Final answer:
The statement that tosylate is a good leaving group while mesylate is not is false. Both are considered strong leaving groups due to their ability to stabilize the negative charge after departure from the substrate, making them useful in various organic synthesis reactions, including the synthesis of oligonucleotides.
Step-by-step explanation:
The statement that tosylate is a good leaving group while mesylate is not is false. Both tosylates and mesylates are considered good leaving groups in organic chemistry. This is due to their ability to stabilize the negative charge after leaving a substrate by dispersing it over an electronegative sulfur atom and surrounding groups. For example, in the synthesis of oligonucleotides, p-toluenesulfonic acid (p-TsOH) is often used to promote reactions where good leaving groups are required. This reinforces the practicality of using tosylates in laboratory procedures. Moreover, both the tosylate and mesylate groups can be used to transform poor leaving groups, like -OH, into better ones that can facilitate nucleophilic substitution and elimination reactions.
In a broader context, the ability of a group to act as a leaving group is determined by how stable the group is after it has left the molecule. More stable leaving groups, such as dimethyl sulfide or the phosphate group in a coenzyme-A molecule, can help drive reactions forward by providing a favorable energetic outcome. These concepts are crucial in understanding reaction mechanisms and designing synthetic pathways in both organic chemistry and biochemistry.