(i)

Step 1:
Cyanohydrin:

Cyanohydrins are organic compounds having the formula RR′C(OH)CN, where R and R′ can be alkyl or aryl groups.
The structure is as follows:

Step 2: 

Aldehydes and ketones react with hydrogen cyanide (HCN) in the presence of excess sodium cyanide (NaCN) as a catalyst to form cyanohydrin. The reaction follows the nucleophilic addition reaction mechanism. 

The reaction is as follows:

(ii)

Step 1:

Acetal:

Aldehydes react with an excess of monohydric alcohol in the presence of dry hydrogen chloride to give a gem-alkoxy compound known as acetal. The structure is as follows:


Step 2:

The reaction is as follows:

(iii)

Step 1:

Semicarbarbazone:

When nucleophiles, such as semicarbazide (derivatives of ammonia) add to the carbonyl group of aldehydes and ketones, then Semicarbazones product is obtained as a product. The product is >C=N-Z. In the case of semicarbazone, Z is NHCONH₂. 

The general reaction for aldehyde and ketone is as follows:



Semicarbazones are useful for the identification and characterization of aldehydes and ketones.

(iv)

Step 1:

Aldol:

A β-hydroxy aldehyde or ketone is known as an aldol. When aldehydes and ketones having at least one α-hydrogen undergo a reaction in the presence of dilute alkali as a catalyst then β-hydroxy aldehydes (aldol) or β-hydroxy ketones (ketol), respectively are obtained as the product. This reaction is known as the Aldol reaction. 

Step 2:

The reaction is as follows:

(v)

Step 1:

Hemiacetal:

Hemiacetals are α−alkoxyalcohols. 

Aldehydes react with one equivalent of monohydric alcohol in the presence of dry hydrogen chloride to yield alkoxyalcohol intermediate, known as hemiacetals. The structure is as follows:

The reaction is as follows: 

(vi)

Step 1:

Oxime:

Nucleophiles, such as NH₂OH(derivative of ammonia) react with the carbonyl group of aldehydes and ketones then oxime is obtained as a product. 

When aldehyde forms oxime it is known as aldoxime, if ketone forms oxime then it is called ketoxime.

The structure is as follows:

Step 2:

The reaction is as follows:

(vii)

Step 1:

Ketal:

Ketals are gem−dialkoxyalkanes in which two alkoxy groups are present on the same carbon atom within the chain. The structure is as follows:

Step 2:

When ketone reacts with an excess of monohydric alcohol in the presence of dry hydrogen chloride to yield gem−dialkoxyalkanes, is known as ketal. The reaction is as follows:

(viii)

Step 1:

Imine:

Imines are chemical compounds containing a carbon-nitrogen double bond. When aldehyde or ketone reacts with ammonia then imine is formed as a product. The general structure of an imine is as follows:



Step 2:

The reaction is as follows:

(ix)

Step 1: 

2, 4−DNP derivative:

2,4−Dinitrophenylhydrazones are 2, 4−DNP−derivatives, which are produced when aldehydes or ketones react with
2, 4−dinitrophenylhydrazine in a weakly acidic medium. The general structure is as follows:



Step 2:

The reaction is as follows:

(x)

Step 1:

Schiff’s base:

Schiff’s base (or azomethine) is a chemical compound containing a carbon-nitrogen double bond with the nitrogen atom connected to an aryl or alkyl group-but, not hydrogen.

When aldehyde or ketone reacts with an amine in the presence of a trace of acid then Schiff's base is obtained as a product.

The structure is as follows:



The reaction is as follows: