Indicate if the following statement is true (T) of false(F). Acetic acid is more
ID: 529921 • Letter: I
Question
Indicate if the following statement is true (T) of false(F). Acetic acid is more acidic than nitroacetic acid. Benzoic acid is more acidic than acetic acid. Boiling point of propapnoic acid is higher that water but lower than 2-butanol A typical IR absorption of ketones around 1720cm^-1 is due to c = O stretching. Both proton NMR of compound and B show absorption around -10, but A shows A near 2720- a broad absorption in the 3500-2500 cm and B shows two weak bands and B a 2820 cm Based on this data one can safely assume that A is an aldehyde carboxylic acid. The intramolecular esterification of hydroxy acids produce lactams. Both LiAIHe and NaBHe are efficient reducing agents which can be used to reduce carboxylic acids to alcohols Pyridinium dichromate (PDC or CrO_3 are milder oxidation agents than KMnO_4. and they can be used for oxidation of secondary or tertiary alcohols to ketones. A dangerous property of ethers is easily oxidized in air to form explosive peroxides. Macrocyclic polyethers are called crown ethers. They could trap a cation such as K in the molecule.Explanation / Answer
1. Electron withdrawing groups increase acidity of carboxylic acids (RCOOH) by increasing the stability of the carboxylate ion (RCOO-) formed by donating the carboxyl hydrogen. Nitro group (-NO2) is a very strong electron-withdrawing group. So when one hydrogen of the methyl group of acetic acid (CH3COOH), which is a weak acid, is replaced by nitro group to form nitroacetic acid (NO2-CH2COOH) the acidity of the carboxyl hydrogen increases multifolds and it gets much fast and easily donated as compared to the carboxyl hydrogen of acetic acid. So the given statement is false as nitroacetic acid is more acidic than acetic acid.
2. Direct attachment of electron withdrawing group to carboxylic acid increases the acidity of the acid whereas electron donating groups decrease the acidity of the carboxylic acid. Benzoic acid (C6H5COOH) is a stronger acid than acetic acid (CH3COOH) because phenyl group (-C6H5 ) is electron withdrawing whereas methyl group (-CH3) electron donating. So the statement is true.
3. Carboxylic acids have higher boiling points as compared to water and alcohols of comparable molecular masses due to more extensive association of carboxylic acid molecules through intermolecular hydrogen bonding. The hydrogen bonds are not broken even in vapour phase. So propanoic acid (CH3CH2COOH) with molecular mass 74 u has higher boiling point than 2-butanol (CH3CH(OH)CH2CH3) with molecular mass 74 u and water. So the given statement is false.
4. The characteristic Infrared (IR) absorption frequency of aldehydes is 1740-1720 cm-1 due to C=O stretching. The characteristic IR absorption frequency in ketones for C=O stretch is in the range 1670-1820 cm-1. So the statement is false.