式I及其子式中之基團R1
較佳表示具有至多8個碳原子之烷基或烯基。R1
尤其較佳表示具有1至7個C原子之直鏈烷基或具有2到8個C原子之非支鏈烯基，尤其具有2到7個C原子之非支鏈烷基。 式I中之基團X較佳表示CF3
、OCF3
、F、-SCN、-C≡C-CF3
或-CH=CH-CF3
，尤其較佳為CF3
、OCF3
或F，且極其較佳為CF3
或OCF3
。基團-CH=CH-CF3
較佳呈反式組態。 含有分支鏈或經取代之翼基R1
的式I化合物可由於在習知液晶基底材料中之較佳溶解度而間或具有重要性。基團R1
較佳為直鏈。 優先考慮式I化合物，其中L1
表示H，尤其其中L1
及L2
表示H。 基團R1
尤其較佳選自以下部分： -CH3
-C2
H5
-C3
H7
-C4
H9
-C5
H11
-C6
H13
-CH=CH2
-CH=CH2
-CH3
-CH2
-CH2
-CH=CH2
-CH2
-CH2
-CH=CH-CH3
其中烷基鏈較佳為非支鏈(正烷基)。 尤其較佳式I化合物為式I-1至I-6化合物，其中R1
獨立地具有上文所指示之含義。在式I-1至I-6化合物中，式I-1、I-2、I-4及I-5為較佳的，尤其為式I-1及I-2化合物。 極尤其較佳的化合物在下文給出： 式I化合物在已知且適於該等反應之反應條件下如描述於文獻(例如描述於標準著作中，諸如Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart)中之本身已知方法來製備。亦可在本文中使用本身已知而未在本文中更詳細地提及之變化形式。 如在以下明顯說明性合成及實例(流程1至3)中所示，可有利地製備典型式I化合物： 流程 1.
製備式I化合物之一般合成流程。Bn表示苯甲基。X表示如式I中之基團X。R1
表示如式I中之基團R1
。 兩個極性端基-CH=CH-CF3
及-C≡C-CF3
可如下製備： 流程 2 .
合成端基X = -CH=CH-CF3
及-C≡C-CF3
；Ar表示式I化合物之經取代之苯基。在第一步驟中，較佳為吸收水而添加分子篩。反應順序從流程1之逆轉得到上升或者至合成流程3。 流程 3 .
製備式I化合物之替代性一般合成流程。R1
及X根據式I定義。 相應起始物質可大體上易於由熟習此項技術者藉由從文獻中已知的合成方法製備或為可商購的。 亦有可能使用芳基鋰化合物代替流程1及3中所示的格林納(Grignard)化合物，該等芳基鋰化合物可類似地藉由低溫下鹵素金屬與烷基鋰化合物交換而獲得(cf.例如US 4,940,822)。 本發明因此亦關於一種製備式I化合物之方法，該方法包括處理步驟，其中式II之芳基金屬化合物，II 其中X、L1
及L2
如關於式I所定義，且 M 表示Li、MgBr或MgCl， 與式III化合物反應III 其中 PG 表示保護基，較佳為苯甲基， 以及在包括移除保護基PG (由H置換)及氧化所得CH2
OH基團以得到醛CH=O的其他反應步驟中， 與式IV之2-經取代之1,3-二醇反應IV 以得到式I化合物I 其中該等基團如上文所定義。 所用反應方法及試劑在原理上從文獻已知。其他反應條件係由實施例揭示。 上文所未提及之其他較佳方法變化形式係由實例或申請專利範圍揭示。 該方法及反應混合物之後續處理可基本上以分批反應或連續反應程序之形式進行。連續反應程序涵蓋例如在連續攪拌槽反應器、級聯的攪拌反應器、環流或交叉流反應器、流管或微反應器中反應。反應混合物視情況(視需要)藉由以下方式處理：經由固相過濾；層析；不可混溶相之間的分離(例如萃取)；吸附至固體支撐物上；藉由蒸餾、選擇性蒸餾、昇華、結晶、共結晶或藉由膜上奈米過濾移除溶劑及/或共沸混合物。 在本發明中，下式之2,5-二取代之二噁烷環較佳表示2,5-反-組態之二噁烷環，亦即取代基呈較佳椅型構形，較佳兩者均在赤道位置。 本發明亦關於包含根據本發明式I化合物中之一或多者的液晶介質。液晶介質包含至少兩種組分。其較佳藉由使組分彼此混合而獲得。因此，用於製備液晶介質的本發明方法之特徵在於：將至少一種式I化合物與至少一種其他液晶原基化合物混合，且視情況添加添加劑。 清澈點、低溫下黏度、熱/UV穩定性、介電各向異性、回應時間及對比度之可達成的組合極優於來自先前技術之先前材料。 根據本發明之液晶介質較佳包含2至40、尤其較佳4至30種組分作為除根據本發明之一或多種化合物以外的其他成分。詳言之，此等介質包含7至25種除根據本發明之一或多種化合物以外的組分。此等其他成分較佳選自向列型或向列原基(單變性或各向同性)物質，尤其來自以下類別之物質：氧偶氮苯、苯亞甲基苯胺、聯苯、聯三苯、苯甲酸苯酯或苯甲酸環己酯、環己烷甲酸苯酯或環己烷甲酸環己酯、環己基苯甲酸苯酯或環己基苯甲酸環己酯、環己基環己烷甲酸苯酯或環己基環己烷甲酸環己酯、苯甲酸環己基苯酯、環己烷甲酸環己基苯酯或環己基環己烷甲酸環己基苯酯、苯基環己烷、環己基聯苯、苯基環己基環己烷、環己基環己烷、環己基環己基環己烷、1,4-雙環己基苯、4,4'-雙環己基聯苯、苯基嘧啶或環己基嘧啶、苯基吡啶或環己基吡啶、苯基二噁烷或環己基二噁烷、苯基-1,3-二硫環己烷或環己基-1,3-二硫環己烷、1,2-二苯乙烷、1,2-二環己基乙烷、1-苯基-2-環己基乙烷、1-環己基-2-(4-苯基環己基)乙烷、1-環己基-2-聯苯乙烷、1-苯基-2-環己基苯乙烷、視情況鹵化茋、苯甲基苯基醚、二苯乙炔以及經取代之肉桂酸。此等化合物中之1,4-伸苯基亦可經氟化。 適合作為根據本發明之介質的其他成分之最重要的化合物可藉由式1、2、3、4以及5表徵： R'-L-E-R" 1 R'-L-COO-E-R" 2 R'-L-CF2
O-E-R" 3 R'-L-CH2CH2-E-R" 4 R'-L-CºC-E-R" 5 在式1、2、3、4以及5中，可相同或不同的L及E各自彼此獨立地表示來自由以下結構要素形成之組的二價基團：-Phe-、-Cyc-、-Phe-Phe-、-Phe-Cyc-、-Cyc-Cyc-、-Pyr-、-Dio-、-Py-、-G-Phe-、-G-Cyc-以及其鏡像，其中Phe表示未經取代或經氟取代之1,4-伸苯基，Cyc表示反-1,4-伸環己基，Pyr表示嘧啶-2,5-二基或吡啶-2,5-二基，Dio表示1,3-二噁烷-2,5-二基，Py表示四氫哌喃-2,5-二基且G表示2-(反-1,4-環己基)乙基。 基團L及E中之一者較佳為Cyc、Phe或Pyr。E較佳為Cyc、Phe或Phe-Cyc。根據本發明之介質較佳包含：一或多種選自式1、2、3、4以及5化合物之組分，其中L及E選自由Cyc、Phe以及Pyr組成之群，且同時一或多種選自式1、2、3、4以及5化合物之組分，其中基團L及E中之一者選自由Cyc、Phe、Py以及Pyr組成之群，且另一基團選自由-Phe-Phe-、-Phe-Cyc-、-Cyc-Cyc-、-G-Phe-以及-G-Cyc-組成之群，且視情況一或多種選自式1、2、3、4以及5化合物之組分，其中基團L及E選自由-Phe-Cyc-、-Cyc-Cyc-、-G-Phe-以及-G-Cyc-組成之群。 R'及/或R"各自彼此獨立地表示具有至多8個C原子之烷基、烯基、烷氧基、烷氧基烷基、烯氧基或烷醯基氧基、-F、-Cl、-CN、-NCS或-(O)i
CH3 - k
Fk
，其中i為0或1，且k為1、2或3。 在式1、2、3、4以及5之化合物之一較小亞組中，R'及R"各自彼此獨立地表示具有至多8個C原子之烷基、烯基、烷氧基、烷氧基烷基、烯氧基或烷醯基氧基。此較小亞組在下文稱為組A，且化合物以子式1a、2a、3a、4a以及5a表示。在大多數此等化合物中，R'及R"彼此不同，此等基團中之一者通常為烷基、烯基、烷氧基或烷氧基烷基。 在稱為組B的式1、2、3、4以及5之化合物之另一較小亞組中，R"表示-F、-Cl、-NCS或-(O)i
CH3 - k
Fk
，其中i為0或1，且k為1、2或3。R"具有此含義之化合物以子式1b、2b、3b、4b以及5b表示。尤其較佳為R"具有-F、-Cl、-NCS、-CF3
、-OCHF2
或-OCF3
