How to Work with Thiols-General SOP

Though thiols are generally benign reagents, they typically have an offensive smell. This SOP is designed to minimize the potential release of thiols into the lab space and into the environment at large.

1. BEFORE STARTING ANYTHING, contact Ray or EH&S directly about the thiol(s) being used in the reaction with information on the duration the thiol(s) will be used. The duration includes all times that thiol could potentially be released, which includes set-up and running the reaction, work-up, and clean-up.
2. Set-up bleach baths. In a plastic container, such as a bucket, combine a 1:1 mixture of bleach and water by adding the desire amount of bleach and then diluting to the final volume with water. The liquid line should be at least four inches below the top of the container to allow for displacement of liquid from the glassware. Bleach baths should be covered with foil, labeled, and kept in a hood in a secondary container.

1. ALWAYS run these reactions in a hood, using reaction vessel set-ups similar to that used in air-sensitive reactions, i.e. closed or isolated systems.
2. All exhaust gas from the reaction should be run through a bleach trap. To set-up a bleach trap, fill a glass bubbler with commercial grade bleach and connect the bubbler’s inlet to the reaction’s exhaust tubing. Clamp the bleach trap in place so that the outlet is pointed towards the back of the hood. The flow rate of the gas through the reaction should result in 1-2 bubbles per second in the bleach trap.

1. This is the part of the experiment where there will most likely be a release of thiols, so the work-up steps should be performed with forethought and care.
2. Work in the hood and keep the reaction products in closed containers as much as possible. Glass stoppers and watch glasses are good, easily cleaned tools to close off containers.
3. When using the rotary evaporator (rotovap) or vacuum filtration, exhaust gas from these systems should be run through a bleach trap, as described in Part B2. Outgas flow rates through these traps will be faster and more voluminous than in Part B2, and thus larger traps may be necessary. A two-liter container should be sufficient for the rotovap exhaust, and a 250 mL filter flask should be sufficient for vacuum filtration exhaust.

1. Dispose of all liquid and solid waste into the appropriate waste containers. Make sure the waste container is labeled to inform EH&S that it contains thiols.
2. All glassware should be placed into a bleach bath immediately after use and should be allowed to soak for at least overnight (~14 hr). Glassware that is too large to fit into the bleach bath and can be sealed (e.g. reaction flasks, separation funnels, etc.) should be filled with bleach, sealed, labeled, and placed into a hood, preferably in a secondary container if possible, to soak overnight.
3. After soaking in bleach, rinse the glassware thoroughly with water and then clean it using normal methods.
4. Bleach baths can be reused many times. Formation of white solid, which is the result of thiol oxidation, build-up of an excessive amount of grime, or a strong unpleasant smell indicate that a bleach bath is no longer functional. Bleach baths should also be disposed of if they will not be used for extended periods of time. Dispose of bleach baths by pouring down the sink and flushing thoroughly with water.
5. Pieces of equipment that cannot be cleaned in a bleach bath (e.g. exhaust gas rubber tubing, rubber septa, etc.) should be placed into a plastic bag, labeled, and reused in subsequent reactions.