脱水

环己醇 → 环己烯：查看反应物、产物、反应条件与来源依据，探索相关转化和合成路径。

试剂
磷酸催化剂
条件
加热；通过蒸馏移出环己烯
反应类别
脱水
方程式
C6H12O -> C6H10 + H2O

概览

环己醇通过脱水生成环己烯。

转化

环己醇 → 环己烯

方程式
C6H12O -> C6H10 + H2O
反应物
环己醇
产物
Cyclohexene + Water
试剂
磷酸催化剂
反应环境
加热；通过蒸馏移出环己烯
反应类别
脱水
机理
脱水
Evidence level
source-backed molecular example

参考步骤

Cyclohexene preparation and purification

Cyclohexanol → cyclohexene + water

物料与用量

  • 环己醇
  • Acid catalyst and work-up materials specified in the full method

仪器装置

  • Heated reaction apparatus
  • Distillation apparatus
  • 分液漏斗

实验步骤

  1. Use the approved dehydration and distillation stages to separate volatile product from the reaction mixture.
  2. Separate the collected organic phase and dry it before any final purity measurement.

后处理与分离

  1. Record a boiling range and test a separate aliquot for unsaturation.
  2. An IR comparison can check loss of the alcohol feature; account for residual water.

关键控制条件

  • Decolourisation indicates unsaturation in the product mixture.
  • Acid residues, water and unreacted alcohol require distinct purification steps.

实验技术

Distillation setup

Rearrange the apparatus to collect a volatile product or fraction instead of returning condensate to the reaction flask.

装置设置

  1. Position the thermometer bulb at the entrance to the condenser so it measures vapour entering the condenser.
  2. Run cooling water into the lower condenser connection and out through the upper connection.
  3. Heat gradually and collect only the fraction specified by the cited boiling range or procedure.

操作检查

  • Do not distil a flask to dryness.
  • Use an electric heat source for flammable mixtures.
  • Change from reflux to distillation only after heating has stopped and the apparatus has cooled enough to handle safely.

Liquid–liquid work-up

Separate the organic product layer from the aqueous reaction mixture, then wash and dry it before final purification.

装置设置

  1. Identify which layer contains the product from density data or a small drop test; do not assume the organic layer is always on top.
  2. Invert gently during washing and vent frequently away from people, especially when carbonate wash produces carbon dioxide.
  3. Drain and retain both layers until product identity has been confirmed.
  4. Dry the isolated organic layer until the drying agent remains free-flowing, then decant or filter before final distillation.

操作检查

  • Remove the stopper before draining through the tap.
  • Release pressure after each inversion during gas-forming washes.
  • Record which layer was retained at every wash.

Drying an organic liquid

Remove residual water from a separated organic layer with a compatible anhydrous drying agent.

装置设置

  1. Remove visible aqueous liquid before treating the organic phase.
  2. Mix with small portions of drying agent, allow contact and separate the clear liquid from the solid before final purification.

操作检查

  • Choose the agent for the product: a drying agent must not react with or strongly retain it.
  • Drying removes water, not dissolved organic impurities; boiling-range or spectroscopic checks are still needed.

Infrared evidence for functional-group change

Use functional-group absorptions and the fingerprint pattern to test a proposed transformation.

装置设置

  1. Check sample identity, background and axis units before assigning absorptions.
  2. Compare the starting material and product: oxidation may introduce C=O while removing an alcohol O–H feature.

操作检查

  • Water, solvent and unreacted substrate can contribute bands.
  • A carbonyl band alone does not distinguish every aldehyde, ketone, acid and ester. Use reference data and complementary evidence; no simulated trace is a measurement.

底物范围

适用范围
Named cyclohexanol example; not a class-wide route prediction.
来源说明
Acid-catalysed elimination.

相关反应

参考文献

  1. Dehydration of alcoholsJim Clark · Chemguide · 2015

    Named molecular transformation examples, checked 2026-09-08.

  2. A Level Chemistry A and B Practical Activities Support GuideOCR · OCR qualifications

    PAG 5.2 covers cyclohexene preparation and purification; PAG 5.3 covers ethanol oxidation. Method summaries remain method overviews.

  3. Pearson Edexcel International Advanced Level Chemistry Student Practical GuidePearson Education Limited · Pearson qualifications · 2018

    Supports the practical distinctions between reflux, distillation, liquid-liquid separation, washing and drying in organic preparations.

  4. Reflux and distillation – practical videosRoyal Society of Chemistry · RSC Education

    Explains the different purposes and apparatus arrangements for reflux and distillation, including organic preparation and work-up.

  5. Infrared spectroscopy: introductionRoyal Society of Chemistry · RSC Education

    Molecular vibrations, functional-group absorptions and fingerprint comparison; no fabricated sample spectra.