之含義的子式1b、2b、3b、4b以及5b之化合物。 在子式1b、2b、3b、4b以及5b之化合物中，R'具有在子式1a至5a之化合物之情況下所指示之含義，且較佳為烷基、烯基、烷氧基或烷氧基烷基。 在式1、2、3、4以及5之化合物之另一較小亞組中，R"表示-CN。此亞組在下文稱為組C，且此亞組之化合物相應地描述為子式1c、2c、3c、4c以及5c。在子式1c、2c、3c、4c以及5c之化合物中，R'具有在子式1a至5a之化合物之情況下所指示之含義，且較佳為烷基、烷氧基或烯基。 除組A、B以及C之較佳化合物以外，具有所提出之取代基之其他變體的其他式1、2、3、4以及5之化合物亦為慣用的。所有此等物質均可藉由自文獻已知的或與其類似之方法獲得。 除根據本發明之式I化合物以外，根據本發明之介質較佳包含一或多種選自組A、B及/或C之化合物。根據本發明之介質中來自此等組之化合物的重量比例較佳為： 組A： 0至90%、較佳20至90%、尤其較佳30至90%； 組B： 0至80%、較佳10至80%、尤其較佳10至65%； 組C： 0至80%、較佳0至80%、尤其較佳0至50%； 其中存在於根據本發明各別介質中之組A、B及/或C化合物的重量比例總和較佳為5至90%，且尤其較佳為10至90%。 根據本發明之介質較佳包含1至40%、尤其較佳3至30%的根據本發明之化合物。 本發明之液晶混合物係以本身習知的方式製備。一般而言，將以較少量使用之所需量的組分較佳地在高溫下溶解於構成主要成分之組分中。亦有可能在有機溶劑中，例如在丙酮、氯仿或甲醇中混合各組分之溶液，且例如藉由在充分混合後蒸餾來再次移除溶劑。進一步可能以其他習知方式製備混合物，例如藉由使用例如同系物混合物之預混物，或使用所謂的「多瓶」系統。 該等介電質亦可包含熟習此項技術者已知且描述於文獻中之其他添加劑。舉例而言，可添加0至15%、較佳0至10%的多色染料、對掌性摻雜劑、穩定劑或奈米粒子。所添加之個別化合物係以0.01至6%、較佳0.1至3%的濃度加以使用。然而，液晶混合物(亦即液晶或液晶原基化合物)之其他成分之濃度資料在本文中給出而不考慮此等添加劑之濃度。 根據本發明之液晶混合物使得可用參數寬容度能夠顯著變寬。 本發明亦關於含有此類介質之電光顯示器(尤其TFT顯示器，其具有與框架一起形成單元之兩個平行平面外板、用於切換外板上之個別像素的整合式非線性元件以及位於單元中具有正介電各向異性及高比電阻的向列型液晶混合物)，且關於此等介質針對電光目的之用途。 表述「烷基」涵蓋具有1至15個碳原子之非支鏈及分支鏈烷基，尤其非支鏈甲基、乙基、正丙基、正丁基、正戊基、正己基以及正庚基。具有2至5個碳原子之基團一般為較佳。 表述「烯基」涵蓋具有至多15個碳原子之非支鏈及分支鏈烯基，尤其非支鏈基團。尤其較佳烯基為C2
-C7
-1E-烯基、C4
-C7
-3E-烯基、C5
-C7
-4-烯基、C6
-C7
-5-烯基及C7
-6-烯基，尤其為C2
-C7
-1E-烯基、C4
-C7
-3E-烯基及C5
-C7
-4-烯基。較佳烯基之實例為乙烯基、1E-丙烯基、1E-丁烯基、1E-戊烯基、1E-己烯基、1E-庚烯基、3-丁烯基、3E-戊烯基、3E-己烯基、3E-庚烯基、4-戊烯基、4Z-己烯基、4E-己烯基、4Z-庚烯基、5-己烯基、6-庚烯基及其類似烯基。具有至多5個碳原子之基團一般為較佳。 表述「鹵化烷基」較佳涵蓋單氟化或多氟化及/或-氯化基團。包括全鹵化基團。尤其較佳為氟化烷基，尤其CF3
、CH2
CF3
、CH2
CHF2
、CHF2
、CH2
F、CHFCF3
以及CF2
CHFCF3
。相應地解釋表述「鹵化烯基」及相關表述。 根據本發明之混合物中的式I化合物之總量並非關鍵。因此，出於使各種特性最佳化之目的，混合物可包含一或多種其他組分。 自偏光器、電極基底板以及表面處理之電極建構本發明之矩陣顯示器對應於此類顯示器之常見設計。術語常見設計在本文中概括地描述，且亦涵蓋矩陣顯示器(尤其亦為基於聚Si TFT之矩陣顯示元件)的所有衍生物及修改。 然而，根據本發明之顯示器與基於扭轉向列單元之迄今習知顯示器之間的顯著差異在於液晶層之液晶參數的選擇。 以下實例用來進一步解釋本發明而不限制本發明。熟習此項技術者將能夠自實例收集未在一般描述中詳細給出之工作細節，根據一般專家知識對其進行概括且將其應用於特定問題。 在上文及下文中，百分比資料表示重量%。以攝氏度指示所有溫度。此外，C=結晶狀態，N=向列相，Sm=近晶相(更尤其SmA、SmB等)Tg=玻璃轉移溫度且I=各向同性相。此等符號之間的資料表示轉移溫度。Dn表示光學各向異性(589 nm，20℃)，Δε表示介電各向異性(1 kHz，20℃)且g1
表示旋轉黏度(20℃；以mPa·s為單位)。 物理、物理化學以及電光參數係藉由通常已知的方法測定，尤其如手冊「Merck Liquid Crystals - Licristal® - Physical Properties of Liquid Crystals - Description of the Measurement Methods」, 1998, Merck KGaA, Darmstadt中所描述。 個別物質的介電各向異性Δε係在20℃及1 kHz下測定。為此目的，對5至10重量%待研究物質溶解於介電正性混合物ZLI-4792 (Merck KGaA)中進行量測，且量測值外推至100%濃度。在20℃及589.3 nm波長下測定光學各向異性Δn，在20℃下測定旋轉黏度γ1
，兩者均亦藉由線性外推。 在本申請案中，除非明確地指示，否則術語之複數形式表示單數形式及複數形式，且反之亦然。根據描述之本發明之實施例及變化形式的其他組合亦由隨附申請專利範圍或多種此等申請專利範圍之組合而產生。 使用以下縮寫： DCM 二氯甲烷 DMSO 二甲亞碸 EA 乙酸乙酯 MTB ether 甲基第三丁基醚 THF 四氫呋喃實例 1 ：
5-丙基-2-[4-(4-三氟甲基苯基)環己-3-烯基]-1,3-二噁烷 步驟 1 首先將2.2 g (16 mmol)的鎂屑引入少量THF中，隨後將20.3 g (90 mmol)的4-溴三氟甲苯1
溶解於50 ml的THF中，且以使得反應混合物沸騰的速率逐滴添加。隨後將反應混合物在回流下加熱1 h。短暫移除加熱源，且將20.0 g (90 mmol)的4-苯甲氧基甲基-環己酮2
添加至分批中，其隨後在回流下再加熱2 h，且隨後在室溫下攪拌18 h。將分批傾入冰水中且使用2 M鹽酸調節至pH 2。分離水相且用MTB醚萃取。經合併之有機相用氯化鈉溶液洗滌，經硫酸鈉乾燥，過濾且蒸發，得到呈紅棕色油狀物之4-苯甲氧基甲基-1-(4-溴苯基)環己醇3
，其未經進一步純化用於下一反應步驟。步驟 2 ： 將12 g的Pd/C催化劑(112 mmol；活性碳上5%)添加至34.1 g (78 mmol)的粗產物3
之340 ml的THF溶液中。使用2.34 l的氫氣裂解保護基。隨後過濾出催化劑。將氫化溶液蒸發至乾，得到呈棕色油狀物之4-羥甲基-1-(4-三氟甲基苯基)環己醇。步驟 3 ： 首先將7.27 ml (85 mmol)的乙二醯氯引入100 ml的DCM中，且逐滴添加含12 ml (170 mmol)的DMSO (乾燥的)之80 ml的DCM。隨後逐滴添加10.2 g (13 mmol)的4-羥甲基-1-(4-三氟甲基苯基)環己醇4
於310 ml的DCM中之溶液。15 min之攪拌時間後，添加53 ml的三乙胺。攪拌5 min後，移除冷卻浴。將混合物隨後使用水在室溫下水解，且用DCM稀釋。分離水相且用DCM萃取。經合併之有機相用水及氯化鈉溶液洗滌，經硫酸鈉乾燥，過濾且蒸發至乾。粗產物隨後藉由來矽膠層析(DCM/EA 8:2)純化，得到呈黃色油狀物之4-羥基-4-(4-三氟甲基苯基)環己烷甲醛5
。步驟 4 ： 首先將16.8 g (54 mmol)的4-羥基-4-(4-三氟甲基苯基)環己烷甲醛5
引入284 ml的甲苯中。添加7.61 g (64 mmol)的2-正丙基丙烷-1,3-二醇及1.39 g (8 mmol)的甲苯-4-磺酸單水合物，且將混合物在水分離器上於回流下加熱1.5 h。反應完成時，直接用矽膠層析反應混合物。自異丙醇/丙酮及甲基環己烷/庚烷之兩種結晶得到呈白色有光澤的晶體之5-丙基-2-[4-(4-三氟甲基苯基)環己-3-烯基]-1,3-二噁烷6
。 C 120 SmB 164 I De = 22 Dn = 0.107 g1
= 395 mPa·s 以相似或類似方式製備以下：C 89 SmA 94 N 117 I De = 13.4 Dn = 0.104 g1
= 299 mPa·sC 72 SmB 160 SmA 166 I De = 17 Dn = 0.106 g1
= 211 mPa·sC 111 I De = 26 Dn = 0.101 g1
