1 / 13

Carboxylic acids: R-COOH, R-CO 2 H, Common names : HCO 2 H formic acid

Carboxylic acids: R-COOH, R-CO 2 H, Common names : HCO 2 H formic acid CH 3 CO 2 H acetic acid CH 3 CH 2 CO 2 H propionic acid CH 3 CH 2 CH 2 CO 2 H butyric acid CH 3 CH 2 CH 2 CH 2 CO 2 H valeric acid . 5 4 3 2 1 C—C—C—C—C=O

loisandrews
Download Presentation

Carboxylic acids: R-COOH, R-CO 2 H, Common names : HCO 2 H formic acid

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Carboxylic acids: R-COOH, R-CO2H, Common names: HCO2H formic acid CH3CO2H acetic acid CH3CH2CO2H propionic acid CH3CH2CH2CO2H butyric acid CH3CH2CH2CH2CO2H valeric acid 5 4 3 2 1 C—C—C—C—C=O δ γ β α used in common names

  2. IUPAC nomenclature for carboxylic acids: parent chain = longest, continuous carbon chain that contains the carboxyl group  alkane, drop –e, add –oic acid HCOOH methanoic acid CH3CO2H ethanoic acid CH3CH2CO2H propanoic acid CH3 CH3CHCOOH 2-methylpropanoic acid Br CH3CH2CHCO2H 2-bromobutanoic acid dicarboxylic acids: HOOC-COOH oxalic acid HO2C-CH2-CO2H malonic acid HO2C-CH2CH2-CO2H succinic acid HO2C-CH2CH2CH2-CO2H glutaric acid HOOC-(CH2)4-COOH adipic acid HOOC-(CH2)5-COOH pimelic acid

  3. salts of carboxylic acids: name of cation + name of acid: drop –ic acid, add –ate CH3CO2Na sodium ethanoate CH3CH2CH2CO2NH4 ammonium butanoate (CH3CH2COO)2Mg magnesium propanoate physical properties: polar + hydrogen bond  relatively high mp/ bp water insoluble exceptions: four carbons or less acidic soluble in 5% NaOH RCO2H + NaOH  RCO2-Na+ + H2O stronger stronger weaker weaker acid base base acid

  4. Carboxylic acids, syntheses: • oxidation of primary alcohols • RCH2OH + K2Cr2O7 RCOOH • 2. oxidation of alkylbenzenes (arenes) • ArR + KMnO4, heat  ArCOOH • 3. carbonation of Grignard reagents • RMgX + CO2 RCO2MgX + H+  RCOOH • 4. hydrolysis of nitriles • RCN + H2O, H+, heat  RCOOH

  5. oxidation of 1o alcohols: • CH3CH2CH2CH2-OH + CrO3 CH3CH2CH2CO2H • 1-butanol butanoic acid • CH3 CH3 • CH3CHCH2-OH + KMnO4  CH3CHCOOH • 2-methyl-1-propanol` 2-methylpropanoic acid • oxidation of alkylbenzenes (arenes):

  6. carbonation of Grignard reagent: • R-X RMgX RCO2MgX RCOOH • Increases the carbon chain by one carbon. • Mg CO2 H+ • CH3CH2CH2-Br CH3CH2CH2MgBr CH3CH2CH2COOH • n-propyl bromide butyric acid Mg CO2 H+ • Hydrolysis of a nitrile: • H2O, H+ • R-CN R-CO2H • heat • H2O, OH- • R-CN R-CO2- + H+ R-CO2H • heat • R-X + NaCN  R-CN + H+, H2O, heat  RCOOH • 1o alkyl halide • Adds one more carbon to the chain. • R-X must be 1o or CH3!

  7. carboxylic acids, reactions: • as acids • conversion into functional derivatives • a)  acid chlorides • b)  esters • c)  amides • reduction • alpha-halogenation

  8. as acids: • with active metals • RCO2H + Na  RCO2-Na+ + H2(g) • with bases • RCO2H + NaOH RCO2-Na+ + H2O • relative acid strength? • ROH < HOH < RCO2H • ionization in water • HA + H2O  H3O+ + A- • Ka for carboxylic acids  10-5 • Effect of substituent groups on acid strength? • Ka • CH3COOH 1.75 x 10-5 • ClCH2COOH 136 x 10-5 • Cl2CHCOOH 5,530 x 10-5 • Cl3CCOOH 23,200 x 10-5

  9. Nucleophilic Acyl Substitution of Carboxylic Acids • Nucleophilic acyl substitution converts carboxylic acids into carboxylic acid derivatives, i.e., acid chlorides, anhydrides, esters and amides. NH3, D, -H2O SOCl2 amide ROH H+ acid chloride D -H2O acidanhydride ester

  10. acid chlorides

  11. esters • “direct” esterification: H+ • RCOOH + R´OH  RCO2R´ + H2O • -reversible and often does not favor the ester • “indirect” esterification: • RCOOH + PCl3 RCOCl + R´OH  RCO2R´ • -convert the acid into the acid chloride first; not reversible • amides • “indirect” only! • RCOOH + SOCl2 RCOCl + NH3  RCONH2 • amide

  12. Reduction: • RCO2H + LiAlH4; then H+ RCH2OH • 1o alcohol • Alpha-halogenation: (Hell-Volhard-Zelinsky reaction) • RCH2COOH + X2, P  RCHCOOH + HX • X • α-haloacid • X2 = Cl2, Br2

More Related