Question

Compound (P) has molecular formula \(\mathrm{C}_{7} \mathrm{H}_{12} \mathrm{O}\) which gives red-orange ppt. with Braddy reagent. (P) gives ( +ve) Tollen's test but does not give yellow crystal with \(\mathrm{NaOI}\), then (P) is (A) CC(=O)C1CCCCC1 (B) C=CC1CCCCO1 (C) O=CC1CCCCC1

Short answer

The compound (P) is (C) O=CC1CCCCC1 as it contains a double bond, an aldehyde functional group, and is not a methyl ketone.

Step-by-step solution

First, we analyze the reaction with Braddy reagent. Braddy reagent is used to test for the presence of a double bond in an organic compound. If the compound contains a double bond, it will form a red-orange precipitate with the Braddy reagent. Since (P) gives a red-orange precipitate with Braddy reagent, it indicates that the compound contains a double bond. We can eliminate options that don't contain a double bond. #Step 2: Test with Tollen's Reagent#

Next, we analyze the positive result with Tollen's reagent. Tollen's reagent is an alkaline solution of silver nitrate, which is used to test for aldehydes or alpha-hydroxy ketones in organic compounds. In positive Tollen's test, the aldehyde (or alpha-hydroxy ketone) will oxidize to a carboxylic acid, while silver ions will reduce to silver metal, producing a silver mirror on the test tube. A positive Tollen's test reveals that compound (P) contains an aldehyde (or less likely, an alpha-hydroxy ketone) functional group. We can eliminate any options that do not have such functional groups. #Step 3: Test with Sodium Iodide (NaOI)#

Finally, we analyze the negative result with \(\mathrm{NaOI}\). Sodium iodide is used to test for the presence of a carbonyl group, either in aldehydes or ketones. In a positive test, a yellow crystal of iodoform is formed when a methyl ketone reacts with \(\mathrm{NaOI}\). Since compound (P) does not produce yellow crystals with \(\mathrm{NaOI}\), it implies that (P) is not a methyl ketone. We can thus eliminate options that have a methyl ketone in their structure. #Step 4: Comparing the Options with the Reaction Results#

Now let's compare the given options with the reaction results: (A) CC(=O)C1CCCCC1 - This compound contains a double bond in the carbonyl group and an aldehyde functional group, but it is a methyl ketone, which fails the \(\mathrm{NaOI}\) test. Therefore, this option is incorrect. (B) C=CC1CCCCO1 - This compound contains a double bond, but there is no aldehyde or ketone functional group. This fails the Tollen's test. Therefore, this option is incorrect. (C) O=CC1CCCCC1 – This compound contains a double bond in the carbonyl group and an aldehyde functional group. It also doesn't have a methyl ketone, which passes the \(\mathrm{NaOI}\) test. Thus, this option is correct and compound (P) is (C) O=CC1CCCCC1.

Key concepts

Tollen's Test

The Tollen's test is a classic method used in organic chemistry to identify the presence of aldehydes. It is named after its creator, Bernhard Tollens. The test involves using a solution of silver nitrate (\(\mathrm{AgNO}_3\)) in ammonia, known as Tollen's reagent.

When an organic compound containing an aldehyde group is added to Tollen's reagent, an oxidation reaction occurs. During this reaction, the aldehyde is transformed into a carboxylic acid, while the silver ions are reduced to silver metal. This results in a distinctive silver mirror forming on the sides of the test tube if the reaction is positive.

In context, a positive result in a Tollen's test confirms the presence of an aldehyde functional group in the compound. Therefore, any compound that doesn't produce this silver mirror appearance lacks an aldehyde group.

Aldehyde Functional Group

Aldehydes are a type of organic compound characterized by the presence of a carbonyl group (\(\mathrm{C}=\mathrm{O}\)) attached directly to at least one hydrogen atom and optionally to a carbon chain or ring.

The typical aldehyde is denoted by the functional group notation \(\mathrm{R}-\mathrm{C}=\mathrm{O}-\mathrm{H}\), where \(\mathrm{R}\) represents any carbon-containing substituent. This structure imparts aldehydes with specific chemical properties, most notably their tendency to oxidize readily.

Aldehydes are easily identifiable due to the reactions they undergo. Tollen's test, as described above, is a key method for confirming their presence. Other tests, however, may involve reactions with solutions or reagents that aldehydes distinctly react with, thereby differentiating them from other organic groups like ketones.

Understanding the presence of an aldehyde group is crucial in determining the structure and reactivity of organic compounds.

Double Bond Identification

Identifying the presence of a double bond in organic compounds is fundamental in structural identification. Double bonds typically involve a pair of atoms sharing two pairs of electrons, often represented by the formula \(\mathrm{C}=\mathrm{C}\) in carbon compounds.

Double bonds significantly alter the chemical properties of a molecule. They can participate in reactions such as addition reactions, where new atoms or groups attach to the carbon atoms formerly involved in the double bond. The Braddy reagent is commonly used to identify such double bonds.

Braddy's test involves reacting the compound in question with a solution known to form precipitates in the presence of unsaturation. When added to a compound containing a double bond, the reagent produces a red-orange precipitate, confirming unsaturation.

Detecting double bonds in compounds helps in understanding the reactivity and types of reactions they can undergo, easing the way for manipulation in synthetic processes.