= 380 mPa·sC 55 SmA 132 I De = 20 Dn = 0.101 g1
= 248 mPa·sC 70 SmA 86 N 89 I De = 18 Dn = 0.090 g1
= 247 mPa·sC 55 SmA (43) N (51) I De = 22.5 Dn = 0.073 g1
= 168 mPa·sC 67 SmA 88 I De = 24.5 Dn = 0.099 g1
= 258 mPa·sC 95 I De = 32 Dn = 0.095 g1
= 275 mPa·sThe group R 1 in formula I and its subformulae preferably represents an alkyl or alkenyl group having up to 8 carbon atoms. R 1 particularly preferably represents a straight-chain alkyl group having 1 to 7 C atoms or an unbranched alkenyl group having 2 to 8 C atoms, especially an unbranched alkyl group having 2 to 7 C atoms. The group X in formula I preferably represents CF 3 , OCF 3 , F, -SCN, -C≡C-CF 3 or -CH=CH-CF 3 , especially preferably CF 3 , OCF 3 or F, and Very preferably CF 3 or OCF 3 . The group -CH=CH-CF 3 is preferably in a trans configuration. Compounds of formula I containing branched or substituted wing groups R1 may be of intermittent importance due to better solubility in conventional liquid crystal substrate materials. The group R 1 is preferably straight-chain. Preference is given to compounds of formula I, wherein L 1 represents H, especially wherein L 1 and L 2 represent H. The group R 1 is especially preferably selected from the moieties: -CH 3 -C 2 H 5 -C 3 H 7 -C 4 H 9 -C 5 H 11 -C 6 H 13 -CH=CH 2 -CH=CH 2 -CH 3 -CH 2 -CH 2 -CH=CH 2 -CH 2 -CH 2 -CH=CH-CH 3 wherein the alkyl chain is preferably unbranched (n-alkyl). Especially preferred compounds of formula I are compounds of formulae I-1 to I-6, wherein R 1 independently has the meaning indicated above. Among the compounds of formulae I-1 to I-6, the compounds of formulae I-1, I-2, I-4 and I-5 are preferred, especially the compounds of formulae I-1 and I-2. Very particularly preferred compounds are given below: Compounds of formula I under known and suitable reaction conditions for these reactions are as described in the literature (for example in standard works such as Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], Georg-Thieme-Verlag, Stuttgart) by methods known per se. Variations known per se but not mentioned in more detail herein may also be used herein. Typical compounds of formula I can be advantageously prepared as shown in the following clearly illustrative syntheses and examples (Schemes 1 to 3): Scheme 1. General synthetic scheme for the preparation of compounds of formula I. Bn represents a benzyl group. X represents a group X as in formula I. R 1 represents a group R 1 as in formula I. The two polar end groups -CH=CH- CF3 and -C≡C- CF3 can be prepared as follows: Scheme 2. Synthesis of terminal groups X=-CH=CH- CF3 and -C≡C- CF3 ; Ar represents a substituted phenyl group of a compound of formula I. In the first step, molecular sieves are preferably added to absorb water. The reaction sequence is reversed from Scheme 1 to ascend or to Synthetic Scheme 3. Scheme 3. Alternative general synthetic scheme for the preparation of compounds of formula I. R 1 and X are defined according to formula I. Corresponding starting materials can generally be readily prepared by those skilled in the art by synthetic methods known from the literature or are commercially available. It is also possible to use aryllithium compounds in place of the Grignard compounds shown in Schemes 1 and 3, which can similarly be obtained by exchanging halogen metals with alkyllithium compounds at low temperature (cf. For example US 4,940,822). The present invention therefore also relates to a process for the preparation of a compound of formula I, the process comprising a treatment step, wherein the arylmetal compound of formula II, II wherein X, L1 and L2 are as defined for formula I , and M represents Li, MgBr or MgCl, reacted with a compound of formula III III wherein PG represents a protecting group, preferably a benzyl group, and in other reaction steps including removal of the protecting group PG (replacement by H) and oxidation of the resulting CH 2 OH group to obtain the aldehyde CH=O, with formula IV 2-substituted 1,3-diol reaction IV to give compounds of formula I I wherein the groups are as defined above. The reaction methods and reagents used are known in principle from the literature. Other reaction conditions are disclosed by the examples. Other preferred method variations not mentioned above are disclosed by the examples or the scope of the claims. The process and subsequent work-up of the reaction mixture can be carried out essentially as a batch reaction or a continuous reaction procedure. Continuous reaction procedures encompass, for example, reactions in continuous stirred tank reactors, cascaded stirred reactors, loop or cross-flow reactors, flow tubes or microreactors. The reaction mixture is optionally (as necessary) worked up by: filtration through solid phase; chromatography; separation between immiscible phases (eg, extraction); adsorption onto solid support; by distillation, selective distillation, Sublimation, crystallization, co-crystallization or removal of solvent and/or azeotrope by on-membrane nanofiltration. In the present invention, the 2,5-disubstituted dioxane ring of the following formula Preferably the dioxane ring in the 2,5-trans-configuration is represented, ie the substituents are preferably in a chair configuration, preferably both are in equatorial positions. The present invention also relates to liquid-crystalline media comprising one or more of the compounds of formula I according to the invention. The liquid-crystalline medium contains at least two components. It is preferably obtained by mixing the components with each other. Thus, the process according to the invention for the preparation of liquid-crystalline media is characterized in that at least one compound of the formula I is mixed with at least one other mesogen-based compound, and additives are optionally added. The achievable combination of clear point, viscosity at low temperature, thermal/UV stability, dielectric anisotropy, response time, and contrast ratio is superior to previous materials from the prior art. The liquid-crystalline media according to the invention preferably comprise 2 to 40, particularly preferably 4 to 30, components as further constituents in addition to one or more compounds according to the invention. In particular, these media contain 7 to 25 components other than one or more compounds according to the invention. These other components are preferably selected from nematic or nematic primordia (monodenature or isotropic) substances, especially from the following classes: oxyazobenzenes, benzylideneanilines, biphenyls, triphenylenes , phenyl benzoate or cyclohexyl benzoate, phenyl cyclohexane carboxylate or cyclohexyl cyclohexane carboxylate, phenyl cyclohexyl benzoate or cyclohexyl cyclohexyl benzoate, phenyl cyclohexyl cyclohexane carboxylate Or cyclohexylcyclohexanecarboxylate, cyclohexylphenyl benzoate, cyclohexylphenyl cyclohexanecarboxylate or cyclohexyl cyclohexanecarboxylate, phenylcyclohexane, cyclohexylbiphenyl, benzene cyclohexylcyclohexane, cyclohexylcyclohexane, cyclohexylcyclohexylcyclohexane, 1,4-biscyclohexylbenzene, 4,4'-biscyclohexylbiphenyl, phenylpyrimidine or cyclohexylpyrimidine, phenylpyridine