nearquantitative

Nearquantitative is a term used in chemistry to describe a reaction or process that yields the product close to the theoretical maximum, typically approaching a quantitative (near 100%) yield after isolation. There is no universal numerical threshold for the term; what counts as nearquantitative depends on context, substrate, and purification method. In practice, high-90s percent yields are commonly described as nearquantitative, though authors may reserve the label for even higher efficiencies in particular systems.

Usage and meaning:

The label refers to isolated yield, i.e., the amount of product obtained after workup and purification relative to the limiting reagent. It emphasizes practical efficiency in a real laboratory setting rather than an exact mathematical conversion. A nearquantitative result can occur even if minor side products form, as long as the main product can be isolated in amounts close to the theoretical maximum.

Measurement considerations:

Yields are typically reported as isolated yields. The calculation accounts for stoichiometry and purity after purification. Reporting can be influenced by scale, purification difficulty, and analytical methods; thus, the same reaction might be described differently in different contexts.

Limitations:

Because there is no strict standard, the term is somewhat subjective. It can obscure significant purification losses or variability between scales or laboratories if not accompanied by explicit yield values.

See also:

quantitative yield, isolated yield, reaction yield, purification losses.