What is Enantiotropic transition?

What is Enantiotropic transition?

For enantiotropic polymorphs, the transition temperature is of great importance since it defines the temperature at which the stability relationship between the two forms becomes inverted. The transition temperature is the temperature at which the two forms have the same solubility.

What is Monotropic and Enantiotropic?

The key difference between enantiotropic and monotropic is that enantiotropic refers to having different polymorphic states that are stable at different temperatures, whereas monotropic refers to having only one polymorph that is stable at all reasonable temperatures.

What is Pseudopolymorphs?

Pseudopolymorphism is the phenomenon wherein a compound is obtained in crystalline forms that differ in the nature or stoichiometry of included solvent molecules. 2 In a supramolecular sense, pseudopolymorphs of a compound are different chemical systems and should be treated as such.

What is Monotropic polymorphism?

Monotropic relationship occurs when one of polymorphs is stable over entire temperature range (Fig. 3a). In the case of enantiotropic system, the transition temperature at which the free energy between two polymorphs is equal occurs below melting point (Fig. 3b).

Why there is no reversible transition in the Monotropic system?

For a monotropic system, the free energy curves do not cross, and therefore no reversible transition can be observed below the melting point; the polymorph with higher free energy curve and solubility is the unstable polymorph.

What does Monotropic mean chemistry?

Definition of monotropy : the relation of two different forms of the same substance (as white and red phosphorus) that have no definite transition point since only one form (as red phosphorus) is stable and the change from the unstable form to the stable form is irreversible.

What is polymorphic transformation?

polymorphic transformation Change in the atomic structure of a mineral (but not in its chemical composition) to produce a different form. In reconstructive transformation there are large energy barriers to overcome in order to break down and re-form bonds, and transition tends to be slow, e.g. graphite to diamond.

What is hydrates and solvates?

Hydrates and Solvates (Pseudomorphism) Hydrates or solvates of a drug substance, similar to polymorphs, are crystal modifications of a drug substance. This characteristic of solvate formation is sometimes known as pseudomorphism.

Why are hydrates less soluble than anhydrous?

Hydrates are generally expected to be thermodynamically more stable, hence less soluble and slower to dissolve than anhydrate forms above the critical water activity for hydrate formation.

What is enantiotropy in chemistry?

Definition of enantiotropy. : the relation of two different forms of the same substance (such as two allotropic forms of tin) that have a definite transition point and can therefore change reversibly each into the other — compare monotropy.

What are Archaic transition words?

Archaic transition words. Words like “hereby,” “therewith,” and most others formed by the combination of “here,” “there,” or “where” with a preposition are typically avoided in modern academic writing. Using them makes your writing feel old-fashioned and strained and can sometimes obscure your meaning.

How do you use transition words in writing?

In sum, use transition words and phrases judiciously to keep your paper moving, hold your readers’ attention, and retain your audience until the final word. Fleming, Grace. “Complete List of Transition Words.”

What are adversative transition words and how to use them?

Adversative transition words always signal a contrast of some kind. They can be used to introduce information that disagrees or contrasts with the preceding text.