an aromatic H (not all of these reactions are always covered); Clue: FeCl3, FeBr3, AlCl3 and Benzene substitute NO2 NO2++H2SO4NO2NO2+ HNO3+ H2O substitute Cl/Br (Cl2/FeCl3 adds Cl) Br++FeBr3BrBr+ Br2+ HBr substitute CH3 or CH3CH2 (CH3Cl adds –CH3) (CH3CH2Cl adds –CH2CH3) ++AlCl3+ CH3Cl + HCl4. REDOX: alcohols, aldehydes, ketones, carboxylic acids; Clue: K2Cr2O7, KMnO4, LiAlH4, NaBH4 oxidizing agents: K2Cr2O7 with H2SO4; KMnO4 with H2SO4; oxidation num ↑, #electrons ↓, # O ↑, # H ↓ reducing agents: LiAlH4 abbreviated LAH, NaBH4; oxidation num ↓, #electrons ↑, # O ↓, # H ↑ 1˚ alcohol + KMnO4 or K2Cr2O7H2SO4aldehyde + KMnO4 or K2Cr2O7H2SO4carboxylic acid+ LiAlH4 or NaBH4+ LiAlH4 or NaBH4 OH O OOHH2SO4+ K2Cr2O7H2SO4+ K2Cr2O7+ LiAlH4+ LiAlH4 Note: During the oxidation of a 1˚ alcohol to a carboxylic acid, it’s generally difficult to stop at the aldehyde product. Some instructors may use the word “excess” next to the K2Cr2O7 or KMnO4 reagent to signify the reaction goes to the carboxylic acid, and when no “excess” is used it can mean to stop at the aldehyde product. Note what your instructor does to clarify this issue. 2˚ alcohol + KMnO4 or K2Cr2O7H2SO4ketone+ LiAlH4 or NaBH4 OH Ono reactionH2SO4+ K2Cr2O7H2SO4+ K2Cr2O7+ LiAlH4 3˚ alcohol + KMnO4 or K2Cr2O7H2SO4no reaction no reactionHOH2SO4+ K2Cr2O7 A Way to Think About Chemical Reactions Question: +H2SO4K2Cr2O7OH? 1. What functional group does the reactant contain? Primary (1˚) alcohol 2. What reactions can this functional group undergo? Oxidation; combustion 3. What reagents/catalysts are present? K2Cr2O7; H2SO4 4. What reactions do the reagents/catalysts correspond with? K2Cr2O7 = oxidizing agent 5. What reaction will this molecule undergo with the reagents/catalysts present? oxidation 6. Write the products and change only the functional group(s) that undergo this reaction; leave all other functional groups/atoms unchanged OH O OOH Answer: +H2SO4K2Cr2O7OHOHO 1. Which of the following statements is false? a. Methane will have a lower boiling point than methanol. b. Ethylene glycol (CH2(OH)CH2(OH)) will have a lower boiling point than ethanol. c. Acetic acid has a higher melting point than