Organic reaction refers to a chemical change that involves the rearrangement of atoms within an organic molecule. It can involve the breaking of existing bonds and the formation of new bonds. Organic reactions are typically catalyzed by enzymes, which are protein molecules that speed up the rate of a chemical reaction without being consumed in the process.

Organic synthesis refers to the intentional and planned construction of organic molecules. It is a multi-step process that typically involves a series of organic reactions. The goal of organic synthesis is to create a desired organic compound, such as a drug, a polymer, or a fragrance.

Here is a table summarizing the key differences between organic reactions and organic synthesis:

| Feature | Organic Reaction | Organic Synthesis |

|---|---|---|

| Definition | Chemical change involving rearrangement of atoms within an organic molecule | Intentional and planned construction of organic molecules |

| Scope | Can occur naturally or be catalyzed by enzymes | Typically involves a series of organic reactions |

| Goal | Rearrangement of atoms within a molecule | Creation of a desired organic compound |

Here are some examples of organic reactions:

* Substitution reactions: In a substitution reaction, one atom or group of atoms is replaced by another atom or group of atoms. For example, when methane reacts with chlorine gas, one of the hydrogen atoms in methane is replaced by a chlorine atom, resulting in the formation of chloromethane.

* Addition reactions: In an addition reaction, two or more molecules combine to form a single larger molecule. For example, when ethylene reacts with hydrogen gas, the two molecules combine to form ethane.

* Elimination reactions: In an elimination reaction, two atoms or groups of atoms are removed from a molecule, resulting in the formation of a double bond or a ring. For example, when ethanol is heated in the presence of sulfuric acid, the hydroxyl group (-OH) and a hydrogen atom are removed, resulting in the formation of ethylene.

Here are some examples of organic synthesis:

* Synthesis of aspirin: Aspirin is a pain reliever that can be synthesized by reacting salicylic acid with acetic anhydride in the presence of a catalyst.

* Synthesis of nylon: Nylon is a synthetic polymer that can be synthesized by reacting adipic acid with hexamethylenediamine.

* Synthesis of penicillin: Penicillin is an antibiotic that can be synthesized by reacting 6-aminopenicillanic acid with a variety of side chains.

Organic reactions and organic synthesis are both important areas of chemistry. Organic reactions are the fundamental chemical changes that occur in living organisms, and organic synthesis is the process by which we create new organic compounds for use in medicine, industry, and everyday life.