or cyclohexylpyridine, phenyldioxane or cyclohexyldioxane, phenyl-1,3-dithiocyclohexane or cyclohexyl-1,3-dithiocyclohexane, 1,2-diphenylethyl Alkane, 1,2-dicyclohexylethane, 1-phenyl-2-cyclohexylethane, 1-cyclohexyl-2-(4-phenylcyclohexyl)ethane, 1-cyclohexyl-2-bi Phenylethane, 1-phenyl-2-cyclohexylphenylethane, optionally halogenated stilbene, benzyl phenyl ether, diphenylacetylene and substituted cinnamic acid. The 1,4-phenylene groups in these compounds can also be fluorinated. The most important compounds suitable as further constituents of the medium according to the invention can be characterized by formulae 1, 2, 3, 4 and 5: R'-LER" 1 R'-L-COO-ER" 2 R'-L -CF 2 OER" 3 R'-L-CH2CH2-ER" 4 R'-L-CºC-ER" 5 In formulas 1, 2, 3, 4 and 5, L and E, which may be the same or different, are each independent of each other represents a divalent group from the group formed by the following structural elements: -Phe-, -Cyc-, -Phe-Phe-, -Phe-Cyc-, -Cyc-Cyc-, -Pyr-, -Dio-, -Py-, -G-Phe-, -G-Cyc- and their mirror images, wherein Phe represents unsubstituted or fluorine-substituted 1,4-phenylene, Cyc represents trans-1,4-cyclohexylene, Pyr means pyrimidine-2,5-diyl or pyridine-2,5-diyl, Dio means 1,3-dioxane-2,5-diyl, Py means tetrahydropyran-2,5-diyl and G represents 2-(trans-1,4-cyclohexyl)ethyl. One of the groups L and E is preferably Cyc, Phe or Pyr. E is preferably Cyc, Phe or Phe-Cyc. According to the present The medium of the invention preferably comprises: one or more components selected from compounds of formulae 1, 2, 3, 4 and 5, wherein L and E are selected from the group consisting of Cyc, Phe and Pyr, and at the same time one or more components are selected from the group consisting of formulae Components of compounds 1, 2, 3, 4 and 5, wherein one of the groups L and E is selected from the group consisting of Cyc, Phe, Py and Pyr, and the other group is selected from -Phe-Phe-, The group consisting of -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-, and optionally one or more components selected from compounds of formulae 1, 2, 3, 4 and 5, wherein the groups L and E are selected from the group consisting of -Phe-Cyc-, -Cyc-Cyc-, -G-Phe- and -G-Cyc-. R' and/or R" each independently of one another represent a group having at most 8 alkyl, alkenyl, alkoxy, alkoxyalkyl, alkenyloxy or alkanoloxy, -F, -Cl, -CN, -NCS or -(O) i CH 3 - k F k , where i is 0 or 1 and k is 1, 2, or 3. In one of the smaller subgroups of compounds of formulae 1, 2, 3, 4 and 5, R' and R" each independently of one another represent alkyl, alkenyl, alkoxy, alkoxy having up to 8 C atoms Alkylalkyl, alkenyloxy or alkanoyloxy. This smaller subgroup is hereinafter referred to as Group A, and the compounds are represented by sub-formulas 1a, 2a, 3a, 4a, and 5a. In most of these compounds, R' and R" are different from each other, and one of these groups is typically an alkyl, alkenyl, alkoxy, or alkoxyalkyl group. In another smaller subgroup of compounds of Formulas 1, 2, 3, 4 and 5, designated Group B , R" represents -F, -Cl, -NCS or - (O) iCH3 - kFk , where i is 0 or 1, and k is 1, 2, or 3. Compounds in which R" has this meaning are represented by sub-formulas 1b, 2b, 3b, 4b, and 5b. Especially preferred are compounds of subformula 1b, 2b, 3b, 4b and 5b in which R" has the meaning of -F, -Cl, -NCS, -CF3 , -OCHF2 or -OCF3 . In subformula 1b, 2b In the compounds of , 3b, 4b and 5b, R' has the meaning indicated in the case of the compounds of sub-formulas 1a to 5a, and is preferably alkyl, alkenyl, alkoxy or alkoxyalkyl. In another smaller subgroup of