含义Meaning
产率衡量得到的产物占理论最大量的比例；转化率衡量某反应物消耗的比例。理论产量由限量试剂决定。
Yield compares the product obtained with the theoretical maximum; conversion is the fraction of a reactant consumed. The limiting reagent sets the theoretical yield.
符号说明Symbols
| 符号Symbol | 含义 Meaning | 单位 Unit |
|---|---|---|
| \(m_{\text{理论}}\) | 按限量试剂完全反应计算的产量theoretical yield from the limiting reagent | g |
| \(\alpha\) | 转化率conversion | % |
推导Derivation
按化学计量比找出限量试剂：\(n_i/\nu_i\) 最小者。
Identify the limiting reagent: the smallest \(n_i/\nu_i\).
理论产量 \(n_{\text{产物}} = \frac{\nu_{\text{产物}}}{\nu_{\text{限量}}}\,n_{\text{限量}}\)，换算为质量。
Theoretical product \(n = \frac{\nu_{\text{prod}}}{\nu_{\text{lim}}}\,n_{\text{lim}}\), converted to mass.
实际产量除以理论产量。多步合成总产率为各步产率之积。
Divide actual by theoretical. Overall yield of a multistep synthesis is the product of the step yields.
\[\eta_{\text{总}} = \prod_k \eta_k\]\[\eta_{\text{total}} = \prod_k \eta_k\]
适用条件与局限Assumptions & limitations
产率 < 100% 的原因：可逆反应、副反应、分离损失；> 100% 通常说明产物不纯或未干燥。
Yields below 100 % come from equilibria, side reactions and work-up losses; above 100 % usually means impure or wet product.
选择性（生成目标产物的反应物占已反应量的比例）与产率、转化率不同：产率 = 转化率 × 选择性。
Selectivity differs: yield = conversion × selectivity.
例题Worked example
一个五步合成每步 80%，总产率 0.8⁵ = 33%。
A five-step synthesis at 80 % per step gives 0.8⁵ = 33 % overall.