The dehydrochlorination of 1,1-diaryl-2,2,2-trichloroethanes in protic and dipolar aprotic solvents

(1)

http://researchspace.auckland.ac.nz

ResearchSpace@Auckland

Copyright Statement

The digital copy of this thesis is protected by the Copyright Act 1994 (New Zealand).

This thesis may be consulted by you, provided you comply with the provisions of the Act and the following conditions of use:

•

Any use you make of these documents or images must be for research or private study purposes only, and you may not make them available to any other person.

•

Authors control the copyright of their thesis. You will recognise the author's right to be identified as the author of this thesis, and due acknowledgement will be made to the author where appropriate.

•

You will obtain the author's permission before publishing any material from their thesis.

To request permissions please use the Feedback form on our webpage.

http://researchspace.auckland.ac.nz/feedback

General copyright and disclaimer

In addition to the above conditions, authors give their consent for the digital copy of

their work to be used subject to the conditions specified on the Library Thesis

Consent Form.

(2)

(3)

(4)

(5)

ABSTRACT

--

PART I

A general i n t r o d u c t i o n i s given t o t h e mechanisms cf olefin-forming p-elimination. The development of mechanistic c r i t e r i a ?ad t h e i r

a p p l i c a t i o n t o t h e various r e a c t i o n s i s discu.sscd. Confljcting t h e o r i e s concerning t h e n a t u r e of t h e t r a n s i t i o n s t a t e s of EW reactions i n p r o t i c s o l v e n t s as well a s the Winstein-Parker E2C-like t r a n s i t i o n s s t a t e s f o r elimination by weak bases i n d i p o l a r a p r o t i c solvents are described.

PART I1

T h e use of primary deuterium isotope e f f e c t s , s t r . ? c . t t ~ e - r e a c t i v i t y r e l a t i o n s h i p s , and r a t e - a c i d i t y c o r r e l a t i o n s as nechar?istic c r i t e r i a f o r t h e E2 mechanism and t h e variants of t h e E l c B mechanism i s reviewed.

These c r i t e r i a have been applied t o the dehydrochlorination of t h e

methanol and t-butoxide-t-buta~ol. L i t e r a t u r e comparisons i n d i c a t e that the k i n e t i c evidence f o r t h e s e two systems i s in accorcl. w i t 3 an

Itirreversible*t E l CE elimination pathway.

PART I11

C h a r a c t e r i s t i c s of wcak base-promoted eliminations i n d i p o l a r e r o t i c sdvents are reviewed. T h e evidence i s not e n t i r e l y c o n s i s t e n t with e i t h e r E2C o r t h e EZ'i mechanism. Deuterilm i s o t o ? e e f f e c t s and equilibrium constants a r e reported f o r t h e c h l o r i d e ion-promoted

elilnination of the 1

,

1-diary?--2,2,2-tri~hloroeth~m in dir.~ctl?ylform&nidc

(6)

and acetone respectively. Thc results are i n accord with an EW mechanism.

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

(19)

(20)

(21)

(22)

(23)

(24)

(25)

(26)

(27)

(28)

(29)

(30)

(31)

(32)

(33)

(34)

(35)

(36)

(37)

(38)

(39)

(40)

(41)

(42)

(43)

(44)

(45)

(46)

(47)

(48)

(49)

(50)

(51)

(52)

(53)

(54)

(55)

(56)

(57)

(58)

(59)

(60)

(61)

(62)

(63)

(64)

(65)

(66)

(67)

(68)

(69)

(70)

(71)

(72)

(73)

(74)

(75)

(76)

(77)

(78)

(79)

(80)

(81)

(82)

(83)

(84)

(85)

(86)

(87)

(88)

(89)

(90)

(91)

(92)

(93)

(94)

(95)

(96)

(97)

(98)

(99)

(100)

(101)

(102)

(103)

(104)

(105)

(106)

(107)

(108)

(109)

(110)

(111)

(112)

(113)

(114)

(115)

(116)

(117)

(118)

(119)

(120)

(121)

(122)

(123)

(124)

(125)

(126)

(127)

(128)

(129)

(130)

(131)

(132)

(133)

(134)

(135)

(136)

(137)

(138)

(139)

(140)

(141)

(142)

(143)

(144)

(145)

(146)

(147)

(148)

(149)

(150)

(151)

(152)

(153)

(154)

(155)

(156)

(157)

(158)

(159)

(160)

(161)

(162)

(163)

(164)

(165)

(166)

(167)

(168)

(169)

(170)

(171)

(172)

(173)

(174)

(175)

(176)

(177)

(178)

(179)

(180)

(181)

(182)

(183)

(184)

(185)

(186)

(187)

(188)

(189)

(190)

(191)

(192)

(193)

(194)

(195)

(196)

(197)

(198)

(199)

(200)