Diols acids

Preparation of diols Acid-catalysed epoxides are easily cleaved by water. Water reacts as the nucleophile, and this is referred to as a hydrolysis. For example, hydrolysis of ethylene oxide in the presence of acid-catalyst produces 1,2-ethanediol (ethylene glycol). 

Hydroxylactonizations (equations 97-99) involve the formation of a stable and, in general, stereo-chemically defined epoxide intermediate with peroxy acids. In an ensuing step these epoxides are cy-clized with acid catalysis under the participation of the carboxylic group. If steric reasons prohibit ring closure, as in equation (98), the diol acid (278) is formed instead of the hydroxy lactone (275).Equation (99) ° shows an example for the stereocontrol of the epoxidation step by an axially oriented carb-oxy group, which is then in an appropriate position to close the lactone ring (281). 

Most acyloxyboranes [MMl] and aminoboranes [Al] do not react either with esters or with lactones. However, Ph2NH BH3 reduces aliphatic esters [GUI]. Substituted boranes are more efficient. 9-BBN reduces esters under reflux in THF [PSl], while ThexBHCl gives rise to alcohols with heating [BN5]. Finally, the ate complex Li 9-BBNH reduces esters to alcohols and lactones to diols. Acids, amides, nitriles, and halogenated derivatives remain intact under these conditions [BMl]. 

The product of this reaction was expected to be a diol-acid, and the infrared (IR) showed an OH peak and a strong carbonyl, but there was no apparent CO2H absorption. Likewise, the NMR showed there was no CO2H group. Show the actual product and explain why the anticipated diol-acid was not isolated. 

Macroazonitriles can be employed, and structures based on (3) in Equation 5.25 with either diol, acid, or acid chloride terminal functions are preferred. Functionalized chains c an be linked to the azo compounds, after which the azo group can be decomposed thermally to produce radic sites for further chain growth. 

Corannulene (1) was synthesized by Lawton and Barth in 1966 [17, 18]. As mentioned by them Within its structural framework is an unusual strain resulting from the geometrical requirement that the bond angles deviate appreciably from the normal values found for benzenoid compounds. Thus, introduction of strain as late as possible is key to their synthetic strategy for the preparation of 1 [19]. Their synthesis started with acenaphthene, and after numerous synthetic steps the key intermediate 4 was obtained (Scheme 1). The diol acid 4 was converted to 5 upon... 

Aldehyde, polyacetal with diol Acid, amino-, polyamide... 

Group Reaction resin type Glycols (diols) Acids Max. styrene content by weight... 

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