compounds of Formulas 1, 2, 3, 4 and 5, R" represents -CN. This subgroup is hereinafter referred to as Group C, and the compounds of this subgroup are correspondingly described as subformulas 1c, 2c, 3c, 4c, and 5c. In the compounds of sub-formulas 1c, 2c, 3c, 4c and 5c, R' has the meaning indicated in the case of the compounds of sub-formulas 1a to 5a, and is preferably an alkyl, alkoxy or alkenyl group. In addition to the preferred compounds of groups A, B and C, other compounds of formulae 1, 2, 3, 4 and 5 with other variants of the proposed substituents are also customary. All such substances can be obtained by methods known from the literature or analogous thereto. In addition to the compounds of formula I according to the invention, the medium according to the invention preferably comprises one or more compounds selected from groups A, B and/or C. The proportions by weight of the compounds from these groups in the medium according to the invention are preferably: Group A: 0 to 90%, preferably 20 to 90%, especially preferably 30 to 90%; Group B: 0 to 80%, preferably 10 to 80%, particularly preferably 10 to 65%; group C: 0 to 80%, preferably 0 to 80%, particularly preferably 0 to 50%; groups among which are present in the respective medium according to the invention The sum of the weight proportions of the A, B and/or C compounds is preferably 5 to 90%, and particularly preferably 10 to 90%. The medium according to the invention preferably contains from 1 to 40%, particularly preferably from 3 to 30%, of the compound according to the invention. The liquid crystal mixtures of the present invention are prepared in a manner known per se. In general, the desired amount of the component to be used in a smaller amount is preferably dissolved in the component constituting the main ingredient at a high temperature. It is also possible to mix the solutions of the components in an organic solvent, for example in acetone, chloroform or methanol, and to remove the solvent again, for example by distillation after thorough mixing. It is further possible to prepare the mixture in other conventional ways, for example by using a premix such as a homolog mixture, or using a so-called "multi-bottle" system. The dielectrics may also contain other additives known to those skilled in the art and described in the literature. For example, 0 to 15%, preferably 0 to 10%, of pleochroic dyes, chiral dopants, stabilizers or nanoparticles can be added. The individual compounds added are used at a concentration of 0.01 to 6%, preferably 0.1 to 3%. However, concentration data for other components of the liquid crystal mixture (ie, liquid crystals or mesogen-based compounds) are given herein without regard to the concentrations of these additives. The liquid crystal mixtures according to the present invention enable a significant broadening of the usable parameter latitude. The invention also relates to electro-optic displays containing such media, in particular TFT displays, having two parallel planar outer plates forming a cell together with a frame, integrated nonlinear elements for switching the individual pixels on the outer plates and located in the cell Nematic liquid crystal mixtures with positive dielectric anisotropy and high specific resistance), and regarding the use of these media for electro-optical purposes. The expression "alkyl" covers unbranched and branched alkyl groups having 1 to 15 carbon atoms, especially unbranched methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl and n-heptyl base. Groups having 2 to 5 carbon atoms are