酸性水解

装置设置

1. Charge the flask before fitting the condenser; do not fill the flask more than about half full.
2. Run cooling water into the lower condenser inlet and out from the upper outlet.
3. Keep the top of an ordinary reflux condenser open to the atmosphere unless the cited procedure specifies a pressure-rated closed system.
4. Heat to a gentle, steady boil so the condensation line remains within the condenser and liquid returns continuously to the flask.

操作检查

• Use an electric bath or mantle for flammable organic liquids; do not use a naked flame.
• Start condenser water before heating and confirm that hoses are secure.
• If addition is exothermic, complete the controlled addition and cooling stage before sustained reflux.

装置设置

1. Fit the column between the boiling flask and still head; position the thermometer in the outgoing vapour path.
2. Record temperature and fraction changes during a steady, controlled distillation.

操作检查

• A narrow boiling range is supporting evidence, not proof of complete purity.
• Ethanol and water cannot be assumed to separate into absolutely pure liquids by ordinary fractional distillation.

装置设置

1. Count distinct environments, then compare chemical shifts, proton integrations and resolved splitting with the proposed structure.
2. Explain solvent and reference signals before assigning unexpected peaks as impurities.

操作检查

• Exchangeable O–H and N–H signals can shift, broaden or disappear; their integrals may be unreliable.
• Simple splitting rules have limits, and routine 13C peak areas do not directly count carbons. Combine NMR with other evidence.