Apparatus for heating under reflux

Fig. 5. Semimicro apparatus for heating under reflux (for inflammable liquids,...

How Do I Know How Hot to Heat It A common problem that inexperienced students encounter when they assemble an apparatus for heating under reflux is that it is difficult to decide what temperature setting to use for heating the contents of a vial or flask fo fhe desired temperature. This problem becomes more acute when the students attempt to reproduce the temperatures that are specified in the laboratory procedures of a fextbook. 

Apparatus A 25- and a 50-mL round-bottom flask, ice-water bath, apparatus for heating under reflux, magnetic stirring, simple distillation, vacuum filtration, and flameless heating. 

Setting Up Place about 4 g of ground nutmeg in the 50-mL round-bottom flask oontaining a spinvane and add 10 ml of diethyl ether, If only seeds of nutmeg are available, grind the seeds in a mortar and pestle or a blender. Attach a water-cooled condenser to the flask, and set up the apparatus for heating under reflux (Fig. 2.66a). 

Assembly Assemble the apparatus for heating under reflux, and attach a gas trap, such as that of Figure 2.69, to the top of the condenser. Place a spinvane in the vial and add 10 mg (0.010 g) of 1,1 -azobis(cyclohexanecarbonitrile) (ABCN). Working at the hood, sequentially add 0.5 mL of 1-chlorobutane and 0.2 ml (200 piL) of sulfuryl chloride to the vial. Cap and weigh the vial, and then attach it to the reflux condenser, working quickly to minimize introducing vapors of sulfuryl chloride into the atmosphere. 

Setting Up and Addition Equip the conical vial with a spinvane and add to it 500 jjlL (0.5 mL) of 1-hexene, 2 mL of 48% aqueous hydrobromic acid, and 150 mg of methyltrioctylammonium chloride. Equip the vial with a water-cooled condenser and assemble the apparatus for heating under reflux. With rapid stirring, heat the... 

Setting Up Piace 0.5 g of ( )-stiibene and 12 mL of 95% ethanol in the round-bottom fiask containing a stirbar and set up the apparatus for heating under reflux. Heat the mixture under refiux untii most of the solid has dissolved. 

Setting Up Place 2.5 g of 3-sulfolene, 1.5 g of finely pulverized maleic anhydride, and 1 mL of dry xylenes in the flask and equip it with a stirbar. Assemble the apparatus for heating under reflux. Attach the condenser to the gas trap specified by your instructor. 

Setting Up Place 11.1 g of sodium bromide in the 100-mL round-bottom flask, and add about 10 mL of water and 10 mL of 1-butanol. Mix the contents of the flask thoroughly by swirling then cool the flask in an ice-water bath. Slowly add 10 mL of concentrated sulfuric acid to the cold mixture with swirling and continuous cooling. Remove the flask from the ice-water bath, add a stirbar. and set up the apparatus for heating under reflux. 

Setting Up Place 2.4 g of commercial calcium hypochlorite (65%) in the round-bottom flask containing a stirbar. Add 20 mL of water to the flask and stir the mixture while adding 2 mL of glacial acetic acid dropwise. Weigh 0.5 g of 4-chlorobenzyl alcohol, and add it to a small Erlenmeyer flask containing 5 mL of acetonitrile swirl the contents to dissolve the alcohol. Set up the apparatus for heating under reflux. 

Reduction Add 4 mL of methanol to the stillpot, stir to dissolve the crude imine, and set up the apparatus for heating under reflux. Prepare a solution of 0.15 g of sodium borohydride in 3 mL of methanol. Because sodium borohydride reacts slowly with methanol to evolve hydrogen gas, this solution should be prepared in an unstoppered vessel immediately betore use. Using a Pasteur pipet or a syringe, transfer the methanolic solution of sodium borohydride dropwise through the top of the reflux condenser to the stirred solution of the imine the addition should be completed within 1 min. Try to add the solution d/recf/y into the flask without touching the walls of the condenser. After all of the borohydride solution is added, heat the reaction mixture under reflux for 15 min. 

Setting Up Add 0.2 g of p-aminobenzoic acid and 2.0 mL of absolute ethanol to the conical vial containing a spinvane. Stir the mixture until the solid is completely dissolved. Add 0.2 mL of concentrated sulfuric acid dropwlse to the ethanolic solution of p-aminobenzoic acid, equip the vial with a condenser, and set up the apparatus for heating under reflux. 

Microscale apparatus for heating under reflux, equipped with a gas trap and a syringe for adding a solution. 

Setting Up Prepare 20 mL of a solution of dilute hydrochloric acid by adding 10 mL of concenfrafed hydrochloric acid to 10 mL of water swirl to mix. Equip the round-bottom flask with a stirbar and add the 4-acetamidobenzenesulfonamide and an amount of dilute hydrochloric acid that is about twice the weight of the crude 4-acetamidobenzenesulfonamide. Assemble the apparatus for heating under reflux. 

Setting Up Mix 11.2 g of crude 4-bromo-2-chloroacetanilide with 20 mL of 95% ethanol and 13 mL of concentrated hydrochloric acid in the flask. Add a stirbar and assemble the apparatus for heating under reflux. 

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