are ketones soluble in water
In this experiment, you will make some models of aldehydes, ketones, and carboxylic acids. You will test the water solubility of several compounds. You will carry out several reactions on various aldehydes, ketones, and carboxylic acids. You will then identify an unknown compound based on its reactivity. 1st, the more reduced a molecule, the more energy is released during oxidation on a molar basis. Methane is fully reduced and gives off more energy during combustion than methanol. 2nd, the number of oxygen molecules required to react with a fuel molecule can give an estimate of how much energy is available. In an aldehyde, the carbonyl group is on the end of the molecule. In a ketone, the carbonyl group is somewhere in the middle of the molecule. Example structures of aldehydes and ketones are given below. Carboxylic acids contain the carboxyl functional group, shown below. Boiling Points of Alcohols Alcohols contain polar OH groups. form hydrogen bonds with other alcohol molecules. have higher boiling points than alkanes and ethers of similar mass. Boiling Points of Ethers Ethers do not have a polar group. have an O atom, but there is no H attached. Solubility of Alcohols and Ethers in Water Alcohols and ethers are more soluble in water than alkanes because the oxygen atom can hydrogen bond with water. with 1-4 C atoms are soluble, but not with 5 or more C atoms. Physical Properties Aldehydes and ketones are polar because they contain a carbonyl group (oxygen is very electronegative compared to carbon). Aldehydes and ketones can form hydrogen bonds with water, so small aldehydes and ketones are water-soluble. In cyclic ketones the carbonyl group is assigned position #1, and this number is not cited in the name, unless more than one carbonyl group is present. If you are uncertain about the IUPAC rules for nomenclature you should review them now. Examples of IUPAC names are provided (in blue) in the following diagram. Ketones and carboxylic acids cannot be oxidized and therefore will not react with chromic acid or Benedict’s reagent. Iodoform Test Compounds that contain a methyl group attached to a carbonyl carbon will react with I 2 in a basic solution to produce a yellow precipitate of iodoform (CHI 3). Many (but not all) ketones will undergo this reaction. Acidity Carboxylic acids are weak acids, and will ionize to a slight extent in water. Alkane CH3─CH2─CH3 44 -42 No Ether CH3─O─CH3 46 -23 Yes Alcohol CH3─CH2─OH 46 78 Yes Solubility of Phenol Phenol is soluble in water. has a hydroxyl group that ionizes slightly (weak acid). is corrosive and irritating to skin. Copyright © 2005 by Pearson Education, Inc. Here the weaker pi-component of the carbonyl double bond, relative to other aldehydes or ketones, and the small size of the hydrogen substituents favor addition. Thus, a solution of formaldehyde in water (formalin) is almost exclusively the hydrate, or polymers of the hydrate.
Yes