Description of Specialized Glassware and Related Equipment

      Although you have had some exposure to the various types of glassware utilized in an organic chemistry laboratory, the following descriptions are provided (with some illustrations) as a supplement to your experience during the CHM 2445 organic chemistry laboratory class. This is by no means meant to be a comprehensive list of common chemical glassware, but the more commonly used items will appear in the pages that follow.

Ground Glass Joints
Ground glass joints are junctions on a piece of glassware which enables an airtight interlock with another piece. You will note that this portion of the glassware item is somewhat opaque (relative to the typical transparency of glass) and that the joint changes in diameter from the end to the other. This change in joint diameter is referred to as a standard taper, and is typically represented by the symbol .  There are literally dozens of standard taper sizes, which are comprised of two numbers: diameter of the joint at its narrowest (in mm), followed by a slash /, and finally the length of the joint (also in mm).   The smallest usually encountered is 10/30, while the middle joints in 22L and 50L flasks are 50/55  (actually, joints get much larger, but at this point the cylindrical type seen here is replaced by ball&socket type joints, which must be held together by large clamps.

There are two partners in a ST joint, generally referred to as the inner ("male") and outer ("female") joints; these fit together to form a very tight seal that is gastight, and, when lightly lubricated, vacuum-tight as well.  In an organic synthetic lab, we use three sizes almost exclusively: 14/20, 19/22, and 24/40.  If you took Organic Chemistry Lab here at EIU, you are already familiar with the 19/22 size.

These are highly precise pieces of glassware and are not cheap.  Typically, the joints cost $10-15 each, so a three- necked flask would be around $40.  Since the #1 enemy of ST joint longevity is dirt and grime, it is important to keep ground glass joints clean, which means cleaning them as soon after use as possible.

Teflon Sleeves
In some applications, ground glass joints are subjected to contact heating-cooling cycles (such as the main joints in our solvent stills), which are virtually guaranteed to freeze the joint.  In such cases, a thin polymer film impregnated with a Teflon7 compound do an excellent job of avoiding this.  Although they look thin and flimsy, they're incredibly strong, and incredibly expensive!  (The cheapest are about $3.00 EACH!)  They are NOT disposable!

Rubber Septa
These items are usually made of chemically resistant rubber and often come in two different colors: white or orange These are typically found in three common sizes. These sizes are made to fit the three most common standard taper joint sizes found among organic glassware: 14/20, 19/22, and 24/40, and are used to seal the ends of the female joints of glassware. They are useful in that they serve as an airtight seal for the ends of ground glass joints; however they may be penetrated with sharp items such as needles, when it becomes necessary to add liquid chemicals to reaction mixtures.

Syringes
Glass syringes are precision ground, expensive pieces of glassware. When you are finished with a glass syringe, please rinse it out with water as soon as practical; it should then be rinsed with a small amount of acetone (to aid drying), dried thoroughly (so that no trace of acetone remains), and placed in the appropriate oven after being assembled (i.e., with the plunger inside the barrel). Storing syringes assembled keeps dust away from the ground glass surfaces, so that they last much longer.

Syringe Needles
Organic synthetic labs use syringe needles by the dozen, of both the disposable and steel reusable type, for anhydrous liquid transfers.  After use, they should be placed in the special red "Sharps" disposal unit.  Steel needles should be cleaned asap after use, since they can be destroyed by prolonged exposure to many chemicals.  Also, be very careful when using needles - most were meant for human use, and are extraordinarily sharp; accidentally injecting yourself is easier than you might think.