4-(Trans-4-pentylcyclohexyl)-benzonitrile (Fluorochem),  300840
Lithium aluminum hydride, Sigma Aldrich, powder, 95%, 19,987-7. freshly opened can
Ether, Sigma Aldrich, anhydrous, 99.8%, 29,608-2, freshly opened bottle
Sodium sulfate, Sigma Aldrich, anhydrous, 99+%, 23,931-3

An oven dried 100ml three neck flask, equipped with magnetic stirrer, water condenser and nitrogen inlet was charged under nitrogen with 1.0 g (4 mmol) 4-(trans-4-pentylcyclohexyl)-benzonitrile (Fluorochem) and  50 ml of anhydrous ether. The mixture was stirred until all of the nitrile had dissolved. 1.0 g of freshly opened powdered lithium aluminum hydride was then added through a powder funnel and the mixture stirred overnight. A 10ml pressure equalized dropping funnel was then attached and the excess hydride decomposed by drop wise addition of 5 ml water over one hour. A copious white precipitate of aluminum hydroxide was then present. The precipitate was filtered off with a small Buchner funnel under water aspirator pressure and washed under vacuum with 5 ml ether. The filtrate of ether/amine was dried for one hour over 2 grams of anhydrous sodium sulfate and the ether solution decanted  into a 100 ml round bottom flask. The sulfate residue was twice stirred, utilizing a glass rod, with  two 5 ml ether portions which were  each decanted and  combined with the filtrate. Ether then was removed on a rotovap (water bath ~80⁰C ) and the residue pipetted into a 2 ml conical distilling flask equipped with a short path distilling head and an oil bath. Distillation under full rotary pump vacuum (bath temperature ~150⁰), yielded 800 mg (80%) of the liquid crystalline amine, which  solidified on standing at room temperature. Yields of all liquid crystalline amines in these references are in the 70-85%  range, with losses mostly mechanical.

Caution! Lithium aluminum hydride is extremely water sensitive. Use a freshley opened can if possible and weigh in glovebox if possible. On contact with excess water it decomposes violently with hydrogen evolution.  It should always be decomposed in a reaction mixture  when necessary by slow dropwise addition of water.  This and other amines described in the primary and secondary references are hydroscopic and should be stored in  dessicators.The methanamines may be converted to N-alkyl substituted liquid crystalline  cyclohexylphenyl amines or biphenyl amines by further reaction with acid chlorides and lithium aluminum hydride reduction (see  references).

B.p. 135⁰(0.1 mm),

m.p. crystal-isotropic (K-I), 27⁰, cooling, isotropic-smectic-A,  (I-S_A) , 9⁰, Smectic-A-crystal, (S_A-K), 0⁰.

I.r. (cm-1) 3300,3250,3010,2900,1600

Analysis: Calculated for C₁₈H₂₉N: C, 83.32, H, 11.27, N, 5.40. Found: C, 83.22, H, 11.40, N, 5.46