What is meant by the following terms? Give an example of the reaction in each case. (i) Cyanohydrin. Draw the structures of the following compounds. (i) 3-Methylbutanal (ii) But-2-ena. Write structural formulas and names of four possible aldol condensation products. O forms. 2
Arrange the following compounds in increasing order of their property as indicate. Give simple chemical tests to distinguish between the following pairs of compounds. (i) Propanal and. How will you prepare the following compounds from benzene? You may use any inorganic reagent and any organic r. (iii) Cross ald. Complete each synthesis by giving missing starting material, reagent or products An organic compound contains 69. 77% carbon, 11. 63% hydrogen and rest oxygen. The. Although phenoxide ion has more number of resonating structures than carboxylate ion, carboxylic acid is a str. The OH (hydroxide) group can occur in three different environments within organic molecules: alcohols, acids, and phenols.
There are three classifications of alcohols, each one dependant on the position of the OH group: Primary alcohols are attached to a carbon with only one R-group (carbon chain or other atoms other than hydrogen). Secondary alcohols are attached to a carbon with two R-groups. Tertiary alcohols are attached carbon with three R-groups. These occur when an OH group is attached to a benzene ring. Phenols behave very differently to alcohols. Carboxylic acids contain a COOH group. So ethanol and water act as weak acids, but with ethanol the position of equilibrium of the reaction lies further to the left than it does in water, thus ethanol is a weaker acid. With phenol, the position of equilibrium lies further to the right, as it is a stronger acid. Carboxylic acids are even stronger acids than phenols; however they are still only weak acids. formed decides how strong the acid is.
If the ve charge on the oxygen can be shared with other atoms, then it will be more stable, thus more of it will be made. No sharing can occur in alcohols; however in phenols and carboxylic acids, sharing can occur as the electrons spread out around the whole ion (delocalised electrons). Only carboxylic acids react with carbonates to produce carbon dioxide. to form their sodium salts. nor any of the carbonates. Primary alcohols can be oxidised to make aldehydes, which can then be oxidised to carboxylic acids. Secondary alcohols are oxidised to ketones. Tertiary alcohols cannot be oxidised. Phenols and carboxylic acids cant be oxidised as they dont have a hydrogen atom on the carbon atom to which the OH group is attached. Two hydrogen atoms are being removed from the molecule (one attached to the carbon and the other from the OH group). The product is a Carbonyl group (either a ketone or aldehyde). The product depends upon the kind of alcohol you start with.
In an aldehyde, the carbonyl group is at the end In a ketone, the carbonyl group is inside the alkyl chain: Primary alcohols are oxidised to aldehydes and then carboxylic acids. For example, ethanol is oxidised to ethanal, which is then oxidised to ethanoic acid: Secondary alcohols are oxidised to ketones. For example, propan-2-ol is oxidised to propanone: Tertiary alcohols are difficult to oxidise, as they do not have a hydrogen atom on the carbon atom to which the OH is attached. Alcohols can lose a molecule of water to become an alkene. Propene is formed when propan-1-ol vapour is passed over a C). It is a dehydration reaction because it involves the removal of a water molecule from a molecule of the reactant. Dehydration can also occur when heated with concentrated sulphuric acid. Dehydration is an example of an elimination reaction (reverse of an addition reaction).