The Use And Synthesis Method Of DL-Mandelic Acid

 

Overview

DL-mandelic acid, also known as bitter almond acid, or α-hydroxybenzene acetic acid. Appearance: White crystalline powder, melting point range 118.0 to 121.0 degrees C. DL-Mandelic acid is toxic and harmful to skin contact and swallowing. Because of its strong antibacterial effect, can be taken directly by mouth in the treatment of urinary system infection diseases. DL-tonsilic acid has a hand molecule, is an important hand drug intermediate and fine chemical products, not only can be used in the synthesis of vascular dilation drug ring tonsil esters, urinary tract infection anti-inflammatory drug DL-tonsils ulototine and anti-spasm drug DL-tonsils and other drugs, but also has the dual role of sperm and trichomoniasis. In 2012, China's consumption of DL-Mandelic acid is about 250t, the current international market demand for DL-Mandelic acid is growing at an average annual rate of about 10%. DL-mandelic acid and its derivatives are widely used in organic synthesis. For example, in medicine, it is an important intermediate of urinary tract fungicides - Mandelic acid ulototropine, and endovascular dilation agents - ring tonsils; In the dye industry, it is also an important intermediate of high-performance heterocyclic dispersion dyes

Use ²

DL-tonsilic acid is used in organic synthesis and pharmaceutical industry, medicine is benzoylate metformin, cephalosporine, urinary tract fungicide tonsillic acid ulotropine, endovascular dilation agent ring tonsillic acid, eye drops hydroxypyrine, pimolin and tote antispasms important intermediates. It is also clinically used as a urethra preservative. Preservatives, chemical reagents, also used in organic synthesis, dyes, pesticide raw materials and intermediates.

Synthesis method ^[3]

There are three common synthesis methods:

Method 1:

The 15 grams of newly distilled benzoal and 50ral saturated sodium sulphate solution mixed, stirred with a glass rod, add-ons are precipitated, stirred for another 15 minutes, filtered, washed with a small amount of cold water sediment, added 12 grams of potassium cyanide under stirring, water 25 ml, crystals disappear, arugol oil is isolated, separated by a split funnel. The water layer is extracted once with l 5 ml benzene, steamed benzene, combined oil in the evaporative dish, added 4 times the amount of concentrated hydrochloric acid, water bath evaporation concentration, until a large number of crystals appear in the liquid surface, placed in the cold place overnight, filter crystals; Combine crystals, dry for 24 hours, wash crystals with cold small amounts of benzene, and then extract with hot benzene, extract benzene liquid in the ice bath cooling, crystallization, filtration, drying. The collection rate is 50 to 60%. It is also possible to hydrolyzate acrylic with concentrated hydrochloric acid for 12 hours and then evaporate and concentrate on the water bath for 5 to 6 hours to filter the crystallization. The filter fluid is steamed dry, solids are combined, and then extracted with thermobenzene.

Method two:

The course of this reaction may be that chloroform is produced under the action of TEBA and sodium hydroxide dichlorocarbene, which is 羰-based bonus with benzoaldehyde and is re-arranged and hydrolyzed to produce the product.

Benzene formaldehyde 0. 1mol, triethyl ampicillin ammonium chloride 0. 005mol mixed, add chloroform 16ml, water bath heating, in stirring slowly add 50% sodium hydroxide solution 25ml (1 to 2 drops per minute, water bath temperature maintained at 56±2 degrees C about 2 hours), after adding, at this temperature Continue stirring for 1 hour, such as the reaction liquid cold to room temperature after dilution with water, aqueous solution with ether extraction twice, the water layer with 50% sulfate acidification, and then with ether extraction, extraction liquid with waterless sodium sulfate drying, steaming ether, the remaining oil cooling curing, Recrystallization with toluene is known.

Method three:

1． Preparation of dichloroben ethyl ketones

Put 384 grams (3. 2m01) Benzoyl ketone and 400 ml of ice acetic acid, at a rate of 200 grams per hour into the reaction fluid into the chlorine gas, and ice water bath to control the temperature at 55 to 57. C, chlorine about 3 hours after the reaction liquid chlorine saturation, there are a large number of yellow-green gas escape liquid surface full of reaction bottle, at this time the reaction fluid temperature drops, and then slowly through the chlorine gas for 10 minutes, remove the reaction poured into a washing bottle filled with 1 liter of water, dichlorobenzene is a pale yellow oil-like material sink at the bottom of the bottle. Pour the upper acetic acid, wash twice with 500 ml of water, oily, isolated oily dichlorobenzene, yield in more than 90%.

2． Preparation of DL-Mandelic acid

In a 1 liter reaction bottle, add 96 grams of sodium hydroxide and add water to 600ral to dissolve. Slowly add 120 grams of dichlorobenzene under rapid stirring, while using a water bath to control the reaction temperature in 60 to 65. C About 2 hours to add, after adding to continue stirring 1. 5 hours, and then to the reaction liquid to add lOOml concentrated hydrochloric acidification, placed in the refrigerator overnight, filter out crystallization, the filter decompression evaporation to dry, with ether extraction of steamed residue and crystallization 3 to 4 times, distillation recovery of ether, crude products, crude products plus the same amount of water heating dissolved. Decolorization, filtration, will filter liquid in the refrigerator overnight crystallization, filter crystallization, dehydrated with benzene,^60.  C dry, yield 62 to 65%.