Foaming citric acid

Plastics. Citric acid and bicarbonate are used as an effervescent blowing agent to foam polystyrene for insulated food and beverage containers replacing blowing agents such as chlorinated fluorocarbons (194—206). 

The observation that trickle-down fragrances often convey a sense of luxury and style points to an aspect of perfumes that is of key importance in the perfuming of functional products The scent of a product connotes specific product qualities to the user. This is obvious when a lemon perfume is used in a dishwashing detergent advertised as containing lemon juice or in a sanitary cleaner based on citric acid, or when a herbaceous perfume is used in a herbal bath foam. But it also occurs in most if not all other uses of fragrance where the message is less specific. 

A mixture consisting of the Step 7 product (0.74 mmol), 4-pyrrolidinopyridine (0.09 mmol), and 927 jxl n-butyl chloroformate dissolved in 6 ml pyridine was stirred 2 days at ambient temperature, then concentrated. The residue was dissolved in CH2C12, washed with a 10% solution of citric acid and with water, dried with Na2S04, and concentrated. The residue was purified by chromatography using CH2Cl2/methyl alcohol, 20 1, and 470 mg of product isolated as a slightly yellow amorphous foam. 

A mixture of chlorotrimethylsilane (0.205 mmol) was added to a suspension of n. v-3-aminocyclohexanecarboxylic acid (0.205 mmol) suspended in 500 ml CH2Cl2/acetonitrile, 5 1, and refluxed for 2 hours. Once cooled, triethylamine (0.410 mmol) was added dropwise to the mixture followed immediately by the portionwise addition of triphenylmethyl chloride (0.205 mmol). The mixture was stirred 18 hours and sufficient methyl alcohol was added to dissolve the vessel contents. The solution was concentrated and the residue was partitioned between 800 ml diethyl ether/10% citric acid, 1 1. The ether layer was collected and combined with a 150 ml diethyl ether extraction from the citric acid layer. Combined fractions were extracted three times with 250 ml 2 M NaOH and once with 100 ml water. These layers were washed twice with 150 ml diethyl ether, cooled to 0°C, acidified to pH 7 with 12 M HC1, and re-extracted three times with 200 ml EtOAc. The extract was dried over MgS04, then concentrated, and the product isolated in 85% yield as a white foam. 

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