調製、精製、および統合的な分析証拠
導入済み| English | 意味 |
|---|---|
| infrared/ˌɪnfrəˈred/ | 赤外線 |
| distil | 蒸留 |
| reflux/ˈriːflʌks/ | 還流 |
| anhydrous/ænˈhaɪdrəs/ | 無水 |
Can one peak prove which liquid you made?
- Propanal and propanone both have formula C₃H₆O, molecular mass 58 and a carbonyl group. One molecular ion or one C=O absorption cannot distinguish them.
- Combine reaction conditions, purification, mass spectra, infrared 红外 data and chemical tests. Give a supported candidate and explain which competing candidate each observation rejects.
Choose preparation conditions for the product
- Acidified potassium dichromate(VI) changes orange to green when reduced. For a primary alcohol, distil 蒸馏 the aldehyde as it forms; excess oxidant under reflux 回流 gives the carboxylic acid. A secondary alcohol gives a ketone under these conditions.
- For propan-1-ol: CH₃CH₂CH₂OH + [O] → CH₃CH₂CHO + H₂O; with further oxidation, CH₃CH₂CH₂OH + 2[O] → CH₃CH₂COOH + H₂O. Propan-2-ol gives CH₃COCH₃ + H₂O with [O]. Distillation removes vapour; reflux returns condensed vapour and allows prolonged heating.
酸性ジクロム酸塩を用いてプロパノール-1-オールからプロパナールを収集するのに適した条件はどれか？
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
蒸留によりアルデヒドが生成されるごとに除去され、さらに酸化されるのを防ぐ。還流下での過剰な酸化剤はプロパン酸の生成を好む。制御装置は承認された監督下で使用しなければならない。
Purify without confusing bulk water and residual water
- In solvent extraction, use a separating funnel to separate immiscible layers. If the organic layer has density $0.87\,\dfrac{\mathrm g}{\mathrm{cm}^3}$ and the aqueous layer $1.00\,\dfrac{\mathrm g}{\mathrm{cm}^3}$, the organic layer is upper; identify it from the stated densities, not an always-upper rule.
- After bulk separation, a suitable anhydrous 无水的 salt removes residual water. Remove the drying salt, then distil as appropriate. Measure boiling temperature with the thermometer bulb at the vapour take-off. A narrow range near the expected value at the stated pressure supports purity but is not unique structural proof.
A dried liquid boils at 85–86°C at a stated pressure. This is consistent with a relatively pure liquid having that boiling range. It does not prove a single named isomer: compare independent spectral or chemical evidence, and consider whether the apparatus measures vapour temperature correctly.
互いに混ざり合わない2層があり、有機層の密度が 0.87 g/cm³ 、水溶液層の密度が 1.00 g/cm³ である。どの記述が正か？
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
この場合、密度の低い有機液体は上部にある。分液ロートで大部分の水溶液を取り除き、分離後に乾燥塩で残留水分を取り除く。
期待される温度での狭い沸点範囲が、分子構造を一意に証明する。
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
狭い範囲は、指定された圧力および測定条件下での相対的な純度を裏付ける。異なる構造は類似した沸点を持つことがあり、独立した同定证据が必要である。
Keep mass and fragment evidence distinct
- A singly charged molecular ion at m/z 58 supports molecular mass 58. C₃H₆O gives $3(12)+6(1)+16=58$. The base peak is the most intense peak; it need not be the molecular ion.
- A peak at m/z 29 could be CHO⁺, mass 12 + 1 + 16, or C₂H₅⁺, mass 24 + 5. Check plausible fragmentation and the full pattern. A positive warmed Fehling's/Benedict's test gives a brick-red precipitate and supports propanal over propanone in this two-candidate comparison.
C = 12, H = 1, O = 16 を用いる。単一電荷の CHO⁺ の nominal m/z は何か？
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
12 + 1 + 16 = 29 （電荷 +1）。C₂H₅⁺ も nominal mass が 29 であるため、このピークは一意の断片式ではない。
Combine infrared bands and tests
- Use the supplied wavenumber table: C–H bands differ in alkanes, alkenes and aldehydes; C=C supports an alkene; alcohol O–H is broad while acid O–H is very broad. C=O can occur in aldehydes, ketones and acids; C–X supports a halogenoalkane and N–H an amine. Predict all relevant bonds from a candidate structure before comparing its spectrum.
- For example, supplied broad O–H at $3200–3600\,\dfrac{1}{\mathrm{cm}}$ and C=O at $1680–1750\,\dfrac{1}{\mathrm{cm}}$ can fit HOCH₂CHO; an acid has a much broader O–H region around $2500–3300\,\dfrac{1}{\mathrm{cm}}$. A carbonate test releasing CO₂ supports an acid. For inorganic unknowns use clean aliquots: warming NH₄⁺ with OH⁻ releases NH₃; acidified barium reagent gives white BaSO₄ with sulfate. These observations are not universally unique outside a stated candidate list.
An absorption shows evidence for a bond, not the whole structure. Overlapping bands and ambiguous fragments require more evidence. These are written method and interpretation checks; they do not certify practical performance or replace approved supervised procedures.
Control the preparation, explain each purification step, and combine molecular mass, plausible fragments, infrared bonds and selective tests. State exactly how far the evidence supports the identification.
候補リストはプロパナールまたはプロパノン。どちらも C₃H₆O および C=O に合致する。温めたフェーリング液テストではレンガ赤色の沈殿が生じる。どちらが支持されるか？
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
プロパナールはアルデヒドであり、この陽性反応を示す。プロパノンはケトンであり、これらの条件下では示さない。化学式とカルボニル証拠だけでは両者を区別できない。