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20813-18-7

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20813-18-7 Usage

Check Digit Verification of cas no

The CAS Registry Mumber 20813-18-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 2,0,8,1 and 3 respectively; the second part has 2 digits, 1 and 8 respectively.
Calculate Digit Verification of CAS Registry Number 20813-18:
(7*2)+(6*0)+(5*8)+(4*1)+(3*3)+(2*1)+(1*8)=77
77 % 10 = 7
So 20813-18-7 is a valid CAS Registry Number.

20813-18-7Downstream Products

20813-18-7Relevant articles and documents

Cyclic Ether Formation in Superacid Media

Carr, Graham,Whittaker, David

, p. 359 - 366 (2007/10/02)

The formation of ethers in superacids by interaction of a primary hydroxy group with a carbocation centre has been investigated by a study of cyclisation of suitable substrates, mainly 1-(2-hydroxyethyl)cyclohexanols to give hydrobenzofurans.Cyclisation traps thermodynamically stable ionic species, with rates of reaction dependent upon the size of the ether ring formed.Three- and four-membered ether rings were not formed, five-membered ether rings formed readily, the reaction being comparable in rate with a 1,2-methyl shift.Six-membered rings formed a little less readily and seven-membered rings less readily still, though a yield of 34 percent from a suitable substrate has been recorded.An unexpected feature of the reactions was their stereospecificity; in one case, this is believed to result from a methyl shift concerted with attack of the primary hydroxy group, the reaction proceeding through hindered transition state, in which methyl loss, probably as CH3+, competes with a 1,2-methyl shift.

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