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We have built a diode-laser-pumped Nd:YAG slab laser that emits 40 W of cw power in a TEM 00 mode and 72 W of power in multimode operation when pumped with 235 W. The slope efficiencies are 22% for TEM 00-mode operation and 36% for multimode operation. The laser uses a zigzag slab geometry to reduce thermally induced distortions and operates at less than one wave of distortion at the full pump power. A significant advantage of our design over those of previous slab lasers is a new Teflon AF protective coating on the slab total-internal-reflection surfaces, which greatly simplifies the mounting and cooling of the slab laser medium.

2-Methyl-2-thiopseudourea hydriodides activated by electron-withdrawing groups undergo attack by alcohols and water to give several types of products whose formation is dependent on the nature of the hydroxylic reactant. When l-benzoyl-2-methyl-2-thiopseudourea hydriodide (5) was heated with alcohols, methyl mercaptan was evolved and there was formed 1-benzoylurea (2) and the iodide corresponding to the alcohol. The yield of 2 was diminished and the formation of l-benzoyl-2-thiourea (1) took on greater prominence in going from a primary to a tertiary alcohol. Methyl JV-benzoylthiolcarbamate (6) and NHJ were also formed when the more hindered alcohols were used and were essentially the only products obtained in the reaction of 5 with water.S-Methiodide derivatives of other activated thioureas, i.e., l-acetyl-2-methyl-2-thiopseudourea (9), 2-methyl-2-thiopseudobiuret (10), 2-methyl-2,4-dithiopseudobiuret (11), and 1-(4-nitropheny 1 )-2-methy 1-2-thiopseudourea (12) hydriodides, reacted with ethanol and water in a similar manner as 5. Thiols could be generated in moderate yields by the reaction of l-acetyl-2-thiourea ( 14) with primary alkyl halides in ethanol.

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