generally preferred. The expression "alkenyl" covers unbranched and branched alkenyl groups, especially unbranched groups, having up to 15 carbon atoms. Especially preferred alkenyl groups are C2 - C7-1E-alkenyl, C4 - C7-3E -alkenyl, C5 - C7-4 -alkenyl, C6 - C7-5 -alkenyl and C7-6-alkenyl, especially C2 - C7-1E -alkenyl, C4 - C7-3E -alkenyl and C5 - C7-4 -alkenyl. Examples of preferred alkenyl groups are vinyl, 1E-propenyl, 1E-butenyl, 1E-pentenyl, 1E-hexenyl, 1E-heptenyl, 3-butenyl, 3E-pentenyl , 3E-hexenyl, 3E-heptenyl, 4-pentenyl, 4Z-hexenyl, 4E-hexenyl, 4Z-heptenyl, 5-hexenyl, 6-heptenyl and their Similar to alkenyl. Groups having up to 5 carbon atoms are generally preferred. The expression "halogenated alkyl" preferably covers mono- or polyfluorinated and/or -chlorinated groups. Including perhalogenated groups. Especially preferred are fluorinated alkyl groups, especially CF3 , CH2CF3 , CH2CHF2 , CHF2 , CH2F , CHFCF3 and CF2CHFCF3 . The expression "haloalkenyl" and related expressions are interpreted accordingly. The total amount of compounds of formula I in the mixtures according to the invention is not critical. Thus, the mixture may contain one or more other components for the purpose of optimizing various properties. Self-polarizers, electrode substrate plates, and surface-treated electrodes construct the matrix display of the present invention corresponding to a common design for such displays. The term common design is generally described herein and also covers all derivatives and modifications of matrix displays, especially also polySi TFT based matrix display elements. However, a significant difference between the display according to the present invention and the hitherto known displays based on twisted nematic cells lies in the choice of liquid crystal parameters of the liquid crystal layer. The following examples serve to further explain the present invention without limiting it. Those skilled in the art will be able to gather details of work from examples that are not given in detail in the general description, generalize them from general expert knowledge, and apply them to specific problems. In the above and below, the percentage data represent % by weight. All temperatures are indicated in degrees Celsius. Furthermore, C=crystalline state, N=nematic phase, Sm=smectic phase (more especially SmA, SmB, etc.) Tg=glass transition temperature and I=isotropic phase. The data between these symbols represents the transition temperature. Dn represents the optical anisotropy (589 nm, 20°C), Δε the dielectric anisotropy (1 kHz, 20°C) and g1 the rotational viscosity (20°C; in mPa·s). Physical, physicochemical and electro-optical parameters are determined by commonly known methods, in particular as described in the handbook "Merck Liquid Crystals - Licristal® - Physical Properties of Liquid Crystals - Description of the Measurement Methods", 1998, Merck KGaA, Darmstadt . The dielectric anisotropy Δε of individual substances was measured at 20°C and 1 kHz. For this purpose, 5 to 10% by weight of the substances to be investigated dissolved in the dielectrically positive mixture ZLI-4792 (Merck KGaA) were measured and the measured values were extrapolated to 100% concentration. The optical anisotropy Δn was determined at 20°C and a wavelength of 589.3 nm, and the rotational viscosity γ 1 was determined at 20°C, both also by linear extrapolation. In this application, unless expressly indicated otherwise, the plural forms of terms refer to both the singular and the plural, and vice versa. Other combinations of embodiments and