Ch 19 textbook - CHAPTER 19 Carboxylic Acids 19-1 Naming...

Info icon This preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
CHAPTER 19 Carboxylic Acids
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Naming the Carboxylic Acids 19-1 Chemical Abstracts retains the common names for the two simplest carboxylic acids, formic acid and acetic acid. The IUPAC system derives the name of carboxylic acids by l i th di i th t lk b th di i replacing the ending –e in the parent alkane by the ending –oic acid .
Image of page 2
The alkanoic acid stem is numbered by assigning 1 to the carbonyl carbon and labeling any substituents along the longest h i i ti th CO H di l chain incorporating the CO 2 H group accordingly. The carbonyl group and the functional groups of its derivatives take precedence in naming over any other groups discussed so far:
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
When other functional groups are present, the main chain is chosen to include other functional groups as much as possible. Saturated cyclic acids are named as cycloalkanecarboxylic acids . Aromatic acids are named benzoic acids . Dicarboxylic acids are referred to as dioic acids .
Image of page 4
Structural and Physical Properties of Carboxylic Acids 19-2 Formic acid is planar. The molecular structure of formic acid is roughly planar, which is characteristic of carboxylic acids in general.
Image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The carboxy group is polar and forms hydrogen- bonded dimers. The carboxy function is strongly polar and forms hydrogen bonds to other polarized molecules such as water, alcohols and other carboxylic acids carboxylic acids. Carboxylic acids up to butanoic acid are completely soluble in water. As neat liquids, and even in fairly dilute solutions, carboxylic acids form hydrogen-bonded dimers (6–8 kcal mol -1 ).
Image of page 6
Carboxylic acids have relatively high melting and boiling points due to hydrogen bonding in both the solid and liquid states.
Image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Volatile carboxylic acids (low MW) exhibit characteristically strong odors (butanoic acid, cheese; (E)-3-methyl-2-hexenoic acid, human sweat).
Image of page 8
NMR and IR Spectroscopy of Carboxylic Acids 19-3 The carboxy hydrogen and carbon are deshielded The carboxy hydrogen and carbon are deshielded. Hydrogens on a carbon next to a carbonyl group are slightly deshielded. The effect diminishes rapidly with increasing distance from the carbonyl. The hydroxyl proton resonates at very low field ( = 10-13 ppm). Its chemical shift varies strongly with concentration, solvent and temperature because of its involvement in hydrogen bonding.
Image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 10
The 13 C NMR chemical shifts of carboxylic acids are similar to those of aldehydes and ketones. The amount of deshielding is smaller because of the presence of the extra OH group smaller because of the presence of the extra OH group. The smaller deshielding can be attributed to the extra resonance form present in carboxylic acids:
Image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
The carboxy group shows two important IR bands. St et hing f eq en ies fo both the a bon l g o p and the Stretching frequencies for both the carbonyl group and the hydroxy substituent are seen in the IR spectra of carboxy groups.
Image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern