Introduction Formaldehyde (CH2O) is a colourless gas that can easily polymerise to a white crystalline substance, known as paraformaldehyde (CH2O)n. On heating of paraformaldehyde, it will decompose back to gaseous formaldehyde. Formaldehyde can also be dissolved in water to form solutions up to 40%, aqueous formaldehyde is known as formalin. Both formalin and paraformaldehyde is sold in some stores (for different purposes). Since it's not widely available in some countries, we can synthesize own formaldehyde. In this text I will describe synthesis of formaldehyde from methanol, reaction will be catalysed by metallic copper. However it is possible to use oxides of copper, since they will be reduced to metallic copper (spongy form). In this method, we will pass methanol/air fumes above heated copper wire, this will drive following reaction: CH3OH --O2/Cu--> CH2O + H2O Since reaction is exothermic, there will be created enough heat to keep reaction going by its own, without external heating of catalyst. As product we will obtain aqueous formaldehyde (<40%), that can be easily converted to solid paraformaldehyde by drying in excicator. Remember that synthesis should be carried out in good sealed apparatus and vented area since both methanol and formaldehyde is poisonous. Remember that formaldehyde is a probable carcinogen. Procedure Materials: Methanol (CH3OH) Copper wire Assemble apparatus as showed on picture (note: original picture from referenced book can be found here): Washer with H2SO4 seems to be optional. It is advised to use a water-bath with strictly controlled temperature at 45-47oC. At lower temperatures (42-44oC), oxygen concentration will rise, which can lead to autoignition of methanol fumes. As a safety precaution, in this setup we use a capillary with inner diameter of 1-1,5 mm to inject methanol/air fumes into combustion pipe. Therefore, in case of autoignition, the capillary will reduce explosion to combustion pipe. Although temperature in water-bath can be regulated by a simple gas burner, I recommend using my simple heat controlled water-bath circuit, it will certainly give a precision of +/- 0,3oC. Round bottomed 500 ml flask in water-bath have air inlet pipe that should go right to the bottom. Flask may have also an optional inlet with a dropping funnel with extra methanol (to make this a continuous process). Combustion pipe have a length of 30 cm and inner diameter of 1 cm, pipe must be made from heat-resistant glass. Here, I use a quartz pipe with inner diameter of 0,8 cm, it was obtained from a microwave oven :) Copper coil of 3 cm should be placed in lower part of combustion pipe. Combustion pipe is connected with two long-necked 200 ml flasks as showed on pic. It is recommended to add a washer with water after second flask, it will further collect escaping formaldehyde. When apparatus is ready, place 200 ml of methanol into round bottomed flask in water-bath. Heat up copper coil with gas burner and attach a sucking pump to output of collecting flasks (see pic). When methanol/air fumes reaches hot copper coil, reaction will start. There will be evolved enough heat that will keep coil glowing, gas burner may then be removed. Adjust the air flow to keep about 2 cm of coil glowing. When reaction is complete (takes several hours), most of the product will be in first receiving flask. Contents of all receiving flasks may be mixed together. Book author1 claim that usual yield in described procedure is 160 ml of 40% formaldehyde (that is with H2SO4 washer). References 1. M.M.Kacnelson Preparation of synthetic chemo-pharmaceutical substances 2:nd ed. 1923 2. Some info was also taken from posts by Megalomania on roguesci forum, specifically info about prevention of autoignition of methanol fumes.