These flasks offer some advantages over regular round-bottom flasks. Especially with heterogeneous reactions, the better mixing through greater turbulence upon stirring is of advantage. Due to improved stirring, their use in Ullmann reactions and Suzuki-type couplings on a larger scale has led to considerable reduction in reaction time. The ring of deposit around the magnetic stirring bar oftentimes observed with heterogeneous reactions in round-bottom flasks may be avoided if comparing the same-scale reaction in the two flask types. The use of cylindrical flasks may substitute, therefore, for a mechanical stirrer. In regular reactions, foaming-up is better contained in a cylidrical than a spherical flask since the there remains a greater volume for foam than in the rapidly-diminishing headspace in a spherical flask. A further adavantage is realized when using heating block: A cylindrical flask cannot tip over when set into the well, while a spherical flask must be clamped. Spills and inconvenience when charging, assembling or sampling is thereby avoided. The two flasks shown have a volume of 1 l each, Joint 24/40. Usable with air-condensers, and all regular attachments.Available in sizes of 50, 100, 250, 500 and 1000 ml and joints sizes 14/19 (50 ml), 19/22 (100 and 250 ml), 24/40 (250, 500 and 1000 ml).