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Karteikarten von J yadonknow, aktualisiert more than 1 year ago
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Erstellt von J yadonknow
vor mehr als 6 Jahre
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| Frage | Antworten |
| Naming carboxylic acids | -oic acid -dioic acid carboxylic acid carbon is ALWAYS number 1, has priority over all other groups The carbon attached to the amine group in amino acids is the alpha carbon, the one not attached to cooh or nh2 is beta so it's a-amino-propanoic acid the same with ketones |
| What are the physical properties of carboxylic acids? | Carboxyl group is highly polar Can form hydrogen bonds with: water themselves other polarised molecules |
| Describe the solubility of COOH | Dependant on length of CH chain C1-C4 Are soluble, can form polar H bonds The longer the HC chain however, the more the london forces outweigh the force of hydrogen bonding and so long HC COOH are insoluble |
| How do COOH relate to membranes? | Fatty acids are COOH, so properties of COOH effect membranes i.e. melting point/reactivity etc. |
| How do carboxylic acids usually exist? | As dimers, hydrogen bonded to one another Have relatively high mpt and bpt due to their ability to hydrogen bond in the solid state and liquid state |
| Are carboxylic acids acids or bases? | Both, can donate or accept a proton relatively easy to lose H More difficult to accept H and be an alkali |
| Why are carboxylic acids more acidic than alcohols? | The OH of COOH have a lower strength than those of alcohols COO- is a more stable ion, negative charge becomes delocalised between the two oxygen molecules creating resonance between two different forms |
| How does anion stability vary with increasing chain length of carboxylic acids? | Anion stability decreases pKA increases acid becomes weaker |
| How are carboxylate salts made? | Readily made by treatment of acid with a strong base |
| How can you explain the polarity of these salts? | Much more soluble than corresponding acid due to the polar anionic group |
| How do we know the precise mechanism of esterification? | Labelled H never appears in H2O, always appears in the ester |
| What do alkyl groups tend to do? | Push charge away from themselves, destabilising the COO- ion. More delocalised. |
| Describe the process of protonation of COOHs | Lone pair of electrons on Oxygen atom can attract protons Difficult process, but important in terms of reactions of COOH |
| How do we know the precise mechanism of esterification? | Labelled methanol |
| Show the mechanism of ester formation | Protonation charge redistribution to OH Alcohol nucleophilic attack +H2O Hydronium ion formation Transfer of H+ from H3O+ to C-OH Movement of electrons to H2O Elimination of H20 Formation of Ester and hydronium |
| What is the alpha carbon? | The carbon next to the functional group |
| Mechanism of Amide formation | Addition of NH3 Proton transfer C=O formation and elimination of H2O |
| Lactam formation | Proton transfer Conformation change |
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