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xine-danlinh
Vietnam
22 Posts
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Posted - 04/10/2003 : 19:40:42
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salem a! y kien cua Nguyen hoang giang la dung day . (bo xung them y kien cua Trang1985 nua la du )
Jame ! cau noi dung do ben cua no phu thuoc vao hai yeu to
-moi truong
-so nhom -OH co trong chat
1112 |
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Hihihahihi
9 Posts
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Posted - 04/16/2003 : 20:21:09
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tr�ch:
Tui thay cai ten hihihahihi nay hoi bi quai do , ong khong the noi chuyen tu te mot teo sao ma cu phan bac nguoi khac ghe the.A, ma ong hoi bi chanh day , ong dam noi Fe2+ khi tac dung voi bat ki chat gi cung cho ra Fe3+ ha? sai bet! cho ong mot vd don gian ne:
FeCl2 + 2AgNO3 = Fe(NO3)3 + 2AgCl(Ket tua)
Phan ung viet sai kia`! Y toi noi la trong phan ung oxi hoa khu,mot chat (vi du Fe2+ trong truong hop nay) khong the giu nguyen so oxi hoa cua no duoc!
Lam gi ma co ve "cay cu" toi the! Hic hic!
Moi cac ban ghe tham CLB Hoa Hoc:
http://ttvnol.com/forum/f_347
http://hoahoc.ttvnonline.net
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Hihihahihi
9 Posts
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Posted - 04/16/2003 : 20:38:29
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Thay cac ban tranh luan ve hien tuong enol hoa hay qua nen toi tham gia chut xiu cho vui!
Can bang xeto-enol phu thuoc vao nhieu yeu to,nhu nhiet do,nong do,dung moi,cau tao,....
Trong truong hop cac hop chay cacbonyl don gian (hop chat co mot nhom cacbonyl lien ket voi cac nhom don gian nhu hidro,alkyl.. can bang xeto-enol se lech han ve phia dang cacbonyl:
CH2=C(OH)-CH3 ----> CH3COCH3
Neu trong phan tu co nhom voi hieu ung -C de co the lien hop voi he enol do do' lam tang do ben cua dang enol thi can bang se lech ve dang enol:
CH3-CO-CH2-CO-CH3 ---> CH3-C(OH)=CH-CO-CH3
Trong truong hop axetylaxeton,axetoaxetat etyl va cac he phan tu tuong tu,do ben vung cua dang enol con duoc quyet dinh boi mot so yeu to quan trong khac nua la su tao thanh lien ket hidro noi phan tu.
Duoi dday la ham luong dang enol doi voi mot so hop chat cacbonyl khac nhau:
.......................Enol, %
CH3-CO-CH3............2,5.10^(-4)
CH3-CHO .............khong dang ke
CH3COOC2H5 ...........khong dang ke
CH3COCH2COOC2H5.......7,5
CH3COCH(C6H5)COOC2H5....30
CH3COCH2COCH3...........80
Ham luong dang enol cua mot hop chat cacbonyl nhat dinh o trang thai nguyen chat khac o trang thai dung dich vi co anh huong cua dung moi.Thi du: axetoaxetat etyl trong nuoc co 0,4% dang enol,trong hexan co 46,4%;axetylaxeton trong nuoc co 15% enol con trong hexan co 92%.So di cac ham luong enol giam manh khi di tu dd hexan den dd nuoc vi nuoc tao lien ket hidro voi dang cacbonyl,do do lam cho cang bang xeto-enol lech ve phia xeto.
(Cac ban co them tham khao them trong "Co so li thuyet hoa hoc,tap 2,phan co che cua thay Tran Quoc Son!)
Moi cac ban ghe tham CLB Hoa Hoc:
http://ttvnol.com/forum/f_347
http://hoahoc.ttvnonline.net |
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