variations of the invention in accordance with the description also arise from the appended claims or combinations of multiple such claims. The following abbreviations are used: DCM Dichloromethane DMSO Dimethyl sulfoxide EA Ethyl acetate MTB ether Methyl tert-butyl ether THF Tetrahydrofuran Example 1 : 5-propyl-2-[4-(4-trifluoromethylphenyl ) cyclohex-3-enyl]-1,3-dioxane Step 1 First 2.2 g (16 mmol) of magnesium turnings were introduced into a small amount of THF, then 20.3 g (90 mmol) of 4-bromotrifluorotoluene 1 were dissolved in 50 ml of THF and dropwise at a rate such that the reaction mixture boiled Add to. The reaction mixture was then heated at reflux for 1 h. The heat source was briefly removed and 20.0 g (90 mmol) of 4-benzyloxymethyl-cyclohexanone 2 was added to the batch, which was then heated at reflux for a further 2 h and then at room temperature Stir for 18 h. The portions were poured into ice water and adjusted to pH 2 using 2M hydrochloric acid. The aqueous phase was separated and extracted with MTB ether. The combined organic phases were washed with sodium chloride solution, dried over sodium sulfate, filtered and evaporated to give 4-benzyloxymethyl-1-(4-bromophenyl)cyclohexanol as a reddish-brown oil 3 , which was used in the next reaction step without further purification. Step 2 : 12 g of Pd/C catalyst (112 mmol; 5% on activated carbon) were added to a solution of 34.1 g (78 mmol) of crude product 3 in 340 ml of THF. The protecting group was cleaved using 2.34 l of hydrogen. The catalyst was then filtered off. The hydrogenated solution was evaporated to dryness to give 4-hydroxymethyl-1-(4-trifluoromethylphenyl)cyclohexanol as a brown oil. Step 3 : 7.27 ml (85 mmol) of oxalonium chloride were first introduced into 100 ml of DCM, and 12 ml (170 mmol) of DMSO (dry) in 80 ml of DCM were added dropwise. A solution of 10.2 g (13 mmol) of 4-hydroxymethyl-1-(4-trifluoromethylphenyl)cyclohexanol 4 in 310 ml of DCM was then added dropwise. After a stirring time of 15 min, 53 ml of triethylamine were added. After stirring for 5 min, the cooling bath was removed. The mixture was then hydrolyzed with water at room temperature and diluted with DCM. The aqueous phase was separated and extracted with DCM. The combined organic phases are washed with water and sodium chloride solution, dried over sodium sulfate, filtered and evaporated to dryness. The crude product was then purified by silica gel chromatography (DCM/EA 8:2) to give 4-hydroxy-4-(4-trifluoromethylphenyl)cyclohexanecarbaldehyde 5 as a yellow oil. Step 4 : First, 16.8 g (54 mmol) of 4-hydroxy-4-(4-trifluoromethylphenyl)cyclohexanecarbaldehyde 5 were introduced into 284 ml of toluene. 7.61 g (64 mmol) of 2-n-propylpropane-1,3-diol and 1.39 g (8 mmol) of toluene-4-sulfonic acid monohydrate were added, and the mixture was placed under reflux on a water separator Heating for 1.5 h. When the reaction was complete, the reaction mixture was directly chromatographed on silica gel. 5-propyl-2-[4-(4-trifluoromethylphenyl)cyclohex- 3-Alkenyl]-1,3-dioxane 6 . C 120 SmB 164 I De = 22 Dn = 0.107 g 1 = 395 mPa s Prepare the following in a similar or analogous manner: C 89 SmA 94 N 117 I De = 13.4 Dn = 0.104 g 1 = 299 mPa·s C 72 SmB 160 SmA 166 I De = 17 Dn = 0.106 g 1 = 211 mPa·s C 111 I De = 26 Dn = 0.101 g 1 = 380 mPa·s C 55 SmA 132 I De = 20 Dn = 0.101 g 1 = 248 mPa s C 70 SmA 86 N 89 I De = 18 Dn = 0.090 g 1 = 247 mPa s C 55 SmA (43) N (51) I De = 22.5 Dn = 0.073 g 1 = 168 mPa·s C 67 SmA 88 I De = 24.5 Dn = 0.099 g 1 = 258 mPa·s C 95 I De = 32 Dn = 0.095 g 1 = 275 mPa·s
