Compounds tor Cooling Curve Experiments
2,6-Di-art-butyl-4-menylphenol (butylated hydroxybluene or BHT, mp 6 S 1 1 O C ) andp-(1,1,3,3-tetramethylbutyl). phenol, (tert-octylphenol or TOP, mp 8&82 OC) are good choices for compounds to melt in inst~ctionallaboratories in order to measure their temperature as a function of time while each cools through its freezing point. Neither of these is a chlorinated hydrocarbon nor a known carcinogen or teratogen. Both compounds have published oral LDso doses and do not sublime a s meater than 2 z k ( I ) , are inemensive and readily available, can be used over and over again, . do p.dichloroGnz;ne and naphihaleno. A sample brtwwn 7 and 13 g of enher substance is placed in a 20- A 150-mm test tube. The test cube ia clamped vertically with its cnd anamst the bottom ofa 100-mLbeaker containine 50 mL of boilinz water. When all the samole is liquid; heating is stopped and 15 mL of cold tap water is added to t& heaker to bring the water's temperatukto ahout 83 OC. At higher altitudes where water boils below 100 "C, the volume of cold water added should be reduced aeeordingly. After the tap water is added, the melt is stirred gently with a thermometer and immediately the recording the temperature drops about 5 'C below the freezing point. of temperature and time data is begun and sustained This entire operation takes less than 40 min, which is an advantage for secondary school laboratories. Literature Cited 1. Fairduld, E. J., Ed. Re#istwof l b i s E f , t s of Chmiml S u b 8 t o w ; U . S . Department ofHealth, Education, and Welfare Cincinnati, 1977: Val. 2, p312 andM9.
H. Graden Kirksey Memphis State University Memphis, TN 38152
164
Journal of Chemical Education
